Thymic deletion and regulatory T cells prevent antimyeloperoxidase GN

Loss of tolerance to neutrophil myeloperoxidase (MPO) underlies the development of ANCA-associated vasculitis and GN, but the mechanisms underlying this loss of tolerance are poorly understood. Here, we assessed the role of the thymus in deletion of autoreactive anti-MPO T cells and the importance of peripheral regulatory T cells in maintaining tolerance to MPO and protecting from GN. Thymic expression of MPO mRNA predominantly localized to medullary thymic epithelial cells. To assess the role of MPO in forming the T cell repertoire and the role of the autoimmune regulator Aire in thymic MPO expression, we compared the effects of immunizing Mpo(-/-) mice, Aire(-/-) mice, and control littermates with MPO. Immunized Mpo(-/-) and Aire(-/-) mice developed significantly more proinflammatory cytokine-producing anti-MPO T cells and higher ANCA titers than control mice. When we triggered GN with a subnephritogenic dose of anti-glomerular basement membrane antibody, Aire(-/-) mice had more severe renal disease than Aire(+/+) mice, consistent with a role for Aire-dependent central deletion in establishing tolerance to MPO. Furthermore, depleting peripheral regulatory T cells in wild-type mice also led to more anti-MPO T cells, higher ANCA titers, and more severe GN after immunization with MPO. Taken together, these results suggest that Aire-dependent central deletion and regulatory T cell-mediated peripheral tolerance both play major roles in establishing and maintaining tolerance to MPO, thereby protecting against the development of anti-MPO GN.

Chest pain and exacerbations of bronchiectasis

Background

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.

Lung T-cell responses to nontypeable Haemophilus influenzae in patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary inflammation that persists after the cessation of smoking. T cells have a major role in driving inflammation in patients with COPD and are activated by specific antigens to produce mediators, such as cytokines. The antigens that activate lung T cells have not been clearly defined. Nontypeable Haemophilus influenzae (NTHi) is the dominant bacterium isolated from the lungs of patients with COPD.

OBJECTIVE

We sought to measure the response of lung tissue T cells to stimulation with NTHi.

METHODS

We obtained lung tissue from 69 subjects having lobectomies for lung cancer. Of the group, 39 subjects had COPD, and 30 without COPD were classified as control subjects. The lung tissue was dispersed into single-cell suspensions and stimulated with live NTHi. Cells were labeled with antibodies for 5 important inflammatory mediators in patients with COPD and analyzed by using flow cytometry.

RESULTS

NTHi produced strong activation of both TH cells and cytotoxic T cells in the COPD cohort. The COPD cohort had significantly higher levels of cells producing TNF-α, IL-13, and IL-17 in both T-cell subsets. When control subjects were divided into those with and without a significant smoking history and compared with patients with COPD, there was a progressive increase in the numbers of T cells producing cytokines from nonsmoking control subjects to smoking control subjects to patients with COPD.

CONCLUSION

NTHi activates lung T cells in patients with COPD. This proinflammatory profibrotic response might be a key cause of inflammation in patients with COPD and has implications for treatment.

Mast cells contribute to peripheral tolerance and attenuate autoimmune vasculitis

Mast cells contribute to the modulation of the immune response, but their role in autoimmune renal disease is not well understood. Here, we induced autoimmunity resulting in focal necrotizing GN by immunizing wild-type or mast cell-deficient (Kit(W-sh/W-sh)) mice with myeloperoxidase. Mast cell-deficient mice exhibited more antimyeloperoxidase CD4+ T cells, enhanced dermal delayed-type hypersensitivity responses to myeloperoxidase, and more severe focal necrotizing GN. Furthermore, the lymph nodes draining the sites of immunization had fewer Tregs and reduced production of IL-10 in mice lacking mast cells. Reconstituting these mice with mast cells significantly increased the numbers of Tregs in the lymph nodes and attenuated both autoimmunity and severity of disease. After immunization with myeloperoxidase, mast cells migrated from the skin to the lymph nodes to contact Tregs. In an ex vivo assay, mast cells enhanced Treg suppression through IL-10. Reconstitution of mast cell-deficient mice with IL-10-deficient mast cells led to enhanced autoimmunity to myeloperoxidase and greater disease severity compared with reconstitution with IL-10-intact mast cells. Taken together, these studies establish a role for mast cells in mediating peripheral tolerance to myeloperoxidase, protecting them from the development of focal necrotizing GN in ANCA-associated vasculitis.

Signal transducer and activation of transcription 6 (STAT6) regulates T helper type 1 (Th1) and Th17 nephritogenic immunity in experimental crescentic glomerulonephritis

Experimental crescentic glomerulonephritis is driven by systemic cellular immune responses. A pathogenic role for T helper type 1 (Th1) and Th17 cells is well established. T-bet, a key transcription factor required for Th1 lineage commitment, and retinoic acid-related orphan receptor-γt (Rorγt), a key Th17 transcription factor, are required for full expression of disease. Similarly, several Th1- and Th17-associated cytokines have been implicated in disease augmentation. The role of Th2 cells in the disease is less clear, although Th2-associated cytokines, interleukin (IL)-4 and IL-10, are protective. We sought to determine the role of signal transducer and activation of transcription 6 (STAT6), a key regulator of Th2 responses, in experimental crescentic glomerulonephritis. Compared to wild-type mice, histological and functional renal injury was enhanced significantly in STAT6(-/-) mice 21 days after administration of sheep anti-mouse glomerular basement membrane globulin. Consistent with the enhanced renal injury, both Th1 and Th17 nephritogenic immune responses were increased in STAT6(-/-) mice. Conversely, production of IL-5, a key Th2-associated cytokine, was decreased significantly in STAT6(-/-) mice. Early in the disease process systemic mRNA expression of T-bet and Rorγ was increased in STAT6(-/-) mice. We conclude that STAT6 is required for attenuation of Th1 and Th17 nephritogenic immune responses and protection from crescentic glomerulonephritis.

Mast cells mediate acute kidney injury through the production of TNF

Leukocyte recruitment contributes to acute kidney injury (AKI), but the mechanisms by which leukocytes promote injury are not completely understood. The degranulation of mast cells releases inflammatory molecules, including TNF, but whether these cells participate in the pathogenesis of AKI is unknown. Here, we induced AKI with cisplatin in mast cell-deficient and wild-type mice. Compared with wild-type mice, deficiency of mast cells attenuated renal injury, reduced serum levels of TNF, and reduced recruitment of leukocytes to the inflamed kidney. Mast cell-deficient mice also exhibited significantly lower intrarenal expression of leukocyte chemoattractants. Mast cell-deficient mice reconstituted with mast cells from wild-type mice exhibited similar cisplastin-induced renal damage and serum levels of TNF as wild-type mice. In contrast, mast cell-deficient mice reconstituted with mast cells from TNF-deficient mice continued to demonstrate significant attenuation of cisplatin-induced renal injury. Furthermore, the mast-cell stabilizer sodium chromoglycate also significantly abrogated renal injury in this model of AKI. Taken together, these results suggest that mast cells mediate AKI through the production of TNF.

Tim-1 promotes cisplatin nephrotoxicity

Nephrotoxicity is a frequent complication of cisplatin-based chemotherapy, in which T cells are known to promote acute kidney injury. In this study, we examined the role of T cell immunoglobulin mucin 1 (Tim-1) in cisplatin-induced acute kidney injury using an inhibitory anti-Tim-1 antibody. Tim-1 acts to modulate T cell responses, but it is also expressed by damaged proximal tubules in the kidney, where it is known as kidney injury molecule-1 (Kim-1). Anti-Tim-1 antibodies attenuated cisplatin nephrotocity, with less histologic damage, improved renal function, and fewer leukocytes infiltrating the kidney compared with control antibody-treated mice. Renal NF-κB activation and apoptosis were reduced, and proinflammatory renal cytokine and chemokine mRNA expression was decreased. Renal Kim-1 expression was reduced, consistent with the diminished kidney injury after anti-Tim-1 antibody treatment. Furthermore, anti-Tim-1 antibodies reduced early systemic CD4+ and CD8+ T cell activation, apoptosis, and cytokine production. To determine whether the protective actions of anti-Tim-1 antibodies were due to effects on renal tubular cells, cisplatin nephrotoxicity was studied in Rag1(-/-) mice. Anti-Tim-1 antibodies did not affect renal dysfunction or histologic damage in Rag1(-/-) mice, showing that the benefits of inhibiting Tim-1 come from T cell effects. As Tim-1 plays an important role in promoting cisplatin nephrotoxicity, inhibiting Tim-1 may be a therapeutic strategy to prevent cisplatin-induced acute kidney injury.

Interleukin-17A promotes early but attenuates established disease in crescentic glomerulonephritis in mice

T helper (Th)17 cells might contribute to immune-mediated renal injury. Thus, we sought to define the time course of IL-17A-induced kidney damage and examined the relation between Th17 and Th1 cells in a model of crescentic anti-glomerular basement membrane glomerulonephritis. Renal injury and immune responses were assessed in wild-type and in IL-17A-deficient mice on days 6, 14, and 21 of disease development. On day 6, when mild glomerulonephritis developed, IL-17A-deficient mice were protected from renal injury. On day 14, when more severe disease developed, protection from renal injury due to IL-17A deficiency was less evident. On day 21, when crescentic glomerulonephritis was fully established, disease was enhanced in IL-17A(-/-) mice, with increased glomerular T-cell accumulation and fibrin deposition, and augmented Th1 responses. Mice lacking the Th17-promoting cytokine, IL-23 (p19), also developed more severe disease than wild-type animals on day 21. In contrast, mice deficient in the key Th1-promoting cytokine, IL-12 (p35), had decreased Th1 and increased Th17 responses and developed less severe crescentic glomerulonephritis than wild-type animals. These studies show that IL-17A contributes to early glomerular injury, but it attenuates established crescentic glomerulonephritis by suppressing Th1 responses. They provide further evidence that Th1 cells mediate crescentic injury in this model and that Th1 and Th17 cells counterregulate each other during disease development.

TLR9 and TLR4 are required for the development of autoimmunity and lupus nephritis in pristane nephropathy

Systemic lupus erythematosus is a common autoimmune disease, with kidney involvement a serious complication associated with poor prognosis. Humoral immune responses constitute the hallmark of disease, however T helper cells are required for the generation of autoantibodies, as well as the induction and progression of renal injury. Administration of pristane to genetically intact mice results in the development of hypergammaglobulinaemia with the production of lupus like autoantibodies and proliferative glomerulonephritis, with similarities to human lupus nephritis. TLRs are intricately linked to the development of autoimmunity and are involved in the development of lupus nephritis. We injected wild type, TLR9-/- and TLR4-/- mice with pristane and assessed cellular and humoral autoimmunity and renal injury, 8 months later. TLR9-/- mice demonstrated a predominant decrease in Th1 cytokine production which resulted in decreased anti-RNP antibody levels, while anti-dsDNA levels remained intact. Compared to wild type mice treated with pristane, functional and histological renal injury and glomerular immunoglobulin and complement deposition was decreased in TLR9-/- mice. TLR4-/- mice demonstrated a global decrease in both Th1, IFNγ, and Th17 associated IL-17A and IL-6 cytokine production. Autoantibody levels of anti-dsDNA and anti-RNP were both decreased. Renal injury was attenuated in TLR4-/- mice which demonstrated less glomerular immunoglobulin and complement deposition. These results demonstrate that both TLR9 and TLR4 are required for 'full-blown' autoimmunity and organ injury in experimental lupus induced by pristane.

The emergence of TH17 cells as effectors of renal injury

IL-17-producing Th17 effector cells directly induce renal inflammation by activating neutrophils or by participating in macrophage-mediated tissue injury. Th17 cells and cytokines participate in human and experimental renal disease, especially in proliferative glomerulonephritis where Th17 effector cells are active. Although growing evidence suggests Th17 cells are particularly relevant to effector responses involving neutrophils, there are still important questions to address before the complete functions of Th17 cells in renal disease are understood fully.

Endogenous foxp3(+) T-regulatory cells suppress anti-glomerular basement membrane nephritis

Foxp3(+) T-regulatory cells (Tregs) may suppress pathogenic inflammation; however, although transferred Tregs lessen glomerulonephritis in mice, the role of endogenous foxp3(+) cells is not known. To study this, we characterized endogenous foxp3(+) cells in accelerated anti-glomerular basement membrane (GBM) nephritis by using foxp3(GFP) reporter mice to track their responses in early and established disease. Further, diphtheria toxin was used to ablate foxp3(+) Tregs in foxp3(DTR) mice after establishing an immune response. In this model, mice were immunized with sheep globulin in adjuvant, and sheep anti-mouse GBM globulin was injected after 4 days to initiate progressive histological and functional injury. Intrarenal leukocytic infiltrates were increased by day 3 but intrarenal foxp3(+) Tregs, present in interstitial and periglomerular areas, were only increased at day 7. Ablation of foxp3(+) Tregs after injection of anti-GBM globulin increased renal injury and systemic T-cell responses, including increased interferon-γ and interleukin-17A (IL-17A) production, but no change in antibody titers. Compared with foxp3(+) Tregs isolated from naive mice, those from immunized mice produced more IL-10 and more effectively regulated CD4(+)foxp3(-) responder T cells. Thus, endogenous foxp3(+) Tregs infiltrate the kidney in glomerulonephritis, and deleting foxp3(+) cells after the induction of immune responses upregulated T-cell reactions and enhanced disease. Hence, endogenous foxp3(+) cells have increased suppressive capacity after immune stimuli.

The Th17-defining transcription factor RORγt promotes glomerulonephritis

Although Th17 responses may contribute to the pathogenesis of glomerulonephritis, whether the key transcription factor in Th17 cell development, RORγt, also promotes glomerulonephritis is unknown. Here, we induced crescentic glomerulonephritis in wild-type and RORγt-deficient (RORγt(-/-)) mice. RORγt(-/-) mice were protected from disease, with reduced histologic and functional injury and decreased leukocyte infiltration. Because RORγt(-/-) mice lack lymph nodes, which may influence the development of nephritis, we performed cell-transfer studies. We reconstituted Rag1(-/-) mice, which lack adaptive immunity but otherwise have normal architecture of the lymphatic system, with splenocytes from naïve wild-type or RORγt(-/-) mice. Mice receiving wild-type splenocytes exhibited high mortality from renal failure after induction of nephritis whereas mice receiving RORγt(-/-) cells were protected. To determine the effect of RORγt deficiency specifically in T helper cells, we isolated naïve CD4(+) T cells from wild-type and RORγt(-/-) mice and transferred them into Rag1(-/-) animals. Recipients of wild-type CD4(+) T cells developed severe glomerulonephritis whereas recipients of RORγt(-/-) cells developed less severe disease. To exclude effects of altered regulatory T cell (Treg) development caused by RORγt deficiency, we transferred naïve CD4(+) T cells depleted of Tregs into Rag1(-/-) mice. Recipients of wild-type, Treg-depleted, CD4(+) T cells developed severe glomerulonephritis whereas recipients of RORγt(-/-), Treg-depleted CD4(+) T cells did not. Taken together, this study demonstrates that RORγt promotes the development of crescentic glomerulonephritis by directing nephritogenic Th17 responses.

Lung diffusing capacity in adult bronchiectasis: a longitudinal study

BACKGROUND

Recent studies described a progressive decline in lung volumes in adult bronchiectasis. Interstitial lung disease is also a feature of bronchiectasis, but whether this is associated with a decline in lung diffusing capacity (measured as the diffusing capacity of the lung for carbon monoxide [D(LCO)]) is not well known.

OBJECTIVE

To assess longitudinal decline in diffusing capacity of the lung for carbon monoxide (D(LCO)) in adult bronchiectasis.

METHODS

Sixty-one subjects had a detailed baseline clinical and laboratory assessment, then were followed regularly with clinical and lung-function assessment for a median 7 years.

RESULTS

Baseline spirometry demonstrated mild obstructive lung disease, with a mean FEV(1) of 72% of predicted, mean forced vital capacity 87% of predicted, and normal D(LCO) (mean D(LCO) 88% of predicted, and mean D(LCO) adjusted for alveolar volume [D(LCO)/V(A)] 100% of predicted). There was an accelerated decline in D(LCO) and D(LCO)/V(A) over the 7-year period. The median D(LCO) decline was 2.9% of predicted per year (95% CI 2.3-4.1% of predicted per year). The median D(LCO)/V(A) decline was 2.4% of predicted per year (95% CI 2.1-4.0% of predicted per year). There was a significant relationship between D(LCO) decline and age and decline in FEV(1).

CONCLUSIONS

In our cohort of patients with bronchiectasis there was a progressive D(LCO) decline.

Review: T helper 17 cells: their role in glomerulonephritis

T helper (Th) cells are an integral part of the host's immune response to eliminate invading pathogens. However, autoimmune or 'autoinflammatory' diseases can develop if Th cell responses are not effectively regulated. Several subsets of Th cells exist, including the Th17 subset that produces interleukin-17A, important in experimental models of organ-specific autoimmune inflammation. Its discovery has explained paradoxical observations in model systems thought to be Th1 mediated but were exacerbated in the absence of interferon-gamma, the prototypic Th1 effector cytokine. Th17 cells express unique transcription factors and secrete a unique pattern of cytokines. Interleukin-17A induces pro-inflammatory cytokines and chemokines and mediates neutrophil recruitment. Th17 cells have a reciprocal relationship with T regulatory cells and can also mediate suppression of Th1 responses. Recent studies also suggest that Th17 cells are not terminally differentiated but can switch into Th1 cells. Th17 cells have themselves been recently shown to induce antigen-specific cell-mediated proliferative glomerulonephritis. There is increasing evidence implicating Th17 cells in anti-glomerular basement membrane disease, lupus nephritis and pauci-immune glomerulonephritis. This review will review the discovery of the Th17 subset, its properties, its relationship with other Th subsets and assess the current evidence implicating Th17 cells in glomerulonephritis.

Toll-like receptor 9 enhances nephritogenic immunity and glomerular leukocyte recruitment, exacerbating experimental crescentic glomerulonephritis

Glomerular disease can be triggered or exacerbated by microbes that activate the immune system by Toll-like receptor (TLR) ligation. TLR9 activation promotes host defenses through the enhancement of innate and adaptive immune responses that facilitate the recruitment of leukocytes to areas of inflammation. We defined the role of TLR9 in experimental crescentic glomerulonephritis. Wild-type mice administered a TLR9 ligand and sheep anti-mouse glomerular basement membrane antibody developed histological injury with impaired renal function, which was attenuated in TLR9 knockout mice. Consistent with enhanced renal injury, wild-type mice exhibited enhanced T helper 1 and T helper 17 cellular immune responses. Kidney mRNA expression of inflammatory cytokines and chemokines as well as leukocyte recruitment were increased in wild-type mice. The use of bone marrow chimeric mice demonstrated that while both bone marrow and tissue cell TLR9 are required for maximal injury, bone marrow TLR9 is more important. Administration of a TLR9 inhibitor before sheep anti-mouse glomerular basement membrane globulin in wild-type mice attenuated cellular nephritogenic immunity that resulted in decreased renal injury. Administration of the inhibitor 7 days after disease initiation decreased glomerular leukocyte recruitment as well as renal injury. These results define the role of TLR9 in experimental crescentic glomerulonephritis and identify therapeutic potential for TLR9 inhibitors in attenuating renal injury, decreasing cellular nephritogenic immunity early in disease, and decreasing kidney effector responses later.

Th17 cells promote autoimmune anti-myeloperoxidase glomerulonephritis

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.

Endogenous CD100 promotes glomerular injury and macrophage recruitment in experimental crescentic glomerulonephritis

CD100 participates in adaptive immune responses and is important in neural cell migration. To determine the role of endogenous CD100 in severe glomerular inflammation, we induced experimental crescentic glomerulonephritis by planting a foreign antigen in glomeruli of sensitized normal and CD100-deficient (CD100(-/-)) mice. Fewer CD100(-/-) glomeruli exhibited crescent formation or severe histological changes. Antigen-specific immune responses were reduced in CD100(-/-) mice. There was less interferon (IFN)-gamma and interleukin (IL)-4 production by splenocytes and fewer activated T and B cells were present in lymph nodes of immunized CD100(-/-) mice. Serum antigen-specific immunoglobulin (IgG) levels were also decreased. Glomerular macrophage and CD4(+) cell infiltration, and IgG and C3 deposition were attenuated. Normal kidneys expressed mRNA for CD100 and plexin-B1 (the tissue receptor of CD100). Direct immunofluorescence showed that renal-CD100 protein was predominantly in tubules, while plexin-B1 was present in both glomeruli and tubules. To determine whether glomerular plexin-B1 mediates leucocyte recruitment via leucocyte CD100, recruitment was studied after passive transfer of heterologous antibody (attracting neutrophils) or isologous antibody (attracting macrophages). Glomerular macrophages were reduced in CD100(-/-) mice, but neutrophil recruitment was equivalent, consistent with CD100 expression on macrophages, but not neutrophils. CD100 promotes severe nephritogenic immune responses and leucocyte CD100-glomerular plexin-B1 interactions enhance macrophage recruitment to glomeruli.

Th1 and Th17 cells induce proliferative glomerulonephritis

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.

Atorvastatin enhances humoral immune responses but does not alter renal injury in experimental crescentic glomerulonephritis

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.

IL-23, not IL-12, directs autoimmunity to the Goodpasture antigen

The autoantigen in Goodpasture disease is the noncollagenous domain of alpha3 type IV collagen [alpha3(IV)NC1]. We previously demonstrated that IL-12p40(-/-) mice are protected from experimental autoimmune anti-glomerular basement membrane (anti-GBM) glomerulonephritis, seemingly defining a role for IL-12 in this disease; however, the recent identification of IL-23, a heterodimer composed of IL-12p40 and IL-23p19 subunits, raises the possibility that IL-23, rather than IL-12, may modulate this disease instead. We immunized wild-type, IL-12p35(-/-) (IL-12 deficient, IL-23 intact), IL-12p40(-/-) (deficient in both IL-12 and IL-23), and IL-23p19(-/-) (IL-12 intact, IL-23 deficient) mice with recombinant mouse alpha3(IV)NC1. Wild-type mice developed autoreactivity to alpha3(IV)NC1: Humoral responses, cellular responses, renal histologic abnormalities, leukocyte accumulation, autoantibody deposition, and IL-17A mRNA expression (a cytokine produced by the IL-23-maintained Th17 subset). IL-23 but not IL-12 was detected in the immune system. Regardless of the presence of IL-12, mice deficient in IL-23 were protected, but mice with IL-23 were not. Both IL-23-deficient strains exhibited lower autoantibody titers, reduced cellular reactivity, diminished cytokine production (IFN-gamma [Th1], IL-17A [Th17], TNF, and monocyte chemoattractant protein 1), and less renal disease and glomerular IgG deposition. The deficient responses in the absence of IL-23 were not due to increased regulatory T cells; IL-12p40(-/-) and IL-23p19(-/-) mice did not show increased proportions of CD4(+)CD25(+)FoxP3(+) cells or IL-10 levels early in the immune response. In conclusion, autoreactivity to the Goodpasture antigen is directed primarily by IL-23, absence of which results in hyporeactivity including but extending beyond a deficient Th17 response.

Systemic humoral immunity to non-typeable Haemophilus influenzae

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.

Cytotoxic T lymphocyte and natural killer cell responses to non-typeable Haemophilus influenzae

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.

Advances in the pathogenesis of Goodpasture's disease: from epitopes to autoantibodies to effector T cells

Goodpasture's disease, an "organ-specific" autoimmune disease is manifest by rapidly progressive glomerulonephritis and pulmonary hemorrhage. Studies into the pathogenesis of this disease have shed light on the autoantigen (the non-collagenous domain of the alpha3 chain of type IV collagen, alpha3(IV)NC1) and its epitopes, as well as the involvement of autoantibodies and cellular effectors in disease. The discovery of alpha3(IV)NC1 lead to studies that defined the structure and biology of type IV collagen and are defining B and T cell epitopes. Goodpasture autoantibody epitopes are "cryptic" in that they are structurally sequestered by adjacent non-collagenous domains of alpha4 and alpha5 type IV collagen. T cell epitope studies in rats demonstrated that a 13-mer could induce experimental autoimmune glomerulonephritis. T cells from patients with Goodpasture's recognize two epitopes, in regions which are highly susceptible in antigen processing by endosomal proteases. Goodpasture's disease is strongly associated with HLA DRB1 genes, whereby DRB1*1501 confers susceptibility and the DRB1*0701 and DRB1*0101 are dominantly protective. Experimental data implicate both autoantibodies and cell mediated immunity as disease effectors. Observations in humans suggest that regulatory T cells are associated with the development of self-immunoregulation in the convalescent phase of disease.

T-bet deficiency attenuates renal injury in experimental crescentic glomerulonephritis

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.

Distinct in vivo roles of CD80 and CD86 in the effector T-cell responses inducing antigen-induced arthritis

CD80 and CD86 play a critical role in the initiation of T-cell responses. However, their role in the in vivo effector CD4+ T-cell responses has been less extensively investigated. The current studies have examined the functional relevance of CD80 and CD86 in the effector CD4+ T-cell responses inducing antigen-induced arthritis. Arthritis was induced in C57BL/6 mice by sensitization to methylated bovine serum albumin (mBSA) on day 0, booster immunization (day 7) and intra-articular injection of mBSA (day 21). Control or anti-CD80 and/or anti-CD86 monoclonal antibodies were administered from day 21 to day 28. Arthritis severity and immune responses were assessed on day 28. The development of arthritis was significantly suppressed by inhibition of CD80 or CD86. Blockade of both CD80 and CD86 caused a trend towards reduced disease severity compared to control antibody-treated mice. Neutralization of CD80 attenuated accumulation of CD4+ T cells in joints and enhanced splenocyte production and circulating levels of interleukin-4. Inhibition of CD86 or both CD80 and CD86 reduced T-cell accumulation in joints without affecting T helper type 1/type 2 (Th1/Th2) differentiation or antibody levels. Blockade of CD86, and not CD80, significantly suppressed splenocyte interleukin-17 (IL-17) production. These results provide further in vivo evidence that CD80 and CD86 play important pathogenic roles in effector T-cell responses. CD80 exacerbates arthritis by downregulating systemic levels of IL-4 and increasing T-cell accumulation in joints without affecting IL-17 production. CD86 enhances disease severity by upregulating IL-17 production and increasing the accumulation of effector T cells in joints without affecting Th1/Th2 development.

Intrarenal antigens activate CD4+ cells via co-stimulatory signals from dendritic cells

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.

Cytokines in Glomerulonephritis

Cytokines play central roles in both innate and adaptive immune responses that lead to renal inflammation. They are involved systemically in cross-talk between antigen-presenting cells, leukocytes, and regulatory cells to initiate and modulate nephritogenic immunity. Within the kidney, cytokines play a central role in signaling between infiltrating leukocytes and intrinsic renal cells and orchestrate the effector responses that lead to renal damage. Glomerulonephritis (GN) is an important cause of renal inflammation leading to renal failure that results from adaptive responses targeted at the kidney. Animal models of GN have shown that cytokines play critical roles in initiation and modulation of renal inflammatory responses through their ability to modulate the T helper 1/T helper 2 balance of nephritogenic immune responses. Evidence from clinical studies is now confirming the importance of this paradigm in directing the inflammatory mechanisms, histologic patterns, and clinical consequences of human GN. Cytokines also have critical intrarenal effector roles in the development, perpetuation, and resolution of GN. The proinflammatory role of intrarenal cytokine production by leukocytes in GN is well recognized, but, more recently, the role of intrinsic renal cell cytokine production in amplifying renal inflammation has been shown in animal models of GN. Studies showing benefits of specific anticytokine therapies directed at tumor necrosis factor in human GN are now appearing.

Microbiologic follow-up study in adult bronchiectasis

There is minimal published longitudinal data about pathogenic microorganisms in adults with bronchiectasis. Therefore a study was undertaken to assess the microbiologic profile over time in bronchiectasis. A prospective study of clinical and microbiologic outcomes was performed. Subjects were assessed by a respiratory physician and sputum sample were collected for analysis. Subjects were followed up and had repeat assessment performed. Eighty-nine subjects were followed up for a period of 5.7+/-3.6 years. On initial assessment the two most common pathogens isolated were Haemophilus influenzae (47%) and Pseudomonas aeruginosa (12%) whilst 21% had no pathogens isolated. On follow-up review results were similar (40% H. influenzae, 18% P. aeruginosa and 26% no pathogens). The prevalence of antibiotic resistance of isolates increased from 13% to 30%. Analysis of a series of H. influenzae isolates showed they were nearly all nontypeable and all were different subtypes. Subjects with no pathogens isolated from their sputum had the mildest disease, while subjects with P. aeruginosa had the most severe bronchiectasis. Many subjects with bronchiectasis are colonized with the same bacterium over an average follow-up of 5 years. Different pathogens are associated with different patterns of clinical disease.

Outcome in adult bronchiectasis

The outcome in adult bronchiectasis has not been well described; in particular there has been a lack of long-term prospective studies. Therefore a follow-up study was performed to assess outcome in bronchiectasis in a cohort of adult patients. One hundred-and-one sequential adults, 33 male and 68 female; age 54 +/- 14 years (mean +/- SD) with bronchiectasis had a clinical assessment and spirometry performed. All were non-smokers and 84 were classified as having idiopathic disease. Patients were commenced on a standardized treatment regime and followed up for a minimum period of 2 years. On their last review when patients were clinically stable, a repeat clinical assessment and spirometry was performed and compared with the initial review. The primary endpoints measured were symptoms and FEV1. Subjects were followed up for 8.0 +/- 4.9 years. Clinical review showed that the patients had persistent symptoms that, in the case of dyspnea and sputum volume, were worse on follow-up. Spirometry showed a significant decline in FEV1 over the follow-up period with an average loss of 49 ml per year. This study showed in this group of predominantly female adult patients with bronchiectasis followed up for 8 years, patients had persistent symptoms and an excess loss in FEV1.

Endogenous myeloperoxidase promotes neutrophil-mediated renal injury, but attenuates T cell immunity inducing crescentic glomerulonephritis

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.

CD100 enhances dendritic cell and CD4+ cell activation leading to pathogenetic humoral responses and immune complex glomerulonephritis

CD100, a member of the semaphorin family, is a costimulatory molecule in adaptive immune responses by switching off CD72's negative signals. However, CD100's potential pathogenetic effects in damaging immune responses remain largely unexplored. We tested the hypothesis that CD100 plays a pathogenetic role in experimental immune complex glomerulonephritis. Daily injection of horse apoferritin for 14 days induced immune complex formation, mesangial proliferative glomerulonephritis and proteinuria in CD100-intact (CD100+/+) BALB/c mice. CD100-deficient (CD100-/-) mice were protected from histological and functional glomerular injury. They exhibited reduced deposition of Igs and C3 in glomeruli, reduced MCP-1 and MIP-2 intrarenal mRNA expression, and diminished glomerular macrophage accumulation. Attenuated glomerular injury was associated with decreased Ag-specific Ig production, reduced CD4+ cell activation and cytokine production. Following Ag injection, CD4+ cell CD100 expression was enhanced and dendritic cell CD86 expression was up-regulated. However, in CD100-/- mice, dendritic cell CD86 (but not CD80) up-regulation was significantly attenuated. Following i.p. immunization, CD86, but not CD80, promotes early Ag-specific TCR-transgenic DO11.10 CD4+ cell proliferation and IFN-gamma production, suggesting that CD100 expression enables full expression of CD86 and consequent CD4+ cell activation. Transfer of CD100+/+ DO11.10 cells into CD100-/- mice resulted in decreased proliferation demonstrating that CD100 from other sources in addition to CD100 from Ag-specific CD4+ cells plays a role in initial T cell proliferation. Although T cell-B cell interactions also may be relevant, these studies demonstrate that CD100 enhances pathogenetic humoral immune responses and promotes the activation of APCs by up-regulating CD86 expression.

Assessing immune function in adult bronchiectasis

Bronchiectasis is characterized by chronic airway infection and damage and remains an important health problem. Recent literature has emphasized the role of host defence and immune deficiency in the pathogenesis of bronchiectasis, but there have been few studies of immune function in adult bronchiectasis. A comprehensive screen of immune function was conducted in 103 adult patients with bronchiectasis, encompassing full blood examinations, immunoglobulins and IgG isotypes, complement levels, lymphocyte subsets and neutrophil function. Full blood examinations were normal in this cohort, as were complement levels. Statistical analysis confirmed that a significant number of subjects had low levels of IgG3 (13 patients), B cell lymphocytes (six patients) and T helper cell lymphocytes (seven patients) when compared with controls (P<0.05). The most common abnormality was found with testing of the neutrophil oxidative burst. All subjects had a normal neutrophil phagocytic function but 33 of the subjects had an oxidative burst that was below the normal range (P<0001). Almost half the group (45 subjects) had abnormally low levels of one of these four parameters. The findings of low B cells, Th cells and oxidative burst in bronchiectasis are novel. The results emphasize the importance of immune function assessment for adult bronchiectasis.

Anti-Neutrophil Cytoplasmic Antibodies and Effector CD4+Cells Play Nonredundant Roles in Anti-Myeloperoxidase Crescentic Glomerulonephritis

Most humans with microscopic polyarteritis and anti-myeloperoxidase (anti-MPO), anti-neutrophil cytoplasmic antibodies (ANCA) develop "pauci-immune" crescentic glomerulonephritis. For dissection of the roles of ANCA and cell-mediated effectors in microscopic polyarteritis, experimental autoimmune anti-MPO glomerulonephritis was induced by immunizing C57BL/6 mice with human MPO. Autoimmunity to mouse MPO (ANCA and CD4+ cell reactivity) was induced. Challenge with anti-glomerular basement membrane globulin resulted in accumulation of neutrophils, CD4+ cells and macrophages, and significant numbers of crescentic glomeruli compared with similarly challenged control-immunized mice. MPO-deficient (Mpo(-/-)) mice immunized with MPO developed similar immune responses to MPO but failed to recruit effector cells to glomeruli or develop significant crescent formation, suggesting that MPO is acting as a planted glomerular autoantigen. Effector CD4+ cell depletion in this model attenuated crescentic glomerulonephritis and effector cell influx without altering ANCA titers. However, B cell-deficient mice, with no ANCA, still developed severe crescentic glomerulonephritis with accumulation of effector cells. Intravital microscopy studies demonstrated that passive transfer of sera from MPO-immunized Mpo(-/-) mice to LPS-primed mice rapidly induced glomerular neutrophil accumulation and release of MPO. These studies provide in vivo evidence in a relevant vascular bed for both humoral and cellular anti-MPO responses as key inducers of injury. ANCA induces glomerular neutrophil infiltration and MPO deposition. Subsequently, anti-MPO CD4+ cells recognize MPO as a planted glomerular antigen and act with macrophages to amplify severe glomerular injury.

Characterisation of the onset and presenting clinical features of adult bronchiectasis

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 1s 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.

T cells in crescentic glomerulonephritis

Crescent formation in glomerulonephritis (GN) is a manifestation of severe glomerular injury that usually results in a poor clinical outcome. In humans, crescentic GN is frequently associated with evidence of either systemic or organ-specific autoimmunity. T cells play a major role in initiation of adaptive immune responses that lead to crescentic injury. In experimental models of crescentic GN, Th1 predominant immune responses have been shown to promote crescent formation. Perturbation of regulatory T cell function may contribute to development of autoimmune crescentic GN. The presence of T cells and macrophages in crescentic glomeruli, frequently in the absence of humoral mediators of immunity, suggest a dominant effector role for T cells in crescentic GN. The association of cellular immune mediators with local fibrin deposition implicates cell-mediated "delayed-type hypersensitivity-like" mechanisms in crescent formation. Intrinsic renal cells also contribute to T cell-driven effector mechanisms in crescentic GN, via expression of MHC II and co-stimulatory molecules and by production of chemokines and cytokines that amplify leukocyte recruitment and injury.

Inducible co-stimulatory molecule ligand is protective during the induction and effector phases of crescentic glomerulonephritis

The inducible co-stimulatory molecule (ICOS)/ICOS ligand (ICOSL) co-stimulatory pathway is critical in T cell activation, differentiation, and effector function. Its role was investigated in a model of Th1-driven crescentic glomerulonephritis (GN). GN was induced by sensitizing mice to sheep globulin (day 0) and challenging them with sheep anti-mouse glomerular basement membrane antibody (Ab; day 10). Disease and immune responses were assessed on day 20. For testing the role of ICOSL in the induction of GN, control or anti-ICOSL mAb were administered from days 0 to 8. For examining the role of ICOSL in the effector phase of GN, treatment lasted from days 10 to 18. Blockade of ICOSL during the induction of GN increased glomerular accumulation of CD4+ T cells and macrophages and augmented renal injury. These results correlated with attenuated splenocyte production of protective Th2 cytokines IL-4 and IL-10 and decreased apoptosis of splenic CD4+ T cells. ICOSL was upregulated within glomeruli of mice with GN. Inhibition of ICOSL during the effector phase of GN enhanced glomerular T cell and macrophage accumulation and augmented disease, without affecting the systemic immune response (cytokine production, T cell apoptosis/proliferation, Ab levels). Increased presence of leukocytes in glomeruli of mice that received anti-ICOSL mAb was associated with enhanced cellular proliferation and upregulation of P-selectin and intercellular adhesion molecule-1 within glomeruli. These studies demonstrate that ICOSL is protective during the induction of GN by augmenting Th2 responses and CD4+ T cell apoptosis. They also show that ICOSL is upregulated in nephritic glomeruli, where it locally reduces accumulation of T cells and macrophages and attenuates renal injury.

Diagnosis of Mycobacterium tuberculosis infection using ESAT-6 and intracellular cytokine cytometry

Diagnosis of infection with Mycobacterium tuberculosis (MTB) using tuberculin skin testing (TST) is often hampered by prior Bacille Calmette-Guérin (BCG) vaccination. ESAT-6 is a protein that is expressed by MTB but absent in BCG. It has been postulated that it might be useful in distinguishing MTB-specific immune responses. This study measured CD4 T cell responder frequencies specific for ESAT-6 and the TST reagent purified protein derivative (PPD) in patients with tuberculosis (n = 16), controls with non-tuberculous pneumonia (n = 8) and normal subjects (n = 7). Responses were identified using the intracellular cytokine staining technique and flow cytometry on whole blood samples, and performed blinded to the patient condition. Antigen-specific CD4 cells were defined by CD69 positivity and one or more cytokine [interleukin (IL)-2, IL-4, IL-10, interferon (IFN)-gamma] and/or CD40L positivity. With ESAT-6 stimulation it was found that TB patients had significantly higher frequencies of IFN-gamma and CD40L-positive CD4 T cells compared to the normal group, while no significant differences were measured with PPD stimulation. A responder frequency of 0.01% or higher for at least one of the measured cytokines/CD40L was defined as a positive response. Using this criterion to compare the two patient groups, PPD had 100% sensitivity but 0% specificity while ESAT-6 had 100% sensitivity and 88% specificity. Use of MTB-specific proteins such as ESAT-6 in combination with intracellular cytokine staining and flow cytometry has the potential to identify individuals with MTB infection.

The isolation and purification of biologically active recombinant and native autoantigens for the study of autoimmune disease

The expression of recombinant, biologically active mouse myeloperoxidase (MPD) and the recombinant non-collagenous (NC1) domain of mouse collagen alpha 3 Type IV was achieved for the first time in Sf21 cells (Spodoptera frugiperda ovarian insect cells) using a baculovirus expression system. Following purification, the proteins were identified by reducing and non-reducing SDS-PAGE electrophoresis. Recombinant mouse MPO has a molecular weight of approximately 90 kDa and mouse alpha3(IV)NC1 approximately 32 kDa. In addition, milligram quantities of native mouse myeloperoxidase were purified from 32Dcl3 cells. Both native and recombinant myeloperoxidase were biologically active. This study also demonstrated that the immunization of myeloperoxidase deficient (Mpo-/-) mice with purified recombinant mouse myeloperoxidase induced a significant antibody response to native myeloperoxidase.

A pathogenetic role for mast cells in experimental crescentic glomerulonephritis

Mast cells infiltrate kidneys of humans with crescentic glomerulonephritis (GN), and the degree of infiltrate correlates with outcome. However, a functional role for mast cells in the pathogenesis of GN remains speculative. GN was induced by intravenous administration of sheep anti-mouse glomerular basement membrane globulin. After 21 d, systemic immune responses and disease severity were analyzed in wild-type, mast cell-deficient (W/Wv), and bone marrow-derived mast cell-reconstituted W/Wv mice (BMMC-->W/Wv). There were no significant differences in the humoral response toward the nephritogenic antigen or in memory T cell number among the three groups; however, antigen-stimulated T cell IFN-gamma production was significantly elevated in BMMC-->W/Wv mice. Dermal delayed-type hypersensitivity in W/Wv mice was reduced compared with wild-type and BMMC-->W/Wv mice. No mast cells were detected in kidneys of W/Wv mice with GN, whereas in BMMC-->W/Wv mice, the numbers of renal mast cells were similar to wild-type mice with GN. W/Wv mice were protected from the development of crescentic GN, exhibiting reduced crescent formation (10 +/- 1% c.f. 36 +/- 2% in wild type), glomerular influx of T cells/macrophages, and interstitial infiltrate compared with wild-type mice. In contrast, BMMC-->W/Wv demonstrated a similar severity of GN as wild-type mice (35 +/- 2% crescentic glomeruli), accompanied by a prominent inflammatory cell infiltrate into glomeruli and interstitial areas. Glomerular expression of intercellular adhesion molecule-1 and P-selectin were reduced in W/Wv mice but restored to wild-type levels in BMMC-->W/Wv mice. These findings suggest that renal mast cells mediate crescentic GN by facilitating effector cell recruitment into glomeruli via augmentation of adhesion molecule expression.

CD80 and CD86 costimulatory molecules regulate crescentic glomerulonephritis by different mechanisms

BACKGROUND

CD80 and CD86 costimulatory molecules have been shown to affect the induction of Th1-mediated crescentic antiglomerular basement membrane (GBM) antibody-initiated glomerulonephritis (GN). The aim of the current studies was to define the mechanisms by which CD80 and CD86 regulate the development of this disease.

METHODS

Anti-GBM GN was induced in CD80-/-, CD86-/-, and CD80/86-/- mice, as well as in C57BL/6 controls. Renal injury and immune responses were assessed after 21 days. To examine whether costimulation by OX40-ligand compensates for the absence of CD80 and CD86 in inducing GN, OX40-ligand was blocked in wild-type and CD80/86-/- mice.

RESULTS

Crescentic GN and glomerular accumulation of CD4+ T cells and macrophages were attenuated in CD80-/- mice, correlating with significantly enhanced apoptosis and decreased proliferation of spleen CD4+ T cells. GN was exacerbated in CD86-/- mice, which was associated with attenuated IL-4 and enhanced IFN-gamma levels. In contrast, CD80/86-/- mice developed crescentic GN similar to that in controls. Inhibition of OX40-ligand exacerbated GN in wild-type mice by enhancing IFN-gamma production, and attenuated disease in CD80/86-/- mice by reducing glomerular CD4+ T-cell and macrophage accumulation.

CONCLUSION

CD80 is pathogenic in crescentic GN by enhancing survival and proliferation of CD4+ T cells, whereas CD86 is protective by enhancing Th2 and attenuating Th1 responses. Furthermore, in the presence of CD80 and CD86, OX40-ligand attenuates, whereas in their absence it enhances GN, suggesting that, in the absence of CD80 and CD86, the OX40/OX40-ligand pathway is an alternative costimulatory pathway in inducing crescentic GN.

Granulocyte Macrophage Colony-Stimulating Factor Expression by Both Renal Parenchymal and Immune Cells Mediates Murine Crescentic Glomerulonephritis

GM-CSF has previously been demonstrated to be important in crescentic glomerulonephritis (GN). As both renal parenchymal cells and infiltrating inflammatory cells produce GM-CSF, their separate contributions to inflammatory renal injury were investigated by creation of two different types of GM-CSF chimeric mice: (1) GM-CSF-deficient (GM-CSF-/-)-->wild-type (WT) chimeras with leukocytes that are unable to produce GM-CSF and (2) WT-->GM-CSF-/- chimeras with deficient renal cell GM-CSF expression. Crescentic anti-glomerular basement membrane GN was induced in WT, GM-CSF(-/-)-->WT chimeras, WT-->GM-CSF-/- chimeras, and GM-CSF-/- mice by planting an antigen (sheep globulin) in their glomeruli. WT mice developed severe crescentic GN, whereas GM-CSF-/- were protected from development of disease. Glomerular T cell recruitment, CD40+ glomerular cells, and renal IFN-gamma and TNF expression were similar in both chimeras and WT mice but significantly reduced in GM-CSF-/- mice, indicating that either leukocyte or renal sources of GM-CSF are sufficient to drive these aspects of the inflammatory response. Restricted expression of GM-CSF revealed a major role for renal cell-derived GM-CSF but a minor role for leukocyte-derived GM-CSF in the formation of cellular crescents; glomerular MHC II expression; serum creatinine; and monocyte chemoattractant protein-1, vascular cellular adhesion molecule, and IL-1beta expression. Glomerular macrophage accumulation, proteinuria, and interstitial infiltrate were equivalent in both chimeric groups but intermediate between WT and GM-CSF-/-, indicating that both sources are required for the full development of glomerular injury in crescentic GN.

Leukocyte phenotype and function predicts infection risk in renal transplant recipients

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.