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Adeno-associated virus (AAV) vectors are proving to be clinically transformative tools in the treatment of monogenic genetic disease. Rapid ongoing development of this technology promises to not only increase the number of monogenic disorders amenable to this approach but also to bring diseases with complex multigenic and nongenetic etiologies within therapeutic reach. In this study, we explore the broader paradigm of converting the liver into a biofactory for systemic output of therapeutic molecules using AAV-mediated delivery of the endonuclease DNaseI as an exemplar. DNaseI can clear neutrophil extracellular traps (NETs), which are nuclear-protein structures possessing antimicrobial action, also involved in the pathophysiology of clinically troubling immune-mediated diseases. However, a translational challenge is short half-life of the enzyme

ANCA-associated vasculitis (AAV) is intricately linked with infections. Toll-like receptors (TLR) provide a potential link between infection and anti-myeloperoxidase (MPO) autoimmunity. TLR9 ligation has been shown to promote anti-MPO autoimmunity and glomerular vasculitis in murine MPO-AAV. This study investigates dendritic cell TLR9 ligation in murine experimental anti-MPO glomerulonephritis. We analyzed autoimmune responses to MPO following transfer of TLR9 stimulated, MPO pulsed dendritic cells and kidney injury following a sub-nephritogenic dose of sheep anti-mouse glomerular basement membrane globulin. TLR9 ligation enhanced dendritic cell activation upregulating CD40 and CD80 expression, promoting systemic anti-MPO autoimmunity and T cell recall responses and exacerbating kidney injury. CD40 upregulation by TLR9 was critical for the induction of nephritogenic autoimmunity. The presence of DEC205, which transports the TLR9 ligand to TLR9 located in the endosome, also promoted kidney injury. This confirms TLR9 mediated dendritic cell activation as a mechanism of anti-MPO autoimmunity in AAV and further defines the link between infection and the generation of MPO specific autoimmune inflammation.

Heterologous immunity, when the memory T cell response elicited by one pathogen recognizes another pathogen, has been offered as a contributing factor for the high variability in coronavirus disease 2019 (COVID-19) severity outcomes. Here we demonstrate that sensitization with bacterial peptides can induce heterologous immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) derived peptides and that vaccination with the SARS-CoV-2 spike protein can induce heterologous immunity to bacterial peptides. Using in silico prediction methods, we identified 6 bacterial peptides with sequence homology to either the spike protein or non-structural protein 3 (NSP3) of SARS-CoV-2. Notwithstanding the effects of bystander activation, in vitro co-cultures showed that all individuals tested (n=18) developed heterologous immunity to SARS-CoV-2 peptides when sensitized with the identified bacterial peptides. T cell recall responses measured included cytokine production (IFN-γ, TNF, IL-2), activation (CD69) and proliferation (CellTrace). As an extension of the principle of heterologous immunity between bacterial pathogens and COVID-19, we tracked donor responses before and after SARS-CoV-2 vaccination and measured the cross-reactive T cell responses to bacterial peptides with similar sequence homology to the spike protein. We found that SARS-CoV-2 vaccination could induce heterologous immunity to bacterial peptides. These findings provide a mechanism for heterologous T cell immunity between common bacterial pathogens and SARS-CoV-2, which may explain the high variance in COVID-19 outcomes from asymptomatic to severe. We also demonstrate proof-of-concept that SARS-CoV-2 vaccination can induce heterologous immunity to pathogenic bacteria derived peptides.

Anti-myeloperoxidase vasculitis (MPO-AAV) is a life-threatening autoimmune disease which causes severe inflammation of small blood vessels, mainly in the kidney. As for many other autoimmune diseases, current treatments, which consist of general immunosuppressants, are partially effective, toxic and broadly immunosuppressive, causing significant and serious adverse effects in many patients. Therefore, there is an urgent need for more targeted and less harmful therapies. Tolerogenic dendritic cells, regulatory T cells and stem cells have emerged as attractive, new and safer options for the treatment for various autoimmune diseases due to their unique and selective immunosuppressive capacity. In this review, we will discuss how these cellular therapies offer potential to become novel and safer treatments for MPO-AAV.

Epidemiological studies and clinical trials suggest Bacillus Calmette-Guérin (BCG) vaccine has protective effects against coronavirus disease 2019 (COVID-19). There are now over 30 clinical trials evaluating if BCG vaccination can prevent or reduce the severity of COVID-19. However, the mechanism by which BCG vaccination can induce severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cell responses is unknown. Here, we identify 8 novel BCG-derived peptides with significant sequence homology to either SARS-CoV-2 NSP3 or NSP13-derived peptides. Using an in vitro co-culture system, we show that human CD4+ and CD8+ T cells primed with a BCG-derived peptide developed enhanced reactivity to its corresponding homologous SARS-CoV-2-derived peptide. As expected, HLA differences between individuals meant that not all persons developed immunogenic responses to all 8 BCG-derived peptides. Nevertheless, all of the 20 individuals that were primed with BCG-derived peptides developed enhanced T cell reactivity to at least 7 of 8 SARS-CoV-2-derived peptides. These findings provide an in vitro mechanism that may account, in part, for the epidemiologic observation that BCG vaccination confers some protection from COVID-19.

Our understanding of immune recognition and response to infection and non-infectious forms of cell damage and death is rapidly increasing. The major focus is on host immunity and microbiological invasion. However, it is also clear that these same pathways are important in the initiation and maintenance of autoimmunity and the damage caused to targeted organs. Understanding the involvement of cell death in autoimmune disease is likely to help define critical pathways in the immunopathogenesis of autoimmune disease and new therapeutic targets. An important immune responder cell population in host defense and autoimmunity is the neutrophil. One autoimmune disease where neutrophils play important roles is MPO-ANCA Microscopic Vasculitis. This a severe disease that results from inflammation to small blood vessels in the kidney, the glomeruli (high blood flow and pressure filters). One of the best studied ways in which neutrophils participate in this disease is by cell death through NETosis resulting in the discharge of proinflammatory enzymes and nuclear fragments. In host defense against infection this process helps neutralize pathogens however in auto immunity NETosis results in injury and death to the surrounding healthy tissues. The major autoimmune target in this disease is myeloperoxidase (MPO) which is found uniquely in the cytoplasm of neutrophils. Although the kidney is the major organ targeted in this disease MPO is not expressed in the kidney. Autoantibodies target surface MPO on activated circulating neutrophils resulting in their lodgment in glomerular capillaries where they NETose releasing extracellularly MPO and nuclear fragments initiating injury and planting the key autoantigen MPO. It is the cell death of neutrophils that changes the kidney from innocent bystander to major autoimmune target. Defining the immunopathogenesis of this autoimmune disease and recognizing critical injurious pathways will allow therapeutic intervention to block these pathways and attenuate autoimmune injury. The insights (regarding mechanisms of injury and potential therapeutic targets) are likely to be highly relevant to many other autoimmune diseases.

Purpose The aim of this study was to determine if measurement of B cell protective immunity was associated with susceptibility to sinopulmonary infection in kidney transplant recipients. Methods and Materials A prospective cohort of 168 patients with stable graft function (median 4.1 years) underwent assessment of B-lymphocyte antigen CD19 (CD19+) cell number, immunoglobulin G concentration, and seroresponses to influenza vaccination upon study entry. Patients received a single dose of a trivalent, seasonal influenza vaccine. Results After 2 years follow-up, 31 patients (18%) developed sinopulmonary infection. CD19+ cell number was strongly associated with future sinopulmonary infection. A higher proportion of patients with CD19+ cell counts below the fifth percentile for controls developed sinopulmonary infections than those above the fifth percentile, 30% (23 of 77 patients) compared with 9% (7 of 79 patients; P = .001). There was a trend toward a higher proportion of patients with reduced immunoglobulin G concentrations developing infections than in the normal range for controls, 29% (14 of 48 patients) compared with 15% (16 of 108 patients; P = .060). Influenza vaccination seroresponses were poor in patients and controls such that they could not be used to identify a subgroup of patients at high risk for the development of severe pulmonary infection. Conclusions Monitoring B-cell numbers represents a simple, inexpensive means of stratifying transplant recipients' risk of sinopulmonary infection.

The effects of formyl peptide receptors (FPRs) on effector T cells and inflammation-causing tissue-resident cells are not well known. Here, we explored the effect of FPR activation on efferent T cell responses in models of rheumatoid arthritis (RA) and on the expansion of fibroblast-like synoviocytes (FLS). Compound 43 (Cpd43; FPR1/2 agonist) was administered to mice with collagen-induced arthritis (CIA) or antigen-induced arthritis (AIA) after disease onset. Joint inflammation/damage and immunity were assessed. FLS were cultured with Cpd43 to test its effects on cell apoptosis and proliferation. To explore the effects of endogenous FPR2 ligands on FLS proliferation, FLS FPR2 was blocked or Annexin A1 (AnxA1) expression silenced. Cpd43 reduced arthritis severity in both models. In CIA, Cpd43 decreased CD4 T cell proliferation and survival and increased the production of the protective cytokine, IFNγ, in lymph nodes. In AIA, Cpd43 increased CD4 apoptosis and production of the anti-inflammatory IL-4, while augmenting the proportion of splenic regulatory T cells and their expression of IL-2Rα. In both models, Cpd43 increased CD4 IL-17A production, without affecting humoral immunity. FPR2 inhibitors reversed Cpd43-mediated effects on AIA and T cell immunity. Cpd43 decreased TNF-induced FLS proliferation and augmented FLS apoptosis in association with intracellular FPR2 accumulation, while endogenous AnxA1 and FPR2 reduced FLS proliferation via the ERK and NFκB pathways. Overall, FPR activation inhibits the expansion of arthritogenic effector CD4 T cells and FLS, and reduces joint injury in experimental arthritis. This suggests the therapeutic potential of FPR ligation for the treatment of RA.

Myeloperoxidase (MPO) anti-neutrophil cytoplasmic Ab (ANCA)–associated vasculitis results from autoimmunity to MPO. IL-17A plays a critical role in generating this form of autoimmune injury but its cell of origin is uncertain. We addressed the hypothesis that IL-17A–producing γδ T cells are a nonredundant requisite in the development of MPO autoimmunity and glomerulonephritis (GN). We studied MPO-ANCA GN in wild type, αβ, or γδ T cell–deficient (C57BL/6, βTCR−/−, and δTCR−/− respectively) mice. Both T cell populations played important roles in the generation of autoimmunity to MPO and GN. Humoral autoimmunity was dependent on intact αβ T cells but was unaffected by γδ T cell deletion. Following MPO immunization, activated γδ T cells migrate to draining lymph nodes. Studies in δTCR−/− and transfer of γδ T cells to δTCR−/− mice show that γδ T cells facilitate the generation of anti-MPO autoimmunity and GN. δTCR−/− mice that received IL-17A−/− γδ T cells demonstrate that the development of anti-MPO autoimmunity and GN are dependent on γδ T cell IL-17A production. Finally, transfer of anti-MPO CD4+ T cell clones to naive δTCR−/− and wild type mice with planted glomerular MPO shows that γδ T cells are also necessary for recruitment of anti-MPO αβ CD4+ effector T cells. This study demonstrates that IL-17A produced by γδ T cells plays a critical role in the pathogenesis of MPO-ANCA GN by promoting the development of MPO-specific αβ T cells.

The NLRP3 inflammasome is an intracellular platform that converts the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 to their active forms in response to 'danger' signals, which can be either host or pathogen derived, and mediates a form of inflammatory cell death called pyroptosis. This component of the innate immune system was initially discovered because of its role in rare autoinflammatory syndromes called cryopyrinopathies, but it has since been shown to mediate injurious inflammation in a broad range of diseases. Inflammasome activation occurs in both immune cells, primarily macrophages and dendritic cells, and in some intrinsic kidney cells such as the renal tubular epithelium. The NLRP3 inflammasome has been implicated in the pathogenesis of a number of renal conditions, including acute kidney injury, chronic kidney disease, diabetic nephropathy and crystal-related nephropathy. The inflammasome also plays a role in autoimmune kidney disease, as IL-1β and IL-18 influence adaptive immunity through modulation of T helper cell subsets, skewing development in favour of Th17 and Th1 cells that are important in the development of autoimmunity. Both IL-1 blockade and two recently identified specific NLRP3 inflammasome blockers, MCC950 and β-hydroxybutyrate, have shown promise in the treatment of inflammasome-mediated conditions. These targeted therapies have the potential to be of benefit in the growing number of kidney diseases in which the NLRP3 inflammasome has been implicated.

Regulatory T cells (Tregs) are CD4+ T cells that can suppress immune responses by effector T cells, B cells and innate immune cells. This review discusses the role that Tregs play in murine models of immune-mediated renal diseases and acute kidney injury and in human autoimmune kidney disease (such as systemic lupus erythematosus, anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic antibody-associated vasculitis). Current research suggests that Tregs may be reduced in number and/or have impaired regulatory function in these diseases. Tregs possess several mechanisms by which they can limit renal and systemic inflammatory immune responses. Potential therapeutic applications involving Tregs include in vivo induction of Tregs or inducing Tregs from naive CD4+ T cells or expanding natural Tregs ex vivo, to use as a cellular therapy. At present, the optimal method of generating a phenotypically stable pool of Tregs with long-lasting suppressive effects is not established, but human studies in renal transplantation are underway exploring the therapeutic potential of Tregs as a cellular therapy, and if successful may have a role as a novel therapy in immune-mediated renal diseases.

Aim Interactions between the co-stimulatory molecule programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, constrain T-cell responses and help maintain peripheral tolerance. Glomerulonephritis can result from a variety of antigens, both self and foreign, and from humoural and cellular effector responses. These studies aimed to define the role of PD1 and its ligands in circulating immune complex glomerulonephritis induced by immunity to a foreign antigen. Methods Immune complex glomerulonephritis was initiated by injecting BALB/c mice with horse spleen apoferritin intraperitoneally daily for 14 days. Inhibitory anti-mouse PD-1, anti-PD-L1 or anti-PD-L2 antibodies were administered every other day. Renal disease and immune responses were studied. Results Daily injection of horse spleen apoferritin-induced proliferative immune complex glomerulonephritis in control antibody-treated mice, but inhibiting PD-1 did not augment renal injury. Specifically, blocking PD-1 did not increase serum antigen-specific antibodies or increase glomerular immunoglobulin G deposition, the hallmark of injury in this model. Furthermore, C3 deposition was unaffected and glomerular macrophages were reduced after anti-PD-1 antibodies. However, anti-PD-1 administration did increase splenocyte proliferation and cytokine production including interferon-γ, interleukin (IL)-4, and IL-17, but not IL-10. Neutralizing either PD-L1 or PD-L2 alone did not result in major alterations in renal injury. Conclusion The endogenous PD-1/PD-L pathway does not limit acute experimental foreign antigen-induced circulating immune complex glomerulonephritis.

Objective Myeloperoxidase (MPO) locally contributes to organ damage in various chronic inflammatory conditions by generating reactive intermediates. The contribution of MPO in the development of experimental lupus is unknown. The aim of this study was to define the role of MPO in murine lupus nephritis (LN). Methods LN was induced in C57BL/6 wild-type (WT) and MPO knockout (MPO–/–) mice by intraperitoneal injection of pristane. Autoimmunity and glomerulonephritis were assessed 20 and 40 weeks after pristane administration. Cell apoptosis, leukocyte accumulation, and cytokine levels in the peritoneal cavity of WT and MPO–/– mice were assessed 3 or 6 days after pristane injection. Results MPO–/– mice developed more severe nephritis than did WT mice 20 and 40 weeks after pristane injection, despite having reduced glomerular deposition of antibody and complement and diminished levels of markers of oxidative stress (oxidized DNA and glutathione sulfonamide). Enhancement of renal disease in MPO-deficient mice correlated with increased accumulation of CD4+ T cells and macrophages in glomeruli, which, in turn, was associated with augmented generation of CD4+ T cell responses and increased activation and migration of dendritic cells in secondary lymphoid organs. In addition, the enhanced renal injury in MPO–/– mice was associated with increased glomerular accumulation of neutrophils and deposition of neutrophil extracellular traps. MPO deficiency also increased early cell apoptosis, leukocyte accumulation, and proinflammatory cytokine expression in the peritoneum. Conclusion MPO attenuates pristane-induced LN by inhibiting early inflammatory responses in the peritoneum and limiting the generation of CD4+ T cell autoimmunity in secondary lymphoid organs.

Inflammation of blood vessels (vasculitis) results from many pathological processes and is found in many different diseases. However, in most situations, the pathological processes inducing vasculitis are unknown. The discovery of anti-neutrophil cytoplasmic autoantibodies (ANCAs) in the 1980s opened the door for studies that eventually led to the description of a new previously undescribed disease, ANCA-associated vasculitis (AAV). Unravelling the immunopathogenesis of this new disease resulted largely from the development of animal models. The major breakthroughs were the description of ANCA, its association with small vessel vasculitis and the discovery of its target autoantigens (myeloperoxidase and Proteinase 3). Three major disease syndromes comprise the AAVs, microscopic polyangiitis, granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis (EGPA). Recent human studies suggest that proteinase 3 and myeloperoxidase associated vasculitis are two separate but related diseases. The ability to induce murine autoimmunity to myeloperoxidase including ANCA (with the same immune staining patterns as human ANCA) and the capacity of this anti-myeloperoxidase autoimmunity to induce disease with many of the characteristic features of human AAV are well developed. However, the development of animal models of anti-proteinase 3 ANCA and EGPA is much less well developed. Animal models are important in understanding the human disease and in particular in defining potential therapeutic targets and in early stage therapeutic testing of potential drugs. Clearly the relevance of animal models depends on how closely they mimic human diseases. The current status of animal models of vasculitis will be described in detail with reference to these criteria.

Objective Myeloperoxidase (MPO) is implicated as a local mediator of tissue damage when released extracellularly in many chronic inflammatory diseases. The purpose of this study was to explore the role of endogenous MPO in experimental rheumatoid arthritis (RA). Methods K/BxN serum–transfer arthritis was induced in C57BL/6 wild-type (WT) and MPO knockout (MPO−/−) mice, and disease development was assessed. MPO activity was measured in joint tissues from mice with or without K/BxN arthritis. Collagen-induced arthritis (CIA) was induced in WT and MPO−/− mice, and disease development and immune responses were examined. MPO expression was assessed in synovial biopsy samples from patients with active RA, and the effect of MPO on synovial fibroblasts was tested in vitro. Results MPO was up-regulated in the joints of mice with K/BxN arthritis, and MPO deficiency attenuated the severity of the disease without affecting circulating cytokine levels. In CIA, MPO−/− mice had enhanced CD4+ T cell responses and reduced frequency of regulatory T cells in the lymph nodes and spleen, as well as augmented interleukin-17A and diminished interferon-γ secretion by collagen-stimulated splenocytes, without an effect on circulating anticollagen antibody levels. Despite enhanced adaptive immunity in secondary lymphoid organs, CIA development was attenuated in MPO−/− mice. Intracellular and extracellular MPO was detected in the synovium of patients with active RA, and human MPO enhanced the proliferation and decreased the apoptosis of synovial fibroblasts in vitro. Conclusion MPO contributes to the development of arthritis despite suppressing adaptive immunity in secondary lymphoid organs. This suggests distinct effects of local MPO on arthritogenic effector responses.

Background The aim of this study was to determine whether a composite score of simple immune biomarkers and clinical characteristics could predict severe infections in kidney transplant recipients. Methods We conducted a prospective study of 168 stable kidney transplant recipients who underwent measurement of lymphocyte subsets, immunoglobulins, and renal function at baseline and were followed up for 2 years for the development of any severe infections, defined as infection requiring hospitalization. A point score was developed to predict severe infection based on logistic regression analysis of factors in baseline testing. Results Fifty-nine (35%) patients developed severe infection, 36 (21%) had two or more severe infections, and 3 (2%) died of infection. A group of 19 (11%) patients had the highest predicted infectious risk (>60%), as predicted by the score. Predictive variables were mycophenolate use, graft function, CD4+, and natural killer cell number. The level of immunosuppression score had an area under the receiver operating curve of 0.75 (95% CI: 0.67-0.83). Conclusion Our level of immunosuppression score for predicting the development of severe infection over 2 years has sufficient prognostic accuracy for identification of high-risk patients. This data can inform research that examines strategies to reduce the risks of infection.

Paul T King,1,2 Stephen R Holdsworth,2 Michael Farmer,1 Nicholas J Freezer,1 Peter W Holmes11Department of Respiratory and Sleep Medicine, 2Monash University Department of Medicine, Monash Medical Centre, Melbourne, Victoria, AustraliaBackground: Bronchiectasis is a common disease and a major cause of respiratory morbidity. Chest pain has been described as occurring in the context of bronchiectasis but has not been well characterized. This study was performed to describe the characteristics of chest pain in adult bronchiectasis and to define the relationship of this pain to exacerbations.Subjects and methods: We performed a prospective study of 178 patients who were followed-up for 8 years. Subjects were reviewed on a yearly basis and assessed for the presence of chest pain. Subjects who had chest pain at the time of clinical review by the investigators were included in this study. Forty-four patients (25%) described respiratory chest pain at the time of assessment; in the majority of cases 39/44 (89%), this occurred with an exacerbation and two distinct types of chest pain could be described: pleuritic (n = 4) and non-pleuritic (n = 37), with two subjects describing both forms. The non-pleuritic chest pain occurred most commonly over both lower lobes and was mild to moderate in severity. The pain subsided as patients recovered. Conclusion: Non-pleuritic chest pain occurs in subjects with bronchiectasis generally in association with exacerbations.Keywords: sputum, collapse, bronchitis, airway obstruction

Progressive renal fibrosis is the final common pathway leading to renal failure irrespective of the initiating cause. Clinical studies of renal fibrosis found that prominent mast cell accumulation correlated with worse outcomes. Mast cells are pluripotent innate immune cells that synthesize and secrete profibrotic mediators. Here we use mast cell–deficient (Kit W-sh/W-sh ) mice to define a functional pathogenic role for these cells in the development of renal fibrosis. Intrarenal collagen deposition was significantly decreased in mast cell–deficient compared to wild-type mice 7 and 14 days after unilateral ureteric obstruction. The intrarenal expression of mRNAs for transforming growth factor-β, α-smooth muscle actin, chemokines, and renal macrophages and CD4 + T cells were also decreased in mast cell–deficient mice. Reconstitution of the mast cell population in mast cell–deficient mice with wild-type bone marrow–derived mast cells restored the pattern and intensity of renal fibrosis to levels seen in wild-type mice following ureteric ligation. Interestingly, the mast cells were recruited, activated, and degranulated within 6h of ureteric ligation. A mast cell stabilizer that impairs degranulation, disodium chromoglycate, significantly attenuated renal fibrosis following ureteric ligation in wild-type mice. Thus, mast cells promote renal fibrosis and their targeting may offer therapeutic potential in the treatment of renal fibrosis.

The T-cell immunoglobulin mucin 1 (Tim-1) modulates CD4 + T-cell responses and is also expressed by damaged proximal tubules in the kidney where it is known as kidney injury molecule-1 (Kim-1). We sought to define the role of endogenous Tim-1 in experimental T-cell–mediated glomerulonephritis induced by sheep anti-mouse glomerular basement membrane globulin acting as a planted foreign antigen. Tim-1 is expressed by infiltrating activated CD4 + cells in this model, and we studied the effects of an inhibitory anti-Tim-1 antibody (RMT1-10) on immune responses and glomerular disease. Crescentic glomerulonephritis, proliferative injury, and leukocyte accumulation were attenuated following treatment with anti-Tim-1 antibodies, but interstitial foxp3 + cell accumulation and interleukin-10 mRNA were increased. T-cell proliferation and apoptosis decreased in the immune system along with a selective reduction in Th1 and Th17 cellular responses both in the immune system and within the kidney. The urinary excretion and renal expression of Kim-1 was reduced by anti-Tim-1 antibodies reflecting diminished interstitial injury. The effects of anti-Tim-1 antibodies were not apparent in the early phase of renal injury, when the immune response to sheep globulin was developing. Thus, endogenous Tim-1 promotes Th1 and Th17 nephritogenic immune responses and its neutralization reduces renal injury while limiting inflammation in cell-mediated glomerulonephritis.

Antimyeloperoxidase antibodies can cause crescentic glomerulonephritis and pulmonary hemorrhage. Toll-like receptors (TLRs) respond to infectious agents activating host defenses, whereas infections potentially initiate disease and provoke relapses. Neutrophils were found to be key effector cells of injury in experimental models, as disease does not occur in their absence and injury is enhanced by lipopolysaccharide (LPS). In this study, highly purified LPS (a pure TLR4 ligand) acted with antimyeloperoxidase antibodies to synergistically increase kidney and lung neutrophil recruitment and functional injury; effects abrogated in TLR4-deficient mice. Increased kidney TLR4 expression after stimulation predominantly occurred in glomerular endothelial cells. Enhanced glomerular neutrophil recruitment correlated with increased kidney mRNA expression of CXCL1 and CXCL2 (homologs of human CXCL8), whereas their preemptive neutralization decreased neutrophil recruitment. Disease induction in bone marrow chimeric mice showed that TLR4 in both bone marrow and renal parenchymal cells is required for maximal neutrophil recruitment and glomerular injury. Further studies in human glomerular cell lines stimulated with LPS found that glomerular endothelial cells were the prominent sources of CXCL8. Thus, our results define a role for TLR4 expression in bone marrow-derived and glomerular endothelial cells in neutrophil recruitment and subsequent functional and histological renal injury in experimental antimyeloperoxidase glomerulonephritis. Kidney International (2010) 78, 1263-1274; doi:10.1038/ki.2010.327; published online 15 September 2010

A major target autoantigen in anti-neutrophil cytoplasmic antibody–associated vasculitis is myeloperoxidase (MPO). Although MPO-specific CD4+ Th cells seem to orchestrate renal injury, the role of the Th17 subset is unknown. We hypothesized that Th17 cells direct injurious anti-MPO autoimmunity in experimental murine anti-MPO–induced glomerulonephritis (GN). We immunized mice with MPO to establish autoimmunity, resulting in systemic IL-17A production with MPO-specific dermal delayed-type hypersensitivity. We triggered disease using antibodies to the glomerular basement membrane to induce glomerular deposition of MPO by neutrophils. Wild-type mice developed necrotizing GN with an influx of glomerular leukocytes and albuminuria. In contrast, mice deficient in the key Th17 effector cytokine IL-17A were nearly completely protected. The protective effects resulted partly from reduced neutrophil recruitment, which led to less disposition of glomerular MPO. To test whether IL-17A also drives autoimmune delayed-type hypersensitivity in the kidney, we injected MPO into the kidneys of MPO-sensitized mice. IL-17A deficiency reduced accumulation of renal macrophages and renal CCL5 mRNA expression. In conclusion, IL-17A contributes to the pathophysiology of autoimmune anti-MPO GN, suggesting that it may be a viable therapeutic target for this disease.

Th1 effector CD4+ cells contribute to the pathogenesis of proliferative and crescentic glomerulonephritis, but whether effector Th17 cells also contribute is unknown. We compared the involvement of Th1 and Th17 cells in a mouse model of antigen-specific glomerulonephritis in which effector CD4+ cells are the only components of adaptive immunity that induce injury. We planted the antigen ovalbumin on the glomerular basement membrane of Rag1(-/-) mice using an ovalbumin-conjugated non-nephritogenic IgG1 monoclonal antibody against alpha3(IV) collagen. Subsequent injection of either Th1- or Th17-polarized ovalbumin-specific CD4+ effector cells induced proliferative glomerulonephritis. Mice injected with Th1 cells developed progressive albuminuria over 21 d, histologic injury including 5.5 +/- 0.9% crescent formation/segmental necrosis, elevated urinary nitrate, and increased renal NOS2, CCL2, and CCL5 mRNA. Mice injected with Th17 cells developed albuminuria by 3 d; compared with Th1-injected mice, their glomeruli contained more neutrophils and greater expression of renal CXCL1 mRNA. In conclusion, Th1 and Th17 effector cells can induce glomerular injury. Understanding how these two subsets mediate proliferative forms of glomerulonephritis may lead to targeted therapies.

SUMMARY: Aim: Statins are widely used for their cholesterol-lowering effects and for prevention of cardiovascular disease. Evidence indicates that these drugs also have immunomodulatory and other non-lipid lowering effects, with studies suggesting benefit in some animal models of immune (particularly T helper (Th)1)-mediated inflammatory disease and their corresponding human disease counterparts. We sought to evaluate the immunomodulatory effects and therapeutic potential of atorvastatin in experimental crescentic glomerulonephritis, a Th1-predominant animal model of glomerulonephritis. Methods: Autologous phase, anti-glomerular basement membrane glomerulonephritis was induced in C57BL/6 mice by intravenous injection of sheep anti-mouse glomerular basement membrane globulin. Mice were administered atorvastatin (10 or 100 mg/kg) or control (phosphate-buffered saline) daily by oral gavage. Immune responses and renal injury were assessed after 21 days. Results: Compared with control-treated mice, treatment with atorvastatin did not alter renal injury (serum creatinine, proteinuria, glomerular crescent formation) or glomerular leukocytic infiltration (CD4+ T cells or macrophages). Atorvastatin resulted in a dose-related increase in circulating serum antibody to the disease-inducing antigen but no differences in antigen-stimulated splenocyte production of Th1/Th2 cytokines. At the higher dose, atorvastatin also led to a significant reduction in apoptosis of splenic CD4+ T lymphocytes. Conclusion: This study demonstrates that statins modulate humoral responses and alter splenic CD4+ T cell apoptosis. However, atorvastatin does not lead to significant changes in T helper cell polarization or renal injury in experimental crescentic glomerulonephritis.

Recent work has shown that the most common abnormality on screening of immune function in cohort of adult subjects with bronchiectasis was a low neutrophil oxidative burst. To assess the functional significance of a low oxidative burst in subjects with idiopathic bronchiectasis. Neutrophils with a low oxidative burst were obtained from six bronchiectasis patients and assessed for their ability to kill Staphylococcus aureus. The results were compared with those obtained using neutrophils from 12 healthy controls subjects and control neutrophils treated with dimethylthiourea (DMTU), an inhibitor of the oxidative burst. The results showed that the bronchiectasis subjects had significantly reduced killing of bacteria compared with controls (p

Bronchiectasis is a heterogeneous disorder with a large number of etiologic factors. The main symptom is a chronic productive cough. The aim of this study was to describe the phenotypes of patients with bronchiectasis who had developed a chronic productive cough in childhood (before 16 years of age) compared with those who had developed a productive cough as adults. One hundred and eighty-two subjects with bronchiectasis diagnosed by computed tomography scanning were studied. Subjects all had a detailed clinical review and assessment of potential etiologic factors performed by the investigators. There were 107 (59%) subjects who developed a chronic productive cough in childhood and 75 (41%) subjects who developed a chronic productive cough in adulthood. There were significant differences in a number of parameters between the two groups including duration of cough, frequency of exacerbations, presence of rhinosinusitis, crackles on examination and lung function. The adult group could be further divided into those who had developed a cough whilst smoking and those who had no obvious relationship with smoking. In conclusion there were a number of significant differences between the child onset and adult onset group that may reflect different phenotypes of bronchiectasis.

Advances in understanding mast cell biology reveal their diverse functional capacity well beyond already established roles in host defense against parasites and allergic disease. Mast cells can initiate, amplify, and direct innate and adaptive immune responses. They also modulate inflammation and regulate immunity. Mast cells potentially induce tissue repair and direct fibrosis; however, they also play other roles in tissue remodeling and repair. Various activation and differentiating signals result in a diverse range of functional phenotypes called "mast cell heterogeneity." Mast cells are significant participants in chronic progressive kidney disease, and their presence is associated with function loss and fibrosis. This suggests a potential role in the fibrotic process, which may involve mast cell activation of local renin-angiotensin systems. Experimental animal studies suggest, however, they do not directly cause renal fibrosis but rather spark inflammation. Evidence for both pro- and anti-inflammatory roles in nephritis is emerging.

Summary Non-typeable Haemophilus influenzae (NTHi) is a major cause of respiratory but rarely systemic infection. The host defence to this bacterium has not been well defined in patients with chronic airway infection. The aim of this study was to assess the effect of humoral immunity in host defence to NTHi. Responses were measured in control and bronchiectasis subjects who had recurrent bronchial infection. Antibody and complement-mediated killing was assessed by incubating NTHi with serum and the role of the membrane–attack complex and classical/alternate pathways of complement activation measured. The effect of one strain to induce protective immunity against other strains was assessed. The effect of antibody on granulocyte intracellular killing of NTHi was also measured. The results showed that both healthy control subjects and bronchiectasis patients all had detectable antibody to NTHi of similar titre. Both groups demonstrated effective antibody/complement-mediated killing of different strains of NTHi. This killing was mediated through the membrane–attack complex and the classical pathway of complement activation. Immunization of rabbits with one strain of NTHi resulted in protection from other strains in vitro. Antibody activated granulocytes to kill intracellular bacteria. These findings may explain why NTHi rarely causes systemic disease in patients with chronic respiratory mucosal infection and emphasize the potential importance of cellular immunity against this bacterium.

Summary Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells have a key role in host defence against infectious pathogens, but their response to bacteria is not well characterized. Non-typeable Haemophilus influenzae is a major cause of respiratory tract infection including otitis media, sinusitis, tonsillitis and chronic bronchitis (especially in chronic obstructive pulmonary disease and bronchiectasis). This bacterium is also present in the pharynx of most healthy adults. The primary factor that may determine whether clinical disease occurs or not is the nature of the lymphocyte response. Here we examined the CTL cell and NK cell responses to nontypeable H. influenzae in healthy control subjects and in subjects who had bronchiectasis and recurrent bronchial infection with this bacterium. Cells were stimulated with live H. influenzae and intracellular cytokine production and release of cytotoxic granules measured. Control subjects had significantly higher levels of interferon gamma production by both CTL and NK cells, while levels of cytotoxic granule release were similar in both groups. The main lymphocyte subsets that proliferated in response to H. influenzae stimulation were the CTL and NK cells. The results suggest that CTL and NK cell responses may be important in preventing disease from nontypeable H. influenzae infection.

Dendritic cells in the kidney take up antigens, but little is known about their role in providing co-stimulatory signals for the activation of CD4(+) cells. This study examined the phenotype of dendritic cells in the renal interstitium and in the lymph node draining the kidney before and after intrarenal ovalbumin injection. After intrarenal injection of the antigen, expression of the co-stimulatory molecules CD86 and programmed cell death ligand 1 (PD-L1) increased on renal dendritic cells, whereas expression of only CD86 increased on dendritic cells of the draining lymph node. The activation and proliferation of antigen-specific CD4(+) cells in the lymph node were assessed by transfer of naïve, fluorescently labeled ovalbumin-specific T cell receptor transgenic cells to mice before antigen administration. Blocking both CD86 and CD80 profoundly inhibited CD4(+) cell proliferation, but CD86 was the dominant CD28 ligand in the early proliferative response of CD4(+) cells. Conversely, activation of PD-1, the receptor expressed on CD4(+) cells that binds PD-L1 and PD-L2, reduced the proliferation of CD4(+) cells in the draining lymph node. Comparing subcutaneous and intrarenal administration of antigen, it was found that CD4(+) cell activation was slower and the effects of combined CD80 and CD86 blockade were more profound when antigen was presented via the kidney compared with the skin. In summary, renal dendritic cells take up antigen and participate in the control of antigen-specific CD4(+) cell proliferation by upregulating co-stimulatory molecules such as CD86 that stimulate CD4(+) cell proliferation and by signaling through PD-1, which prevents an inappropriately exuberant immune response.

T-bet is a transcription factor that is essential for T helper (Th)1 lineage commitment and optimal IFN-gamma production by CD4(+) T cells. We examined the role of T-bet in the development of experimental crescentic glomerulonephritis, which is induced by Th1-predominant, delayed-type hypersensitivity-like responses directed against a nephritogenic antigen. Anti-glomerular basement membrane (GBM) glomerulonephritis was induced in T-bet(-/-) and wild-type C57BL/6 mice. Compared with wild-type controls, renal injury was attenuated in T-bet(-/-) mice with glomerulonephritis, evidenced by less proteinuria, glomerular crescents, and tubulointerstitial inflammation. Accumulation of glomerular CD4(+) T cells and macrophages was decreased, and was associated with reduced intrarenal expression of the potent Th1 chemoattractants CCL5/RANTES and CXCL9/Mig. Supporting the pro-inflammatory nature of T-bet signaling, assessment of systemic immunity confirmed that T-bet(-/-) mice had a reduction in Th1 immunity. The kinetic profile of T-bet mRNA in wild-type mice supported the hypothesis that T-bet deficiency attenuates renal injury in part by shifting the Th1/Th2 balance away from a Th1 phenotype. Expression of renal and splenic IL-17A, characteristically expressed by the Th17 subset of effector T cells, which have been implicated in the pathogenesis of autoimmune disease, was increased in T-bet(-/-) mice. We conclude that T-bet directs Th1 responses that induce renal injury in experimental crescentic glomerulonephritis.

The glomerulonephritides are a collection of separate diseases with differing pathogeneses that collectively are common and important causes of renal disease. Effective, non-toxic immunomodulatory treatments for glomerulonephritis are lacking. This review will focus on our understanding of the role of leukocytes in immune glomerular disease, specifically in severe and rapidly progressive forms of glomerulonephritis, and provide examples of potential therapeutic targets. The glomerulus is a high flow, high pressure capillary plexus bounded by arterioles that is vulnerable to a variety of immune or inflammatory insults. The variety in the pathogenesis of different forms of glomerulonephritis, together with the capacity of both humoral and cellular effector arms to induce injury, means that understanding the pathogenesis of glomerulonephritis is necessary to effectively apply new treatments. Leukocytes are involved in the pathogenesis of glomerulonephritis at several levels, including the loss of tolerance, adaptive immune responses directed by T cells, cellular effectors inducing injury in delayed type hypersensitivity-like reactions, and by macrophage/neutrophil recruitment via the deposition of circulating immune complexes or in situ immune complexes. Evidence is emerging that anti-neutrophil cytoplasmic antibodies activate neutrophils, leading to glomerular capillaritis. Some therapeutic options limit local inflammation, while others modify the underlying pathogenetic immune response. Areas of current interest include the relationship between infiltrating and local cells, limiting effector cell activation, particularly macrophages; as well as understanding and targeting leukocyte recruitment to this unique vasculature. Modifying pathogenetic T or B cells also is a promising strategy in both systemic autoimmunity affecting the kidney and organ specific autoimmunity.

The NLRP3 inflammasome is an intracellular platform that converts the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 to their active forms in response to 'danger' signals, which can be either host or pathogen derived, and mediates a form of inflammatory cell death called pyroptosis. This component of the innate immune system was initially discovered because of its role in rare autoinflammatory syndromes called cryopyrinopathies, but it has since been shown to mediate injurious inflammation in a broad range of diseases. Inflammasome activation occurs in both immune cells, primarily macrophages and dendritic cells, and in some intrinsic kidney cells such as the renal tubular epithelium. The NLRP3 inflammasome has been implicated in the pathogenesis of a number of renal conditions, including acute kidney injury, chronic kidney disease, diabetic nephropathy and crystal-related nephropathy. The inflammasome also plays a role in autoimmune kidney disease, as IL-1β and IL-18 influence adaptive immunity through modulation of T helper cell subsets, skewing development in favour of Th17 and Th1 cells that are important in the development of autoimmunity. Both IL-1 blockade and two recently identified specific NLRP3 inflammasome blockers, MCC950 and β-hydroxybutyrate, have shown promise in the treatment of inflammasome-mediated conditions. These targeted therapies have the potential to be of benefit in the growing number of kidney diseases in which the NLRP3 inflammasome has been implicated.

Myeloperoxidase (MPO) is an enzyme that is found in neutrophils and monocytes/macrophages. Intracellularly, it plays a major role in microbial killing, but extracellularly, it may cause host tissue damage. The role of endogenous MPO was studied during neutrophil-mediated (heterologous) and T helper 1 (Th1)/macrophage-mediated (autologous) phases of crescentic glomerulonephritis. Glomerulonephritis was induced in C57BL/6 wild-type (WT) and MPO-deficient (MPO(-/-)) mice by intravenous injection of sheep anti-mouse glomerular basement membrane globulin. MPO activity was increased in kidneys of WT mice during both the heterologous and autologous phases of glomerulonephritis. During the heterologous phase of glomerulonephritis, proteinuria was decreased, whereas glomerular neutrophil accumulation and P-selectin expression were enhanced in MPO(-/-) mice. In the autologous, crescentic phase of glomerulonephritis, MPO(-/-) mice had increased accumulation of CD4(+) cells and macrophages in glomeruli compared with WT mice. However, no difference in renal injury (crescent formation, proteinuria, and serum creatinine levels) was observed. Neutrophils and macrophages from MPO(-/-) mice exhibited reduced production of reactive oxygen species. Assessment of systemic immunity to sheep globulin showed that MPO(-/-) mice had increased splenic CD4(+) cell proliferation, cytokine production, and dermal delayed-type hypersensitivity, as well as enhanced levels of circulating IgG, IgG1, and IgG3. MPO(-/-) mice also had an augmented Th1:Th2 ratio compared with WT mice (IFN-gamma:IL-4 and IgG3:IgG1 ratios). These results suggest that endogenous MPO locally contributes to glomerular damage during neutrophil-mediated glomerulonephritis, whereas it attenuates initiation of the adaptive immune response inducing crescentic, autologous-phase glomerulonephritis by suppressing T cell proliferation, cytokine production, and Th1:Th2 ratio.

Interactions between the co-stimulatory molecule programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, constrain T-cell responses and help maintain peripheral tolerance. Glomerulonephritis can result from a variety of antigens, both self and foreign, and from humoural and cellular effector responses. These studies aimed to define the role of PD1 and its ligands in circulating immune complex glomerulonephritis induced by immunity to a foreign antigen.Immune complex glomerulonephritis was initiated by injecting BALB/c mice with horse spleen apoferritin intraperitoneally daily for 14 days. Inhibitory anti-mouse PD-1, anti-PD-L1 or anti-PD-L2 antibodies were administered every other day. Renal disease and immune responses were studied.Daily injection of horse spleen apoferritin-induced proliferative immune complex glomerulonephritis in control antibody-treated mice, but inhibiting PD-1 did not augment renal injury. Specifically, blocking PD-1 did not increase serum antigen-specific antibodies or increase glomerular immunoglobulin G deposition, the hallmark of injury in this model. Furthermore, C3 deposition was unaffected and glomerular macrophages were reduced after anti-PD-1 antibodies. However, anti-PD-1 administration did increase splenocyte proliferation and cytokine production including interferon-γ, interleukin (IL)-4, and IL-17, but not IL-10. Neutralizing either PD-L1 or PD-L2 alone did not result in major alterations in renal injury.The endogenous PD-1/PD-L pathway does not limit acute experimental foreign antigen-induced circulating immune complex glomerulonephritis.

T helper (Th) cells belong to the adaptive immune system and provide an effective and antigen-specific means of host protection. Th17 cells are a subset of Th cells, characterized by the production of the inflammatory cytokines interleukin (IL)-17A (IL-17A) and IL-17F, which bind to a receptor complex comprised of IL-17RA and IL-17RC subunits. Th17 cells combat extracellular and fungal infections, but have been implicated in autoimmune diseases. In many autoimmune conditions, the dysregulated immune response involves several parts of the immune system, including autoantibodies, B and T cells. Targeted biological therapies are appealing, as they may prevent unwanted side effects in patients. There is evolving evidence that Th17 cells are important in the kidney, mediating injury in response to vascular or chemical insults to the renal tubules, and in autoimmune diseases of the glomerulus, either through a specific attack on the glomerular basement membrane or as part of a generalized systemic inflammatory disease. Therapies targeting IL-17A, IL-12p40 and IL-17RA are being explored in clinical trials or are being utilized in clinical practice for the treatment of other IL-17 mediated diseases, such as psoriasis. This review explores the current evidence that IL-17A and Th17 cells may be pathogenic in immune kidney disease, including anti-glomerular basement membrane disease, antineutrophil cytoplasmic antibody associated vasculitis and lupus nephritis, as well as in acute kidney injury. It will discuss the place that biological agents against IL-17A, IL-12p40 and IL-17RA may have in the treatment of these conditions.

Summary Background There is little information available on the features of initial presentation of bronchiectasis and documentation of the onset and progress of symptoms leading up to this. Therefore a study was performed on a large cohort of adult patients presenting to Monash Medical Centre (MMC) to survey the course of their disease up to the time of diagnosis. Objectives To characterise the onset and presenting clinical features of bronchiectasis in adults. Methods A cross-sectional study of 103 adults presenting to a tertiary referral hospital with newly diagnosed bronchiectasis. Clinical features of bronchiectasis and results of spirometry, sputum microbiology and radiology were assessed and correlated. Results Most patients had idiopathic bronchiectasis (74%) and did not have other significant disease. The dominant symptom was chronic productive cough present in 98% of patients with other important symptoms being chronic rhinosinusitis (70%), dyspnoea (62%), and fatigue (74%). Most patients had had a chronic productive cough for over 30 years prior to diagnosis and over 80% of patients had chronic respiratory symptoms from childhood. The dominant finding on physical examination was the presence of crackles which were generally bi-basal. Spirometry showed mild airway obstruction with an average forced expiratory volume in 1 s of the cohort of 76% predicted. Radiologic imaging generally showed multilobar disease (80%). Conclusions The typical profile of bronchiectasis in this group of patients was of longstanding productive cough, rhinosinusitis and fatigue in non-smokers with crackles on chest auscultation.

Airway pathologies have been comprehensively researched in adult asthma, but in children, the extent of airway inflammation associated with episodic wheeze, often diagnosed as asthma, has not been fully characterized. It is not clear whether persistent airway inflammation is present in the absence of wheezing symptoms, and there is controversy regarding the role of age and atopy. This study assessed cellular and cytokine markers of airway inflammation in asymptomatic children with a history of episodic wheeze. Children with a history of episodic wheeze and cough (study group) and nonasthmatic patients requiring elective surgery (control group) were recruited. All subjects in the study group had a history of significant episodic wheezing (>2 episodes per year), and used only as-needed beta-agonist treatment. Bronchoalveolar lavage (BAL) was obtained using bronchoscopic lavage (study group) and nonbronchoscopic lavage (control group). Differential cell counts of BAL and flow cytometry were performed to identify T-lymphocyte phenotypes, and intracellular cytokine profiles were measured after phorbol-12-myristate 13-acetate (PMA) stimulation of BAL fluid T-cells. Twenty-one children with a history of 2-12 episodes of wheeze per year and 21 nonasthmatic subjects without respiratory symptoms were recruited. Study and control subjects were matched for age (median age, 5 years) and demographic characteristics. Study subjects had higher IgE levels, but their measurements were still within normal range. No significant differences in BAL differential cell counts were noted, and in both groups, the majority of T-cells were CD3+ CD8+, with a median CD4:CD8 ratio of 0.6. There was no significant difference in T-cell expression of the activation markers HLA-DR and CD25 (IL-2 receptor), or in PMA-induced production of the intracellular cytokines IFN-gamma, IL-2, IL-4, IL-5, and IL-10. The results of this study suggest that significant T-cell-driven airway inflammation is absent in mild or nonatopic, asymptomatic children of this age group who have episodic wheeze. Our findings support asthma management guidelines that do not recommend long-term treatment of this group of patients with anti-inflammatory medications.

BACKGROUND : The degree to which transplant recipients are immunosuppressed influences their risks of rejection, infection and cancer. Current measures of immune suppression are crude (clinical events) or indirect (drug exposure). We assessed a direct measure of immune status, leukocyte phenotype and function (LPF, a composite measure of five aspects of peripheral blood leukocyte phenotype and function), as a predictor of infection. METHODS : A double-blind, prospective, cohort study was conducted, to determine the burden of infection in stable renal transplant recipients with moderate-severe (Group I, n = 34) or minimal (Group II, n = 36) impairment of LPF, a composite score of: (i) CD4 count; (ii) lymphocyte proliferation in response to phytohaemagglutinin A (PHA); (iii) serum Ig concentrations; (iv) neutrophil phagocytic function; and (v) reactive oxygen species generation. Subjects completed a 6 month diary and each recorded infection was scored 1-4: 1, minor undefined infection (e.g. URTI); 2, minor, microbiologically defined infection (e.g. UTI); 3, major defined infection (requiring hospitalization); 4, opportunistic infection (e.g. Herpes zoster). Final infection score was the sum of all infective episodes. Subjects were then followed-up for 5 years for outcome measures. RESULTS : Groups were well matched for age, sex, diabetes, serum creatinine, rejection and trough cyclosporin concentrations. Group I (moderate to severe impairment of LPF) recorded a higher infection score, 2.4+/-2.8 vs 1.2+/-1.2 for Group II, P = 0.02, due to a higher incidence of moderate to severe infection. This relationship was confirmed by multivariate analysis (OR 1.83, CI 1.08, 3.11, P = 0.03 per unit increase in infection score). During the 5 year follow-up period they had significantly more episodes of admission to hospital, and twice as many admissions due to infections, but no difference in malignancy, graft or patient outcome. CONCLUSION : LPF testing prospectively identified a cohort who incurred a higher burden of infection. Further studies are required to determine the predictive value of LPF for acute rejection, infection and cancer, and to determine whether adjustments to therapy on the basis of LPF can lead to improved outcomes.

Fibrin independent proinflammatory effects of tissue factor in experimental crescentic glomerulonephritis.BackgroundTissue factor initiated glomerular fibrin deposition is an important mediator of injury in crescentic glomerulonephritis. Recent data have suggested noncoagulant roles for tissue factor in inflammation.MethodsTo test the hypothesis that in addition to its effects in initiating coagulation, tissue factor has proinflammatory effects in glomerulonephritis, rabbits given crescentic anti-glomerular basement membrane (GBM) antibody–induced glomerulonephritis were defibrinogenated with ancrod. One group of defibrinogenated rabbits was also given anti-tissue factor antibodies. Comparisons were made between these groups, as well as a third group that was neither defibrinogenated with ancrod nor given anti-tissue factor antibodies.ResultsDefibrinogenation alone abolished glomerular fibrin deposition, reduced crescent formation, and limited renal impairment (ancrod-treated, serum creatinine 274 ± 37 μmol/L; untreated 415 ± 51 μmol/L; P < 0.01). Tissue factor inhibition in defibrinogenated rabbits resulted in further protection of renal function (creatinine 140 ± 19 μmol/L, P < 0.01) and reduced proteinuria (0.4 ± 0.2g/day, untreated 2.6 ± 0.4 g/day, P

Background Advances in immunosuppression have made renal transplantation an effective therapy for end stage renal failure; with low rejection rates and long graft survival times. However, the major adverse consequences, infection and malignancy have not diminished. To predict this risk a score of immune competence has been developed from the simultaneous laboratory assessment of multiple parameters of immune function. Methods The immune status of 152 transplant recipients (138 renal and 14 pancreas/renal) was assessed by measurement of lymphocyte subsets, mitogen-induced T-cell proliferative responses, neutrophil phagocytic capacity and reactive oxygen species (ROS) generation. A scoring system was devised based on the average number of these parameters below 10th percentile of normal. Results The most common abnormality was B-cell lymphopenia (85%) followed by reduced neutrophil ROS production (63% of patients), NK cell lymphopenia (50%), lymphocyte mitogen response (49%) and CD4 number (23%). The abnormalities were unrelated to the duration of immunosuppression (up to 15 years), and variable combinations of cyclosporine A, azathioprine, prednisolone and mycophenolate mofetil (MMF) (except for a consistent reduction in lymphocyte mitogen response in MMF treated patients). Retrospective comparison of infective episodes showed a significantly greater index of infections in patients with the worst score compared with a normal score. Conclusions The data suggests that this quantification of immune function may allow assessment of the level of host immune defence reflecting the level of drug-induced immunosuppression and thus risks of immunosuppressive complications.

SUMMARYThe effect of cytotoxic T-lymphocyte-associated molecule 4-immunoglobulin fusion protein (CTLA4-Fc) on humorally-mediated glomerulonephritis was studied in accelerated anti-glomerular basement membrane (anti-GBM) glomerulonephritis induced in BALB/c mice. This strain of mice develops antibody and complement dependent glomerulonephritis under this protocol. Sensitized BALB/c mice developed high levels of circulating autologous antibody titres, intense glomerular deposition of mouse immunoglobulin and complement, significant proteinuria, renal impairment, significant glomerular necrosis and a minor component of crescent formation 10 days after challenge with a nephritogenic antigen (sheep anti-GBM globulin). Early treatment during the primary immune response, or continuous treatment throughout the disease with CTLA4-Fc, significantly suppressed mouse anti-sheep globulin antibody titres in serum, and immunoglobulin and complement deposition in glomeruli. The degree of glomerular necrosis was improved and proteinuria was reduced, particularly in the earlier stages of disease. Late treatment by CTLA4-Fc starting one day after challenge with sheep anti-mouse GBM did not affect antibody production and did not attenuate glomerulonephritis. The low level of crescent formation found in BALB/c mice developing glomerulonephritis was not prevented by the administration of CTLA4-Fc. These results demonstrate that CTLA4-Fc is of benefit in this model of glomerulonephritis by its capacity to attenuate antibody production, without affecting the minor degree of cell-mediated glomerular injury.

Endogenous interleukin-10 regulates Th1 responses that induce crescentic glomerulonephritis.BackgroundInterleukin (IL)-10 plays a pivotal role in regulating the Th1/Th2 predominance of immune responses. Exogenously administered IL-10 suppresses nephritogenic Th1 responses, inhibits macrophage function, and attenuates crescentic glomerulonephritis (GN). To determine the role of endogenous IL-10, the development of the nephritogenic immune response and crescentic GN was compared in IL-10–deficient (IL-10-/-) and normal (IL-10+/+) C57BL/6 mice.MethodsGN was initiated in sensitized mice by the intravenous administration of sheep antimouse glomerular basement membrane globulin. Renal injury was evaluated 21 days later.ResultsFollowing the administration of anti-glomerular basement membrane globulin, normal (IL-10+/+) C57BL/6 mice developed proliferative GN with occasional crescents, glomerular CD4+ T-cell and macrophage accumulation, and fibrin deposition. Using an identical induction protocol, IL-10-/-mice developed more severe GN. Crescent formation (IL-10-/-, 23 ± 2% of glomeruli; IL-10+/+, 5 ± 2%), glomerular CD4+ T cells [IL-10-/-, 1.0 ± 0.2 cells per glomerular cross-section (c/gcs); IL-10 +/+, 0.3 ± 0.05 c/gcs], glomerular macrophages (IL-10-/-, 4.8 ± 0.3 c/gcs; IL-10 +/+, 1.7 ± 0.2 c/gcs), fibrin deposition [fibrin score (range 0 to 3+); IL-10-/-, 1.10 ± 0.04; IL-10+/+, 0.6 ± 0.07], and serum creatinine (IL-10-/-, 30 ± 2 μmol/L; IL-10 +/+, 23 ± 1 μmol/L) were all significantly increased in IL-10-/- mice (P < 0.05). Circulating antibody (IL-10-/-, 1.05 ± 0.16 OD units; IL-10+/+, 0.63 ± 0.08 OD units) and cutaneous delayed-type hypersensitivity (skin swelling; IL-10-/-, 0.21 ± 0.03 mm; IL-10+/+, 0.12 ± 0.02 mm) to the nephritogenic antigen (sheep globulin) were also increased (both P < 0.05). Interferon-γ production by cultured splenocytes was increased (IL-10-/- 7.9 ± 2.5 ng/4 × 106 cells, IL-10+/+ 0.28 ± 0.09 ng/4 × 106 cells, P < 0.05), but IL-4 production was unchanged.ConclusionsEndogenous IL-10 counter-regulates nephritogenic Th1 responses and attenuates crescentic GN.

The contribution of B7.1 and B7.2 co-stimulation to Th1-directed, cell-mediated renal injury was studied in a murine model of crescentic glomerulonephritis (GN) initiated by a "planted" antigen. Mice treated with anti-B7.2 monoclonal antibody (mAb), starting prior to disease initiation, developed more severe renal injury with increased glomerular crescent formation (p = 0.031), glomerular accumulation of T cells (p = 0.014) and proteinuria (p = 0.022) compared to mice treated with control antibodies. Mice treated with anti-B7.1 mAb had reduced crescent formation (p = 0.019) compared to control treated mice, but reductions in glomerular CD4(+) T cell accumulation and proteinuria were not statistically significant. B7. 1 mAb treatment significantly reduced all parameters of renal injury (above) compared to anti-B7.2 mAb treatment. Neither treatment altered the circulating antibody titer or cutaneous delayed type hypersensitivity to the nephritogenic antigen. Antibody subclasses and antigen-stimulated ex vivo splenocyte IL-4, IL-10 and IFN-gamma production did not indicate effects on Th subset responses. Treatment with CTLA4-Fc or combined treatment with anti-B7.1 and B7. 2 antibodies did not significantly attenuate crescentic GN. These data indicate that B7.1 and B7.2 are important co-stimulatory molecules involved in crescentic GN, which have opposing effects on disease development without altering the T helper cell subset response to the nephritogenic antigen.

SUMMARY The influence of endogenous glucocorticoids (GC) on glomerular injury was studied in a rat model of heterologous anti-glomerular basement membrane (GBM) glomerulonephritis (GN). Sprague-Dawley rats underwent adrenalectomy (ADX) or sham-operation 3 days prior to i.v. administration of both nephritogenic (100 μg/g) and subnephritogenic (50 μg/g) doses of sheep anti-rat GBM globulin. Administration of a subnephritogenic dose of anti-GBM globulin resulted in GN in adrenalectomized animals only. Similarly, ADX performed prior to administration of anti-GBM in the nephritogenic dose range resulted in exacerbation of GN compared with sham-operated animals (24 h protein excretion: 190.8 ± 32.8 versus 42.5 ± 2.6 mg/24 h; P

OBJECTIVE: Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine whose involvement in tumor necrosis factor alpha (TNFalpha) synthesis and T cell activation suggests a role in the pathogenesis of rheumatoid arthritis (RA). Antagonism of MIF is associated with marked inhibition of animal models of RA. Uniquely, MIF is inducible by low concentrations of glucocorticoids. We sought to investigate the expression of MIF in RA synovial tissue. METHODS: MIF was demonstrated in human RA synovium by immunohistochemistry, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and reverse transcription-polymerase chain reaction (RT-PCR). Regulation of MIF expression was investigated by treatment of cultured fibroblast-like synoviocytes (FLS) with interleukin-1beta (IL-1beta), TNFalpha, or interferon-gamma (IFNgamma), and dexamethasone (DEX). Mononuclear cell TNFalpha release after exposure to FLS-conditioned medium was measured by ELISA. RESULTS: MIF was present in RA synovial lining CD14+ macrophages and FLS. Constitutive MIF messenger RNA (mRNA) expression was demonstrated by RT-PCR of RNA from unstimulated cultured RA FLS, which also released abundant MIF. Serum, synovial fluid, and FLS intracellular MIF were significantly higher in RA patients than in controls. Synoviocyte MIF was not increased by IL-1beta, TNFalpha, or IFNgamma. In contrast, DEX 10(-7)M significantly reduced synoviocyte MIF, while DEX 10(-10)-10(-12)M induced a significant increase in MIF and MIF mRNA. Peripheral blood mononuclear cell TNFalpha release was induced by culture in RA FLS-conditioned medium, and this induction was significantly abrogated by monoclonal anti-MIF antibody, suggesting that MIF is an upstream regulator of TNFalpha release. CONCLUSION: These data represent the first demonstration of the cytokine MIF in human autoimmune disease and suggest MIF as a potential therapeutic target in RA.

Tissue factor pathway inhibitor expression in human crescentic glomerulonephritis. Background Tissue factor (TF) pathway inhibitor (TFPI), the major endogenous inhibitor of extrinsic coagulation pathway activation, protects renal function in experimental crescentic glomerulonephritis (GN). Its glomerular expression and relationship to TF expression and fibrin deposition in human crescentic GN have not been reported. Methods Glomerular TFPI, TF, and fibrin-related antigen (FRA) expression were correlated in renal biopsies from 11 patients with crescentic GN. Biopsies from 11 patients with thin basement membrane disease and two normal kidneys were used as controls. Results TFPI was undetectable in control glomeruli but was detectable in interstitial microvessels. In crescentic biopsies, TFPI was detected in cellular crescents and was more prominent in fibrous/fibrocellular crescents, indicating a correlation with the chronicity of crescentic lesions. TFPI appeared to be associated with macrophages but not endothelial or epithelial cells. TFPI was generally undetectable in regions of the glomerular tuft with minimal damage. In contrast, TF and FRA were strongly expressed in regions of minimal injury, as well as in more advanced proliferative and necrotizing lesions. Despite prominent TF expression, FRA was less prominent in fibrous/fibrocellular crescents in which TFPI expression was maximal. Conclusions These data suggest that TFPI is strongly expressed in the later stages of crescent formation and is inversely correlated with the presence of FRA in human crescentic GN. This late induction of TFPI may inhibit TF activity and favor reduced fibrin deposition in the chronic stages of crescent formation.