The CCL2-CCR2 axis determines whether glomerular endocapillary hypercellularity or wire-loop lesions develop through glomerular macrophage and neutrophil infiltration in lupus nephritis.

The CCL2-CCR2 axis is involved in lupus nephritis, however the precise roles in the mechanisms by which different pathological lesions develop after glomerular immune complex deposition remain elusive. Previously, we demonstrated that genetic CCR2 inhibition induced a histological switch from glomerular endocapillary hypercellularity to wire-loop lesions in murine lupus nephritis. This study aimed to clarify the CCL2-CCR2 axis-mediated cellular mechanism in the formation of these different pathological lesions. We injected MRL/lpr mouse-derived monoclonal IgG3 antibody-producing hybridomas, 2B11.3 or B1, into wild-type (WT) mice to selectively induce glomerular endocapillary hypercellularity or wire-loop lesions. The expression of chemokine and chemokine receptors was analyzed using RT-quantitative PCR and/or immunofluorescence. We found 2B11.3 caused glomerular endocapillary hypercellularity in WT mice with glomerular infiltration of larger numbers of CCR2-expressing macrophages and neutrophils phagocyting immune complex, whereas B1 induced wire-loop lesions. In glomerular endocapillary hypercellularity, CCL2 was identified as the ligand involved in the CCR2-positive cell infiltration; it was expressed by glomerular endothelial cells and macrophages. Notably, 2B11.3-induced glomerular endocapillary hypercellularity converted to wire-loop lesions with reduced glomerular macrophage and neutrophil infiltration in CCL2-deficient (Ccl2-/-) mice similarly observed in Ccr2-/- mice. Moreover, this histological conversion was also observed when both glomerular macrophage and neutrophil infiltration were inhibited in anti-Ly6G antibody-treated Ccr5-/- mice but not when only glomerular macrophage infiltration was inhibited in Ccr5-/- mice or when only glomerular neutrophil infiltration was inhibited in anti-Ly6G antibody-treated WT mice. In contrast, B1 injection caused wire-loop lesions in Ccl2-/- and Ccr2-/- mice, as observed in WT mice. Moreover, 2B11.3 induced CCL2 from glomerular endothelial cells to a larger extent than B1 when injected into Ccr2-/- mice. In conclusion, the CCL2-CCR2 axis determines whether glomerular endocapillary hypercellularity or wire-loop lesions develop by regulating glomerular infiltration of phagocytic cells: macrophages and neutrophils. © 2024 The Pathological Society of Great Britain and Ireland.

Preventive effects of vasohibin-2-targeting peptide vaccine for diabetic nephropathy.

Diabetic nephropathy remains the leading cause of end-stage kidney disease in many countries, and additional therapeutic targets are needed to prevent its development and progression. Some angiogenic factors are involved in the pathogenesis of diabetic nephropathy. Vasohibin-2 (VASH2) is a novel proangiogenic factor, and our previous study showed that glomerular damage is inhibited in diabetic Vash2 homozygous knockout mice. Therefore, we established a VASH2-targeting peptide vaccine as a tool for anti-VASH2 therapy in diabetic nephropathy. In this study, the preventive effects of the VASH2-targeting peptide vaccine against glomerular injury were examined in a streptozotocin (STZ)-induced diabetic mouse model. The mice were subcutaneously injected with the vaccine at two doses 2 wk apart and then intraperitoneally injected with 50 mg/kg STZ for 5 consecutive days. Glomerular injury was evaluated 20 wk after the first vaccination. Treatment with the VASH2-targeting peptide vaccine successfully induced circulating anti-VASH2 antibody without inflammation in major organs. Although the vaccination did not affect blood glucose levels, it significantly prevented hyperglycemia-induced increases in urinary albumin excretion and glomerular volume. The vaccination did not affect increased VASH2 expression but significantly inhibited renal angiopoietin-2 (Angpt2) expression in the diabetic mice. Furthermore, it significantly prevented glomerular macrophage infiltration. The preventive effects of vaccination on glomerular injury were also confirmed in db/db mice. Taken together, the results of this study suggest that the VASH2-targeting peptide vaccine may prevent diabetic glomerular injury in mice by inhibiting Angpt2-mediated microinflammation.NEW & NOTEWORTHY This study demonstrated preventive effects of VASH2-targeting peptide vaccine therapy on albuminuria and glomerular microinflammation in STZ-induced diabetic mouse model by inhibiting renal Angpt2 expression. The vaccination was also effective in db/db mice. The results highlight the importance of VASH2 in the pathogenesis of early-stage diabetic nephropathy and the practicability of anti-VASH2 strategy as a vaccine therapy.

Sparsentan ameliorates glomerular hypercellularity and inflammatory-gene networks induced by IgA1-IgG immune complexes in a mouse model of IgA nephropathy.

IgA nephropathy (IgAN) is characterized by glomerular deposition of immune complexes (ICs) consisting of IgA1 with O-glycans deficient in galactose (Gd-IgA1) and Gd-IgA1-specific IgG autoantibodies. These ICs induce kidney injury, and in the absence of disease-specific therapy, up to 40% of patients with IgAN progress to kidney failure. IgA1 with its clustered O-glycans is unique to humans, which hampered development of small-animal models of IgAN. Here, we used a model wherein engineered ICs (EICs) formed from human Gd-IgA1 and recombinant human IgG autoantibody are injected into nude mice to induce glomerular injury mimicking human IgAN. In this model, we assessed the protective effects of sparsentan, a single-molecule dual endothelin angiotensin receptor antagonist (DEARA) versus vehicle on EIC-induced glomerular proliferation and dysregulation of gene expression in the kidney. Oral administration of sparsentan (60 or 120 mg/kg daily) to mice intravenously injected with EIC attenuated the EIC-induced glomerular hypercellularity. Furthermore, analysis of changes in the whole kidney transcriptome revealed that key inflammatory and proliferative biological genes and pathways that are upregulated in this EIC model of IgAN were markedly reduced by sparsentan, including complement genes, integrin components, members of the mitogen-activated protein kinase family, and Fc receptor elements. Partial overlap between mouse and human differentially expressed genes in IgAN further supported the translational aspect of the immune and inflammatory components from our transcriptional findings. In conclusion, our data indicate that in the mouse model of IgAN, sparsentan targets immune and inflammatory processes leading to protection from mesangial hypercellularity.NEW & NOTEWORTHY The mechanisms by which deposited IgA1 immune complexes cause kidney injury during early phases of IgA nephropathy are poorly understood. We used an animal model we recently developed that involves IgA1-IgG immune complex injections and determined pathways related to the induced mesangioproliferative changes. Treatment with sparsentan, a dual inhibitor of endothelin type A and angiotensin II type 1 receptors, ameliorated the induced mesangioproliferative changes and the associated alterations in the expression of inflammatory genes and networks.

The role of complement in kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference.

Uncontrolled complement activation can cause or contribute to glomerular injury in multiple kidney diseases. Although complement activation plays a causal role in atypical hemolytic uremic syndrome and C3 glomerulopathy, over the past decade, a rapidly accumulating body of evidence has shown a role for complement activation in multiple other kidney diseases, including diabetic nephropathy and several glomerulonephritides. The number of available complement inhibitor therapies has also increased during the same period. In 2022, Kidney Diseases: Improving Global Outcomes (KDIGO) convened a Controversies Conference, "The Role of Complement in Kidney Disease," to address the expanding role of complement dysregulation in the pathophysiology, diagnosis, and management of various glomerular diseases, diabetic nephropathy, and other forms of hemolytic uremic syndrome. Conference participants reviewed the evidence for complement playing a primary causal or secondary role in progression for several disease states and considered how evidence of complement involvement might inform management. Participating patients with various complement-mediated diseases and caregivers described concerns related to life planning, implications surrounding genetic testing, and the need for inclusive implementation of effective novel therapies into clinical practice. The value of biomarkers in monitoring disease course and the role of the glomerular microenvironment in complement response were examined, and key gaps in knowledge and research priorities were identified.

Podocyte injury as a potential therapeutic target in IgA nephropathy: should pathology guide us?

The Oxford histopathologic classification (MEST-C: scores for lesions indicating active glomerular inflammation, mesangial [M] and endocapillary [E] hypercellularity as well as cellular or fibrocellular crescents [C], and for segmental glomerulosclerosis [S] and interstitial fibrosis and/or tubular atrophy [T]) is useful in helping assess prognosis in patients with IgA nephropathy. Elements of this classification indicative of active glomerular inflammation, endocapillary hypercellularity and crescents, also have been found to be responsive to immunosuppressive therapy, potentially including newer agents specifically targeting mediators of such inflammation. In this issue of Kidney International, Bellur and coworkers identify histopathologic subtypes of segmental glomerulosclerosis in IgA nephropathy showing podocyte injury that also behave like active lesions, including showing improved outcomes with immunosuppression. This podocyte injury, identifiable only by kidney biopsy, may represent a potential therapeutic target in some patients with IgA nephropathy.

Evidence from the large VALIGA cohort validates the subclassification of focal segmental glomerulosclerosis in IgA nephropathy.

Evidence from the Oxford IgA nephropathy (IgAN) cohort supports the clinical value of subclassifying focal segmental glomerulosclerosis lesions (S1). Using the larger Validation in IgA (VALIGA) study cohort, we investigated the association between podocytopathic changes and higher proteinuria, kidney outcome and response to immunosuppressive therapy. All biopsies were evaluated for glomeruli with segmental capillary occlusion by matrix ("not otherwise specified", NOS lesion), simple capsular adhesion without capillary occlusion (Adh), tip lesions, and podocyte hypertrophy (PH). S1 required a NOS lesion and/or Adh. A Chi-Squared Automatic Interaction Detection method was used to identify subgroups of FSGS lesions associated with distinctive proteinuria at biopsy. We assessed survival from a combined event (kidney failure or 50% decline in estimated glomerular filtration rate). Finally, we evaluated within each subgroup if immunosuppression was associated with a favorable outcome using propensity analysis. In 1147 patients, S1 was found in 70% of biopsies. Subclassification found NOS lesions in 44%, Adh in 59%, PH in 13%, and tip lesions in 3%, with much overlap. Four subgroups were identified with progressively higher proteinuria: from lowest, S1 without NOS, S1 with NOS but without Adh/PH, to highest, S1 with NOS and Adh but without PH, and S1 with NOS and PH. These four subgroups showed progressively worse kidney survival. Immunosuppression was associated with a better outcome only in the two highest proteinuria subgroups. Propensity analysis in these two groups, adjusted for clinical and pathological findings, found a significantly reduced time-dependent hazard of combined outcome with corticosteroids. Podocyte hypertrophy and glomeruli with simple adhesions appeared to reflect active lesions associated with a response to corticosteroids, while other S1 lesions defined chronicity. Thus, our findings support subclassifying S1 lesions in IgAN.

Galectin-3 contributes to pathogenesis of IgA nephropathy.

IgA nephropathy (IgAN) is the most common type of glomerulonephritis that frequently progresses to kidney failure. However, the molecular pathogenesis underlying IgAN remains largely unknown. Here, we investigated the role of galectin-3 (Gal-3), a galactoside-binding protein in IgAN pathogenesis, and showed that Gal-3 expression by the kidney was significantly enhanced in patients with IgAN. In both TEPC-15 hybridoma-derived IgA-induced, passive, and spontaneous "grouped" ddY IgAN models, Gal-3 expression was clearly increased with disease severity in the glomeruli, peri-glomerular regions, and some kidney tubules. Gal-3 knockout (KO) in the passive IgAN model had significantly improved proteinuria, kidney function and reduced severity of kidney pathology, including neutrophil infiltration and decreased differentiation of Th17 cells from kidney-draining lymph nodes, despite increased percentages of regulatory T cells. Gal-3 KO also inhibited the NLRP3 inflammasome, yet it enhanced autophagy and improved kidney inflammation and fibrosis. Moreover, administration of 6-de-O-sulfated, N-acetylated low-molecular-weight heparin, a competitive Gal-3 binding inhibitor, restored kidney function and improved kidney lesions in passive IgAN mice. Thus, our results suggest that Gal-3 is critically involved in IgAN pathogenesis by activating the NLRP3 inflammasome and promoting Th17 cell differentiation. Hence, targeting Gal-3 action may represent a new therapeutic strategy for treatment of this kidney disease.

Complement system is overactivated in patients with IgA nephropathy after COVID-19.

IgA nephropathy (IgAN), which has been confirmed as a complement mediated autoimmune disease, is also one form of glomerulonephritis associated with COVID-19. Here, we aim to investigate the clinical and immunological characteristics of patients with IgAN after COVID-19. The level of plasma level of C5a (p < 0.001), soluble C5b-9 (p = 0.018), FHR5 (p < 0.001) were all significantly higher in Group CoV (33 patients with renal biopsy-proven IgAN experienced COVID-19) compared with Group non-CoV (44 patients with IgAN without COVID-19), respectively. Compared with Group non-CoV, the intensity of glomerular C4d (p = 0.017) and MAC deposition (p < 0.001) and Gd-IgA1 deposition (p = 0.005) were much stronger in Group CoV. Our finding revealed that for IgAN after COVID-19, mucosal immune responses to SARS-CoV-2 infection may result in the overactivation of systemic and renal local complement system, and increased glomerular deposition of Gd-IgA1, which may lead to renal dysfunction and promote renal progression in IgAN patients.

The Immunosuppressive Drug LF15-0195 Acts Also on Glomerular Lesions, by a Change in Cytoskeleton Distribution in Podocyte.

INTRODUCTION: Buffalo/Mna rats spontaneously develop nephrotic syndrome (NS) which recurs after renal transplantation. The immunosuppressive drug LF15-0195 can promote regression of the initial and post-transplantation nephropathy via induction of regulatory T cells. We investigate if this drug has an additional effect on the expression and localization of podocyte specific proteins. METHODS: Buffalo/Mna kidney samples were collected before and after the occurrence of proteinuria, and after the remission of proteinuria induced by LF15-0195 treatment and compared by quantitative RT-PCR, Western blot, electron, and confocal microscopy to kidney samples of age-matched healthy rats. Cytoskeleton changes were assessed in culture by stress fibers induction by TNFα. RESULTS: We observed, by electron microscopy, a restoration of foot process architecture in the LF15-0195-treated Buff/Mna kidneys, consistent with proteinuria remission. Nephrin, podocin, CD2AP, and α-actinin-4 mRNA levels remained low during the active disease in the Buff/Mna, in comparison with healthy rats which increase, while podocalyxin and synaptopodin transcripts were elevated before the occurrence of the disease but did not differ from healthy animals after. No difference in the mRNA and protein expression between the untreated and the LF15-0195-treated proteinuric Buff/Mna were seen for these 6 proteins. No changes were observed by confocal microscopy in the protein distribution at a cellular level, but a more homogenous distribution similar to healthy rats, was observed within the glomeruli of LF15-0195-treated rats. In addition, LF15-0195 could partially restore actin cytoskeleton of endothelial cells in TNFα-induced-cell stress experiment. CONCLUSION: The effect of LF15-0195 treatment appears to be mediated by 2 mechanisms: an immunomodulatory effect via regulatory T cells induction, described in our previous work and which can act on immune cell involved in the disease pathogenesis, and an effect on the restoration of podocyte cytoskeleton, independent of expression levels of the proteins involved in the slit diaphragm and podocyte function, showed in this article.

Natural Killer Cell Presence in Antibody-Mediated Rejection.

Transcript analyses highlight an important contribution of natural killer (NK) cells to microvascular inflammation (MVI) in antibody-mediated rejection (ABMR), but only few immunohistologic studies have quantified their spatial distribution within graft tissue. This study included 86 kidney transplant recipients who underwent allograft biopsies for a positive donor-specific antibody (DSA) result. NK cells were visualized and quantified within glomeruli and peritubular capillaries (PTC), using immunohistochemistry for CD34 alongside CD16/T-bet double-staining. Staining results were analyzed in relation to histomorphology, microarray analysis utilizing the Molecular Microscope Diagnostic System, functional NK cell genetics, and clinical outcomes. The number of NK cells in glomeruli per mm2 glomerular area (NKglom) and PTC per mm2 cortical area (NKPTC) was substantially higher in biopsies with ABMR compared to those without rejection, and correlated with MVI scores (NKglom Spearman's correlation coefficient [SCC] = 0.55, p < 0.001, NKPTC 0.69, p < 0.001). In parallel, NK cell counts correlated with molecular classifiers reflecting ABMR activity (ABMRprob: NKglom 0.59, NKPTC 0.75) and showed a trend towards higher levels in association with high functional FCGR3A and KLRC2 gene variants. Only NKPTC showed a marginally significant association with allograft function and survival. Our immunohistochemical results support the abundance of NK cells in DSA-positive ABMR.

Clinical significance of glomerular IgM deposit in IgA nephropathy: a 5-year follow-up study.

The significance of glomerular IgM deposit intensity in IgA Nephropathy (IgAN) remained ambiguous and requires further research. Patients with biopsy-proven IgAN in our hospital from January 2018 to May 2023 were recruited into this retrospective single-center study. Patients who presented with positive IgM deposit were included in IgM + cohort while patients with negative IgM deposit were included in IgM- cohort. Of the IgM+, patients whose IF intensity of IgM deposits exceeded 1+ formed IgM-H cohort while patients whose IF intensity of IgM deposits was equal to 1+ consisted IgM-L cohort. Pairwise comparisons were performed among these cohorts to determine clinical disparities, following the propensity score matching process. Among 982 IgAN patients, 539 patients presented with positive IgM deposit. The Kaplan-Meier analysis showed that the IgM deposit did not contribute adversely to the outcomes (eGFR decreased from the baseline ≥ 50% continuously or reached end-stage renal disease). However, the Cox regression analysis showed that increased intensity of IgM deposit was an independent risk factor (p = 0.03) in IgM+. The IgM-H exhibited more pronounced segmental glomerulosclerosis (p = 0.02) than the IgM-L, which may also be associated more directly with higher urine protein levels (p = 0.02). Moreover, our generalized linear mixed model demonstrated a remarkably higher urine albumin/creatinine ratio (p < 0.01) and serum creatinine (p = 0.04) levels as well as lower serum albumin (p < 0.01) level in IgM-H persistently during the 5-year follow-up. This study concluded that increased intensity of glomerular IgM deposits may contribute adversely to clinicopathologic presentation and outcome in those IgM + patients.

Extraglomerular immune complex deposition in lupus nephritis.

BACKGROUND: Lupus nephritis (LN) is a common manifestation and a major cause of morbidity and mortality in systemic lupus erythematosus (SLE) patients. It is characterized by glomerular and often extraglomerular immune complex deposition. PURPOSE: Given the emerging importance of the tubulointerstitial compartment, we conducted a retrospective study of 78 LN biopsies to enumerate the spectrum of extraglomerular immune complex deposition that can be observed in lupus nephritis by electron microscopy and to identify possible clinical or pathologic correlates. RESULTS: The presence of tubulointerstitial immune complex deposition often accompanied interstitial inflammation, but some discrepancies were also seen. CONCLUSIONS: As target antigens are identified, correlation with glomerular, tubulointerstitial, and vascular immune complex deposition will be of increasing interest.

Renal deposition and clearance of recombinant poly-IgA complexes in a model of IgA nephropathy.

IgA nephropathy (IgAN) is the most common type of glomerulonephritis worldwide, which follows a chronic but nonetheless highly variable course of progression. IgA immune complexes are the primary source of renal deposits in IgAN. Apart from the presence of granular IgA1 deposits in the glomerular mesangium and mesangial hypercellularity as common features, the detailed process of IgA1 deposition and clearance in the kidney remains unclear. We sought to examine the dynamics of IgA deposition and tissue plasticity in response to deposits including their intrarenal clearance. We followed a synthetic approach to produce a recombinant fusion between IgA Fc (rIgA) and a biotin tag, which was subsequently induced with streptavidin (SA) to form an oligomeric poly-IgA mimic. Both uninduced rIgA (mono-rIgA) and polymeric SA-rIgA (poly-rIgA) were injected intravenously into Wistar rats. Plasma IgA levels and renal and liver histology were examined in a time series. In contrast to mono-rIgA, this synthetic poly-rIgA analog formed renal deposits exclusively in the glomerulus and were mostly cleared in 3 h. However, repeated daily injections for 12 days caused long-lasting and stronger glomerular IgA deposition together with IgG and complement C3, in association with mesangial cell proliferation, matrix expansion, and variable degrees of albuminuria and hematuria that phenocopied IgAN. Ex vivo, poly-rIgA bound cultured mesangial cells and elicited cytokine production, in addition to activating plasma C3 that was consistent with the actions of IgA immune complexes in IgAN pathogenesis. Remarkably, the kidneys were able to reverse all pathologic manifestations and restore normal glomerular histology 2 weeks after injections were halted. The synthetic model showed the kinetics between the intricate balance of renal deposition and clearance, as well as glomerular plasticity towards healing. Together, the results revealed a priming effect of existing deposits in promoting stronger and longer-lasting IgA deposition to cause renal damage. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The Metalloproteinase ADAMTS5 Is Expressed by Interstitial Inflammatory Cells in IgA Nephropathy and Is Proteolytically Active on the Kidney Matrix.

In IgA nephropathy (IgAN), IgA immune complexes are deposited in the mesangium and drive inflammation and extracellular matrix (ECM) remodelling. The functional links between IgA deposition, inflammation, and matrix remodelling are not well characterized. We recently performed urine liquid chromatography-tandem mass spectrometry proteomics and identified multiple ECM glycoproteins whose expression and function in IgAN is unclear. None of the urine glycoproteins was regulated in IgAN transcriptomics, indicating that tissue remodelling rather than increased expression might contribute to their presence in urine. To investigate this, we examined the IgAN expression profile of metalloproteinases, enzymes involved in the remodelling of ECM proteins, and noted that the proteoglycanase ADAMTS5 was upregulated in IgAN kidneys. ADAMTS5 accumulated in areas of inflammation, and ADAMTS5+ cells were seen in the tubulointerstitium and glomeruli. The enzyme was expressed by CD64+ cells and its expression was increased by IL-1 and LPS. Analysis of myeloid cell transcriptomics revealed that ADAMTS5 is enriched in human classical monocytes. ADAMTS5+ cells were present in areas of matrix remodelling and associated with ECM proteins lumican, versican, and collagen-4. Liquid chromatography-tandem mass spectrometry proteomics of kidney explants digested with ADAMTS5, identified multiple kidney proteins affected by ADAMTS5 and revealed specific proteolysis of complement C3 and fibronectin associated with IgA on immune complexes. ADAMTS5 processing of immune complex proteins reduced binding to cultured mesangial cells. ADAMTS5 is associated with interstitial inflammatory cells in IgAN and other kidney lesions and fragments relevant extracellular proteins. The proteolytic enzyme might be a new translational target relevant to inflammation and scarring in kidney disease.

IgA Nephropathy Benefits from Compound K Treatment by Inhibiting NF-κB/NLRP3 Inflammasome and Enhancing Autophagy and SIRT1.

IgA nephropathy (IgAN), the most common primary glomerular disorder, has a relatively poor prognosis yet lacks a pathogenesis-based treatment. Compound K (CK) is a major absorbable intestinal bacterial metabolite of ginsenosides, which are bioactive components of ginseng. The present study revealed promising therapeutic effects of CK in two complementary IgAN models: a passively induced one developed by repeated injections of IgA immune complexes and a spontaneously occurring model of spontaneous grouped ddY mice. The potential mechanism for CK includes 1) inhibiting the activation of NLRP3 inflammasome in renal tissues, macrophages and bone marrow-derived dendritic cells, 2) enhancing the induction of autophagy through increased SIRT1 expression, and 3) eliciting autophagy-mediated NLRP3 inflammasome inhibition. The results support CK as a drug candidate for IgAN.

Tris DBA Ameliorates Accelerated and Severe Lupus Nephritis in Mice by Activating Regulatory T Cells and Autophagy and Inhibiting the NLRP3 Inflammasome.

Tris (dibenzylideneacetone) dipalladium (Tris DBA), a small-molecule palladium complex, has been shown to inhibit cell growth and proliferation in pancreatic cancer, lymphocytic leukemia, and multiple myeloma. In the current study, we examined the therapeutic effects of Tris DBA on glomerular cell proliferation, renal inflammation, and immune cells. Treatment of accelerated and severe lupus nephritis (ASLN) mice with Tris DBA resulted in improved renal function, albuminuria, and pathology, including measurements of glomerular cell proliferation, cellular crescents, neutrophils, fibrinoid necrosis, and tubulointerstitial inflammation in the kidneys as well as scoring for glomerulonephritis activity. The treated ASLN mice also showed significantly decreased glomerular IgG, IgM, and C3 deposits. Furthermore, the compound was able to 1) inhibit bone marrow-derived dendritic cell-mediated T cell functions and reduce serum anti-dsDNA autoantibody levels; 2) differentially regulate autophagy and both the priming and activation signals of the NLRP3 inflammasome; and 3) suppress the phosphorylation of JNK, ERK, and p38 MAPK signaling pathways. Tris DBA improved ASLN in mice through immunoregulation by blunting the MAPK (ERK, JNK)-mediated priming signal of the NLRP3 inflammasome and by regulating the autophagy/NLRP3 inflammasome axis. These results suggest that the pure compound may be a drug candidate for treating the accelerated and deteriorated type of lupus nephritis.

Autoimmunity in Acute Poststreptococcal GN: A Neglected Aspect of the Disease.

Acute poststreptococcal GN (APSGN) is the prototype of immune complex GN and is associated with manifestations of autoimmune reactivity that have been neglected as epiphenomena. Recently, studies have demonstrated transient antifactor B autoantibodies that activate the alternative complement pathway, bringing self-immunity to a central position in the pathogenesis of APSGN. Therefore, examining other manifestations of autoimmunity that have been reported in association with poststreptococcal GN is of interest. This article reviews the renal and extrarenal manifestations of autoimmune reactivity in APSGN and considers their potential relevance in modifying the usually benign clinical course of the disease. It also discusses related aspects of the nephritogenic antigens, complement activation, and genetic elements associated with immune reactivity and their potential relevance to the familial incidence of the disease.

CRISPR/Cas9-Engineered HLA-Deleted Glomerular Endothelial Cells as a Tool to Predict Pathogenic Non-HLA Antibodies in Kidney Transplant Recipients.

BACKGROUND: After kidney transplantation, donor-specific antibodies against human leukocyte antigen donor-specific antibodies (HLA-DSAs) drive antibody-mediated rejection (ABMR) and are associated with poor transplant outcomes. However, ABMR histology (ABMRh) is increasingly reported in kidney transplant recipients (KTRs) without HLA-DSAs, highlighting the emerging role of non-HLA antibodies (Abs). METHODS: W e designed a non-HLA Ab detection immunoassay (NHADIA) using HLA class I and II-deficient glomerular endothelial cells (CiGEnCΔHLA) that had been previously generated through CRISPR/Cas9-induced B2M and CIITA gene disruption. Flow cytometry assessed the reactivity to non-HLA antigens of pretransplantation serum samples from 389 consecutive KTRs. The intensity of the signal observed with the NHADIA was associated with post-transplant graft histology assessed in 951 adequate biopsy specimens. RESULTS: W e sequentially applied CRISPR/Cas9 to delete the B2M and CIITA genes to obtain a CiGEnCΔHLA clone. CiGEnCΔHLA cells remained indistinguishable from the parental cell line, CiGEnC, in terms of morphology and phenotype. Previous transplantation was the main determinant of the pretransplantation NHADIA result (P<0.001). Stratification of 3-month allograft biopsy specimens (n=298) according to pretransplantation NHADIA tertiles demonstrated that higher levels of non-HLA Abs positively correlated with increased glomerulitis (P=0.002), microvascular inflammation (P=0.003), and ABMRh (P=0.03). A pretransplantation NHADIA threshold of 1.87 strongly discriminated the KTRs with the highest risk of ABMRh (P=0.005, log-rank test). A multivariate Cox model confirmed that NHADIA status and HLA-DSAs were independent, yet synergistic, predictors of ABMRh. CONCLUSION: The NHADIA identifies non-HLA Abs and strongly predicts graft endothelial injury independent of HLA-DSAs.

Role of Palatine Tonsil and Epipharyngeal Lymphoid Tissue in the Development of Glomerular Active Lesions (Glomerular vasculitis) in Immunoglobulin A Nephropathy.

Hematuria is an essential symptom of immunoglobulin A nephropathy (IgAN). Although the etiology of hematuria in IgAN has not been fully elucidated, it is thought that the rupture of the glomerular basement membranes caused by intra-capillary leukocyte influx, so-called glomerular vasculitis, is the pathological condition responsible for severe hematuria. Glomerular vasculitis are active lesions that exist in the glomeruli of acute phase IgAN and it is important because it is suspected to make the transition to segmental glomerular sclerosis (SGS) as a repair scar lesion in the chronic phase, and the progression of SGS would eventually lead to glomerular obsolescence. Worsening of hematuria concomitant with acute pharyngitis is common in patients with IgAN; therefore, elucidating the relationship between the immune system of Waldeyer's ring, including the palatine tonsil and epipharyngeal lymphoid tissue, and the glomerular vasculitis may lead to understanding the nature of IgAN. The epipharynx is an immunologically activated site even under normal conditions, and enhanced activation of innate immunity is likely to occur in response to airborne infection. Hyperactivation of innate immunity via upregulation of Toll-like receptors in the interfollicular area of the palatine tonsil and epipharyngeal lymphoid tissue, followed by enhanced fractalkine/CX3CR1 interactions, appears to play an important role in the development of glomerular vasculitis in IgAN. As latent but significant epipharyngitis is present in most patients with IgAN, it is plausible that acute upper respiratory infection may contribute as a trigger for the innate epipharyngeal immune system, which is already upregulated in a chronically inflamed environment. Given that epipharyngitis and its effects on IgAN are not fully understood, we propose that the so-called "epipharynx-kidney axis" may provide an important focus for future research.

Natural antibody and complement activation characterize patients with idiopathic nephrotic syndrome.

Focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) are common forms of idiopathic nephrotic syndrome. The causes of these diseases are incompletely understood, but the response of patients to immunosuppressive therapies suggests that their pathogenesis is at least in part immune mediated. Preclinical and clinical research indicates that activation of the classical pathway of complement contributes to glomerular injury in FSGS. Glomerular IgM deposits are also prominent in some patients, raising the possibility that IgM is a trigger of classical pathway activation. In the present study, we examined the pattern of complement activation in the glomeruli and plasma of patients with nephrotic syndrome. We also tested whether patients with FSGS and MCD have elevated levels of natural IgM reactive with epitopes on glomerular endothelial cells and cardiolipin. We found evidence of classical pathway activation in patients with idiopathic nephrotic syndrome compared with healthy control subjects. We also detected higher levels of self-reactive IgM to both targets. Based on these results, IgM and classical pathway activation may contribute to disease pathogenesis in some patients with FSGS and MCD.NEW & NOTEWORTHY IgM is detected in biopsies from some patients with nephrotic syndrome, although this has been attributed to passive trapping of the protein. We found, however, that IgM colocalizes with complement activation fragments in some glomeruli. We also found that affected patients had higher levels of IgM reactive to glomerular endothelial cell epitopes. Thus, IgM activates the complement system in the glomeruli of some patients with nephrotic syndrome and may contribute to injury.