Publications by authors named "Sergio Aguilera"

31 Publications

Type I Interferon Dependent hsa-miR-145-5p Downregulation Modulates MUC1 and TLR4 Overexpression in Salivary Glands From Sjögren's Syndrome Patients.

Front Immunol 2021 2;12:685837. Epub 2021 Jun 2.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.

Sjögren's syndrome (SS) is an autoimmune disease that mainly affects salivary glands (SG) and is characterized by overactivation of the type I interferon (IFN) pathway. Type I IFNs can decrease the levels of hsa-miR-145-5p, a miRNA with anti-inflammatory roles that is downregulated in SG from SS-patients. Two relevant targets of hsa-miR-145-5p, mucin 1 (MUC1) and toll-like receptor 4 (TLR4) are overexpressed in SS-patients and contribute to SG inflammation and dysfunction. This study aimed to evaluate if hsa-miR-145-5p modulates MUC1 and TLR4 overexpression in SG from SS-patients in a type I IFN dependent manner. Labial SG (LSG) biopsies from 9 SS-patients and 6 controls were analyzed. We determined hsa-miR-145-5p levels by TaqMan assays and the mRNA levels of MUC1, TLR4, IFN-α, IFN-β, and IFN-stimulated genes (MX1, IFIT1, IFI44, and IFI44L) by real time-PCR. We also performed assays using type I IFNs and chemically synthesized hsa-miR-145-5p mimics and inhibitors. We validated the decreased hsa-miR-145-5p levels in LSG from SS-patients, which inversely correlated with the type I IFN score, mRNA levels of IFN-β, MUC1, TLR4, and clinical parameters of SS-patients (Ro/La autoantibodies and focus score). IFN-α or IFN-β stimulation downregulated hsa-miR-145-5p and increased MUC1 and TLR4 mRNA levels. Hsa-miR-145-5p overexpression decreased MUC1 and TLR4 mRNA levels, while transfection with a hsa-miR-145-5p inhibitor increased mRNA levels. Our findings show that type I IFNs decrease hsa-miR-145-5p expression leading to upregulation of MUC1 and TLR4. Together, this suggests that type I interferon-dependent hsa-miR-145-5p downregulation contributes to the perpetuation of inflammation in LSG from SS-patients.
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http://dx.doi.org/10.3389/fimmu.2021.685837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8208490PMC
June 2021

Dysfunctional mitochondria as critical players in the inflammation of autoimmune diseases: Potential role in Sjögren's syndrome.

Autoimmun Rev 2021 Aug 9;20(8):102867. Epub 2021 Jun 9.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. Electronic address:

Relevant reviews highlight the association between dysfunctional mitochondria and inflammation, but few studies address the contribution of mitochondria and mitochondria-endoplasmic reticulum (ER) contact sites (MERCs) to cellular homeostasis and inflammatory signaling. The present review outlines the important role of mitochondria in cellular homeostasis and how dysfunctional mitochondrion can release and misplace mitochondrial components (cardiolipin, mitochondrial DNA (mtDNA), and mitochondrial formylated peptides) through multiple mechanisms. These components can act as damage-associated molecular patterns (DAMPs) and induce an inflammatory response via pattern recognition receptors (PRRs). Accumulation of damaged ROS-generating mitochondria, accompanied by the release of mitochondrial DAMPs, can activate PRRs such as the NLRP3 inflammasome, TLR9, cGAS/STING, and ZBP1. This process would explain the chronic inflammation that is observed in autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type I diabetes (T1D), and Sjögren's syndrome. This review also provides a comprehensive overview of the importance of MERCs to mitochondrial function and morphology, cellular homeostasis, and the inflammatory response. MERCs play an important role in calcium homeostasis by mediating the transfer of calcium from the ER to the mitochondria and thereby facilitating the production of ATP. They also contribute to the synthesis and transfer of phospholipids, protein folding in the ER, mitochondrial fission, mitochondrial fusion, initiation of autophagosome formation, regulation of cell death/survival signaling, and regulation of immune responses. Therefore, alterations within MERCs could increase inflammatory signaling, modulate ER stress responses, cell homeostasis, and ultimately, the cell fate. This study shows severe ultrastructural alterations of mitochondria in salivary gland cells from Sjögren's syndrome patients for the first time, which could trigger alterations in cellular bioenergetics. This finding could explain symptoms such as fatigue and malfunction of the salivary glands in Sjögren's syndrome patients, which would contribute to the chronic inflammatory pathology of the disease. However, this is only a first step in solving this complex puzzle, and several other important factors such as changes in mitochondrial morphology, functionality, and their important contacts with other organelles require further in-depth study. Future work should focus on detecting the key milestones that are related to inflammation in patients with autoimmune diseases, such as Sjögren´s syndrome.
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http://dx.doi.org/10.1016/j.autrev.2021.102867DOI Listing
August 2021

Tofacitinib counteracts IL-6 overexpression induced by deficient autophagy: implications in Sjögren's syndrome.

Rheumatology (Oxford) 2021 04;60(4):1951-1962

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.

Objective: Altered homeostasis of salivary gland (SG) epithelial cells in Sjögren's syndrome (SS) could be the initiating factor that leads to inflammation, secretory dysfunction and autoimmunity. Autophagy is an important homeostatic mechanism, whose deficiency is associated with inflammation and accumulation of Janus kinase (JAK)-signal transducer and activator of transcription (STAT) components. We aimed to evaluate whether autophagy is altered in labial SG (LSG) epithelial cells from primary SS (pSS) patients and whether this contributes to inflammation through the JAK-STAT pathway. Furthermore, we investigated the anti-inflammatory effect of the JAK inhibitor tofacitinib in autophagy-deficient (ATG5 knockdown) three-dimensional (3D)-acini.

Methods: We analysed LSG biopsies from 12 pSS patients with low focus score and 10 controls. ATG5-deficient 3D-acini were generated and incubated with IL-6 in the presence or absence of tofacitinib. Autophagy markers, pro-inflammatory cytokine expression, and JAK-STAT pathway activation were evaluated by PCR or western blot, along with correlation analyses between the evaluated markers and clinical parameters.

Results: LSG from pSS patients showed increased p62 and decreased ATG5 expression, correlating negatively with increased activation of JAK-STAT pathway components (pSTAT1 and pSTAT3). Increased expression of STAT1 and IL-6 correlated with EULAR Sjögren's syndrome disease activity index and the presence of anti-Ro antibodies. ATG5-deficient 3D-acini reproduced the findings observed in LSG from pSS patients, showing increased expression of pro-inflammatory markers such as IL-6, which was reversed by tofacitinib.

Conclusion: Decreased expression of ATG5 in LSG epithelial cells from pSS patients possibly contributes to increased inflammation associated with JAK-STAT pathway activation, as evidenced in ATG5-deficient 3D-acini. Interestingly, these results suggest that tofacitinib could be used as an anti-inflammatory agent in pSS patients.
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http://dx.doi.org/10.1093/rheumatology/keaa670DOI Listing
April 2021

Potentially Severe (Moderate) Traumatic Brain Injury: A New Categorization Proposal.

Crit Care Med 2020 12;48(12):1851-1854

Neuroscience ICU, Mayo Clinic, Rochester, MN.

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http://dx.doi.org/10.1097/CCM.0000000000004575DOI Listing
December 2020

Global health, global surgery and mass casualties: II. Mass casualty centre resources, equipment and implementation.

BMJ Glob Health 2020 13;5(1):e001945. Epub 2020 Jan 13.

World Federation of Neurosurgical Societies, Nyon, Switzerland.

Trauma/stroke centres optimise acute 24/7/365 surgical/critical care in high-income countries (HICs). Concepts from low-income and middle-income countries (LMICs) offer additional cost-effective healthcare strategies for limited-resource settings when combined with the trauma/stroke centre concept. Mass casualty centres (MCCs) integrate resources for both routine and emergency care-from prevention to acute care to rehabilitation. Integration of the various healthcare systems-governmental, non-governmental and military-is key to avoid both duplication and gaps. With input from LMIC and HIC personnel of various backgrounds-trauma and subspecialty surgery, nursing, information technology and telemedicine, and healthcare administration-creative solutions to the challenges of expanding care (both daily and disaster) are developed. MCCs are evolving initially in Chile and Pakistan. Technologies for cost-effective healthcare in LMICs include smartphone apps (enhance prehospital care) to electronic data collection and analysis (quality improvement) to telemedicine and drones/robots (support of remote regions and resource optimisation during both daily care and disasters) to resilient, mobile medical/surgical facilities (eg, battery-operated CT scanners). The co-ordination of personnel (within LMICs, and between LMICs and HICs) and the integration of cost-effective advanced technology are features of MCCs. Providing quality, cost-effective care 24/7/365 to the 5 billion who lack it presently makes MCCs an appealing means to achieve the healthcare-related United Nations Sustainable Development Goals for 2030.
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http://dx.doi.org/10.1136/bmjgh-2019-001945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7042577PMC
December 2020

Consensus-Based Management Protocol (CREVICE Protocol) for the Treatment of Severe Traumatic Brain Injury Based on Imaging and Clinical Examination for Use When Intracranial Pressure Monitoring Is Not Employed.

J Neurotrauma 2020 06 4;37(11):1291-1299. Epub 2020 Mar 4.

Hospital Clinico Viedma, Cochabamba, Bolivia.

Globally, intracranial pressure (ICP) monitoring use in severe traumatic brain injury (sTBI) is inconsistent and susceptible to resource limitations and clinical philosophies. For situations without monitoring, there is no published comprehensive management algorithm specific to identifying and treating suspected intracranial hypertension (SICH) outside of the one ad hoc Imaging and Clinical Examination (ICE) protocol in the Benchmark Evidence from South American Trials: Treatment of Intracranial Pressure (BEST:TRIP) trial. As part of an ongoing National Institutes of Health (NIH)-supported project, a consensus conference involving 43 experienced Latin American Intensivists and Neurosurgeons who routinely care for sTBI patients without ICP monitoring, refined, revised, and augmented the original BEST:TRIP algorithm. Based on BEST:TRIP trial data and pre-meeting polling, 11 issues were targeted for development. We used Delphi-based methodology to codify individual statements and the final algorithm, using a group agreement threshold of 80%. The resulting CREVICE (Consensus REVised ICE) algorithm defines SICH and addresses both general management and specific treatment. SICH treatment modalities are organized into tiers to guide treatment escalation and tapering. Treatment schedules were developed to facilitate targeted management of disease severity. A decision-support model, based on the group's combined practices, is provided to guide this process. This algorithm provides the first comprehensive management algorithm for treating sTBI patients when ICP monitoring is not available. It is intended to provide a framework to guide clinical care and direct future research toward sTBI management. Because of the dearth of relevant literature, it is explicitly consensus based, and is provided solely as a resource (a "consensus-based curbside consult") to assist in treating sTBI in general intensive care units in resource-limited environments.
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http://dx.doi.org/10.1089/neu.2017.5599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249475PMC
June 2020

A management algorithm for adult patients with both brain oxygen and intracranial pressure monitoring: the Seattle International Severe Traumatic Brain Injury Consensus Conference (SIBICC).

Intensive Care Med 2020 05 21;46(5):919-929. Epub 2020 Jan 21.

Department of Neurosurgery, Humanitas University and Research Hospital, Milan, Italy.

Background: Current guidelines for the treatment of adult severe traumatic brain injury (sTBI) consist of high-quality evidence reports, but they are no longer accompanied by management protocols, as these require expert opinion to bridge the gap between published evidence and patient care. We aimed to establish a modern sTBI protocol for adult patients with both intracranial pressure (ICP) and brain oxygen monitors in place.

Methods: Our consensus working group consisted of 42 experienced and actively practicing sTBI opinion leaders from six continents. Having previously established a protocol for the treatment of patients with ICP monitoring alone, we addressed patients who have a brain oxygen monitor in addition to an ICP monitor. The management protocols were developed through a Delphi-method-based consensus approach and were finalized at an in-person meeting.

Results: We established three distinct treatment protocols, each with three tiers whereby higher tiers involve therapies with higher risk. One protocol addresses the management of ICP elevation when brain oxygenation is normal. A second addresses management of brain hypoxia with normal ICP. The third protocol addresses the situation when both intracranial hypertension and brain hypoxia are present. The panel considered issues pertaining to blood transfusion and ventilator management when designing the different algorithms.

Conclusions: These protocols are intended to assist clinicians in the management of patients with both ICP and brain oxygen monitors but they do not reflect either a standard-of-care or a substitute for thoughtful individualized management. These protocols should be used in conjunction with recommendations for basic care, management of critical neuroworsening and weaning treatment recently published in conjunction with the Seattle International Brain Injury Consensus Conference.
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http://dx.doi.org/10.1007/s00134-019-05900-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7210240PMC
May 2020

Global health, global surgery and mass casualties. I. Rationale for integrated mass casualty centres.

BMJ Glob Health 2019 22;4(6):e001943. Epub 2019 Dec 22.

World Federation of Neurosurgical Societies, Nyon, Switzerland.

It has been well-documented recently that 5 billion people globally lack surgical care. Also well-documented is the need to improve mass casualty disaster response. Many of the United Nations (UN) Sustainable Development Goals (SDGs) for 2030-healthcare and economic milestones-require significant improvement in global surgical care, particularly in low-income and middle-income countries. Trauma/stroke centres evolved in high-income countries with evidence that 24/7/365 surgical and critical care markedly improved morbidity and mortality for trauma and stroke and for cardiovascular events, difficult childbirth, acute abdomen. Duplication of emergency services, especially civilian and military, often results in suboptimal, expensive care. By combining all healthcare resources within the ongoing healthcare system, more efficient care for both individual emergencies and mass casualty situations can be achieved. We describe progress in establishing mass casualty centres in Chile and Pakistan. In both locations, planning among the stakeholders (primarily civilian and military) indicates the feasibility of such integrated surgical and emergency care. We also review other programmes and initiatives to provide integrated mass casualty disaster response. Integrated mass casualty centres are a feasible means to improve both day-to-day surgical care and mass casualty disaster response. The humanitarian aspect of mass casualty disasters facilitates integration among stakeholders-from local healthcare systems to military resources to international healthcare organisations. The benefits of mass casualty centres-both healthcare and economic-can facilitate achieving the 2030 UN SDGs.
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http://dx.doi.org/10.1136/bmjgh-2019-001943DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6936385PMC
December 2019

A management algorithm for patients with intracranial pressure monitoring: the Seattle International Severe Traumatic Brain Injury Consensus Conference (SIBICC).

Intensive Care Med 2019 12 28;45(12):1783-1794. Epub 2019 Oct 28.

Department of Neurosurgery, Humanitas University and Research Hospital, Milan, Italy.

Background: Management algorithms for adult severe traumatic brain injury (sTBI) were omitted in later editions of the Brain Trauma Foundation's sTBI Management Guidelines, as they were not evidence-based.

Methods: We used a Delphi-method-based consensus approach to address management of sTBI patients undergoing intracranial pressure (ICP) monitoring. Forty-two experienced, clinically active sTBI specialists from six continents comprised the panel. Eight surveys iterated queries and comments. An in-person meeting included whole- and small-group discussions and blinded voting. Consensus required 80% agreement. We developed heatmaps based on a traffic-light model where panelists' decision tendencies were the focus of recommendations.

Results: We provide comprehensive algorithms for ICP-monitor-based adult sTBI management. Consensus established 18 interventions as fundamental and ten treatments not to be used. We provide a three-tier algorithm for treating elevated ICP. Treatments within a tier are considered empirically equivalent. Higher tiers involve higher risk therapies. Tiers 1, 2, and 3 include 10, 4, and 3 interventions, respectively. We include inter-tier considerations, and recommendations for critical neuroworsening to assist the recognition and treatment of declining patients. Novel elements include guidance for autoregulation-based ICP treatment based on MAP Challenge results, and two heatmaps to guide (1) ICP-monitor removal and (2) consideration of sedation holidays for neurological examination.

Conclusions: Our modern and comprehensive sTBI-management protocol is designed to assist clinicians managing sTBI patients monitored with ICP-monitors alone. Consensus-based (class III evidence), it provides management recommendations based on combined expert opinion. It reflects neither a standard-of-care nor a substitute for thoughtful individualized management.
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http://dx.doi.org/10.1007/s00134-019-05805-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6863785PMC
December 2019

Aberrant MUC1 accumulation in salivary glands of Sjögren's syndrome patients is reversed by TUDCA in vitro.

Rheumatology (Oxford) 2020 04;59(4):742-753

Programa de Biología Celular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.

Objectives: Xerostomia in SS patients has been associated with low quality and quantity of salivary mucins, which are fundamental for the hydration and protection of the oral mucosa. The aim of this study was to evaluate if cytokines induce aberrant mucin expression and whether tauroursodeoxycholic acid (TUDCA) is able to counteract such an anomaly.

Methods: Labial salivary glands from 16 SS patients and 15 control subjects, as well as 3D acini or human submandibular gland cells stimulated with TNF-α or IFN-γ and co-incubated with TUDCA, were analysed. mRNA and protein levels of Mucin 1 (MUC1) and MUC7 were determined by RT-qPCR and western blot, respectively. Co-immunoprecipitation and immunofluorescence assays for mucins and GRP78 [an endoplasmic reticulum (ER)-resident protein] were also performed. mRNA levels of RelA/p65 (nuclear factor-κB subunit), TNF-α, IL-1β, IL-6, SEL1L and EDEM1 were determined by RT-qPCR, and RelA/p65 localization was evaluated by immunofluorescence.

Results: MUC1 is overexpressed and accumulated in the ER of labial salivary gland from SS patients, while MUC7 accumulates throughout the cytoplasm of acinar cells; however, MUC1, but not MUC7, co-precipitated with GRP78. TUDCA diminished the overexpression and aberrant accumulation of MUC1 induced by TNF-α and IFN-γ, as well as the nuclear translocation of RelA/p65, together with the expression of inflammatory and ER stress markers in 3D acini.

Conclusion: Chronic inflammation alters the secretory process of MUC1, inducing ER stress and affecting the quality of saliva in SS patients. TUDCA showed anti-inflammatory properties decreasing aberrant MUC1 accumulation. Further studies are necessary to evaluate the potential therapeutic effect of TUDCA in restoring glandular homeostasis in SS patients.
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http://dx.doi.org/10.1093/rheumatology/kez316DOI Listing
April 2020

Synaptotagmin-1 overexpression under inflammatory conditions affects secretion in salivary glands from Sjögren's syndrome patients.

J Autoimmun 2019 02 31;97:88-99. Epub 2018 Oct 31.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. Electronic address:

Sjögren's syndrome (SS) is an autoimmune exocrinopathy associated with severe secretory alterations by disruption of the glandular architecture integrity, which is fundamental for a correct function and localization of the secretory machinery. Syt-1, PI(4,5)P and Ca are significant factors controlling exocytosis in different secretory cells, the Ca role being the most studied. Salivary acinar cells from SS-patients show a defective agonist-regulated intracellular Ca release together with a decreased IP3R expression level, and this condition may explain a reduced water release. However, there are not reports where Syt-1, PI(4,5)P and Ca in acinar cells of SS patients had been studied. In the present study, we analyzed the expression and/or localization of Syt-1 and PI(4,5)P in acinar cells of labial salivary gland biopsies from SS-patients and control individuals. Also, we evaluated whether the overexpression of Syt-1 and the loss of cell polarity induced by TNF-α or loss of interaction between acinar cell and basal lamina, alters directionality of the exocytosis process, Ca signaling and α-amylase secretion in a 3D-acini model stimulated with cholinergic or β-adrenergic agonists. In addition, the correlation between Syt-1 protein levels and clinical parameters was evaluated. The results showed an increase of Syt-1 mRNA and protein levels, and a high number of co-localization points of Syt-1/STX4 and PI(4,5)P/Ezrin in the acinar basolateral region of LSG from SS-patients. With regard to 3D-acini, Syt-1 overexpression increased exocytosis in the apical pole compared to control acini. TNF-α stimulation increased exocytic events in the basal pole, which was further enhanced by Syt-1 overexpression. Additionally, altered acinar cell polarity affected Ca signaling and amylase secretion. Overexpression of Syt-1 was associated with salivary gland alterations revealing that the secretory dysfunction in SS-patients is linked to altered expression and/or localization of secretory machinery components together with impaired epithelial cell polarity. These findings provide a novel insight on the pathological mechanism implicated in ectopic secretory products to the extracellular matrix of LSG from SS-patients, which might initiate inflammation.
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http://dx.doi.org/10.1016/j.jaut.2018.10.019DOI Listing
February 2019

Association of high 5-hydroxymethylcytosine levels with Ten Eleven Translocation 2 overexpression and inflammation in Sjögren's syndrome patients.

Clin Immunol 2018 11 9;196:85-96. Epub 2018 Jun 9.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile. Electronic address:

Here, we determined the 5-hydroxymethylcytosine (5hmC), 5-methylcytosine (5mC), Ten Eleven Translocation (TETs), and DNA methyltransferases (DNMTs) levels in epithelial and inflammatory cells of labial salivary glands (LSG) from Sjögren's syndrome (SS)-patients and the effect of cytokines on HSG cells. LSG from SS-patients, controls and HSG cells incubated with cytokines were analysed. Levels of 5mC, 5hmC, DNMTs, TET2 and MeCP2 were assessed by immunofluorescence. In epithelial cells from SS-patients, an increase in TET2, 5hmC and a decrease in 5mC and MeCP2 were observed, additionally, high levels of 5mC and DNMTs and low levels of 5hmC were detected in inflammatory cells. Cytokines increased TET2 and 5hmC and decreased 5mC levels. Considering that the TET2 gene.promoter contains response elements for transcription factors activated by cytokines, together to in vitro results suggest that changes in DNA hydroxymethylation, resulting from altered levels of TET2 are likely to be relevant in the Sjögren's syndrome etiopathogenesis.
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http://dx.doi.org/10.1016/j.clim.2018.06.002DOI Listing
November 2018

Endoplasmic reticulum stress in autoimmune diseases: Can altered protein quality control and/or unfolded protein response contribute to autoimmunity? A critical review on Sjögren's syndrome.

Autoimmun Rev 2018 Aug 8;17(8):796-808. Epub 2018 Jun 8.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile. Electronic address:

For many years, researchers in the field of autoimmunity have focused on the role of the immune components in the etiopathogenesis of autoimmune diseases. However, some studies have demonstrated the importance of target tissues in their pathogenesis and the breach of immune tolerance. The immune system as well as target tissue cells (plasmatic, β-pancreatic, fibroblast-like synoviocytes, thyroid follicular and epithelial cells of the lachrymal glands, salivary glands, intestine, bronchioles and renal tubules) share the characteristic of secretory cells with an extended endoplasmic reticulum (ER). The function of these cells depends considerably on a normal ER function and calcium homeostasis, so they can produce and secrete their main components, which include glycoproteins involved in antigenic presentation such as major histocompatibility complex (MHC) class I and II. All these proteins are synthesized and modified in the ER, and for this reason disturbances in the normal functions of this organelle such as protein folding, protein quality control, calcium homeostasis and redox balance, promote accumulation of unfolded or misfolded proteins, a condition known as ER stress. Autoimmune diseases are characterized by inflammation, which has been associated with an ER stress condition. Interestingly, patients with these diseases contain circulating auto-antibodies against chaperone proteins (such as Calnexin and GRP94), thus affecting the folding and assembly of MHC class I and II glycoproteins and their loading with peptide. The main purpose of this article is to review the involvement of the protein quality control and unfolded protein response (UPR) in the ER protein homeostasis (proteostasis) and their alterations in autoimmune diseases. In addition, we describe the interaction between ER stress and inflammation and evidences are shown of how autoimmune diseases are associated with an ER stress condition, with a special emphasis on the second most prevalent autoimmune rheumatic disease, Sjögren's syndrome.
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http://dx.doi.org/10.1016/j.autrev.2018.02.009DOI Listing
August 2018

Impaired IRE1α/XBP-1 pathway associated to DNA methylation might contribute to salivary gland dysfunction in Sjögren's syndrome patients.

Rheumatology (Oxford) 2018 06;57(6):1021-1032

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Santiago, Chile.

Objectives: Labial salivary glands (LSGs) of SS patients show alterations related to endoplasmic reticulum stress. Glandular dysfunction could be partly the consequence of an altered inositol-requiring enzyme 1α (IRE1α)/X box-binding protein 1 (XBP-1) signalling pathway of the unfolded protein response, which then regulates genes involved in biogenesis of the secretory machinery. This study aimed to determine the expression, promoter methylation and localization of the IRE1α/XBP-1 pathway components in LSGs of SS patients and also their expression induced by IFN-γ in vitro.

Methods: IRE1α, XBP-1 and glucose-regulated protein 78 (GRP78) mRNA and protein levels were measured by qPCR and western blot, respectively, in LSGs of SS patients (n = 47) and control subjects (n = 37). Methylation of promoters was evaluated by methylation-sensitive high resolution melting, localization was analysed by immunofluorescence and induction of the IRE1α/XBP-1 pathway components by IFN-γ was evaluated in 3D acini.

Results: A significant decrease of IRE1α, XBP-1u, XBP-1s, total XBP-1 and GRP78 mRNAs was observed in LSGs of SS patients, which was correlated with increased methylation levels of their respective promoters, and consistently the protein levels for IRE1α, XBP-1s and GRP78 were observed to decrease. IFN-γ decreased the mRNA and protein levels of XBP-1s, IRE1α and GRP78, and increased methylation of their promoters. Significant correlations were also found between IRE1α/XBP-1 pathway components and clinical parameters.

Conclusion: Decreased mRNA levels for IRE1α, XBP-1 and GRP78 can be partially explained by hypermethylation of their promoters and is consistent with chronic endoplasmic reticulum stress, which may explain the glandular dysfunction observed in LSGs of SS patients. Additionally, glandular stress signals, including IFN-γ, could modulate the expression of the IRE1α/XBP-1 pathway components.
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http://dx.doi.org/10.1093/rheumatology/key021DOI Listing
June 2018

Development of a Severe Traumatic Brain Injury Consensus-Based Treatment Protocol Conference in Latin America.

World Neurosurg 2018 Feb 5;110:e952-e957. Epub 2017 Dec 5.

Harborview Medical Center, University of Washington, Seattle, Washington, USA. Electronic address:

Background: Severe traumatic brain injury (sTBI) is a significant global health problem disproportionately affecting low- and middle-income countries (LMICs). Management of intracranial hypertension in sTBI is crucial to survival and optimal recovery. Practitioners in high-income countries routinely use intracranial pressure (ICP) monitors although their usefulness has been questioned. ICP monitors are usually unavailable in LMICs. No consensus-based/tested protocols or literature exists for sTBI treatment without ICP monitoring.

Methods: Investigators developed serial SurveyMonkey surveys for Latin American neurointensivists and neurosurgeons to determine current practice. These clinicians had extensive routine ongoing experience in sTBI without ICP monitoring. Surveys were administered and analyzed before/during/after a 2015 Buenos Aires consensus conference. Investigators identified areas of convergence blinded from colleagues' responses. A 47-clinician task force, representing 15 countries, who routinely manage patients with sTBI without monitors developed consensus-based treatment guidelines during a 3-day facilitated conference.

Results: Elements were added to the protocol at an 80% agreement threshold. Follow-on surveys resolved remaining elements to 97% agreement. The protocol addresses both tapering (on improvement) and neuroworsening. Staged treatment options were identified, plus unique clinical practice issues. This process introduced a research method to a large multidisciplinary group of LMIC clinicians. This report describes the process used to develop an LMIC-specific protocol that is transferable to other diseases/injuries. The protocol is being tested in 5 LMICs.

Conclusions: We derived consensus-based guidelines for sTBI treatment without ICP monitoring, and introduced a research method to a large multidisciplinary group of LMIC clinicians naive to such methods.
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http://dx.doi.org/10.1016/j.wneu.2017.11.142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214355PMC
February 2018

Pro-inflammatory cytokines enhance ERAD and ATF6α pathway activity in salivary glands of Sjögren's syndrome patients.

J Autoimmun 2016 Dec 25;75:68-81. Epub 2016 Jul 25.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile. Electronic address:

Salivary gland (SG) acinar-cells are susceptible to endoplasmic reticulum (ER) stress related to their secretory activity and the complexity of synthesized secretory products. SGs of Sjögren's syndrome patients (SS)-patients show signs of inflammation and altered proteostasis, associated with low IRE1α/XBP-1 pathway activity without avert increases in apoptosis. Acinar-cells may avoid apoptosis by activation of the ATF6α pathway and ER-associated protein degradation (ERAD). The aim of this study was to evaluate the role of pro-inflammatory cytokines in ATF6α pathway/ERAD activation and cell viability in labial salivary glands (LSG) of SS-patients. In biopsies from SS-patients increased ATF6α signaling pathway activity, as evidenced by generation of the ATF6f cleavage fragment, and increased expression of ERAD machinery components, such as EDEM1, p97, SEL1L, gp78, UBE2J1, UBE2G2, HERP and DERLIN1, were observed compared to controls. Alternatively, for pro- (active-caspase-3) and anti-apoptotic (cIAP2) markers no significant difference between the two experimental groups was detected. Increased presence of ATF6f and ERAD molecules correlated significantly with increased expression of pro-inflammatory cytokines. These observations were corroborated in vitro in 3D-acini treated with TNF-α and/or IFN-γ, where an increase in the expression and activation of the ATF6α sensor and ERAD machinery components was detected under ER stress conditions, while changes in cell viability and caspase-3 activation were not observed. Cytokine stimulation protected cells from death when co-incubated with an ERAD machinery inhibitor. Alternatively, when cytokines were eliminated from the medium prior to ERAD inhibition, cell death increased, suggesting that the presence of pro-inflammatory cytokines in the medium is essential to maintain cell viability. In conclusion, the ATF6α pathway and the ERAD machinery are active in LSG of SS-patients. Both were also activated by TNF-α and IFN-γ in vitro in 3D-acini and aided in preventing apoptosis. IFN-γ levels were elevated in SS-patients and UPR responses triggered in vitro by this cytokine closely matched those observed in LSG from SS-patients, suggesting that cytokines may induce ER stress.
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http://dx.doi.org/10.1016/j.jaut.2016.07.006DOI Listing
December 2016

Salivary mucins induce a Toll-like receptor 4-mediated pro-inflammatory response in human submandibular salivary cells: are mucins involved in Sjögren's syndrome?

Rheumatology (Oxford) 2015 Aug 22;54(8):1518-27. Epub 2015 Mar 22.

Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile,

Objectives: A hallmark characteristic of SS patients is the ectopic presence of the mucins MUC5B and MUC7 in the extracellular matrix of salivary glands that have lost apical-basolateral acinar-cell polarity. This study aims to determine whether exogenous salivary mucins induce gene expression of pro-inflammatory cytokines, as well as to evaluate whether the Toll-like receptor-4 (TLR4) pathway is involved in this response.

Methods: Differentiated human submandibular gland (HSG) cells were stimulated with mucins or oligosaccharide residues at different concentrations and for different periods of time. The expression of pro-inflammatory cytokines and their receptors was determined by semi-quantitative real time PCR (sqPCR). TLR4-mediated responses induced by mucin were evaluated with the Toll-IL-1 receptor domain containing adaptor protein (TIRAP) inhibitory peptide or using anti-hTLR4 blocking antibody. TLR4-receptor expression was also determined in SS patients, controls and HSG cells.

Results: Mucins induced a significant increase in CXCL8, TNF-α, IFN-α, IFN-β, IL-6 and IL-1β, but not B cell activating factor (BAFF). Cytokine induction was mediated by TLR4, as shown using TIRAP or using anti-hTLR4 antibody. Sugar residues present in MUC5B, such as sulpho-Lewis (SO3-3Galβ1-3GlcNAc), also induced cytokines. Unexpectedly, mucins induced MUC5B, but not MUC7 expression.

Conclusion: Salivary mucins were recognized by TLR4 in epithelial cells initiating a pro-inflammatory response that could attract inflammatory cells to amplify and perpetuate inflammation and thereby contribute to the development of a chronic state characteristic of SS. The ectopic localization of MUC5B and MUC7 in the salivary gland extracellular matrix from SS patients and the current results reveal the importance of salivary epithelial cells in innate immunity, as well as in SS pathogenesis.
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http://dx.doi.org/10.1093/rheumatology/kev026DOI Listing
August 2015

Aberrant localization of fusion receptors involved in regulated exocytosis in salivary glands of Sjögren's syndrome patients is linked to ectopic mucin secretion.

J Autoimmun 2012 Aug 30;39(1-2):83-92. Epub 2012 Jan 30.

Faculty of Medicine, Institute of Biomedical Sciences (ICBM), University of Chile, Postal Code 8389100, Santiago, Chile.

Sjögren's syndrome (SS) is a chronic inflammatory autoimmune disease that mainly affects tear and salivary glands, whereby SS-patients frequently complain of eye and mouth dryness. Salivary acinar cells of SS-patients display alterations in their cell polarity; which may affect the correct localization and function of proteins involved in regulated exocytosis. Here we determined whether the expression and localization of SNARE proteins (membrane fusion receptors) involved in regulated secretion, such as VAMP8, syntaxin 3 (STX3), STX4 and SNAP-23 were altered in salivary glands (SG) from SS-patients. Additionally, we investigated SNARE proteins function, by evaluating their ability to form SNARE complexes under basal conditions. In SG from SS-patients and control subjects mRNA and proteins levels of SNARE complex components were determined by real-time PCR and Western blotting, respectively. SNARE protein distribution and mucin exocytosis were determined by indirect immunofluorescence. In SS-patients, the expression levels of mRNA and protein for VAMP8, STX4 and STX3 were altered. STX4, STX3, SNAP-23 and VAMP8 relocated from the apical to the basal region of acinar cells. Increased formation of SNARE complexes in a manner independent of external stimuli for secretion was detected. Mucins were detected in the extracellular matrix (ECM). Presence of mucins in the ECM, together with the observed alterations in SNARE protein localization is indicative of ectopic exocytosis. In the context of SS, such aberrantly localized mucins are likely to favor a pro-inflammatory response, which may represent an important initial step in the pathogenesis of this disease.
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http://dx.doi.org/10.1016/j.jaut.2012.01.011DOI Listing
August 2012

Decreased salivary sulphotransferase activity correlated with inflammation and autoimmunity parameters in Sjogren's syndrome patients.

Rheumatology (Oxford) 2012 Mar 17;51(3):482-90. Epub 2011 Nov 17.

Institute of Biomedical Sciences, University of Chile, Casilla, Chile.

Objectives: To determine the expression and enzymatic activities of sulphotransferases involved in mucin hyposulphation in labial salivary glands (LSGs) from SS patients and to correlate sulphotransferase activity with clinical parameters such as secretion, inflammation and serology.

Methods: LSG from 31 SS patients and 31 control subjects were studied. Relative mRNA and protein levels of Gal3-O-sulphotransferases (Gal3STs) and β1,3-galactosyltransferase-5 (β3GalT5) were determined by quantitative RT-PCR and western blotting, respectively. Enzymatic activities were quantified using radioactively labelled donor substrates and specific acceptor substrates. Products were purified by chromatography. Spearman's correlation analysis was used to compare data.

Results: The levels of Gal3ST activity were significantly decreased in SS patients, without changes in mRNA and protein levels, while the enzymatic activities of glycosyltransferases involved in mucin glycosylation were similar in both groups. An inverse correlation was observed between Gal3ST activity and glandular function measured by scintigraphy, but not with unstimulated salivary flow. Gal3ST activity was inversely correlated with focus score, TNF-α levels and presence of the autoantibodies Ro/SS-A and La/SS-B.

Conclusion: The decrease in sulphotransferase activity provides an explanation for mucin hyposulphation observed in the LSGs from SS patients. The decrease in Gal3STs activity was not a consequence of reduced gene expression, but probably due to alterations in the enzyme activity regulation. Interestingly, the levels of sulphotransferase activity detected correlated well with secretory function, inflammation and serology. Finally, we postulate that pro-inflammatory cytokines induced by autoantibodies, such as Ro/SS-A and La/SS-B in SS patients, may modulate Gal3ST activity, thereby altering mucin quality and leading to mouth dryness.
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http://dx.doi.org/10.1093/rheumatology/ker351DOI Listing
March 2012

Changes in Rab3D expression and distribution in the acini of Sjögren's syndrome patients are associated with loss of cell polarity and secretory dysfunction.

Arthritis Rheum 2011 Oct;63(10):3126-35

Instituto de Ciencias Biomédicas, Facultad de Medicina, University of Chile, Santiago, Chile.

Objective: Oral and ocular dryness are frequent and serious symptoms of Sjögren's syndrome (SS) that reflect problems in secretion due to glandular dysfunction. Exocytosis, an important process in the secretory pathway, requires the participation of Rab family GTPases. This study was undertaken to analyze the expression and localization of Rab3D and Rab8A and to examine their correlation with acinar cell polarity and glandular secretory function.

Methods: Nineteen patients with SS and 17 controls were evaluated. Levels of Rab3D and Rab8A messenger RNA (mRNA) and protein were determined by real-time polymerase chain reaction and Western blotting. Subcellular localization of proteins was determined by indirect immunofluorescence analysis.

Results: In patients with SS, total Rab3D protein levels decreased significantly, while mRNA levels remained unchanged. For Rab8A, no changes in either mRNA or protein levels were detected. In serous acini of labial salivary glands from patients with SS, the following 4 patterns of Rab3D staining were distinguishable: severely decreased, distribution throughout the cytoplasm, distribution throughout the cytoplasm combined with loss of nuclear polarity, and normal apical localization. Basal localization of Rab8A was not modified. Rab3D changes were accompanied by apicobasolateral redistribution of ezrin, loss of nuclear polarity, thicker Golgi stacks, and mucin 7 accumulation in the cytoplasm. Finally, low Rab3D protein levels correlated with alterations in scintigraphy measurements.

Conclusion: Our findings indicate that Rab3D regulates the exocytosis of many components critical for the maintenance of oral physiology. Hence, the changes observed in Rab3D expression and distribution are likely to contribute to the decrease in or loss of saliva components (i.e., mucins), which may explain the variety of oral and ocular symptoms associated with SS.
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http://dx.doi.org/10.1002/art.30500DOI Listing
October 2011

Mechanotransduction and epigenetic control in autoimmune diseases.

Autoimmun Rev 2011 Jan 20;10(3):175-9. Epub 2010 Oct 20.

University of Chile, Chile.

Differentiation of epithelial cells is required to define tissue architecture and appropriate function of these cells is associated with a specific pattern of gene expression. DNA methylation, post-translational modification of histones and chromatin remodeling are nuclear mechanisms implicated in epigenetic control of gene expression. All factors relevant to tissue differentiation, including cell adhesion and shape, extracellular stimuli and transcriptional control, modulate gene expression and, thus, some of them are likely to impact on nuclear mechanisms of epigenetic control. The epithelial cells of salivary glands from Sjögren's syndrome patients display alterations in cell adhesion and shape. In this review, we summarize how these alterations are thought to lead to chromatin remodeling and, in doing so, bring about changes in transcriptional patterns. Additionally, we discuss how mechanotransduction in cells with impaired structural organization is implicated in modifying gene expression in these patients.
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http://dx.doi.org/10.1016/j.autrev.2010.09.022DOI Listing
January 2011

Aberrant localization of ezrin correlates with salivary acini disorganization in Sjogren's Syndrome.

Rheumatology (Oxford) 2010 May 25;49(5):915-23. Epub 2010 Feb 25.

Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Casilla 70061, Santiago 7, Chile.

Objectives: To analyse whether the alterations in the structure and organization of microvilli in salivary acinar cells from SS patients are linked to changes in the expression and/or cellular localization of ezrin.

Methods: Salivary gland (SG) acini from controls and SS patients were used to evaluate ezrin expression by western blot and localization of total and activated (phospho-Thr567) ezrin by IF and EM.

Results: In acini from control labial SGs, ezrin was located predominantly at the apical pole and to a lesser extent at the basal region of these cells. Conversely, in acini extracts from SS patients, ezrin showed significantly elevated levels, which were accompanied with localization mostly at the basal region. Moreover, F-actin maintained its distribution in both the apical region and basolateral cortex; however, it was also observed in the acinar cytoplasm. Phospho-ezrin (active form) was located exclusively at the apical pole of acinar cells from control subjects and abundantly located at the basal cytoplasm in SS samples. These results were confirmed by immunogold studies.

Conclusions: The decrease of ezrin and phospho-ezrin at the apical pole and the cytoplasmic redistribution of F-actin suggest an altered interaction between the F-actin-cytoskeleton and plasma membrane in SS patient acini, which may explain the microvilli disorganization. These alterations could eventually contribute to SG hyposecretion in SS patients.
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http://dx.doi.org/10.1093/rheumatology/keq033DOI Listing
May 2010

Disruption of tight junction structure in salivary glands from Sjögren's syndrome patients is linked to proinflammatory cytokine exposure.

Arthritis Rheum 2010 May;62(5):1280-9

University of Chile, Santiago, Chile.

Objective: Disorganization of acinar cell apical microvilli and the presence of stromal collagen in the acinar lumen suggest that the labial salivary gland (LSG) barrier function is impaired in patients with Sjögren's syndrome. Tight junctions define cell polarity and regulate the paracellular flow of ions and water, crucial functions of acinar cells. This study was undertaken to evaluate the expression and localization of tight junction proteins in LSGs from patients with SS and to determine in vitro the effects of tumor necrosis factor alpha (TNFalpha) and interferon-gamma (IFNgamma) on tight junction integrity of isolated acini from control subjects.

Methods: Twenty-two patients and 15 controls were studied. The messenger RNA and protein levels of tight junction components (claudin-1, claudin-3, claudin-4, occludin, and ZO-1) were determined by semiquantitative reverse transcriptase-polymerase chain reaction and Western blotting. Tight junction protein localization was determined by immunohistochemistry. Tight junction ultrastructure was examined by transmission electron microscopy. Isolated acini from control subjects were treated with TNFalpha and IFNgamma.

Results: Significant differences in tight junction protein levels were detected in patients with SS. ZO-1 and occludin were strongly down-regulated, while claudin-1 and claudin-4 were overexpressed. Tight junction proteins localized exclusively to apical domains in acini and ducts of LSGs from controls. In SS patients, the ZO-1 and occludin the apical domain presence of decreased, while claudin-3 and claudin-4 was redistributed to the basolateral plasma membrane. Exposure of isolated control acini to TNFalpha and IFNgamma reproduced these alterations in vitro. Ultrastructural analysis associated tight junction disorganization with the presence of endocytic vesicles containing electron-dense material that may represent tight junction components.

Conclusion: Our findings indicate that local cytokine production in LSGs from SS patients may contribute to the secretory gland dysfunction observed in SS patients by altering tight junction integrity of epithelial cells, thereby decreasing the quality and quantity of saliva.
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http://dx.doi.org/10.1002/art.27362DOI Listing
May 2010

Gene expression and chromosomal location for susceptibility to Sjögren's syndrome.

J Autoimmun 2009 Sep 11;33(2):99-108. Epub 2009 Jun 11.

University of Chile, Santiago, Chile.

Primary Sjögren's syndrome (SS) is a chronic inflammatory autoimmune disease affecting mainly the exocrine glands. Its physio-pathology is poorly understood and most of the knowledge has been related to the inflammatory component. The aim of this work was to evaluate gene expression profiling in fractions enriched in epithelial cells from labial salivary glands (LSGs) of patients with primary SS and identify chromosomal regions harboring susceptibility genes expressed in epithelial cells. A combined approach of gene expression and genome-wide association study was used. Enriched epithelial cell fractions were obtained from LSGs of patients and controls. Amplified total RNA was labeled and hybridized to 10K cDNA microarrays. Results were normalized and subjected to statistical and functional analysis. A genome-wide microsatellite screen at 10 cM resolution (393 markers) was performed. In salivary gland-epithelial cells from patients 528 genes were expressed differentially in comparison to controls. Pathways not previously linked to disease were found to be altered. Twenty-eight and 15 genes associated with apoptosis were up-regulated and down regulated, respectively. Interferon-related genes, most of which participated in interferon signaling, were also found to be up-regulated. From the genome-wide screen, 6 markers showed evidence of highly significant association with the disease. Of these, five loci harbor genes differentially expressed in patients LSG-epithelial cells. Our results show that in enriched gland-epithelial cells of pSS, both pro-apoptotic/anti-apoptotic and interferon signaling inhibition/stimulation balances may occur. Genes found over-expressed in epithelial cells are candidates for disease susceptibility.
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http://dx.doi.org/10.1016/j.jaut.2009.05.001DOI Listing
September 2009

Temporal lobectomy in acute complicated herpes simplex encephalitis: technical case report.

Neurosurgery 2008 May;62(5):E1174-5; discussion E1175

Department of Paediatrics, Paediatric Neurology Unit, University Clinic of Navarra, University of Navarra, Pamplona, Spain.

Objective: Herpes virus encephalitis is a rare, life-threatening complication of therapy in patients with brain tumors. A surgical therapeutic approach may be needed because the infection can be resistant to acyclovir in immunocompromised patients, and complications and long-term sequelae are frequent.

Clinical Presentation: We present the case of a right-handed, 6-year-old girl with a brainstem tumor who had herpes virus encephalitis with refractory seizures while on immunosuppressive treatment. The virus was resistant to acyclovir but responded to gancyclovir. The patient developed local refractory brain edema with right uncal herniation.

Intervention: To reduce the intracranial pressure, internal decompressive craniotomy was performed, which consisted of a right temporal lobectomy that allowed us to remove the focal necrotic-hemorrhagic tissue, decrease inflammation, and avoid subsequent chronic gliotic scarring. Clinical improvement was clear with prompt recovery and acute control of seizures. The only remaining deficits were mild memory and attention impairments. Seizures did not recur in the next 6 months.

Conclusion: Antiviral resistance should be suspected in immunocompromised patients with herpes virus encephalitis if there is no early response to acyclovir. If uncal herniation of the nondominant temporal lobe develops, temporal lobectomy, as an internal decompressive procedure, can be lifesaving. Lobectomy stopped the acute refractory seizures and can be considered a good approach to prevent later epilepsy, with only mild residual cognitive deficits.
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http://dx.doi.org/10.1227/01.neu.0000325885.00033.c3DOI Listing
May 2008

Involvement of specific laminins and nidogens in the active remodeling of the basal lamina of labial salivary glands from patients with Sjögren's syndrome.

Arthritis Rheum 2006 Nov;54(11):3465-75

University of Chile, Santiago, Chile.

Objective: To investigate remodeling of the basal lamina of labial salivary glands (LSGs) from patients with Sjögren's syndrome (SS) by analyzing the expression of specific components that participate in its assembly and attachment to acinar and ductal cells.

Methods: Two groups of SS patients with similar levels of remnant glandular tissue but with low and high levels of interacinar fibrosis, respectively, were studied. The expression of laminin alpha1, alpha4, and gamma2 chains and nidogens was examined at the messenger RNA (mRNA) and protein levels. Nidogens 1 and 2 were also studied in situ by immunohistochemistry.

Results: Increases in the amount of mRNA and protein for both the processed and unprocessed laminin gamma2-chain were more pronounced in patients with low interacinar fibrosis. Increases in the protein levels of laminin alpha1 and alpha4 chains were observed in patients with low interacinar fibrosis, but not in those with high interacinar fibrosis. Nidogen mRNA and protein levels were similar in SS patients and controls. Interestingly, high levels of nidogen degradation were observed in patients with low interacinar fibrosis. Nidogens were readily detected by immunofluorescence in the basal lamina of the capillaries and stroma in SS patients, but were less apparent in the basal lamina of the acini and ducts.

Conclusion: These results suggest that the basal lamina of LSGs from patients with SS is undergoing active remodeling, such that alterations are less evident in patients who have advanced morphologic signs of the disease (high interacinar fibrosis). Nidogen proteolysis might account for the disorganization of the basal lamina that is typically observed in LSGs from SS patients, assuming that cleavage impairs their ability to crosslink type IV collagen and laminin networks.
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http://dx.doi.org/10.1002/art.22177DOI Listing
November 2006

Increased acinar damage of salivary glands of patients with Sjögren's syndrome is paralleled by simultaneous imbalance of matrix metalloproteinase 3/tissue inhibitor of metalloproteinases 1 and matrix metalloproteinase 9/tissue inhibitor of metalloproteinases 1 ratios.

Arthritis Rheum 2005 Sep;52(9):2751-60

University of Chile, Santiago, Chile.

Objective: Previous findings in labial salivary glands (LSGs) from patients with Sjögren's syndrome (SS) suggest that increased activity and expression of matrix metalloproteinase 9 (MMP-9) and MMP-3 trigger the destruction of acinar structures in these glands. Tissue inhibitors of matrix metalloproteinases (TIMPs) tightly control MMP activity, and TIMP expression is an important modulator of effects attributed to MMPs. This study was undertaken to investigate the correlation between the balance of MMPs/TIMPs in the LSGs of SS patients and the degree of inflammatory infiltration and acinar structure integrity.

Methods: Three groups of SS patients classified according to focus score and residual tissue were studied. The expression of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 was examined at the messenger RNA and protein levels. The ratio of MMP/TIMP expression (R value) was calculated. Focus score and acinar structure were evaluated by histologic analysis.

Results: In SS patients the MMP-3/TIMP-1 ratio was higher than 1 and the MMP-9/TIMP-1 ratio was much higher than 1 whereas the MMP-2/TIMP-2 ratio nearly equaled 1, suggesting elevated proteolytic activity due mainly to MMP-9. R values were independent of the focus score of inflammatory cells, but correlated well with the dramatic changes observed in morphologic integrity of acini, as revealed mainly by the lack of nuclear polarity. Acinar changes were more evident when R values for both MMP-9/TIMP-1 and MMP-3/TIMP-1 were higher.

Conclusion: This study provides evidence that an altered balance between MMPs and their inhibitors is associated with acinar damage. Since salivary gland acinar cells express both MMPs and TIMPs, these cells may play an important role in extracellular matrix destruction and in the LSG pathophysiology in SS.
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http://dx.doi.org/10.1002/art.21265DOI Listing
September 2005

Enhanced degradation of proteins of the basal lamina and stroma by matrix metalloproteinases from the salivary glands of Sjögren's syndrome patients: correlation with reduced structural integrity of acini and ducts.

Arthritis Rheum 2003 Sep;48(9):2573-84

University of Chile, Santiago, Chile.

Objective: To determine the effect of matrix metalloproteinase (MMP) activity from the labial salivary glands (LSGs) of Sjögren's syndrome (SS) patients on proteins of the extracellular matrix (ECM) that form the basal lamina and stroma, and to compare this effect with the structural integrity of acini and ducts as well as the functionality of the LSGs.

Methods: Gelatinase activity was determined by zymography. The digestion pattern of extracellular matrix (ECM) macromolecules was detected by gel electrophoresis and quantified by densitometry. The structural integrity of acini and ducts was evaluated by light and electron microscopy. Secretory function was evaluated by measuring unstimulated salivary flow and by scintigraphy.

Results: LSG extracts showed increased levels of proteolytic activity toward purified proteins of the basal lamina (laminin and type IV collagen) and stroma (types I and III collagen and fibronectin). Enhanced degradation was most evident for fibronectin, laminin, and type IV collagen. Analysis of the ultrastructure of the acinar and ductal basal lamina revealed abnormalities ranging from disorganization to disappearance of this ECM structure. These changes were paralleled by an important loss of microvilli on the apical surface, as well as decreased unstimulated salivary flow. Interestingly, the results were similar in LSGs from all SS patients, regardless of the proximity of infiltrating mononuclear cell foci.

Conclusion: Our observation that the proteolytic action of MMPs toward ECM macromolecules is increased in SS patients provides a rationale for understanding the dramatic changes in the structural organization observed in the basal lamina and apical surface of acini in these patients. The results provide new evidence that acinar and ductal cells from the LSGs of SS patients display a molecular potential, with increased capacity to markedly disorganize their ECM environment and, thus, damage their architecture and functionality.
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http://dx.doi.org/10.1002/art.11178DOI Listing
September 2003

[Antibodies against recombinant Ro 60 Kd, Ro 52 and La 48 Kd proteins in primary Sjogren's Syndrome. Utility of analytic methods combination to detect antibodies anti Ro and La].

Rev Med Chil 2002 Aug;130(8):841-9

Reumatólogo. Clínica Indisa, Av. Santa María 1810, Providencia, Santiago, Chile.

Background: The use of new recombinant antigens may increase the sensitivity and specificity of the detection of anti Ro and anti La antibodies in Sjögren's syndrome.

Aim: To determine the immune reactivity of sera from patients with Sjögren's syndrome, against fusion recombinant proteins (prf) Ro60 Kd, Ro52 Kd and La48 Kd expressed in E coli and recombinant protein Ro52 Kd, expressed in baculovirus (prb).

Material And Methods: Serum samples from 46 patients with a diagnosis of Sjögren's syndrome, according to the European criteria of 1997, were studied. Using conventional ELISA assays, 32 patients had positive anti Ro antibodies (group A) and 16 patients had negative anti Ro and anti La antibodies, but had positive antinuclear antibodies or rheumatoid factors (group B). Antibodies against recombinant proteins were measured by ELISA or Western Blot.

Results: Reactivity against prf Ro60 was present in 69% of samples from group A patients and in 36% of samples from group B. Reactivity against prf Ro52 was present in 94% of samples from group A and 50% of samples from group B. Reactivity against prb Ro52 was present in 75% of samples from group A and 40% of samples from group B. Reactivity against prf La was present in 78% of samples by ELISA and 97% of samples by Western Blot. In 10 of 14 serum samples from group B patients, there was reactivity against at least one recombinant protein.

Conclusions: A high prevalence of reactivity against recombinant Ro and La proteins was detected in serum samples from patients with Sjögren syndrome.
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August 2002
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