Pathogenesis of experimental lupus nephritis: a role for anti-basement membrane and anti-tubular brush border antibodies in murine chronic graft-versus-host disease

TIGIT-Fc fusion protein alleviates murine lupus nephritis through the regulation of SPI-B-PAX5-XBP1 axis-mediated B-cell differentiation

OBJECTIVES

T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is a newly discovered immune checkpoint (IC) that exhibits immunosuppressive function in the regulation of immune system. Activation of TIGIT signaling has emerged as a promising approach for autoimmune disease immunotherapy, such as systemic lupus erythematosus (SLE).

METHODS

We generated a chimeric protein, TIGIT-immunoglobulin (Ig), by fusing the extracellular domain of murine TIGIT to the Fc region of mouse IgG2a, which was used to investigated the effect of activating the TIGIT signaling in murine lupus models (MRL/lpr and chronic graft-versus-host disease mice). Treated mice were harvested, and samples of serum, kidney, and spleen were collected for outcome evaluation. In vitro treatment of TIGIT-Ig in B cells was used for exploring the roles of TIGIT in toll-like receptor 7 (TLR7)-mediated B cell differentiation and antibody production.

RESULTS

TIGIT-Ig treatment delayed disease progression in both lupus models, accompanied by a decrease in the production of anti-double stranded DNA antibodies (anti-dsDNA), proteinuria, proteinuria/creatinine, and Ig kidney deposition. Additionally, the group treated with TIGIT-Ig displayed a decreased proportion of T helper cell (Th)1 cells, T follicular helper (Tfh) cells, and B-cell subsets, including germinal center B cells (GC B), plasmablasts, and plasma cells, compared to the group treated with control IgG. Interestingly, we also observed an increased proportion of Tregs in the spleen of the TIGIT-Ig group. We have discovered a new way in which activating the TIGIT pathway can regulate B-cell differentiation through the SPI-B-PAX5-XBP1 pathway, resulting in a reduction in autoantibodies.

CONCLUSION

Together, TIGIT may be a promising IC target for SLE treatment.

Towards a Better Understanding of the Atypical Features of Chronic Graft-Versus-Host Disease: A Report from the 2020 National Institutes of Health Consensus Project Task Force

Alloreactive and autoimmune responses after allogeneic hematopoietic cell transplantation can occur in non-classical chronic graft-versus-host disease (chronic GVHD) tissues and organ systems or manifest in atypical ways in classical organs commonly affected by chronic GVHD. The National Institutes of Health (NIH) consensus projects were developed to improve understanding and classification of the clinical features and diagnostic criteria for chronic GVHD. While still speculative whether atypical manifestations are entirely due to chronic GVHD, these manifestations remain poorly captured by the current NIH consensus project criteria. Examples include chronic GVHD impacting the hematopoietic system as immune mediated cytopenias, endothelial dysfunction, or as atypical features in the musculoskeletal system, central and peripheral nervous system, kidneys, and serous membranes. These purported chronic GVHD features may contribute significantly to patient morbidity and mortality. Most of the atypical chronic GVHD features have received little study, particularly within multi-institutional and prospective studies, limiting our understanding of their frequency, pathogenesis, and relation to chronic GVHD. This NIH consensus project task force report provides an update on what is known and not known about the atypical manifestations of chronic GVHD, while outlining a research framework for future studies to be undertaken within the next three to seven years. We also provide provisional diagnostic criteria for each atypical manifestation, along with practical investigation strategies for clinicians managing patients with atypical chronic GVHD features.

Kidney Pathology after Hematologic Cell Transplantation-A Single-Center Observation Study of Indication Biopsies and Autopsies

Hematopoietic cell transplantation (HCT) is an increasingly used treatment for hematologic malignancies as well as for nonmalignant diseases. Kidney impairment remains an important early and late post-transplantation complication. Although numerous histopathological changes have been reported, the pathophysiology remains incompletely understood. Furthermore, correlations between clinical findings and morphological changes have not been well studied. Between 2000 and 2016, 17 recipients of allogeneic (n = 12) or autologous (n = 5) HCT underwent kidney biopsy for either proteinuria or deterioration of kidney function at our center. The most common biopsy findings were therapy-related changes with thrombotic microangiopathy (n = 5), calcineurin inhibitor toxicity (n = 4), and membranous glomerulonephritis (n = 3), representing the majority of cases in this category. In addition, kidney findings from 137 autopsies performed between 1995 and March 2017 were analyzed. The most common changes were acute kidney injury (n = 55), most likely due to the patients' premortal deteriorated state, and thrombotic microangiopathy (n = 14). Several cases demonstrated involvement by either infectious agents (n = 6) or tumors (n = 9). Distinct kidney diseases, such as glomerulonephritis, were rare (3% of cases). Uncommon and yet rarely described diagnoses for this patient cohort were IgG4-related tubulointerstitial nephritis and fibrillary nephritis. This study provides a comprehensive overview of the histomorphological findings in kidney biopsy specimens from HCT recipients. Along with treatment-related complications, one putative correlate of chronic GVHD of the kidney could be documented: membranous glomerulonephritis. In contrast, no morphological correlate of acute GVHD of the kidney was identified. Findings at the time of autopsy varied greatly, spanning a wider range than those of indication biopsies.

Nephrotic syndrome as a complication of chronic graft-versus-host disease after allogeneic haemopoietic stem cell transplantation

Nephrotic syndrome (NS) is a rare complication following allogeneic haemopoietic stem cell transplantation (allo-HSCT), with limited current understanding of its pathogenesis. Here, we describe four cases of NS following allo-HSCT diagnosed at our institutions to identify key clinical and pathological features. In addition, a PubMed search was performed to identify existing reports that were pooled together with our cases for analysis. NS occurred as a late complication following allo-HSCT, with median onset 19.5 months after transplant (range: 3.9-84 months). The most common histopathology observed was membranous nephropathy; however, cases of minimal change disease have also been reported. There is a high incidence of prior extra-renal graft-versus-host disease (GvHD), with all four of our cases and 82% of published cases having prior GvHD. Glucocorticosteroids are the most common treatment, with variable degrees of response. Responses to immunosuppression with calcineurin inhibitors and rituximab have been described in steroid-refractory cases.

Emergence of Dipstick Proteinuria Predicts Overt Nephropathy in Patients Following Stem Cell Transplantation

BACKGROUND

Stem cell transplantation (SCT) places a heavy burden on the kidneys, often resulting in renal dysfunction or nephrotic syndrome. This study attempted to show that early-onset proteinuria predicts the development of overt nephropathy.

METHODS

A total of 831 patients who received allogeneic SCT were surveyed. Excluding those with prior kidney disease and those lacking in an observation period ≥1 year after SCT, 251 patients were eligible for the study. Dipstick proteinuria ≥1+ within 1 year after SCT was defined as 'incident proteinuria', and subsequent persistence of an estimated glomerular filtration rate of <60 ml/min/1.73 m2 at 1 year or longer after SCT was defined as 'incident chronic kidney disease (CKD)'. Between-group differences were analyzed using the chi-square or Mann-Whitney U test. Factors associated with the incidence of CKD were investigated by multivariate Cox proportional regression analysis. Kidney-biopsied tissue was examined in all nephrotic syndrome patients.

RESULTS

The mean duration of follow-up was 4 years. Thirty-four (13.5%) and 66 (26.3%) patients developed incident proteinuria and incident CKD, respectively. Nine (3.6%) patients developed nephrotic syndrome mainly due to membranous nephropathy. The incidence of CKD was significantly greater in patients with incident proteinuria than those without (61.8 vs. 20.7%, p < 0.0001), and incident dipstick proteinuria was a significant risk for incident CKD (hazard ratio 4.39, 95% CI 2.44-7.73, p < 0.0001).

CONCLUSION

SCT patients who manifest dipstick proteinuria are predisposed to overt nephropathy. Routine monitoring of the urine dipstick test is strongly recommended, as it facilitates early nephrology care for post-SCT patients.

Immune Complex Tubulointerstitial Nephritis Due to Autoantibodies to the Proximal Tubule Brush Border

Immune complex tubulointerstitial nephritis due to antibodies to brush border antigens of the proximal tubule has been demonstrated experimentally and rarely in humans. Our patient developed ESRD and early recurrence after transplantation. IgG and C3 deposits were conspicuous in the tubular basement membrane of proximal tubules, corresponding to deposits observed by electron microscopy. Rare subepithelial deposits were found in the glomeruli. The patient had no evidence of SLE and had normal complement levels. Serum samples from the patient reacted with the brush border of normal human kidney, in contrast with the negative results with 20 control serum samples. Preliminary characterization of the brush border target antigen excluded megalin, CD10, and maltase. We postulate that antibodies to brush border antigens cause direct epithelial injury, accumulate in the tubular basement membrane, and elicit an interstitial inflammatory response.

De novo glomerulitis associated with graft-versus-host disease after allogeneic hematopoietic stem cell transplantation: A single-center experience

BACKGROUND

Nephrotic syndrome (NS) and proteinuria are uncommon, often unrecognized manifestations of graft-versus-host disease (GVHD) after hematopoietic stem cell transplantation (HSCT). Only a few isolated case reports and case series involving smaller number of patients who developed NS after HSCT have been published.

METHODS

We reviewed the renal histopathological examination findings and clinical records of 15 patients who developed proteinuria after HSCT at Seoul and Yeouido St. Mary's Hospital (Seoul, Korea). We also measured the anti-PLA2R antibodies (M-type phospholipase A2 receptor) in the serum samples from the seven patients at the time of renal biopsy.

RESULTS

All patients had GVHD. The most common indication for biopsy was proteinuria (>1 g/day), with nine patients having nephrotic range proteinuria. The most common histopathological finding was membranous nephropathy (MN; n = 12). Other findings were membranoproliferative glomerulonephritis, C1q nephropathy, and diabetic nephropathy. Eleven patients were treated with immunosuppressive agents, and three patients were treated only with angiotensin II receptor blocker. The overall response rate, including complete remission (urinary protein level <0.3 g/day) and partial remission (urinary protein level = 0.31-3.4 g/day), was 73%. The mean follow-up period was 26 months, and none of the patients developed end-stage renal disease. All of the seven patients with MN had negative findings for anti-PLA2R antibodies, measured using an enzyme-linked immunosorbent assay kit.

CONCLUSION

In this study the findings of 15 renal biopsies were analyzed and to our knowledge this is the largest clinicopathological study of GVHD-related biopsy-proven nephropathy. Approximately 80% of the patients were MN and 73% responded either partially or completely to immunosuppressive treatment. Currently, there is an increase in the incidence of GVHD-mediated renal disease, and therefore, renal biopsy is essential for diagnosing the nephropathy and preventing the progression of renal disease.

A case of membranous nephropathy as a manifestation of graft-versus-host disease

Nephrotic syndrome (NS) rarely occurs after hematopoietic stem cell transplantation (HSCT) as a late manifestation of graft-versus-host disease (GVHD). Herein, we report a case of HSCT-associated membranous nephropathy in a female patient with aplastic anemia. The patient received an allogeneic HSCT from her human leukocyte antigen-identical brother following myeloablative conditioning chemotherapy. NS occurred 21 months after HSCT without any concurrent features of chronic GVHD. The patient was treated with prednisolone and cyclosporine after renal biopsy confirmed membranous nephropathy, and achieved complete remission. Our report contradicts previous assumptions that concomitant chronic GVHD is responsible for the development of NS, suggesting that NS can develop as a new, independent manifestation of GVHD.

Renal involvement in bone marrow transplantation

Bone marrow transplantation (BMT) is an effective therapeutic strategy for leukaemic malignancies and depressed bone marrow following cancer. However, its side effects on kidneys have been reported. Some drugs and irradiation are also suggested to be nephrotoxic. It is well known that haemolytic uraemic syndrome (HUS) after BMT develops as late-onset BMT nephropathy. Cyclosporine A (CsA) is a possible cause. Radiation nephropathy shows changes that are similar to the histology of HUS. These findings suggest that endothelial damage is closely associated with the pathogenesis of post-BMT nephropathy. Recently, some patients have developed glomerulonephritis accompanied by graft-versus-host disease (GVHD) after BMT. In these patients immune deposits are found mainly in subepithelium and mesangium equal to those of secondary membranous glomerulonephritis. A murine experimental model of GVHD manifests similar symptoms and histological changes to those of actual patients and may suggest the pathogenesis of glomerulonephritis.

Autoantibody explosion in systemic lupus erythematosus: more than 100 different antibodies found in SLE patients

OBJECTIVE

Description of the various autoantibodies that can be detected in patients with systemic lupus erythematosus (SLE).

METHODS

A literature review, using the terms "autoantibody" and "systemic lupus erythematosus", was conducted to search for articles on autoantibodies in SLE, their target antigens, association with disease activity, or other clinical associations.

RESULTS

One hundred sixteen autoantibodies were described in SLE patients. These include autoantibodies that target nuclear antigens, cytoplasmic antigens, cell membrane antigens, phospholipid-associated antigens, blood cells, endothelial cells, and nervous system antigens, plasma proteins, matrix proteins, and miscellaneous antigens. The target of autoantibody, the autoantigen properties, autoantibody frequencies in SLE, as well as clinical associations, and correlation with disease activity are described for all 116 autoantibodies.

CONCLUSIONS

SLE is the autoimmune disease with the largest number of detectable autoantibodies. Their production could be antigen-driven, the result of polyclonal B cell activation, impaired apoptotic pathways, or the outcome of idiotypic network dysregulation.

Quinoline-3-carbothioamides and related compounds as novel immunomodulating agents

A series of quinoline-3-carbothioamides and their analogues was prepared via four synthetic routes and evaluated for their antinephritic and immunomodulating activities. The optimal compound 9g strongly inhibited the T-cell independent antibody production in mice immunized with TNP-LPS and was highly effective in two nephritis models, namely chronic graft-versus-host disease and autoimmune MRL/l mice.

Synthesis and antinephritic activities of quinoline-3-carboxamides and related compounds

A series of linomide-related quinoline-3-carboxamides and their analogues was prepared and evaluated for antinephritic activities. The 6-MeS derivative 7a was highly effective in two nephritis models, namely chronic graft-versus-host disease and autoimmune MRL/l mice.

Lupus nephritis: lessons from experimental animal models

Lupus nephritis is a frequent and severe complication of SLE. In the last decades, animal models for SLE have been studied widely to investigate the immunopathology of this autoimmune disease because abnormalities can be studied and manipulated before clinical signs of the disease become apparent. In this review an overview is given of our current knowledge on the development of lupus nephritis, as derived from animal models, and a hypothetical pathway for the development of lupus nephritis is postulated. The relevance of the studies in experimental models in relationship with our knowledge of human SLE is discussed.

Administration of an IL-12-Encoding DNA Plasmid Prevents the Development of Chronic Graft-Versus-Host Disease (GVHD)

The transfer of DBA/2 spleen cells into (C57BL/10 × DBA/2)F1 mice induces chronic graft-vs-host disease (GVHD), which is characterized by the production of Th2 cytokines, hypergammaglobulinemia, and immune complex-mediated glomerulonephritis like systemic lupus erythematosus. IL-12 strongly induces the production of Th1 cytokines and reduces Th2 activity in vivo. In this study, the effect of gene therapy on the development of murine chronic GVHD was examined using an IL-12-encoding plasmid (pCAGGSIL-12), with the expectation that it might regulate Th1/Th2 activity and have a beneficial impact on the clinical manifestations of disease. pCAGGSIL-12 or its p40 antagonist plasmid (pCAGGSp40) were injected i.m. every 3 wk in GVHD-induced (C57BL/10 × DBA/2)F1 mice. A total of 100 μg of pCAGGSIL-12 improved the Th1/Th2 balance in vivo, suppressed the production of IgG, and significantly reduced the development of glomerulonephritis. GVHD was exacerbated by injection of the pCAGGSp40 antagonist. Our results demonstrate that GVHD can be treated successfully by the administration of an IL-12-encoding plasmid, and that such therapy does not induce acute GVHD.

Association between leukocyte infiltration and development of glomerulosclerosis in experimental lupus nephritis

Mice with chronic graft-versus-host disease (GvHD) induced by injection of DBA/2 lymphocytes into (DBA/2 x C57BL/10) F1 hybrids (DBA/2 GvHD) develop a lupus-like glomerulonephritis with global glomerulosclerosis 12 weeks after induction of the disease. In two other strain combinations with similar H-2 incompatibilities [BALB/c into BALB/c x BL10 (BALB/c GvHD) and BALB.D2 into BALB.D2 x BL10 (BALB.D2 GvHD)], GvHD induction leads to lupus nephritis without global glomerulosclerosis. This study investigated the identity of kidney-infiltrating leukocytes and their involvement in the development of glomerulosclerosis in these three strain combinations. In mice with DBA/2 GvHD, a significant increase in glomerular CD11a-positive cells was found 4 weeks after disease induction. Mice with BALB/c or BALB.D2 GvHD did not show an increase in glomerular CD11a-positive cells at any time point. In the interstitium, CD11a-positive cells were observed 4 weeks after disease induction only in mice with DBA/2 GvHD. In mice with BALB.D2 GvHD, no increase was found in interstitial CD11a-positive cells. In mice with BALB/c GvHD, interstitial CD11a-positive cells were found from week 4 onward. Further immunohistochemical analysis of the glomerular CD11a-positive cells in mice with DBA/2 GvHD showed that these cells were neither polymorphonuclear leukocytes (PMN), nor CD3-positive (T cells), B220-positive (B cells), or F4/80-positive (macrophages). They were all CD45-positive (leukocytes) and MHC class II-positive. In conclusion, we have shown in this model of chronic lupus nephritis that glomerular influx of as yet unidentified CD11a-positive leukocytes is associated with the development of glomerulosclerosis.

Discovery of FR115092: a novel antinephritic agent

A series of dapsone-related 4-aminopheynl and 2-aminothiazolyl derivatives was prepared, and their antinephritic activity and blood toxicity were evaluated. 5-(2-Pyridylsulfonyl)-2-thiazolamine (FR115092, 26) was effective against two nephritis models, namely graft-versus-host disease (GVHD) and autoimmune W/BF1 mice, and showed none of the blood toxicity observed with dapsone.

Qualitative alterations in laminin expression in experimental lupus nephritis

Previous studies have revealed quantitative alterations in laminin-1 expression at the mRNA and protein levels during the development of glomerulonephritis and glomerulosclerosis in chronic graft-versus-host disease in mice, a model for lupus nephritis. We have now studied the qualitative alterations in laminin expression with two monoclonal antibodies that recognize epitopes on either the E8 or the P1 fragment of laminin-1. Both of these fragments are involved in cell-matrix and matrix-matrix interactions. In normal glomeruli these laminin epitopes are present only in the mesangial matrix; during embryogenesis, however, they are also present in the glomerular basement membrane. The distribution of laminin epitopes was first studied by using immunofluorescence in kidneys of mice with graft-versus-host disease at different points in time after disease induction. Reflection contrast and immunoelectron microscopy were performed after in vivo injection of the horseradish peroxidase-coupled monoclonal antibodies. In glomeruli of mice 8 weeks after disease induction, both injected antibodies bound specifically in electron-dense immune deposits in the mesangium and subepithelially along the glomerular basement membrane as well as in the expanded mesangial matrix. At 11 and 12 weeks after disease induction, when focal and segmental glomerulosclerosis had developed, the antibodies additionally bound in the matrix subendothelially along the glomerular basement membrane and at the periphery of end-stage sclerotic lesions. To study changes in the distribution of laminin epitopes over time, mice were injected with either monoclonal antibody before induction of graft-versus-host disease. The antibodies were detected 8 and 12 weeks later in the mesangial matrix of mice with lupus nephritis. Once segmental glomerulosclerosis had developed, the antibodies were additionally detected within the thickened glomerular capillary wall. The specific binding of anti-laminin monoclonal antibodies in electron-dense immune deposits further substantiates the hypothesis that anti-laminin autoantibodies participate in glomerular immune complex formation in this model, as suggested by earlier studies. Furthermore, our results show that the distribution of glomerular laminin epitopes in the matrix is altered during the development of glomerular disease. These changes in the structure of the glomerular basement membrane may contribute to the abnormal cell-matrix and matrix-matrix interactions during the development of glomerular disease in this model for lupus nephritis.

Prevention of glomerulosclerosis by early cyclosporine treatment of experimental lupus nephritis

The influence of cyclosporine A (CsA) treatment on the development of glomerulonephritis and glomerulosclerosis was investigated in chronic graft-versus-host disease (GvHD), a murine model for lupus nephritis. The renal disease is characterized by the formation of IgG-containing electron-dense deposits along the glomerular basement membrane (GBM) and in the mesangium, followed by the onset of proteinuria which starts, varying per individual mouse, about six weeks after the induction of the disease. Glomerular mRNA levels for matrix molecules were increased from week 4, preceding mesangial matrix expansion and GBM thickening which occurred from week 6. These initial events finally led to development of glomerulosclerosis, and end-stage renal failure. Groups of mice received three intraperitoneal (i.p.) injections per week with different doses of CsA, and treatment was started 2, 4, or 6 weeks after induction of the disease. Treatment with 10 or 50 mg CsA/kg/week did not influence the development of glomerulonephritis or glomerulosclerosis. Injection of 100 mg CsA/kg/week delayed the onset of proteinuria only when treatment was started in week 2. In week 6 some mice had already developed proteinuria whereas others had not. Treatment with 250 mg CsA/kg/week starting in week 6 abrogated glomerulonephritis and glomerulosclerosis only in those animals which were not yet proteinuric at that time. This, despite comparable increased autoantibody levels against DNA, GBM, and renal tubular epithelium (RTE) in both treated and untreated GvHD mice. Further increase in proteinuria and development of glomerulosclerosis could not be prevented if the mice already had developed proteinuria when CsA treatment was started. Dot blot analysis and in situ hybridization showed significantly decreased mRNA levels for alpha 1(I) and alpha 1(IV) collagen in kidneys of CsA-treated mice as compared to those of untreated mice 12 weeks after induction of the disease, if the highest dose of CsA was administered before the onset of proteinuria. No effect on these whole-kidney mRNA levels was observed in mice which had already developed proteinuria before CsA injections were started. Increased mRNA expression for matrix molecules in this group and in untreated GvHD mice was observed mainly in the interstitium. The kidneys of the treated GvHD mice and those of mice injected with 250 mg CsA/kg/week without induction of GvHD showed no morphological signs of CsA nephrotoxicity. We conclude that treatment with 250 mg CsA/kg/week prevents the development of glomerulonephritis and glomerulosclerosis in this model of lupus nephritis, if started before the onset of proteinuria.(ABSTRACT TRUNCATED AT 400 WORDS)

Significance of anti-entactin antibodies in patients with systemic lupus erythematosus and related disorders

OBJECTIVES

To further evaluate the association of anti-entactin antibodies with clinical manifestations in patients with systemic lupus erythematosus (SLE) and related disorders.

METHODS

Sera were analysed for anti-entactin antibodies from 79 patients with SLE, 38 patients with rheumatoid arthritis, 20 patients with progressive systemic sclerosis and five with Behçet's syndrome. Sera from 150 healthy blood donors and 20 patients with pneumonia were analysed as controls. To study the association of anti-entactin antibodies with severity and activity in SLE, 30 patients were assigned into three groups with 10 patients in each: (1) with mild manifestations; (2) severe disease without renal involvement and (3) frank lupus nephritis. Two blood samples from each patient were analysed, one from the active and the other from the inactive phase of the disease. Additionally, serial sera from 12 patients with SLE were also analysed.

RESULTS

Thirty one patients with SLE (39%) had IgG, IgM or both anti-entactin antibodies. Twenty three of these patients (29%) had biopsy verified glomerulonephritis and 12 (50%) were positive for anti-entactin antibodies. Of the remaining 56 patients without apparent renal involvement, 18 (36%) were positive for anti-entactin antibodies. (chi squared = 2.77, p > 0.05). With the exception of rheumatoid arthritis where six patients (24%) had IgM anti-entactin antibodies, the antibodies were present much less frequently in other diseases (two patients with systemic vasculitis whilst none of the patients with PSS or Behçet's syndrome). Only one patient with pneumonia and none of the 150 sera from healthy blood donors had anti-entactin antibodies. Among Group 1, three (30%) were positive for IgG or IgM anti-entactin antibodies. Six (60%) patients in group 2, and five patients (50%) in group 3 were positive for anti-entactin antibodies. However, the difference between the presence of anti-entactin antibodies between group 1 and 2 or between group 1 and 3 was not significant (p = 0.15 and 0.19 respectively). There was no significant correlation between the titres of anti-entactin antibodies and total serum concentration of IgG (r = 0.141, p > 0.10) and IgM. (r = 0.130, p > 0.10). Furthermore, no significant correlation was observed between SLE disease activity index (SLEDAI) scores and the titres of IgG (r = 0.067, p > 0.10) or IgM (r = -0.033, p > 0.10) anti-entactin antibodies.

CONCLUSION

The study demonstrates that anti-entactin antibodies are present in a significant number of patients with SLE and tend to be more common in those with severe disease, with or without nephritis, than in patients with mild disease manifestations. There is no correlation between the titre of anti-entactin antibodies and severity or activity of SLE.

The glomerular basement membrane in lupus nephritis

Systemic lupus erythematosus is a disease that is particularly suited for studies of glomerular basement membrane pathology. Classification of the renal pathology of lupus nephritis is usually based on light microscopic features, combined with immunofluorescence findings and electron microscopic alterations. Study of renal biopsy helps to distinguish potentially reversible and irreversible disease, and to estimate prognosis of patients with lupus nephritis. Moreover, studies of human disease, as well as the availability of animal models and in vitro cell culture systems employing biochemical and molecular biological studies of extracellular matrix, have led to a considerable increase in knowledge of the pathogenetic events underlying derangements of the glomerular basement membrane in lupus nephritis.

Effect of chronic graft-versus-host disease on the intestine in adult BDF1 mice

This study was performed to characterize the intestinal lesions in chronic graft-versus-host disease (GVHD) in mice and to determine a possible role of intestinal intraepithelial lymphocytes (ilEL) in the development of these lesions. Chronic GVHD was induced by transfer of DBA/2 lymphocytes into non-irradiated (C57BL/10 x DBA/2)F1 (BDF1) recipients. There was mild to moderate mucosal oedema with multifocal mixed inflammatory cell infiltrations in the small intestine. The caecum was more severely affected with severe oedema, progressive loss of crypts and severe distortion of the mucosal architecture. The total number of ilEL did not change during the development of chronic GVHD, but there were alterations in the composition of the ilEL population. An increase of CD3+, Thy-1+ cells was accompanied by an increase of TCR alpha beta + cells and a decrease of TCR gamma delta + cells. There was no evidence of infiltration of donor lymphocytes into the intestinal epithelium as determined by the H2K haplotype of the ilEL. These lesions differ from previously described models of chronic GVHD, induced by DBA/2 donor lymphocytes in BDF1 recipients. We suggest that the haemopoietic organs that are used as the source of donor lymphocytes determine the outcome of the GVHD. Modulation of the composition of the donor lymphocyte population may be useful in the establishment of relevant animal models of human enteropathy.

Gender-related influences on the development of chronic graft-versus-host disease-induced experimental lupus nephritis

Autoimmune diseases are far more common in women than in men. In the incidence of systemic lupus erythematosus (SLE), the female-to-male ratio is as high as 10:1. This suggests that sex hormones may play a fundamental role in determining the susceptibility to these diseases. In order to investigate the sex-related differences in the inducibility of chronic graft-versus-host disease-related experimental lupus nephritis, lymphocytes from female DBA/2 donor mice were administered to either male or female (C57BL10 x DBA/2)F1 recipients. An additional group of male recipients received lymphocytes from male DBA/2 donors. After four cell transfers, female recipients developed a significantly higher albuminuria than both male groups. Serum concentrations of autoantibodies against glomerular basement membrane (GBM), collagen IV, and laminin were significantly higher in females 2-4 weeks after induction. Levels of circulating autoantibodies against renal tubular epithelial antigens (RTE) and nuclear antigens were not different between the sexes. In transfer studies, the necessity of the presence of anti-GBM and anti-RTE autoantibodies for the development of glomerulonephritis was confirmed. These findings indicate that: (i) in this model of lupus nephritis, susceptibility to glomerulonephritis is strongly influenced by sex-related genes; and (ii) among the variety of autoantibodies occurring in this model of SLE, both anti-GBM and anti-RTE autoantibodies play a key role in the pathogenesis of glomerulonephritis.

Susceptibility for infection-related glomerulopathy depends on non-MHC genes

BALB/c mice infected with Trypanosoma brucei and treated seven days after inoculation with Diminazene aceturate develop polyclonal B-cell stimulation, including production of antibodies to known nephritogenic autoantigens and glomerular disease associated with severe albuminuria. To investigate if the susceptibility for glomerular disease in this model is linked to MHC or non-MHC genes, we studied this disease in six mouse strains that were partly congenic for their MHC and partly congenic for their non-MHC genes. The course of the infection was measured by parasitemia and related to (auto)antibody production, proteinuria and glomerular deposition of immunoglobulins. The mouse strains could be divided into two groups. The first group consisted of the C57BL/6 (H-2b), C57BL/10 (H-2b) and B10.D2 (H-2d) strains, which proved to be relatively resistant to infection with Trypanosoma brucei (that is, spontaneous survival > 25 days). In sera of these mice antibodies to a broad range of antigens could be found 14 days after inoculation; no proteinuria was observed. The second group consisted of the BALB/c (H-2d), BALB.B (H-2b) and DBA/2 (H-2d) strains, which were relatively susceptible to the infection. In these animals proteinuria occurred and a broad polyclonal B-cell stimulation was seen 42 days after inoculation. No correlation was found between the specificity of circulating antibodies and the occurrence of proteinuria or a glomerular fluorescence pattern. These results indicate that in this model non-MHC genes govern the outcome of the infection as well as the development of polyclonal B-cell stimulation and proteinuria.(ABSTRACT TRUNCATED AT 250 WORDS)

Epitope specificity of anti-gp330 autoantibodies determines the development of proteinuria in active Heymann nephritis

In active Heymann nephritis, an experimental autoimmune disease in the rat, gp330 is regarded as the main antigenic target. Immunization with detergent-solubilized renal tubular epithelium (RTE-DOC) has been shown to be less nephritogenic than immunization with crude RTE. In this study immunization with either crude RTE or affinity-purified gp330 did, but immunization with RTE-DOC did not induce proteinuria. Both a possible aberrant subclass distribution of anti-gp330 autoantibodies and the involvement of additional nephritogenic autoantigens such as DPP IV (gp90) or laminin could be excluded. Circulating anti-gp330 autoantibody titers were significantly higher in RTE-DOC-immunized rats than in RTE-immunized animals. In contrast, significantly more antibodies were shown to bind in the glomeruli in the latter group. The time of onset of abnormal proteinuria was shown to be related to the recognition of a particular V8 protease-induced 250 kD fragment of gp330 in Western blots. This study shows that a particular fragment-specific subset of autoantibodies against gp330 is involved in the glomerular damage in Heymann nephritis.

A histologic study of the extracellular matrix during the development of glomerulosclerosis in murine chronic graft-versus-host disease

The development of glomerulosclerosis was studied in murine chronic graft-versus-host disease (GvHD), which is a model for human systemic lupus erythematosus. The authors investigated the distribution patterns of six components of the extracellular matrix (ECM), i.e., laminin, fibronectin, collagen types I, III, IV, and VI during the course of the disease. All of these ECM components except collagen type I were found in the glomeruli of normal mice, where all of them were intrinsic constituents of the mesangium. Laminin, fibronectin, and collagen type IV were also found in the glomerular capillary walls. Starting 6 weeks after the induction of GvHD and continuing at week 8, the onset of an expansion of the mesangial matrix was observed. At the same time, the amounts of laminin, fibronectin, and collagen types IV and VI increased. Ten weeks after the onset of the disease, glomerulosclerosis developed. Traces of the interstitial collagen type I were found in sclerotic glomeruli. The levels of four ECM components, i.e., collagens III, IV, VI, and laminin were markedly decreased in the sclerotic glomeruli as compared with week 8. In contrast, the amount of fibronectin in the sclerotic glomeruli increased dramatically. Immunoelectron microscopic examination showed fibronectin in the sclerotic lesions, in contrast to laminin, collagen type I, and collagen type IV. It is concluded that the sclerotic lesions in murine chronic GvHD contain fibronectin. The small amounts of the ECM components laminin, as well as collagens III, IV, and VI in the sclerotic glomeruli in GvHD, might represent remnants of mesangial material and collapsed capillary walls. These components are probably replaced by increased production and/or accumulation of collagen type I and fibronectin.

Autoimmunity and glomerulonephritis

Autoimmunity is now unequivocally regarded as the predominant pathogenic process underlying most forms of primary and secondary glomerulonephritis in humans. Most of the investigations so far have been focused upon humoral mechanisms. Consequently, the role of cell-mediated immunity in nephritis is still incompletely understood. Nonetheless, as a result of contemporary studies, a number of previously unidentified auto-antibodies in association with glomerulonephritis have been discovered. However, apart from anti-NC1 antibodies in the classical Goodpasture syndrome, the exact role of these auto-antibodies in the pathogenesis of glomerulonephritis yet remains undefined. This fact, however, does not undermine the relevance of exploring these auto-antibodies. They have been of immense help in sub-classifying glomerulonephritis previously thought homogeneous (Figure 3). Besides, analysis of auto-antibodies has assisted tremendously in the early diagnosis of rapidly progressive glomerulonephritis. This, in turn, has aided in early commencement of therapy thus contributing to regression in morbidity and mortality resulting from these disorders. Moreover, investigation of these auto-antibodies is of enormous value for future studies aimed at understanding the pathogenic mechanisms involved in glomerulonephritis.

Renal immunopathology in murine host-versus-graft disease

BALB/c mice neonatally injected with 1 x 10(8) (A/J x BALB/c)F1 hybrid spleen cells develop polyclonal B cell activation and autoimmune features as a consequence of a host-versus-graft (HVG) reaction. In this study, we first analyzed the time-course development of the renal lesions in HVG mice. From week 2 to week 6, linear deposits of IgG were observed by immunofluorescence along the glomerular capillary walls. From week 8 to week 12, the immunofluorescence pattern of IgG changed from linear to granular, and by immunoelectron microscopy, the IgG deposits were located on the epithelial side of the glomerular basement membrane (GBM). In addition, focal glomerulosclerosis complicated this membranous glomerulopathy in about 50% of the 12-week-old HVG mice and albuminuria was increased in most of them. Circulating antibodies to antigens of the GBM (laminin, type IV collagen) and of the renal tubular epithelial (RTE) cells (dipeptidyl peptidase IV, gp330) were already detected at week 2 and were still present at week 12. Immunoglobulins eluted from isolated glomeruli contained antibodies directed against type IV collagen, laminin, and to a lesser degree against gp330. F1 donor B cells were involved in the production of nephritogenic antibodies as indicated by (a) the presence of A/J allotypic determinants on serum anti-laminin antibodies and (b) the abrogation of the in vitro production of anti-GBM, anti-laminin and anti-RTE antibodies when spleen cells from HVG mice were depleted of F1 donor B cells. Finally, mixed lymphocyte culture experiments established that T cells from HVG mice stimulate normal B cells from F1 donor hybrids to produce anti-GBM, anti-laminin, anti-type IV collagen, anti-RTE, anti-gp330 and anti-dipeptidyl peptidase IV antibodies. We conclude that mice neonatally injected with semi-allogeneic spleen cells develop a glomerulonephritis characterized by the transition from a linear to a granular IF pattern, and that the production of nephritogenic antibodies results from the activation of donor B cells by host helper T cells.

Fine specificities of anti-nuclear antibodies in murine models of graft-versus-host disease

Two models of murine graft-versus-host disease (GVHD) were studied with respect to autoantibody production and development of systemic lupus erythematosus (SLE) like disease. One model was induced by injection of (B10.A(4R) x B10.A(2R]F1 mice with parental (B10.A(4R] spleen and lymph node cells (groups I GVHD), the other by injection of (DBA/2 x C57/B16)F1 mice with DBA/2 cells (group II GVHD). Group I GVHD mice remained in a seemingly healthy condition and did not show any proteinuria, in spite of high titres of anti-nuclear antibodies including antibodies to dsDNA, anti-Sm and anti-ribosomal P protein antibodies. Measured levels of these autoantibodies as well as their isotypes were comparable with those found in MRL/lpr and NZB/W mice. Group II GVHD mice developed SLE-like disease signs, including severe proteinuria. At 4 months after induction of the GVHD, almost 50% of these mice had died. At the time nephritis was present, group II mice also produced anti-dsDNA and anti-nuclear antibodies of other (unknown) specificities, but no anti-Sm or anti-P. Furthermore, the incidence of these antibodies was lower than observed in group I GVHD, MRL/lpr or NZB/W mice. It is concluded that (high avidity) anti-dsDNA as well as anti-Sm and anti-P may be present in the circulation without giving rise to the development of nephritis.