Publications by authors named "Hanna Jarva"

59 Publications

Real-life clinical sensitivity of SARS-CoV-2 RT-PCR test in symptomatic patients.

PLoS One 2021 21;16(5):e0251661. Epub 2021 May 21.

HUSLAB Clinical Microbiology, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Background: Understanding the false negative rates of SARS-CoV-2 RT-PCR testing is pivotal for the management of the COVID-19 pandemic and it has implications for patient management. Our aim was to determine the real-life clinical sensitivity of SARS-CoV-2 RT-PCR.

Methods: This population-based retrospective study was conducted in March-April 2020 in the Helsinki Capital Region, Finland. Adults who were clinically suspected of SARS-CoV-2 infection and underwent SARS-CoV-2 RT-PCR testing, with sufficient data in their medical records for grading of clinical suspicion were eligible. In addition to examining the first RT-PCR test of repeat-tested individuals, we also used high clinical suspicion for COVID-19 as the reference standard for calculating the sensitivity of SARS-CoV-2 RT-PCR.

Results: All 1,194 inpatients (mean [SD] age, 63.2 [18.3] years; 45.2% women) admitted to COVID-19 cohort wards during the study period were included. The outpatient cohort of 1,814 individuals (mean [SD] age, 45.4 [17.2] years; 69.1% women) was sampled from epidemiological line lists by systematic quasi-random sampling. The sensitivity (95% CI) for laboratory confirmed cases (repeat-tested patients) was 85.7% (81.5-89.1%) inpatients; 95.5% (92.2-97.5%) outpatients, 89.9% (88.2-92.1%) all. When also patients that were graded as high suspicion but never tested positive were included in the denominator, the sensitivity (95% CI) was: 67.5% (62.9-71.9%) inpatients; 34.9% (31.4-38.5%) outpatients; 47.3% (44.4-50.3%) all.

Conclusions: The clinical sensitivity of SARS-CoV-2 RT-PCR testing was only moderate at best. The relatively high false negative rates of SARS-CoV-2 RT-PCR testing need to be accounted for in clinical decision making, epidemiological interpretations, and when using RT-PCR as a reference for other tests.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0251661PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8139477PMC
June 2021

Clinical characteristics and evaluation of the incidence of cryptococcosis in Finland 2004-2018.

Infect Dis (Lond) 2021 09 11;53(9):684-690. Epub 2021 May 11.

HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Background: Cryptococcosis is one of the major causes of mortality among HIV patients worldwide. Though most often associated with late stage HIV infection/AIDS, a significant number of cases occur in other immunocompromised patients such as solid organ transplant recipients and patients with hematological malignancies. Immunocompromised patients are a heterogeneous group and their number increases constantly. Since little is known about the incidence and the clinical features of cryptococcosis in Northern Europe, our aim was to investigate the clinical characteristics of cryptococcosis patients in Finland.

Methods: We retrospectively reviewed the laboratory confirmed cryptococcosis cases in Finland during 2004-2018. Only those who were treated for cryptococcosis were included in the study. Initial laboratory findings and medical records were also collected.

Results: A total of 22 patients with cryptococcosis were included in our study. The annual incidence of cryptococcosis was 0.03 cases per 100,000 population. Ten patients were HIV-positive and 12 out of 22 were HIV-negative. Hematological malignancy was the most common underlying condition among HIV-negative patients.

Conclusions: To our knowledge, this is the first study of the clinical presentation and incidence of cryptococcosis in Finland. We demonstrate that invasive cryptococcal infection occurs not only in HIV/AIDS patients or otherwise immunocompromised patients but also in immunocompetent individuals. Even though cryptococcosis is extremely rare in Finland, its recognition is important since the prognosis depends on rapid diagnostics and early antifungal therapy.
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http://dx.doi.org/10.1080/23744235.2021.1922753DOI Listing
September 2021

Heterologous boosting of nonrelated toxoid immunity during acute Puumala hantavirus infection.

Vaccine 2021 03 4;39(13):1818-1825. Epub 2021 Mar 4.

Department of Bacteriology and Immunology, University of Helsinki, PO BOX 21 (Haartmaninkatu 3), FI-00014 Helsinki, Finland; Translational Immunology Research Program, University of Helsinki, PO. Box 63 (Haartmaninkatu 8), FI-00014 Helsinki, Finland.

Persistence of immune memory in humans is a crucial yet poorly understood aspect of immunology. Here we have studied the effect of Puumala hantavirus infection on unrelated, pre-existing immune memory by studying T cell- and antibody responses against toxoid vaccine antigens of diphtheria, tetanus and pertussis in a cohort of 45 patients. We found that tetanus- and pertussis -specific IgG concentrations elevate during acute Puumala virus infection. Increase in vaccine IgG was associated with proliferation of heterologous T cells. Interestingly, increases in tetanus-specific IgG persisted a year after the infection while pertussis-specific IgG declined rapidly; a difference in IgG kinetics resembling the difference seen after vaccination against tetanus and pertussis. These results suggest that persistence of immune memory is facilitated by heterologous boosting of old memory during memory formation against newly encountered antigens. They also show that different toxoid antigens may be treated differently. Our study gives new insight into how immune memory formation may alter pre-existing immune memory, and also shows that heterologous immunity may have an impact on vaccination outcomes.
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http://dx.doi.org/10.1016/j.vaccine.2021.02.046DOI Listing
March 2021

Activation of the Complement System in the Lower Genital Tract During Pregnancy and Delivery.

Front Immunol 2020 11;11:563073. Epub 2021 Jan 11.

Department of Bacteriology and Immunology and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland.

Background: Human pregnancy alters profoundly the immune system. The local involvement and mechanisms of activation of the complement system in the cervicovaginal milieu during pregnancy and delivery remain unexplored.

Objectives: To determine whether normal pregnancy and delivery are associated with local activation of complement or changes in the immunoglobulin profile in the cervix.

Study Design: This study was designed to assess IgA, IgG, and complement activation in the cervicovaginal area in three groups of patients: i) 49 pregnant women (week 41+3-42+0) not in active labor, ii) 24 women in active labor (38+4-42+2), and iii) a control group of nonpregnant women (n=23) at child-bearing age. We collected mucosal samples from the lateral fornix of the vagina and external cervix during routine visits and delivery. The Western blot technique was used to detect complement C3 and its activation products. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and analyzed. IgA and IgG were analyzed by Western blotting and quantified by ELISA. One-way ANOVA and Tukey's Multiple Comparison tests were used for statistical comparisons.

Results: A higher abundance but lower activation level of C3 in both the external cervix (P<0.001) and lateral fornix of the vagina (P<0.001) was observed during delivery (58 ± 22, n= 24) in comparison to the groups of nonpregnant (72 ± 13%; mean ± SD, n=23) and pregnant women (78 ± 22%, n=49). Complement activating IgG was detected in higher abundance than IgA in the cervicovaginal secretions of pregnant women. In a small proportion samples also C3-IgG complexes were detected.

Conclusions: Our results reveal an unexpectedly strong activation of the complement system and the presence IgG immunoglobulins in the cervicovaginal area during pregnancy, active labor, and among nonpregnant women. In contrast to the higher amounts of C3 in the cervicovaginal secretions during labor, its activation level was lower. Complement activating IgG was detected in higher concentrations than IgA in the mucosal secretions during pregnancy and labor. Taken together our results imply the presence a locally operating humoral immune system in the cervicovaginal mucosa.
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http://dx.doi.org/10.3389/fimmu.2020.563073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829332PMC
May 2021

Comparison of Two Commercial Platforms and a Laboratory-Developed Test for Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA.

J Mol Diagn 2021 04 21;23(4):407-416. Epub 2021 Jan 21.

HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Mitigation of the ongoing coronavirus disease 2019 (COVID-19) pandemic requires reliable and accessible laboratory diagnostic services. In this study, the performance of one laboratory-developed test (LDT) and two commercial tests, cobas SARS-CoV-2 (Roche) and Amplidiag COVID-19 (Mobidiag), were evaluated for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory specimens. A total of 183 specimens collected from suspected COVID-19 patients were studied with all three methods to compare their performance. In relation to the reference standard, which was established as the result obtained by two of the three studied methods, the positive percent agreement was highest for the cobas test (100%), followed by the Amplidiag test and the LDT (98.9%). The negative percent agreement was lowest for the cobas test (89.4%), followed by the Amplidiag test (98.8%), and the highest value was obtained for the LDT (100%). The dilution series of positive specimens, however, suggests significantly higher sensitivity for the cobas assay in comparison with the other two assays, and the low negative percent agreement value may be due to the same reason. In general, all tested assays performed adequately. Clinical laboratories need to be prepared for uninterrupted high-throughput testing during the coming months to mitigate the pandemic. To ensure no interruption, it is critical that clinical laboratories maintain several simultaneous platforms in their SARS-CoV-2 nucleic acid testing.
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http://dx.doi.org/10.1016/j.jmoldx.2021.01.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7825913PMC
April 2021

Saliva-based testing for diagnosis of SARS-CoV-2 infection: A meta-analysis.

J Med Virol 2021 03 10;93(3):1256-1258. Epub 2020 Nov 10.

Clinical Microbiology, HUS Diagnostic Center, HUSLAB, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.

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http://dx.doi.org/10.1002/jmv.26613DOI Listing
March 2021

SARS-CoV-2 sample-to-answer nucleic acid testing in a tertiary care emergency department: evaluation and utility.

J Clin Virol 2020 10 27;131:104614. Epub 2020 Aug 27.

HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Finland.

Background: Rapid sample-to-answer tests for detection of SARS-CoV-2 are emerging and data on their relative performance is urgently needed.

Objectives: We evaluated the analytical performance of two rapid nucleic acid tests, Cepheid Xpert® Xpress SARS-CoV-2 and Mobidiag Novodiag® Covid-19, in comparison to a combination reference of three large-scale PCR tests. Moreover, utility of the Novodiag® test in tertiary care emergency departments was assessed.

Results: In the preliminary evaluation, analysis of 90 respiratory samples resulted in 100% specificity and sensitivity for Xpert®, whereas analysis of 107 samples resulted in 93.4% sensitivity and 100% specificity for Novodiag®. Rapid SARS-CoV-2 testing with Novodiag® was made available for four tertiary care emergency departments in Helsinki, Finland between 18 and 31 May, coinciding with a rapidly declining epidemic phase. Altogether 361 respiratory specimens, together with relevant clinical data, were analyzed with Novodiag® and reference tests: 355/361 of the specimens were negative with both methods, and 1/361 was positive in Novodiag® and negative by the reference method. Of the 5 remaining specimens, two were negative with Novodiag®, but positive with the reference method with late Ct values. On average, a test result using Novodiag® was available nearly 8 hours earlier than that obtained with the large-scale PCR tests.

Conclusions: While the performance of novel sample-to-answer PCR tests need to be carefully evaluated, they may provide timely and reliable results in detection of SARS-CoV-2 and thus facilitate patient management including effective cohorting.
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http://dx.doi.org/10.1016/j.jcv.2020.104614DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7451096PMC
October 2020

Microbial complement evasion and vaccine development.

FEBS Lett 2020 08;594(16):2475-2479

Department of Bacteriology and Immunology and Translational Immunology Research Program, University of Helsinki, Finland.

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http://dx.doi.org/10.1002/1873-3468.13892DOI Listing
August 2020

Identifying the inheritable component of human thymic T cell repertoire generation in monozygous twins.

Eur J Immunol 2020 05 14;50(5):748-751. Epub 2020 Jan 14.

Research Programs Unit, Translational Immunology, University of Helsinki, Helsinki, Finland.

We have analyzed T cell receptor repertoires in a unique set of thymus samples from a pair of monozygotic twins. While genetics affect the V(D)J rearrangement and generation of junctional sequences, the thymic selections seem largely stochastic and import no detectable inheritable effect at clonal level.
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http://dx.doi.org/10.1002/eji.201948404DOI Listing
May 2020

Spontaneous Remission in Paroxysmal Nocturnal Hemoglobinuria-Return to Health or Transition Into Malignancy?

Front Immunol 2018 2;9:1749. Epub 2018 Aug 2.

Immunobiology Research Program, Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired syndrome characterized by intravascular hemolysis, thrombosis, and bone marrow failure. The disease is caused by a mutation in the gene that leads to the lack of glycosylphosphatidylinositol-anchored complement regulatory molecules CD55 and CD59 on affected blood cell surfaces. In previous studies, spontaneous clinical remissions have been described. The disease manifestations are very heterogeneous, and we wanted to examine if true remissions and disappearance of the clone occur. In a follow-up of a nation-wide cohort of 106 Finnish patients with a PNH clone, we found six cases, where the clone disappeared or was clearly diminished. Two of the patients subsequently developed leukemia, while the other four are healthy and in clinical remission. According to our data, spontaneous remissions are not as frequent as described earlier. Since the disappearance of the PNH cell clone may indicate either a favorable or a poor outcome-remission or malignancy-careful clinical monitoring in PNH is mandatory. Nevertheless, true remissions occur, and further studies are needed to understand the immunological background of this phenomenon and to obtain a better understanding of the natural history of the disease.
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http://dx.doi.org/10.3389/fimmu.2018.01749DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6082924PMC
October 2019

Soluble HLA-DR serum levels are associated with smoking but not with acute coronary syndrome.

Atherosclerosis 2017 Nov 21;266:58-63. Epub 2017 Sep 21.

Transplantation Laboratory, University of Helsinki, Helsinki, Finland.

Background & Aims: Elevated soluble HLA-DR (sHLA-DR) serum levels have been reported in HLA class II-associated inflammatory disorders. We have previously shown that the HLA class II allele HLA-DRB1*01 may predispose to acute coronary syndromes (ACS). To our knowledge, sHLA-DR serum levels have not been studied in ACS.

Methods: sHLA-DR serum levels were measured in 477 ACS patients as cases and 475 area- and sex-matched controls by sandwich enzyme-linked immunosorbent assay. Binary logistic regression and ordinal logistic regression analyses adjusted for clinical parameters were conducted to evaluate the associations of sHLA-DR levels.

Results: ACS patients had lower sHLA-DR serum levels compared to controls (OR = 0.837; 95% CI = 0.704-0.994; p = 0.043). After adjustment for smoking status, this association was no longer significant. This was explained by the notion that current smoking was inversely associated with sHLA-DR levels both in cases (OR = 0.592; 95% CI = 0.553-0.908; p = 0.016) and in controls (OR = 0.356; 95% CI = 0.226-0.563; p = 0.000010). A similar effect was not seen with other cardiovascular risk factors.

Conclusions: The results indicate, for the first time, that lower sHLA-DR levels are associated with smoking, but not with ACS. This is an important finding because previous studies of sHLA-DR have not accounted for the possible associations between smoking and sHLA-DR levels. Further studies are required to confirm these novel results and explore the mechanisms behind the observed associations.
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http://dx.doi.org/10.1016/j.atherosclerosis.2017.09.023DOI Listing
November 2017

Genotypic and phenotypic diversity of Lactobacillus rhamnosus clinical isolates, their comparison with strain GG and their recognition by complement system.

PLoS One 2017 11;12(5):e0176739. Epub 2017 May 11.

Department of Bacteriology & Immunology and Research Programs Unit, Immunobiology, University of Helsinki, Finland.

Lactobacillus rhamnosus strains are ubiquitous in fermented foods, and in the human body where they are commensals naturally present in the normal microbiota composition of gut, vagina and skin. However, in some cases, Lactobacillus spp. have been implicated in bacteremia. The aim of the study was to examine the genomic and immunological properties of 16 clinical blood isolates of L. rhamnosus and to compare them to the well-studied L. rhamnosus probiotic strain GG. Blood cultures from bacteremic patients were collected at the Helsinki University Hospital laboratory in 2005-2011 and L. rhamnosus strains were isolated and characterized by genomic sequencing. The capacity of the L. rhamnosus strains to activate serum complement was studied using immunological assays for complement factor C3a and the terminal pathway complement complex (TCC). Binding of complement regulators factor H and C4bp was also determined using radioligand assays. Furthermore, the isolated strains were evaluated for their ability to aggregate platelets and to form biofilms in vitro. Genomic comparison between the clinical L. rhamnosus strains showed them to be clearly different from L. rhamnosus GG and to cluster in two distinct lineages. All L. rhamnosus strains activated complement in serum and none of them bound complement regulators. Four out of 16 clinical blood isolates induced platelet aggregation and/or formed more biofilms than L. rhamnosus GG, which did not display platelet aggregation activity nor showed strong biofilm formation. These findings suggest that clinical L. rhamnosus isolates show considerable heterogeneity but are clearly different from L. rhamnosus GG at the genomic level. All L. rhamnosus strains are still normally recognized by the human complement system.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0176739PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426626PMC
September 2017

Multi-parametric surface plasmon resonance platform for studying liposome-serum interactions and protein corona formation.

Drug Deliv Transl Res 2017 04;7(2):228-240

Centre for Drug Research and Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5, P.O. Box 56, FI-00014, Helsinki, Finland.

When nanocarriers are administered into the blood circulation, a complex biomolecular layer known as the "protein corona" associates with their surface. Although the drivers of corona formation are not known, it is widely accepted that this layer mediates biological interactions of the nanocarrier with its surroundings. Label-free optical methods can be used to study protein corona formation without interfering with its dynamics. We demonstrate the proof-of-concept for a multi-parametric surface plasmon resonance (MP-SPR) technique in monitoring the formation of a protein corona on surface-immobilized liposomes subjected to flowing 100 % human serum. We observed the formation of formulation-dependent "hard" and "soft" coronas with distinct refractive indices, layer thicknesses, and surface mass densities. MP-SPR was also employed to determine the affinity (K ) of a complement system molecule (C3b) with cationic liposomes with and without polyethylene glycol. Tendency to create a thick corona correlated with a higher affinity of opsonin C3b for the surface. The label-free platform provides a fast and robust preclinical tool for tuning nanocarrier surface architecture and composition to control protein corona formation.
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http://dx.doi.org/10.1007/s13346-016-0320-0DOI Listing
April 2017

Expanded CD4(+) Effector/Memory T Cell Subset in APECED Produces Predominantly Interferon Gamma.

J Clin Immunol 2016 08 4;36(6):555-63. Epub 2016 Jun 4.

Department of Bacteriology and Immunology, Immunobiology Research Program, Haartman Institute, University of Helsinki, PB21, Haartmaninkatu 3, 00014, Helsinki, Finland.

Purpose: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare human autoimmune disorder caused by mutations in the AIRE (autoimmune regulator) gene. Loss of AIRE disrupts thymic negative selection and gives rise to impaired cytotoxic and regulatory T cell populations. To date, CD4(+) T helper (Th) cells remain little studied. This study aims to elucidate their role in APECED pathogenesis.

Methods: Th cells were explored in ten APECED patients and ten healthy controls using cell culture assays, multiparameter flow cytometry, and transcriptome analysis.

Results: The proportions of effector/memory populations were increased while the fraction of naive cells was diminished. The naive population was abnormally activated, with an increased number of cells expressing characteristic Th1, Th2, and Th17 cytokines. No clear deviation to any Th subclass was observed, but transcriptome analysis suggested abnormalities in the Th1 cytokine interferon gamma (IFN-γ) pathway and flow cytometry showed that INF-γ had the highest expression. The augmented INF-γ signaling may promote the function of the putative pathogenic CD8(+) cytotoxic population in the patients. In addition, the frequency of CD4(+) recent thymic emigrants (RTEs) was decreased in the patients, and RTEs also contained cytokine-producing cells at an increased frequency.

Conclusion: These data reveal abnormalities in the Th population and suggest that they may in part be traced to premature activation already in the thymus.
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http://dx.doi.org/10.1007/s10875-016-0302-5DOI Listing
August 2016

Anticommensal Responses Are Associated with Regulatory T Cell Defect in Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy Patients.

J Immunol 2016 Apr 22;196(7):2955-64. Epub 2016 Feb 22.

Department of Bacteriology and Immunology, University of Helsinki, 00290 Helsinki, Finland; Research Programs Unit, Immunobiology Research Program, University of Helsinki, 00014 Helsinki, Finland;

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a monogenic autoimmune disease caused by mutations in the AIRE gene. Although mainly an endocrine disease, a substantial fraction of patients have gastrointestinal manifestations. In this study, we have examined the role of anticommensal responses and their regulation. APECED patients had increased levels of Abs against Saccharomyces cerevisiae (p < 0.0001) and against several species of commensal gut bacteria, but not against species predominantly associated with other locations. The anticommensal Ab levels did not correlate with gastrointestinal autoantibodies, neutralizing anti-IL-17 or -IL-22 Abs, or gastrointestinal symptoms, although scarcity of the available clinical data suggests that further study is required. However, the anti-S. cerevisiae Ab levels showed a significant inverse correlation with FOXP3 expression levels in regulatory T cells (Treg), previously shown to be dysfunctional in APECED. The correlation was strongest in the activated CD45RO(+) population (ρ = -0.706; p < 0.01). APECED patients also had decreased numbers of FOXP3(+) cells in gut biopsies. These results show that APECED patients develop early and sustained responses to gut microbial Ags in a pattern reminiscent of Crohn's disease. This abnormal immune recognition of gut commensals is linked to a systemic Treg defect, which is also reflected as a local decrease of gut-associated Treg. To our knowledge, these data are the first to show dysregulated responses to non-self commensal Ags in APECED and indicate that AIRE contributes to the regulation of gut homeostasis, at least indirectly. The data also raise the possibility of persistent microbial stimulation as a contributing factor in the pathogenesis of APECED.
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http://dx.doi.org/10.4049/jimmunol.1500301DOI Listing
April 2016

The Salivary Scavenger and Agglutinin (SALSA) in Healthy and Complicated Pregnancy.

PLoS One 2016 1;11(2):e0147867. Epub 2016 Feb 1.

Immunobiology Research Program, Research Programs Unit, and Department of Bacteriology & Immunology, Medical Faculty, University of Helsinki, Helsinki, Finland.

Pre-eclampsia is a leading cause of maternal and perinatal morbidity and mortality worldwide. The etiology is not clear, but an immune attack towards components of placenta or fetus has been indicated. This involves activation of the complement system in the placenta. We have previously described the presence of the complement-regulating protein salivary scavenger and agglutinin (SALSA) in amniotic fluid. In this study we investigated the potential role of SALSA in pregnancy by analyzing its presence in amniotic fluid and placental tissue during healthy and complicated pregnancies. SALSA levels in amniotic fluid increased during pregnancy. Before 20 weeks of gestation the levels were slightly higher in patients who later developed pre-eclampsia than in gestation age-matched controls. In the placenta of pre-eclamptic patients syncytial damage is often followed by the formation of fibrinoid structures. SALSA was found clustered into these fibrinoid structures in partial co-localization with complement C1q and fibronectin. In vitro analysis showed direct protein binding of SALSA to fibronectin. SALSA binds also to fibrin/fibrinogen but did not interfere with the blood clotting process in vitro. Thus, in addition to antimicrobial defense and epithelial differentiation, the data presented here suggest that SALSA, together with fibronectin and C1q, may be involved in the containment of injured placental structures into fibrinoids.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147867PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734712PMC
July 2016

Dysregulation of adaptive immune responses in complement C3-deficient patients.

Eur J Immunol 2015 Mar 19;45(3):915-21. Epub 2015 Jan 19.

Haartman Institute and Research Programs Unit, Immunobiology, University of Helsinki, Helsinki, Finland.

In addition to its effector functions, complement is an important regulator of adaptive immune responses. Murine studies suggest that complement modulates helper T-cell differentiation, and Th1 responses in particular are impaired in the absence of functional complement. Here, we have studied humoral responses to toxoid vaccines in eight patients with C3 deficiency, representing more than 25% of all the known patients worldwide. Serum cytokine levels were also studied. The patients developed normal Ig responses to tetanus and diphtheria toxoids, but IgE levels were low. The pattern of antigen-specific IgG subclasses was abnormal, with increased Th1-related IgG3 responses, low IgG2, and almost completely undetectable IgG4. The patients also had increased amounts of Th1-related cytokines IL-12p70 and IL-21, and these showed a positive correlation with IgG3 levels. Our results confirm that complement modulates Th differentiation, but reveal a more nuanced outcome than previously reported. Since IgG4 has been linked to tolerogenic responses, the data also suggest that in the absence of functional complement at least some aspects of systemic tolerance are impaired.
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http://dx.doi.org/10.1002/eji.201444948DOI Listing
March 2015

The salivary scavenger and agglutinin in early life: diverse roles in amniotic fluid and in the infant intestine.

J Immunol 2014 Nov 15;193(10):5240-8. Epub 2014 Oct 15.

Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki FI-00014, Finland; Immunobiology Research Program, Research Programs Unit, University of Helsinki, Helsinki FI-00014, Finland; Helsinki University Central Hospital Laboratory, Helsinki FI-00029, Finland;

The salivary scavenger and agglutinin (SALSA), also known as gp340 and dmbt1, is an antimicrobial and inflammation-regulating molecule located at the mucosal surfaces. The present study revealed that SALSA was present in the amniotic fluid (AF) and exceptionally enriched in both meconium and feces of infants. Based on immunological and mass spectrometric analysis, SALSA was estimated to constitute up to 4-10% of the total protein amount in meconium, making it one of the most abundant proteins. SALSA proteins in the AF and intestinal samples were polymorphic and exhibited varying polypeptide compositions. In particular, a different abundance of peptides corresponding to functionally important structures was found in the AF and intestinal SALSA. The AF form of SALSA had a more intact structure and contained peptides from the zona pellucida domain, which is involved in cell differentiation and oligomerization. In contrast, the intestinal SALSA was more enriched with the scavenger receptor cysteine-rich domains. The AF, but not the meconium SALSA, bound to Streptococcus pyogenes, S. agalactiae, S. gordonii, and Escherichia coli. Furthermore, differential binding was observed also to known endogenous ligands C1q, mannose-binding lectin, and secretory IgA. Our results have thus identified mucosal body compartments, where SALSA is particularly abundant, and suggest that SALSA exhibits varying functions in the different mucosal locations. The high levels of SALSA in AF and the infant intestine suggest a robust and important function for SALSA during the fetal development and in the mucosal innate immune defense of infants.
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http://dx.doi.org/10.4049/jimmunol.1401631DOI Listing
November 2014

Acinetobacter species in the skin microbiota protect against allergic sensitization and inflammation.

J Allergy Clin Immunol 2014 Dec 26;134(6):1301-1309.e11. Epub 2014 Sep 26.

Unit of Systems Toxicology, Finnish Institute of Occupational Health, Helsinki, Finland. Electronic address:

Background: The human commensal microbiota interacts in a complex manner with the immune system, and the outcome of these interactions might depend on the immune status of the subject.

Objective: Previous studies have suggested a strong allergy-protective effect for Gammaproteobacteria. Here we analyze the skin microbiota, allergic sensitization (atopy), and immune function in a cohort of adolescents, as well as the influence of Acinetobacter species on immune responses in vitro and in vivo.

Methods: The skin microbiota of the study subjects was identified by using 16S rRNA sequencing. PBMCs were analyzed for baseline and allergen-stimulated mRNA expression. In in vitro assays human monocyte-derived dendritic cells and primary keratinocytes were incubated with Acinetobacter lwoffii. Finally, in in vivo experiments mice were injected intradermally with A lwoffii during the sensitization phase of the asthma protocol, followed by readout of inflammatory parameters.

Results: In healthy subjects, but not in atopic ones, the relative abundance of Acinetobacter species was associated with the expression of anti-inflammatory molecules by PBMCs. Moreover, healthy subjects exhibited a robust balance between anti-inflammatory and TH1/TH2 gene expression, which was related to the composition of the skin microbiota. In cell assays and in a mouse model, Acinetobacter species induced strong TH1 and anti-inflammatory responses by immune cells and skin cells and protected against allergic sensitization and lung inflammation through the skin.

Conclusion: These results support the hypothesis that skin commensals play an important role in tuning the balance of TH1, TH2, and anti-inflammatory responses to environmental allergens.
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http://dx.doi.org/10.1016/j.jaci.2014.07.059DOI Listing
December 2014

Pathophysiology of a severe case of Puumala hantavirus infection successfully treated with bradykinin receptor antagonist icatibant.

Antiviral Res 2014 Nov 3;111:23-5. Epub 2014 Sep 3.

Tampere University Hospital, Finland; School of Medicine, University of Tampere, Finland.

We recently described a patient with very severe Puumala hantavirus infection manifested by capillary leakage syndrome and shock. He was successfully treated with the bradykinin receptor antagonist, icatibant (Antonen et al., 2013). Here we report analysis of the pathophysiology which indicated pronounced complement activation, prolonged leukocytosis, extensive fibrinolysis, circulating histones, and defects in liver function. The patient had an uncommon HLA-phenotype, which may have contributed to the severe course of the disease.
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http://dx.doi.org/10.1016/j.antiviral.2014.08.007DOI Listing
November 2014

Complement activation and regulation in preeclamptic placenta.

Front Immunol 2014 9;5:312. Epub 2014 Jul 9.

Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki , Helsinki , Finland ; Immunobiology Research Program, Research Programs Unit, University of Helsinki , Helsinki , Finland ; Division of Clinical Microbiology, Helsinki University Central Hospital Laboratory (HUSLAB) , Helsinki , Finland.

Preeclampsia (PE) is a common disorder of pregnancy originating in the placenta. We examined whether excessive activation or poor regulation of the complement system at the maternal-fetal interface could contribute to the development of PE. Location and occurrence of complement components and regulators in placentae were analyzed. Cryostat sections of placentae were processed from 7 early-onset PE (diagnosis <34 weeks of gestation), 5 late-onset PE, 10 control pregnancies, and immunostained for 6 complement activators and 6 inhibitors. Fluorescence was quantified and compared between PE and control placentae. Gene copy numbers of complement components C4A and C4B were assessed by a quantitative PCR method. Maternal C4 deficiencies (≥1 missing or non-functional C4) were most common in the early-onset PE group (71%), and more frequent in late-onset PE compared to healthy controls (60 vs. 38%). Complement C1q deposition differed significantly between control and patient groups: controls and early-onset PE patients had more C1q than late-onset PE patients (mean p = 0.01 and p = 0.005, respectively). C3 activation was analyzed by staining for C3b/iC3b and C3d. C3d was mostly specific to the basal syncytium and C3b/iC3b diffuse in other structures, but there were no clear differences between the study groups. Activated C4 and membrane-bound regulators CD55, CD46, and CD59 were observed abundantly in the syncytiotrophoblast. Syncytial knots, structures enriched in PE, stained specifically for the classical pathway inhibitor C4bp, whereas the key regulator alternative pathway, factor H (FH) showed a wider distribution in the placenta. Differences in C1q deposition between late- and early-onset PE groups may be indicative of the different etiology of PE symptoms in these patients. Irregular distribution of the complement regulators C4bp and FH in the PE placenta and a higher frequency of C4A deficiencies suggest a disturbed balance between complement activation and regulation in PE.
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http://dx.doi.org/10.3389/fimmu.2014.00312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4088925PMC
July 2014

Significance of zinc in innate immune defense against Streptococcus pyogenes.

Authors:
Hanna Jarva

J Infect Dis 2014 May 20;209(10):1495-6. Epub 2014 Jan 20.

Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Finland.

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http://dx.doi.org/10.1093/infdis/jiu055DOI Listing
May 2014

Human APECED; a Sick Thymus Syndrome?

Front Immunol 2013 Oct 7;4:313. Epub 2013 Oct 7.

Department of Bacteriology and Immunology, Immunobiology Research Program, Haartman Institute, University of Helsinki , Helsinki , Finland.

Loss-of-function mutations in the Autoimmune Regulator (AIRE) gene cause a rare inherited form of autoimmune disease, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, also known as autoimmune polyglandular syndrome type 1. The patients suffer from multiple endocrine deficiencies, the most common manifestations being hypoparathyroidism, Addison's disease, hypogonadism, and secondary amenorrhea, usually accompanied by typical autoantibodies against the target tissues. Chronic mucocutaneous candidiasis is also a prominent part of the disease. The highest expression of AIRE is found in medullary thymic epithelial cells (mTECs). Murine studies suggest that it promotes ectopic transcription of self antigens in mTECs and is thus important for negative selection. However, failed negative selection alone is not enough to explain key findings in human patients, necessitating the search for alternative or additional pathogenetic mechanisms. A striking feature of the human AIRE-deficient phenotype is that all patients develop high titers of neutralizing autoantibodies against type I interferons, which have been shown to downregulate the expression of interferon-controlled genes. These autoantibodies often precede clinical symptoms and other autoantibodies, suggesting that they are a reflection of the pathogenetic process. Other cytokines are targeted as well, notably those produced by Th17 cells; these autoantibodies have been linked to the defect in anti-candida defenses. A defect in regulatory T cells has also been reported in several studies and seems to affect already the recent thymic emigrant population. Taken together, these findings in human patients point to a widespread disruption of T cell development and regulation, which is likely to have its origins in an abnormal thymic milieu. The absence of functional AIRE in peripheral lymphoid tissues may also contribute to the pathogenesis of the disease.
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http://dx.doi.org/10.3389/fimmu.2013.00313DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3791424PMC
October 2013

Impaired intestinal tolerance in the absence of a functional complement system.

J Allergy Clin Immunol 2013 Apr 23;131(4):1167-75. Epub 2012 Oct 23.

Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, and Helsinki University Central Hospital, Helsinki, Finland.

Background: Cells of the innate immune system regulate both adaptive immune responses and the maintenance of tolerance, especially in the gut. However, relatively little is known about the effects of complement on lymphocyte homeostasis.

Objective: This study explored complement C3 deficiency in mice and human subjects for its effect on intestinal tolerance.

Methods: C3-deficient mice and control C57BL/6 mice were fed ovalbumin (OVA) by means of gavage, and subsequent response to immunization with OVA in Freund's adjuvant was monitored. Serum antibodies against commensal microbes were measured, and the activation status of peripheral blood lymphocytes bearing mucosal homing markers was determined from 2 rare cases of C3-deficient patients.

Results: We show in C3-deficient mice and human patients that intestinal tolerance fails in the absence of functional complement. In contrast to wild-type control animals, in which oral tolerance was induced, intragastric administration of OVA did not result in a significantly decreased response to subsequent subcutaneous OVA challenge in C3-deficient mice. In the jejunum of C3-deficient mice the cytokine ratio between IL-10 and IFN-γ or IL-17 levels was decreased, indicating a shift in favor of proinflammatory cytokines. In 2 C3-deficient children the frequency of gut-homing T cells expressing activation markers was increased, and the patients had increased serum IgG levels against gut commensal microbes. The data also suggest that the impaired oral tolerance was at least partly caused by the absence of signaling through C3-binding complement regulators in T cells.

Conclusions: Taken together, our results identify complement as an important and nonredundant regulator of intestinal tolerance.
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http://dx.doi.org/10.1016/j.jaci.2012.09.004DOI Listing
April 2013

Opc expression, LPS immunotype switch and pilin conversion contribute to serum resistance of unencapsulated meningococci.

PLoS One 2012 20;7(9):e45132. Epub 2012 Sep 20.

University of Würzburg, Institute for Hygiene and Microbiology, Würzburg, Germany.

Neisseria meningitidis employs polysaccharides and outer membrane proteins to cope with human serum complement attack. To screen for factors influencing serum resistance, an assay was developed based on a colorimetric serum bactericidal assay. The screening used a genetically modified sequence type (ST)-41/44 clonal complex (cc) strain lacking LPS sialylation, polysaccharide capsule, the factor H binding protein (fHbp) and MutS, a protein of the DNA repair mechanism. After killing of >99.9% of the bacterial cells by serum treatment, the colorimetric assay was used to screen 1000 colonies, of which 35 showed enhanced serum resistance. Three mutant classes were identified. In the first class of mutants, enhanced expression of Opc was identified. Opc expression was associated with vitronectin binding and reduced membrane attack complex deposition confirming recent observations. Lipopolysaccharide (LPS) immunotype switch from immunotype L3 to L8/L1 by lgtA and lgtC phase variation represented the second class. Isogenic mutant analysis demonstrated that in ST-41/44 cc strains the L8/L1 immunotype was more serum resistant than the L3 immunotype. Consecutive analysis revealed that the immunotypes L8 and L1 were frequently observed in ST-41/44 cc isolates from both carriage and disease. Immunotype switch to L8/L1 is therefore suggested to contribute to the adaptive capacity of this meningococcal lineage. The third mutant class displayed a pilE allelic exchange associated with enhanced autoaggregation. The mutation of the C terminal hypervariable region D of PilE included a residue previously associated with increased pilus bundle formation. We suggest that autoaggregation reduced the surface area accessible to serum complement and protected from killing. The study highlights the ability of meningococci to adapt to environmental stress by phase variation and intrachromosomal recombination affecting subcapsular antigens.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045132PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3447861PMC
February 2013

The salivary scavenger and agglutinin binds MBL and regulates the lectin pathway of complement in solution and on surfaces.

Front Immunol 2012 16;3:205. Epub 2012 Jul 16.

Infection Biology Research Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland.

The salivary scavenger and agglutinin (SALSA), also known as gp340, salivary agglutinin and deleted in malignant brain tumor 1, is a 340-kDa glycoprotein expressed on mucosal surfaces and secreted into several body fluids. SALSA binds to a broad variety of microbes and endogenous ligands, such as complement factor C1q, surfactant proteins D and A, and IgA. Our search for novel ligands of SALSA by direct protein-interaction studies led to the identification of mannan-binding lectin (MBL) as a new binding partner. We observed that surface-associated SALSA activates complement via binding of MBL. On the other hand, soluble SALSA was found to inhibit Candida albicans-induced complement activation. Thus, SALSA has a dual complement activation modifying function. It activates the lectin pathway when bound to a surface and inhibits it when free in the fluid phase. These activities are mediated via a direct interaction with MBL. This suggests that SALSA could target the innate immune responses to certain microorganisms and simultaneously limit complement activation in the fluid phase.
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http://dx.doi.org/10.3389/fimmu.2012.00205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397308PMC
August 2012

Functional recruitment of the human complement inhibitor C4BP to Yersinia pseudotuberculosis outer membrane protein Ail.

J Immunol 2012 May 30;188(9):4450-9. Epub 2012 Mar 30.

Infection Biology Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, FIN-00014 Helsinki, Finland.

Ail is a 17-kDa chromosomally encoded outer membrane protein that mediates serum resistance (complement resistance) in the pathogenic Yersiniae (Yersinia pestis, Y. enterocolitica, and Y. pseudotuberculosis). In this article, we demonstrate that Y. pseudotuberculosis Ail from strains PB1, 2812/79, and YPIII/pIB1 (serotypes O:1a, O:1b, and O:3, respectively) can bind the inhibitor of the classical and lectin pathways of complement, C4b-binding protein (C4BP). Binding was observed irrespective of serotype tested and independently of YadA, which is the primary C4BP receptor of Y. enterocolitica. Disruption of the ail gene in Y. pseudotuberculosis resulted in loss of C4BP binding. Cofactor assays revealed that bound C4BP is functional, because bound C4BP in the presence of factor I cleaved C4b. In the absence of YadA, Ail conferred serum resistance to strains PB1 and YPIII, whereas serum resistance was observed in strain 2812/79 in the absence of both YadA and Ail, suggesting additional serum resistance factors. Ail from strain YPIII/pIB1 alone can mediate serum resistance and C4BP binding, because its expression in a serum-sensitive laboratory strain of Escherichia coli conferred both of these phenotypes. Using a panel of C4BP mutants, each deficient in a single complement control protein domain, we observed that complement control protein domains 6-8 are important for binding to Ail. Binding of C4BP was unaffected by increasing heparin or salt concentrations, suggesting primarily nonionic interactions. These results indicate that Y. pseudotuberculosis Ail recruits C4BP in a functional manner, facilitating resistance to attack from complement.
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http://dx.doi.org/10.4049/jimmunol.1103149DOI Listing
May 2012

Capsule null locus meningococci: typing of antigens used in an investigational multicomponent meningococcus serogroup B vaccine.

Vaccine 2012 Jan 19;30(2):155-60. Epub 2011 Nov 19.

University of Würzburg, Institute for Hygiene and Microbiology, Würzburg, Germany.

The investigational multicomponent meningococcus serogroup B vaccine (4CMenB) targets the antigenetically variable population of serogroup B meningococci. Forty-one strains of capsule null locus (cnl) meningococci, which are frequent among healthy carriers, were selected from nine sequence types (ST), which belong to four clonal complexes (cc), and three countries. They were antigen sequence typed and analyzed for antigen expression to predict whether these strains harbor the genes and express the four vaccine antigens of 4CMenB as measured by the meningococcal antigen typing system (MATS). The PorA variant used in the vaccine was not found. The nadA gene was absent in all but one strain, which did not express the antigen in vitro. Only strains of clonal complex ST-198 harbored a factor H binding protein (FHBP) allele of the cross-reactive variant 1 family which is included in the vaccine. All these strains expressed the antigen. Five variants of the Neisserial heparin binding antigen (NHBA) gene were identified. Expression of NHBA was observed in all strains with highest levels in ST-198 cc and ST-845. The data suggest a potential impact of 4CMenB immunization at least on cnl meningococci of the ST-198 cc and ST-845.
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http://dx.doi.org/10.1016/j.vaccine.2011.11.050DOI Listing
January 2012

Functional recruitment of human complement inhibitor C4B-binding protein to outer membrane protein Rck of Salmonella.

PLoS One 2011 10;6(11):e27546. Epub 2011 Nov 10.

Infection Biology Program, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland.

Resistance to complement mediated killing, or serum resistance, is a common trait of pathogenic bacteria. Rck is a 17 kDa outer membrane protein encoded on the virulence plasmid of Salmonella enterica serovars Typhimurium and Enteritidis. When expressed in either E. coli or S. enterica Typhimurium, Rck confers LPS-independent serum resistance as well as the ability to bind to and invade mammalian cells. Having recently shown that Rck binds the inhibitor of the alternative pathway of complement, factor H (fH), we hypothesized that Rck can also bind the inhibitor of the classical and lectin pathways, C4b-binding protein (C4BP). Using flow cytometry and direct binding assays, we demonstrate that E. coli expressing Rck binds C4BP from heat-inactivated serum and by using the purified protein. No binding was detected in the absence of Rck expression. C4BP bound to Rck is functional, as we observed factor I-mediated cleavage of C4b in cofactor assays. In competition assays, binding of radiolabeled C4BP to Rck was reduced by increasing concentrations of unlabeled protein. No effect was observed by increasing heparin or salt concentrations, suggesting mainly non-ionic interactions. Reduced binding of C4BP mutants lacking complement control protein domains (CCPs) 7 or 8 was observed compared to wt C4BP, suggesting that these CCPs are involved in Rck binding. While these findings are restricted to Rck expression in E. coli, these data suggest that C4BP binding may be an additional mechanism of Rck-mediated complement resistance.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0027546PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3213152PMC
May 2012
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