Publications by authors named "Silvia Berra"

12 Publications

  • Page 1 of 1

Anti-C1-Inhibitor Autoantibody Detection by ELISA.

Methods Mol Biol 2021 ;2227:115-120

ASST-Fatebenefratelli-Sacco, Milan, Italy.

Enzyme-linked immunosorbent assay (ELISA) is a quantitative analytical method used to measure the concentration of molecules in biological fluids through antigen-antibody reactions. Here we describe the measurement of anti-C1-inhibitor autoantibodies by an indirect ELISA. In this method patients' sera are incubated in a microplate coated with plasma derived C1-inhibitor.
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http://dx.doi.org/10.1007/978-1-0716-1016-9_11DOI Listing
January 2021

IgM Autoantibodies to Complement Factor H in Atypical Hemolytic Uremic Syndrome.

J Am Soc Nephrol 2021 Mar 12. Epub 2021 Mar 12.

Center for Hemolytic Uremic Syndrome Prevention, Control and Management, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.

Background: Atypical hemolytic uremic syndrome (aHUS), a severe thrombotic microangiopathy, is often related to complement dysregulation, but the pathomechanisms remain unknown in at least 30% of patients. Researchers have described autoantibodies to complement factor H of the IgG class in 10% of patients with aHUS but have not reported anti-factor H autoantibodies of the IgM class.

Methods: In 186 patients with thrombotic microangiopathy clinically presented as aHUS, we searched for anti-factor H autoantibodies of the IgM class and those of the IgG and IgA classes. We used immunochromatography to purify anti-factor H IgM autoantibodies and immunoenzymatic methods and a competition assay with mapping mAbs to characterize interaction with the target protein.

Results: We detected anti-factor H autoantibodies of the IgM class in seven of 186 (3.8%) patients with thrombotic microangiopathy presented as aHUS. No association was observed between anti-factor H IgM and homozygous deletions involving . A significantly higher proportion of patients with bone marrow transplant-related thrombotic microangiopathy had anti-factor H IgM autoantibodies versus other patients with aHUS: three of 20 (15%) versus four of 166 (2.4%), respectively. The identified IgM autoantibodies recognize the SCR domain 19 of factor H molecule in all patients and interact with the factor H molecule, inhibiting its binding to C3b.

Conclusions: Detectable autoantibodies to factor H of the IgM class may be present in patients with aHUS, and their frequency is six-fold higher in thrombotic microangiopathy forms associated with bone marrow transplant. The autoantibody interaction with factor H's active site may support an autoimmune mechanism in some cases previously considered to be of unknown origin.
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http://dx.doi.org/10.1681/ASN.2020081224DOI Listing
March 2021

The central role of endothelium in hereditary angioedema due to C1 inhibitor deficiency.

Int Immunopharmacol 2020 Feb 27;82:106304. Epub 2020 Feb 27.

Department of Biomedical and Clinical Sciences, ASST Fatebenefratelli Sacco, University of Milan, Milan, Italy; IRCCS-ICS Maugeri, Milan, Italy.

An impairment of the endothelial barrier function underlies a wide spectrum of pathological conditions. Hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE) can be considered the "pathophysiological and clinical paradigm" of Paroxysmal Permeability Diseases (PPDs), conditions characterized by recurrent transient primitively functional alteration of the endothelial sieving properties, not due to inflammatory-ischemic-degenerative injury and completely reversible after the acute flare. It is a rare yet probably still underdiagnosed disease which presents with localized, non-pitting swelling of the skin and submucosal tissues of the upper respiratory and gastrointestinal tracts, without significant wheals or pruritus. The present review addresses the pathophysiology of C1-INH-HAE with a focus on the crucial role of the endothelium during contact and kallikrein/kinin system (CAS and KKS) activation, currently available and emerging biomarkers, methods applied to get new insights into the mechanisms underlying the disease (2D, 3D and in vivo systems), new promising investigation techniques (autonomic nervous system analysis, capillaroscopy, flow-mediated dilation method, non-invasive finger plethysmography). Hints are given to the binding of C1-INH to endothelial cells. Finally, crucial issues as the local vs systemic nature of CAS/KKS activation, the episodic nature of attacks vs constant C1-INH deficiency, pros and cons as well as future perspectives of available methodologies are briefly discussed.
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http://dx.doi.org/10.1016/j.intimp.2020.106304DOI Listing
February 2020

Intermittent C1-Inhibitor Deficiency Associated with Recessive Inheritance: Functional and Structural Insight.

Sci Rep 2018 01 17;8(1):977. Epub 2018 Jan 17.

"L. Sacco" Department of Biomedical and Clinical Sciences, University of Milan, via GB Grassi 74, 20157, Milan, Italy.

C1-inhibitor is a serine protease inhibitor (serpin) controlling complement and contact system activation. Gene mutations result in reduced C1-inhibitor functional plasma level causing hereditary angioedema, a life-threatening disorder. Despite a stable defect, the clinical expression of hereditary angioedema is unpredictable, and the molecular mechanism underlying this variability remains undisclosed. Here we report functional and structural studies on the Arg378Cys C1-inhibitor mutant found in a patient presenting reduced C1-inhibitor levels, episodically undergoing normalization. Expression studies resulted in a drop in mutant C1-innhibitor secretion compared to wild-type. Notwithstanding, the purified proteins had similar features. Thermal denaturation experiments showed a comparable denaturation profile, but the mutant thermal stability decays when tested in conditions reproducing intracellular crowding.Our findings suggest that once correctly folded, the Arg378Cys C1-inhibitor is secreted as an active, although quite unstable, monomer. However, it could bear a folding defect, occasionally promoting protein oligomerization and interfering with the secretion process, thus accounting for its plasma level variability. This defect is exacerbated by the nature of the mutation since the acquired cysteine leads to the formation of non-functional homodimers through inter-molecular disulphide bonding. All the proposed phenomena could be modulated by specific environmental conditions, rendering this mutant exceptionally vulnerable to mild stress.
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http://dx.doi.org/10.1038/s41598-017-16667-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5772639PMC
January 2018

Response.

Biol Blood Marrow Transplant 2017 11 15;23(11):2014-2015. Epub 2017 Aug 15.

Medicina Interna, Dipartimento di Fisiopatologia Medico Chirurgica, Università degli Studi di Milano, IRCCS Fondazione Ca' Granda, Ospedale Maggiore Policlinico, Milano, Italy.

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http://dx.doi.org/10.1016/j.bbmt.2017.07.017DOI Listing
November 2017

Acquired Complement Regulatory Gene Mutations and Hematopoietic Stem Cell Transplant-Related Thrombotic Microangiopathy.

Biol Blood Marrow Transplant 2017 Sep 15;23(9):1580-1582. Epub 2017 May 15.

Laboratory of Medical Genetics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy.

Hematopoietic stem cell transplant-related thrombotic microangiopathy (HSCT-TMA) is a severe complication whose pathophysiology is unknown. We describe 6 patients in which the disease was associated with complement regulatory gene abnormalities received from their respective donors. It is suggested that mutated and transplanted monocyte-derived cells are responsible for production of abnormal proteins, complement dysregulation, and, ultimately, for the disease. This observation might have important drawbacks as far as HSCT-TMA pathophysiology and treatment are concerned.
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http://dx.doi.org/10.1016/j.bbmt.2017.05.013DOI Listing
September 2017

Rapid isolation of pure Complement Factor H from serum for functional studies by the use of a monoclonal antibody that discriminates FH from all the other isoforms.

Mol Immunol 2016 Apr 9;72:65-73. Epub 2016 Mar 9.

"L. Sacco" Department of Biomedical and Clinical Sciences (DIBIC), University of Milan, Italy.

Several mutations have been identified in the gene coding for Complement Factor H (FH) from patients with atypical Hemolytic Uraemic Syndrome (aHUS), Age-related Macular Degeneration (AMD) and Membranoproliferative Glomerulonephritis (MPGN). These data allow for a precise description of the structural changes affecting FH, but a simple test for specifically assessing FH function routinely is not yet of common use. We have produced and characterised a monoclonal antibody (5H5) which discriminates between FH and the smaller FH-like 1 and FH-related proteins and show here that it specifically binds to FH without detecting the smaller isoforms. We therefore used this mAb for a quick, one-step micro-purification of FH directly from control sera and showed that this affinity chromatography procedure is not disruptive of its cofactor function. We also developed a modified sheep erythrocytes haemolysis test using our antibody and affinity-purified FH. These tests can be used in conjunction for assessing the function of FH purified from patients affected by FH-related diseases. Moreover we used this mAb to develop a FH-specific ELISA test.
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http://dx.doi.org/10.1016/j.molimm.2016.03.001DOI Listing
April 2016

BDNF repairs podocyte damage by microRNA-mediated increase of actin polymerization.

J Pathol 2015 Apr 7;235(5):731-44. Epub 2015 Jan 7.

Renal Research Laboratory, Fondazione D'Amico per la Ricerca sulle Malattie Renali & Fondazione IRCCS Ca', Granda Ospedale Maggiore Policlinico, Milano, Italy.

Idiopathic focal segmental glomerulosclerosis (FSGS) is a progressive and proteinuric kidney disease that starts with podocyte injury. Podocytes cover the external side of the glomerular capillary by a complex web of primary and secondary ramifications. Similar to dendritic spines of neuronal cells, podocyte processes rely on a dynamic actin-based cytoskeletal architecture to maintain shape and function. Brain-derived neurotrophic factor (BDNF) is a pleiotropic neurotrophin that binds to the tropomyosin-related kinase B receptor (TrkB) and has crucial roles in neuron maturation, survival, and activity. In neuronal cultures, exogenously added BDNF increases the number and size of dendritic spines. In animal models, BDNF administration is beneficial in both central and peripheral nervous system disorders. Here we show that BDNF has a TrkB-dependent trophic activity on podocyte cell processes; by affecting microRNA-134 and microRNA-132 signalling, BDNF up-regulates Limk1 translation and phosphorylation, and increases cofilin phosphorylation, which results in actin polymerization. Importantly, BDNF effectively repairs podocyte damage in vitro, and contrasts proteinuria and glomerular lesions in in vivo models of FSGS, opening a potential new perspective to the treatment of podocyte disorders.
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http://dx.doi.org/10.1002/path.4484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356648PMC
April 2015

Podocyte glutamatergic signaling contributes to the function of the glomerular filtration barrier.

J Am Soc Nephrol 2009 Sep 2;20(9):1929-40. Epub 2009 Jul 2.

Renal Research Laboratory, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena and Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milan, Italy.

Podocytes possess the complete machinery for glutamatergic signaling, raising the possibility that neuron-like signaling contributes to glomerular function. To test this, we studied mice and cells lacking Rab3A, a small GTPase that regulates glutamate exocytosis. In addition, we blocked the glutamate ionotropic N-methyl-d-aspartate receptor (NMDAR) with specific antagonists. In mice, the absence of Rab3A and blockade of NMDAR both associated with an increased urinary albumin/creatinine ratio. In humans, NMDAR blockade, obtained by addition of ketamine to general anesthesia, also had an albuminuric effect. In vitro, Rab3A-null podocytes displayed a dysregulated release of glutamate with higher rates of spontaneous exocytosis, explained by a reduction in Rab3A effectors resulting in freedom of vesicles from the actin cytoskeleton. In addition, NMDAR antagonism led to profound cytoskeletal remodeling and redistribution of nephrin in cultured podocytes; the addition of the agonist NMDA reversed these changes. In summary, these results suggest that glutamatergic signaling driven by podocytes contributes to the integrity of the glomerular filtration barrier and that derangements in this signaling may lead to proteinuric renal diseases.
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http://dx.doi.org/10.1681/ASN.2008121286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2736779PMC
September 2009

Interstitial vascular rarefaction and reduced VEGF-A expression in human diabetic nephropathy.

J Am Soc Nephrol 2007 Jun 2;18(6):1765-76. Epub 2007 May 2.

Nephrologisches Zentrum, Medizinische Poliklinik, University of Munich, Pettenkoferstrasse 8a, 80336 Munich, Germany.

Diabetic nephropathy (DN) is a frequent complication in patients with diabetes. Although the majority of DN models and human studies have focused on glomeruli, tubulointerstitial damage is a major feature of DN and an important predictor of renal dysfunction. This study sought to investigate molecular markers of pathogenic pathways in the renal interstitium of patients with DN. Microdissected tubulointerstitial compartments from biopsies with established DN and control kidneys were subjected to expression profiling. Analysis of candidate genes, potentially involved in DN on the basis of common hypotheses, identified 49 genes with significantly altered expression levels in established DN in comparison with controls. In contrast to some rodent models, the growth factors vascular endothelial growth factor A (VEGF-A) and epidermal growth factor (EGF) showed a decrease in mRNA expression in DN. This was validated on an independent cohort of patients with DN by real-time reverse transcriptase-PCR. Immunohistochemical staining for VEGF-A and EGF also showed a reduced expression in DN. The decrease of renal VEGF-A expression was associated with a reduction in peritubular capillary densities shown by platelet-endothelial cell adhesion molecule-1/CD31 staining. Furthermore, a significant inverse correlation between VEGF-A and proteinuria, as well as EGF and proteinuria, and a positive correlation between VEGF-A and hypoxia-inducible factor-1alpha mRNA was found. Thus, in human DN, a decrease of VEGF-A, rather than the reported increase as described in some rodent models, may contribute to the progressive disease. These findings and the questions about rodent models in DN raise a note of caution regarding the proposal to inhibit VEGF-A to prevent progression of DN.
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http://dx.doi.org/10.1681/ASN.2006121304DOI Listing
June 2007

Glomerular podocytes contain neuron-like functional synaptic vesicles.

FASEB J 2006 May 3;20(7):976-8. Epub 2006 Apr 3.

Renal Immunopathology Laboratory, Associazione Nuova Nefrologia and Fondazione D'Amico per la Ricerca sulle Malattie Renali, c/o San Carlo Borromeo Hospital, via Pio II, 3, Milan 20153, Italy.

Although patients with chronic renal failure are increasing worldwide, many aspects of kidney biology remain to be elucidated. Recent research has uncovered several molecular properties of the glomerular filtration barrier, in which podocytes, highly differentiated, ramified cells that enwrap the glomerular basement membrane, have been reported to be mainly responsible for filter's selectivity. We previously described that podocytes express Rab3A, a GTPase restricted to cell types that are capable of highly regulated exocytosis, such as neuronal cells. Here, we first demonstrate by a proteomic study that Rab3A in podocytes coimmmunoprecipitates with molecules once thought to be synapse specific. We then show that podocytes possess structures resembling synaptic vesicles, which contain glutamate, coexpress Rab3A and synaptotagmin 1, and undergo spontaneous and stimulated exocytosis and recycling, with glutamate release. Finally, from the results of a cDNA microarray study, we describe the presence of a series of neuron- and synapse-specific molecules in normal human glomeruli and confirm the glomerular protein expression of both metabotropic and ionotropic glutamate receptors. These data point toward a synaptic-like mechanism of communication among glomerular cells, which perfectly fits with the molecular composition of the glomerular filter and puts in perspective several previous observations, proposing a different working hypothesis for understanding glomerular signaling dynamics.
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http://dx.doi.org/10.1096/fj.05-4962fjeDOI Listing
May 2006

Glomerular podocytes possess the synaptic vesicle molecule Rab3A and its specific effector rabphilin-3a.

Am J Pathol 2003 Sep;163(3):889-99

Renal Immunopathology Laboratory, Associazione Nuova Nefrologia, c/o San Carlo Borromeo Hospital, Via Pio II, 20153 Milan, Italy.

Several recent studies have focused on similarities between glomerular podocytes and neurons because the two cells share a specialized cytoskeletal organization and several expression-restricted proteins, such as nephrin and synaptopodin. In neurons, the small guanosine triphosphatase Rab3A and its effector rabphilin-3A form a complex required for the correct docking of synaptic vesicles to their target membrane. Because rabphilin-3A binds in neurons to cytoskeletal proteins also important for podocyte homeostasis, and the complex rabphilin-3A-Rab3A has been demonstrated in neurons and neuroendocrine cells, the aim of our work was to investigate their possible expression and regulation in podocytes. Normal kidneys from mouse, rat, and human were studied by immunohistochemistry, Western blotting, and reverse transcriptase-polymerase chain reaction to evaluate the expression of Rab3A and rabphilin-3A. Double-staining immunohistochemistry and immunogold electron microscopy were then used to precisely localize the two proteins at the cellular and subcellular levels. Rab-3A and rabphilin-3A regulations in disease were then analyzed in growth hormone-transgenic mice, a well established model of focal and segmental glomerulosclerosis, and in human biopsies from proteinuric patients. Our results demonstrated that rabphilin-3A and Rab3A are present in normal mouse, rat, and human kidneys, with an exclusively glomerular expression and a comma-like pattern of positivity along the glomerular capillary wall, suggestive for podocyte staining. Co-localization of both molecules with synaptopodin confirmed their presence in podocytes. By immunogold electron microscopy both proteins were found around vesicles contained in podocyte foot processes. Their expression was increased in growth hormone-transgenic mice compared to their wild-type counterpart, and in a subset of biopsies from proteinuric patients. Our data, demonstrating the presence of two synaptic proteins in podocytes, further supports similarities between cytoskeletal and vesicular organization of podocytes and neurons. The altered expression observed in mouse and human proteinuric diseases suggests a possible role for these molecules in glomerulopathies.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1868247PMC
http://dx.doi.org/10.1016/S0002-9440(10)63449-9DOI Listing
September 2003