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Autoantibodies against the first component of the classical pathway of complement (anti-C1q) can be found in a number of autoimmune and renal diseases. They are best described in patients with Systemic Lupus Erythematosus (SLE). In adult patients with SLE, there is a strong correlation between the occurrence of anti-C1q and severe lupus nephritis. However, the role of anti-C1q in children with SLE has not yet been determined. Furthermore, the clinical importance of anti-C1q in other forms of glomerulonephritis (GN) remains to be elucidated. The aim of this study was to investigate the role of anti-C1q in children with different forms of GN including SLE nephritis. 100 children with different forms of GN were analyzed (52m, 48 f, age range 2 to17, median12 years) and compared to 29 healthy controls (age range 5 to 17, median 12 years). Renal biopsies were available in 62 patients. From the patients 35 had acute and 65 chronic GN. In the group with acute GN 14 had post-streptococcal GN (APGN) and 21 other causes. In the group with chronic GN 11 patients had proliferative lupus nephritis (WHO class III or IV). In acute GN only patients with APGN were positive for anti-C1q (3/14). From the APGN patients only the 3 anti-C1q positive did not resolve spontaneously. In chronic GN, anti-C1q were mainly found in patients with lupus nephritis (6/11). From the 6 anti-C1q positive SLE patients 5 had clinically active and one had inactive GN. Of the anti- C1q negative SLE patients, two had active lupus nephritis. One of them was under aggressive long-term immunosupression, the other one had spontaneously improving disease in spite of a positive renal biopsy. Another 6 patients with chronic GN were anti-C1q positive: 5 with mesangioproliferative GN (5/26) and 1 with Rheumatoid vasculitis. In conclusion, as observed in adults, anti-C1q are associated with active lupus nephritis. In children with APGN anti-C1q were only found in patients without spontaneous resolution of the disease suggesting a disease modifying role of anti-C1q in APGN. [ABSTRACT FROM AUTHOR]

Introduction: diabetes is a leading cause of death, disability, and high healthcare costs, especially among patients with poor glycemic control. Providing decentralized diabetes care to patients in low-income countries remains a major challenge. We aimed to assess hemoglobin A1C (HbA1c) level of patients enrolled in primary-level non-communicable disease clinics of Rwamagana, Rwanda, and identify predictors associated with a) change in HbA1c level over a 6-month period or b) achieving HbA1c <7%. We also explored whether living in a community with a home-based care practitioner was associated with HbA1c-related outcomes., Methods: we conducted structured interviews and HbA1c testing among patients with type 2 diabetes at baseline and after six months. Multivariable linear regression and multivariable logistic regression were used., Results: hundred and thirty (130) participants enrolled at baseline, and 123 patients remained in the study after six months. At baseline, 26% of patients had HbA1c <7%. After 6-months, 37% of patients had HbA1c <7%. Factors correlated with the greatest improvements in HbA1c were having HbA1c >9% at baseline, while factors associated with having HbA1c <7% after six months included older age and having HbA1c <7% at baseline. We did not find significant associations between home-based care practitioners and improvement in HbA1c level or achieving HbA1c <7., Conclusion: the number of patients with well-controlled glycemia improved over time during this study but was still low overall. Care provided by home-based care practitioners was not associated with six-month HbA1c outcomes. Enhanced care is needed to achieve glycemia control in primary healthcare settings., Competing Interests: The authors declare no competing interests., (Copyright: Sadallah Bahizi et al.)

Acute post-infections glomerulonephritis (APIGN) is a frequent cause of glomerulonephritis and represents the most common cause of acute glomerulonephritis in children. It can evolve to severe acute renal failure and chronic kidney disease or even end-stage kidney disease. The precise pathophysiological mechanisms of APIGN are still incompletely understood. The implication of the alternative complement pathway and the potential benefits of C5 blockade have been recently highlighted, in particular in the presence of a C3 Nephritic Factor (C3Nef), anti-Factor B or H autoantibodies. We report two children with severe APIGN, successfully treated with eculizumab. The first patient presented a severe form of APIGN with advanced renal failure and anuria, associated with a decreased level of C3 and an increased level of soluble C5b-9, in the presence of a C3NeF autoantibody. The second case had a severe oliguric APIGN associated with low C3 level. Kidney biopsy confirmed the diagnosis of APIGN in both cases. Eculizumab allowed full renal function recovery and the avoidance of dialysis in both cases. In conclusion, the alternative and terminal complement pathways activation might be common in PIGN, and in severe cases, eculizumab might help., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Chehade, Guzzo, Cachat, Rotman, Teta, Pantaleo, Sadallah, Sharma, Rosales, Tolkoff-Rubin and Pascual.)

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Despite appropriate therapy, 20-40% of affected-patients evolve toward end-stage kidney disease (ESKD). Mesangial IgA deposits are the hallmark of IgAN, and complement deposition (C3) seems to differentiate latent IgA mesangial deposits from active IgAN. Atypical hemolytic uremic syndrome (aHUS), another disease in which complement plays an important role, is caused by inherited or acquired deregulation of the alternative pathway (AP) of complement. A subgroup of IgAN shows thrombotic microangiopathy (TMA) lesions in kidney biopsies, the histological characteristic of aHUS. Genetic variants of complement Factor H (CFH), known to be present in aHUS, have been associated with rapidly progressive forms of IgAN and a clinical pattern of aHUS. Genome-wide association studies (GWAS) have confirmed that the 1q32 region, encoding for CFH and its related proteins, is an IgAN susceptibility locus. A 30 year-old man was admitted for seizures and malignant hypertension. The kidney biopsy showed IgAN associated with features of TMA. Despite five plasma exchanges, the patient remained dialysis-dependent, and ESKD was diagnosed. Functional and genetic complement analysis were performed. A monoallelic protein-truncating, likely loss-of-function variant was identified in the CFHR5 gene. Eculizumab is the treatment of aHUS. As it has been successfully used in a few cases of rapidly progressive IgAN, it was decided to administer eculizumab over a period of 12 months in addition to the usual immunosuppression for renal transplantation. After a follow-up of 3 years, there was no clinical disease recurrence. Systematic biologic and genetic screening of complement in individuals with IgAN might be useful to better delineate the role of the AP of complement in renal disease progression, and this may have therapeutic implications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Guzzo, Sadallah, Fodstad, Venetz, Rotman, Teta, Gauthier, Pantaleo, Superti-Furga and Pascual.)

In the last few years, there has been a growing interest in the study of complement, fueleld mainly by the design of complement modulators, especially the C5-blocker eculizumab. The latter has significantly improved the prognosis of some nephropathies, such as the atypical hemolytic uremic syndrome. This breakthrough is a perfect example of fundamental translational research leading to clinical applications for patients. Currently, new molecules are being developed and some of them have already demonstrated clinical efficacy, such as avacopan (C5aR blocker) in ANCA vasculitis. As for kidney transplantation, complement modulators may lead to a new perspective in the treatment of some complications, such as humoral rejection. However, complement modulators carry the side effects, especially the infectious, and high costs., Competing Interests: Fadi Fakhouri a reçu des honoraires de consultant de la part de Roche, Alexion, Novartis et Achillion. Les autres auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Objective: To first describe and estimate the potential pathogenic role of Ig4 autoantibodies in complement-mediated thrombotic microangiopathy (TMA) in a patient with IgG4-related disease (IgG4-RD)., Methods: This study is a case report presenting a retrospective review of the patient's medical chart. Plasma complement C3 and C4 levels, immunoglobulin isotypes and subclasses were determined by nephelometry, the complement pathways' activity (CH50, AP50, MBL) using WIESLAB ® Complement System assays. Human complement factor H levels, anti-complement factor H auto-antibodies were analyzed by ELISA, using HRP-labeled secondary antibodies specific for human IgG, IgG4, and IgA, respectively. Genetic analyses were performed by exome sequencing of 14 gens implicated in complement disorders, as well as multiplex ligation-dependent probe amplification looking specifically for CFH, CFHR1-2-3, and 5 ., Results: Our brief report presents the first case of IgG4-RD with complement-mediated TMA originating from both pathogenic CFHR 1 and CFHR 4 genes deletions, and inhibitory anti-complement factor H autoantibodies of the IgG4 subclass. Remission was achieved with plasmaphereses, corticosteroids, and cyclophosphamide. Following remission, the patient was diagnosed with lymphocytic meningitis and SARS-CoV-2 pneumonia with an uneventful recovery., Conclusion: IgG4-RD can be associated with pathogenic IgG4 autoantibodies. Genetic predisposition such as CFHR 1 and CFHR 4 gene deletions enhance the susceptibility to the formation of inhibitory anti-Factor H IgG4 antibodies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Breville, Zamberg, Sadallah, Stephan, Ponte and Seebach.)

Background: Global investments in neonatal survival have resulted in a growing number of children with morbidities surviving and requiring ongoing care. Little is known about the caregivers of these children in low- and middle-income countries, including maternal mental health which can further negatively impact child health and development outcomes. We aimed to assess the prevalence and factors associated with poor maternal mental health in mothers of children born preterm, low birthweight (LBW), and with hypoxic ischemic encephalopathy (HIE) at 24-47 months of age in rural Rwanda., Methods: Cross-sectional study of children 24-47 months born preterm, LBW, or with HIE, and their mothers discharged from the Neonatal Care Unit (NCU) at Kirehe Hospital between May 2015-April 2016 or discharged and enrolled in a NCU follow-up program from May 2016-November 2017. Households were interviewed between October 2018 and June 2019. Mothers reported on their mental health and their child's development; children's anthropometrics were measured directly. Backwards stepwise procedures were used to assess factors associated with poor maternal mental health using logistic regression., Results: Of 287 total children, 189 (65.9%) were born preterm/LBW and 34.1% had HIE and 213 (74.2%) screened positive for potential caregiver-reported disability. Half (n = 148, 51.6%) of mothers reported poor mental health. In the final model, poor maternal mental health was significantly associated with use of violent discipline (Odds Ratio [OR] 2.29, 95% Confidence Interval [CI] 1.17,4.45) and having a child with caregiver-reported disability (OR 2.96, 95% CI 1.55, 5.67). Greater household food security (OR 0.80, 95% CI 0.70-0.92) and being married (OR = 0.12, 95% CI 0.04-0.36) or living together as if married (OR = 0.13, 95% CI 0.05, 0.37) reduced the odds of poor mental health., Conclusions: Half of mothers of children born preterm, LBW and with HIE had poor mental health indicating a need for interventions to identify and address maternal mental health in this population. Mother's poor mental health was also associated with negative parenting practices. Specific interventions targeting mothers of children with disabilities, single mothers, and food insecure households could be additionally beneficial given their strong association with poor maternal mental health.

Acute antibody-mediated rejection (AMR) early after transplant remains a challenge, both in allotransplantation and in xenotransplantation. We report the case of an early and severe acute AMR episode in a kidney transplant recipient that was successfully treated with upfront eculizumab. A 58-year-old woman had been on dialysis since 2014. She underwent a first kidney transplant in 2018 with primary non-function and received several blood transfusions. Postoperatively, she developed anti-HLA antibodies. One year later, she received a second allograft from a deceased donor. At day 0, there was only one preformed low-level donor-specific antibody (DSA) anti-DQ7. After initial excellent allograft function, serum creatinine increased on days 7-9, and this was associated with oligo-anuria. On day 7, there was an increase in her DSA anti-DQ7 and 4 de novo DSA had developed at high MFI values. Allograft biopsy showed severe active AMR with diffuse C4d deposits in peritubular capillaries. The early acute AMR episode was treated with upfront eculizumab administration (2 doses) with efficient CH50 blockade (< 10% CH50). Rituximab was also administered on day 12, and intravenous immunoglobulin (IVIG) was given over the following days. There was an excellent clinical response to eculizumab administration. Eculizumab administration rapidly reversed the acute AMR episode without the need for plasmapheresis. Rituximab and IVIG were also used as B-cell immunomodulators to decrease DSA. Blocking efficiently the terminal complement pathway may become a useful strategy to treat acute AMR in sensitized recipients of allografts, and possibly in recipients of discordant xenografts., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Introduction: Primary breast tuberculosis is a rare form of extrapulmonary tuberculosis even in endemic regions. To our knowledge, this is the first report of Primary breast tuberculosis from Syria., Case Presentation: We report a case of a 37-year-old female who admitted to the surgical clinic with a 4-month history of gradually growing mass in the breast. On physical examination there were a palpable mass, painful superficial abscess in her left lateral upper quarter of breast, redness and nipple retraction and ulceration. The patient history and physical examination were clear except for uncontrolled hypothyroidism. Radiological tests including mammography, echography and laboratory investigations were performed. The patient underwent lumpectomy. Histopathologic examination showed caseating Tuberculous Mastitis and a large tuberculous abscess, with no malignancy. Patient was put on anti-tubercular chemotherapy, but recurred after three months with three masses in the same area because she did not adhere to the treatment. Lumpectomy and Anti-tuberculous therapy were repeated again with close follow-up, and the patient recovered., Discussion: Primary breast tuberculosis forms about 0.025-0.1 % of all surgically treated breast diseases. Diagnosis is based on bacteriological and histological examination. We can get higher accuracy in diagnosis by biopsy such as a core needle or surgical biopsy, surgical biopsy is necessary to confirm the diagnosis of tuberculous mastitis., Conclusion: Tuberculous mastitis is extremely rare variant of extrapulmonary tuberculosis. However, it should be kept in the mind of physicians and pathologists while approaching a breast mass, especially in endemic area., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Appendiceal duplication is a rare congenital anomaly with an estimated incidence ranging from 0.004 to 0.009%. Preoperative diagnosis of a duplicated appendix is often difficult and is usually done intraoperatively. Histopathological examination of the surgical specimen is mandatory to confirm the presence of two appendices. In this case we report a female patient with acute inflammation in one of her two appendices. Surgeons should always bear in mind this rare anomaly to avoid serious ethical and legal consequences.

The complement system is part of the innate immunity. It is a multifunctional system including more than 30 plasma and membrane proteins. These are activated by an enzymatic cascade and proteolytic reactions producing activating fragments. Complement is : 1) among the first line of defense towards a pathogen, 2) increasing efficacy of the acquired immunity, 3) responsible for the elimination of immune complexes apoptotic and or necrotic cells (waste removal function) and many other cellular and tissue functions. The aim of this article is to analyze the consequences of complement dysregulation in the development of various diseases., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Activation of the complement cascade plays an important role in the pathogenesis of postinfectious glomerulonephritis. We report successful terminal complement pathway blockade using an anti-C5 monoclonal antibody (eculizumab) in an 8-year-old child with severe acute postinfectious glomerulonephritis requiring hemodialysis. The child presented with clinical, serologic, and histopathologic criteria for diffuse crescentic postinfectious glomerulonephritis. Complement measurements showed low C3 and C4 levels, with increased SC5b-9 titers. The presence of a transient anti-factor H autoantibody was also identified. Eculizumab (600mg, 2 doses at a 1-week interval) was administered, with a striking recovery of kidney function. There were no additional hemodialysis sessions needed after the first dose of eculizumab, and glomerular filtration rate measured using inulin clearance at 12 months of follow-up was within the normal range (92mL/min/1.73m 2 ). Prompt terminal complement blockade may have improved the outcome in this case of severe acute postinfectious glomerulonephritis., (Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Platelet (PLT) transfusions are potentially life saving for individuals with low PLT numbers; however, previous work revealed that PLT transfusions are associated with increased infection risk. During storage, PLT intended for transfusion continuously shed ectosomes (Ecto) from their surface, which express immunomodulatory molecules like phosphatidylserine or TGF-β1. Recently, PLT-Ecto were shown to reduce proinflammatory cytokine release by macrophages and to favor the differentiation of naive T cells toward regulatory T cells. Whether PLT-Ecto modify NK cells remains unclear. We exposed purified NK cells and full PBMCs from healthy donors to PLT-Ecto. We found a reduced expression of several activating surface receptors (NKG2D, NKp30, and DNAM-1) and decreased NK cell function, as measured by CD107a expression and IFN-γ production. Pretreatment of PLT-Ecto with anti-TGF-β1 neutralizing Ab restored surface receptor expression and NK cell function. We further observed a TGF-β1-mediated upregulation of miR-183, which, in turn, reduced DAP12, an important protein for stabilization and downstream signaling of several activating NK cell receptors. Again, these effects could antagonized, in part, when PLT-Ecto were preincubated with anti-TGF-β1 Ab. Erythrocyte Ecto did not affect NK cells. Polymorphonuclear cell Ecto expressed MHC class I and inhibited NK cell function. In addition, they induced the secretion of TGF-β1 by NK cells, which participated in an auto/paracrine manner in the suppressive activity of polymorphonuclear cell-derived Ecto. In sum, our study showed that PLT-Ecto could inhibit NK cell effector function in a TGF-β1-dependent manner, suggesting that recipients of PLT transfusions may experience reduced NK cell function., (Copyright © 2016 by The American Association of Immunologists, Inc.)

Aortic valve-sparing procedures are alternative options to aortic valve replacement in patients with aortic root aneurysm and/or severe aortic regurgitation reducing the risk of prosthesis-related complications, such as thromboembolism, and have no need for long-term oral anticoagulation. However, these techniques are technically demanding and long-term results are highly dependent on perfect intraoperative restoration of valve function. We describe a systematic approach to aortic valve-sparing aortic root replacement with the reimplantation technique the way it is currently performed in our institution., (© The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Accumulating evidence suggests an immune-modulatory role for platelets (PLT) and PLT-derived microvesicles. In particular, ectosomes, i.e. vesicles budding from PLT surface, have been shown to exert immunosuppressive activities on phagocytes. Here we investigated the effects mediated by PLT-derived ectosomes (PLT-Ecto) on CD4+ T cells. Exposure of activated CD4+ T cells to PLT-Ecto decreased their release of IFNγ, TNFα and IL-6, and increased the production of TGF-β1. Concomitantly, PLT-Ecto-exposed CD4+ T cells displayed increased frequencies of CD25high Foxp3+ cells. These phenomena were dose-dependent and PLT-Ecto specific, since they were not observed in the presence of polymorphonuclear- and erythrocyte-derived ectosomes. Analysis of specific T cell subsets revealed that PLT-Ecto induced differentiation of naïve T cells into Foxp3+ cells, but had no effect on pre-differentiated Foxp3+ regulatory T cells (Tregs). Importantly, PLT-Ecto-induced Foxp3+ cells were as effective as peripheral blood Tregs in suppressing CD8+ T cell proliferation. PLT-Ecto-mediated effects were partly dependent on PLT-derived TGF-β1, as they were to some extent inhibited by PLT-Ecto pretreatment with TGF-β1-neutralising antibodies. Interestingly, ectosome-derived TGF-β1 levels correlated with Foxp3+ T cell frequencies in blood of healthy donors. In conclusion, PLT-Ecto induce differentiation of CD4+ T cells towards functional Tregs. This may represent a mechanism by which PLT-Ecto enhance peripheral tolerance.

Ectosomes are vesicles shed directly from the cell surface. Human polymorphonuclear neutrophils release ectosomes (PMN-Ect) upon their activation. PMN-Ect expose phosphatidylserine (PS) on the outer leaflet of the plasma membrane, and down-modulate the inflammatory response of human macrophages and dendritic cells exposed to TLR-2 and -4 ligands. This down-modulation is mediated by PS via the engagement and activation of the Mer receptor tyrosine kinase (MerTK). In the present study, we demonstrate that exposure of macrophages to PMN-Ect activates directly 2 additional pathways, an immediate Ca(2+) flux and a rapid release of TGF-β1. As expected, the Ca(2+) flux was necessary for the activation of TLR-2 pathway with the release of cytokines. However, MerTK blockade with antibodies did not modify the Ca(2+) flux, indicating an independent activation of Ca(2+) by PMN-Ect. Striking was that the rapid release of TGF-β1 was independent of the MerTK pathway and did not require a Ca(2+) flux. TGF-β1 was present in cytosolic storage pools, which were depleted after exposure of the macrophages to PMN-Ect, and no increase in TGF-β1 mRNA could be detected in the 3 first hours when maximal release had occurred. The release of TGF-β1 by macrophages was seen only for PMN-Ect and not for PS-liposomes or erythrocyte ectosomes, which express PS. However, blocking the PS of PMN-Ect inhibited TGF-β1 release, suggesting that PS expression was necessary although not sufficient for this release. Interestingly, the effects of PMN-Ect pre-exposure were lasting for 24h with the macrophages being less receptive to TLR-2 activation and TGF-β1 stores remaining low. In sum, PMN-Ect induce several signaling pathways in resting and stimulated macrophages, which include independently the MerTK pathway, Ca(2+) flux and the release of stored TGF-β1, and each might influence the immunomodulatory effects of macrophages., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

Considerable progress has been made in recognizing microvesicles as important mediators of intercellular communication rather than irrelevant cell debris. Microvesicles released by budding directly from the cell membrane surface (i.e., ectocytosis) either spontaneously or in response to various stimuli are called shed vesicles or ectosomes. Ectosomes are rightside-out vesicles with cytosolic content, and they expose phosphatidylserine in the outer leaflet of their membrane. Depending on their cellular origin, ectosomes have been associated with a broad spectrum of biological activities. In the light of recent findings, we now know that ectosomes derived from polymorphonuclear leukocytes, erythrocytes, platelets, and tumor cells have profound effects on the innate immune system, as well as on the induction of the adaptive immunity, globally reprogramming cells such as macrophages or dendritic cells toward an immunosuppressive and possibly tolerogenic phenotype. Although the effects observed in the circulation are mainly procoagulant and pro-inflammatory, ectosomes might be anti-inflammatory/immunosuppressive in local inflammation.

Microparticles (MP) shed by platelets (PLT) during storage have procoagulant activities, but little is known about their properties to modify inflammation or immunity. In this study, we studied the capacity of MP present in PLT concentrates to alter the function of macrophages and dendritic cells (DC). The size of the purified MP was between 100 and 1000 nm, and they expressed phosphatidylserine; surface proteins of PLT (CD61, CD36, CD47), including complement inhibitors (CD55, CD59), but not CD63; and proteins acquired from plasma (C1q, C3 fragments, factor H). These characteristics suggest that the MP shed by PLT are formed by budding from the cell surface, corresponding to ectosomes. The purified PLT ectosomes (PLT-Ect) reduced the release of TNF-α and IL-10 by macrophages activated with LPS or zymosan A. In addition, PLT-Ect induced the immediate release of TGF-β from macrophages, a release that was not modified by LPS or zymosan A. Macrophages had a reduced TNF-α release even 24 h after their exposure to PLT-Ect, suggesting that PLT-Ect induced a modification of the differentiation of macrophages. Similarly, the conventional 6-d differentiation of monocytes to immature DC by IL-4 and GM-CSF was modified by the presence of PLT-Ect during the first 2 d. Immature DC expressed less HLA-DP DQ DR and CD80 and lost part of their phagocytic activity, and their LPS-induced maturation was downmodulated when exposed to PLT-Ect. These data indicate that PLT-Ect shed by stored PLT have intrinsic properties that modify macrophage and DC differentiation toward less reactive states.

At the earliest stage of activation, human polymorphonuclear neutrophils release vesicles derived directly from the cell surface. These vesicles, called ectosomes (PMN-Ect), expose phosphatidylserine in the outer membrane leaflet. They inhibit the inflammatory response of human monocyte-derived macrophages and dendritic cells to zymosan A (ZymA) and LPS and induce TGF-β1 release, suggesting a reprogramming toward a tolerogenic phenotype. The receptors and signaling pathways involved have not yet been defined. Here, we demonstrate that PMN-Ect interfered with ZymA activation of macrophages via inhibition of NFκB p65 phosphorylation and NFκB translocation. The MerTK (Mer receptor tyrosine kinase) and PI3K/Akt pathways played a key role in this immunomodulatory effect as shown using specific MerTK-blocking antibodies and PI3K inhibitors LY294002 and wortmannin. As a result, PMN-Ect reduced the transcription of many proinflammatory genes in ZymA-activated macrophages. In sum, PMN-Ect interacted with the macrophages by activation of the MerTK pathway responsible for down-modulation of the proinflammatory signals generated by ZymA.

Several clinical studies have suggested that blood transfusions are immunosuppressive. Whereas there have been reports describing immunosuppression induced by leukocytes or fragments thereof, the possibility that microparticles, released by erythrocytes during storage, are also involved was not investigated. We present evidence here that such microparticles have all the properties of ectosomes including size, the presence of a lipid membrane, and the specific sorting of proteins. These erythrocyte-derived ectosomes (E-ecto) fixed C1q, which was followed by activation of the classical pathway of complement with binding of C3 fragments. Similarly to ectosomes released by PMN, they express phosphatidylserine on their surface membrane, suggesting that they may react with and down-regulate cells of the immune system. In vitro, they were taken up by macrophages, and they significantly inhibited the activation of these macrophages by zymosan A and LPS, as shown by a significant drop in TNF-alpha and IL-8 release (respectively, 80% and 76% inhibitions). In addition, the effect of E-ecto was not transient but lasted for at least 24 h. In sum, E-ecto may interfere with the innate immune system/inflammatory reaction. Therefore, E-ecto transfused with erythrocytes may account for some of the immunosuppressive properties attributed to blood transfusions.

Objective: Autoantibodies against C1q (anti-C1q) have been found in a number of autoimmune and renal diseases. They are best described in adult patients with systemic lupus erythematosus, where a strong correlation between the occurrence of anti-C1q and severe lupus nephritis (LN) has been observed. However, the role of anti-C1q in children with systemic lupus erythematosus has not yet been determined. Furthermore, the clinical importance of anti-C1q in other forms of glomerulonephritis remains to be elucidated. The aim of this study was to investigate anti-C1q in children with different forms of glomerulonephritis including LN., Methods: We prospectively investigated 112 children with different forms of newly diagnosed glomerulonephritis for the presence of anti-C1q by an enzyme-linked immunosorbent assay and compared them with healthy controls. Associations between anti-C1q and disease manifestations at the time of the measurements and during follow-up were investigated., Results: Twenty-one of 112 patients were positive for anti-C1q compared with 0 of 40 healthy controls. Anti-C1q was associated with activity in LN and with disease severity in patients with acute poststreptococcal glomerulonephritis (APSGN). In LN, 7 of 12 patients were found to be anti-C1q positive. Six of these 7 had active disease at the time of the serum sampling compared with 1 of 5 of the anti-C1q-negative children. In children with APSGN, 8 of 24 were positive for anti-C1q. Anti-C1q-positive APSGN patients had significantly higher proteinuria and more often hypertension than those without anti-C1q. All 4 patients in which APSGN did not resolve spontaneously were anti-C1q positive., Conclusions: Anti-C1q is associated with active LN in children. In addition, children with anti-C1q-positive APSGN have more severe disease than those who are anti-C1q negative. These data suggest APSGN is another disease in which anti-C1q has a pathogenic role.