Both Classical and Non-Classical Monocytes Patrol Glomerular Capillaries and Promote Acute Glomerular Inflammation.

Monocyte patrolling of the vasculature has been ascribed primarily to the non-classical monocyte subset. However, a recent study of the glomerular microvasculature provided evidence that both classical and non-classical monocytes undergo periods of intravascular retention and migration. Despite this, whether these subsets contribute differentially to acute glomerular inflammation is unknown. This study used glomerular multiphoton intravital microscopy to investigate the capacity of classical and non-classical monocytes to patrol the glomerular microvasculature and promote acute, neutrophil-dependent glomerular inflammation. In imaging experiments in monocyte reporter Cx3cr1gfp/+ mice, co-staining with anti-Ly6B or anti-Ly6C revealed that both non-classical monocytes [CX3C chemokine receptor 1-green fluorescent protein positive (CX3CR1-GFP+)] and classical monocytes (CX3CR1-GFP+ and Ly6B+ or Ly6C+) underwent prolonged (>10 minutes) retention and migration in the glomerular microvasculature. On induction of acute glomerulonephritis, in these behaviors were increased in classical but not non-classical monocytes. Using non-classical monocyte-deficient Csf1rCreNr4a1fl/fl mice, or anti-CCR2 to deplete classical monocytes, the removal of either subset reduced neutrophil retention and activation in acutely inflamed glomeruli, while the depletion of both subsets, via anti-CCR2 treatment in Csf1rCreNr4a1fl/fl mice, led to further reductions in neutrophil activity. In contrast, in a model of CD4+ T cell-dependent glomerulonephritis, the depletion of either monocyte subset failed to alter neutrophil responses. These findings indicate that both classical and non-classical monocytes patrol the glomerular microvasculature and promote neutrophil responses in acutely inflamed glomeruli.

The implication of anti-Ro60 with or without anti-Ro52 antibody in patients with systemic lupus erythematosus.

OBJECTIVES: Anti-Ro60 and anti-Ro52 autoantibodies are frequently used as diagnostic biomarkers for Sjogren's disease, but their clinical significance in systemic lupus erythematosus (SLE) is not well characterised. METHODS: Patients fulfilling SLE classification criteria were studied according to their anti-Ro status. We defined Ro positivity (Ro+) as those who have either anti-Ro60 or anti-Ro52 positivity. Patient characteristics and disease outcomes, including High Disease Activity Status (HDAS) defined as an ever attainment of SLEDAI2K ≥10, adjusted mean SLEDAI (AMS), and time-adjusted mean clinical SLEDAI (excluding serologic activities) were compared using linear or logistic regressions. Furthermore, isolated or dual positivity of anti-Ro60 and anti-Ro52 were studied. RESULTS: Out of 409 patients, 47.2% were Ro+. Ro+ patients were predominantly Asian, had positive dsDNA and hypocomplementemia. They showed a higher likelihood of HDAS (OR 1.65, 95% CI 1.10-2.48, p= 0.015), AMS > 4 (OR 1.84, 1.18-2.88, p= 0.007), and more frequent use of glucocorticoids (OR 1.87, 1.16-3.03, p= 0.011) and immunosuppressants (OR 2.0, 1.26-3.17, p= 0.003). Additionally, 24.4% of Ro+ patients experienced sicca symptoms, and hypergammaglobulinemia was significantly more common. Multivariate analysis confirmed that Asian ethnicity, severe flares, AMS, hypocomplementemia, rheumatoid factor, proteinuria, leucopenia, and sicca symptoms were significantly linked to Ro positivity. CONCLUSION: Anti-Ro positivity is associated with higher disease activity and increased treatment needs. Ro positivity correlates with laboratory abnormalities such as hypocomplementemia and leucopenia. These findings highlight the importance of anti-Ro60/Ro52 testing in the clinical evaluation of SLE.

RORing toward immunoregulation in glomerulonephritis?

CD4+ T cells that express forkhead box protein 3 are important in maintaining tolerance and restraining effector responses. Herrnstadt et al. use a model of rapidly progressive glomerulonephritis to examine the nature and role of forkhead box protein 3-positive and retinoid acid-related orphan receptor γt-positive regulatory T cells. These cells are prominent in experimental glomerulonephritis, both locally and systemically, and are present in kidneys of people with anti-neutrophil cytoplasmic antibody-associated vasculitis. Functionally, despite their expression of retinoid acid-related orphan receptor γt, associated with T-helper cell 17 cells, they regulate cellular immunity, both systemically and within the kidney.

International Society of Nephrology first consensus guidance for preclinical animal studies in translational nephrology.

Preclinical tests in animal models are key steps in early drug development. Consequently, the International Society of Nephrology held a consensus meeting that connected experts in the global kidney community in order to provide guidance on optimal management of translational animal studies for the development of new drugs to treat kidney disease, entitled "TRANSFORM; TRAnslational Nephrology Science FOR new Medications." The meeting covered various themes, including the following: (i) selection of disease model; (ii) pharmacokinetics; (iii) interventions in late preclinical models; (iv) choice of animal; (v) statistical power; (vi) organoids and organ-on-a-chip models; and (vii) reporting of results. This guidance is the first to be provided on the optimal conduct of translational animal studies for the development of new drugs to treat kidney disease. These recommendations are designed to accelerate development of new drugs for efficacious treatment of kidney diseases, and to improve the prognosis and quality of life of patients with a variety of kidney diseases.

T-cell receptor αß+ double-negative T cells in the kidney are predominantly extravascular and increase in abundance in response to ischemia-reperfusion injury.

T-cell receptor+ CD4- CD8- double-negative (DN) T cells are a population of T cells present in low abundance in blood and lymphoid organs, but enriched in various organs including the kidney. Despite burgeoning interest in these cells, studies examining their abundance in the kidney have reported conflicting results. Here we developed a flow cytometry strategy to clearly segregate DN T cells from other immune cells in the mouse kidney and used it to characterize their phenotype and response in renal ischemia-reperfusion injury (IRI). These experiments revealed that in the healthy kidney, most DN T cells are located within the renal parenchyma and exhibit an effector memory phenotype. In response to IRI, the number of renal DN T cells is unaltered after 24 h, but significantly increased by 72 h. This increase is not related to alterations in proliferation or apoptosis. By contrast, adoptive transfer studies indicate that circulating DN T cells undergo preferential recruitment to the postischemic kidney. Furthermore, DN T cells show the capacity to upregulate CD8, both in vivo following adoptive transfer and in response to ex vivo activation. Together, these findings provide novel insights regarding the phenotype of DN T cells in the kidney, including their predominant extravascular location, and show that increases in their abundance in the kidney following IRI occur in part as a result of increased recruitment from the circulation. Furthermore, the observation that DN T cells can upregulate CD8 in vivo has important implications for detection and characterization of DN T cells in future studies.

Removal of the endothelial surface layer via hyaluronidase does not modulate monocyte and neutrophil interactions with the glomerular endothelium.

OBJECTIVE: The endothelial surface layer (ESL), a layer of macromolecules on the surface of endothelial cells, can both impede and facilitate leukocyte recruitment. However, its role in monocyte and neutrophil recruitment in glomerular capillaries is unknown. METHODS: We used multiphoton intravital microscopy to examine monocyte and neutrophil behavior in the glomerulus following ESL disruption with hyaluronidase. RESULTS: Constitutive retention and migration of monocytes and neutrophils within the glomerular microvasculature was unaltered by hyaluronidase. Consistent with this, inhibition of the hyaluronan-binding molecule CD44 also failed to modulate glomerular trafficking of these immune cells. To investigate the contribution of the ESL during acute inflammation, we induced glomerulonephritis via in situ immune complex deposition. This resulted in increases in glomerular retention of monocytes and neutrophils but did not induce marked reduction in the glomerular ESL. Furthermore, hyaluronidase treatment did not modify the prolonged retention of monocytes and neutrophils in the acutely inflamed glomerular microvasculature. CONCLUSIONS: These observations indicate that, despite evidence that the ESL has the capacity to inhibit leukocyte-endothelial cell interactions while also containing adhesive ligands for immune cells, neither of these functions modulate trafficking of monocytes and neutrophils in steady-state or acutely-inflamed glomeruli.

The five types of glomerulonephritis classified by pathogenesis, activity and chronicity (GN-AC).

Glomerulonephritis (GN) is a diverse group of immune-mediated disorders. Currently, GN is classified largely by histological patterns that are difficult to understand and teach, and most importantly, do not indicate treatment choices. Indeed, altered systemic immunity is the primary pathogenic process and the key therapeutic target in GN. Here, we apply a conceptual framework of immune-mediated disorders to GN guided by immunopathogenesis and hence immunophenotyping: (i) infection-related GN require pathogen identification and control; (ii) autoimmunity-related GN, defined by presence of autoantibodies and (iii) alloimmunity-related GN in transplant recipients both require the suppression of adaptive immunity in lymphoid organs and bone marrow; (iv) autoinflammation-related GN, e.g. inborn errors of immunity diagnosed by genetic testing, requires suppression of single cytokine or complement pathways; and (v) Monoclonal gammopathy-related GN requires B or plasma cell clone-directed therapy. A new GN classification should include disease category, immunological activity to tailor the use of the increasing number of immunomodulatory drugs, and chronicity to trigger standard chronic kidney disease care including the evolving spectrum of cardio-renoprotective drugs. Certain biomarkers allow diagnosis and the assessment of immunological activity and disease chronicity without kidney biopsy. The use of these five GN categories and a therapy-focused GN classification is likely to overcome some of the existing hurdles in GN research, management and teaching by reflecting disease pathogenesis and guiding the therapeutic approach.

Primary aldosteronism: an unsuspected culprit of hypertension in systemic lupus erythematosus?

Primary aldosteronism (PA) is the most common endocrine cause of secondary hypertension and is associated with a high risk of cardiovascular disease in the general population. Patients suffering from systemic lupus erythematosus (SLE), a multisystem and multifactorial autoimmune disease, experience a high burden of hypertension and cardiovascular disease. Importantly, cardiovascular disease is one of the leading causes of death in SLE. Very limited evidence suggests an increased proportion of autoimmune diseases such as SLE in patients with PA. However, studies evaluating the prevalence of PA in the SLE population are lacking. Despite the potential for curative or targeted treatments, guidelines for the management of hypertension in SLE do not currently recommend testing for PA. This review highlights PA as a potentially over-looked secondary cause of hypertension in SLE, and offers future directions in research to improve the detection of this highly modifiable cardiovascular risk factor in the SLE population.

Dominant protection from HLA-linked autoimmunity by antigen-specific regulatory T cells.

Susceptibility and protection against human autoimmune diseases, including type I diabetes, multiple sclerosis, and Goodpasture disease, is associated with particular human leukocyte antigen (HLA) alleles. However, the mechanisms underpinning such HLA-mediated effects on self-tolerance remain unclear. Here we investigate the molecular mechanism of Goodpasture disease, an HLA-linked autoimmune renal disorder characterized by an immunodominant CD4+ T-cell self-epitope derived from the α3 chain of type IV collagen (α3135-145). While HLA-DR15 confers a markedly increased disease risk, the protective HLA-DR1 allele is dominantly protective in trans with HLA-DR15 (ref. 2). We show that autoreactive α3135-145-specific T cells expand in patients with Goodpasture disease and, in α3135-145-immunized HLA-DR15 transgenic mice, α3135-145-specific T cells infiltrate the kidney and mice develop Goodpasture disease. HLA-DR15 and HLA-DR1 exhibit distinct peptide repertoires and binding preferences and present the α3135-145 epitope in different binding registers. HLA-DR15-α3135-145 tetramer+ T cells in HLA-DR15 transgenic mice exhibit a conventional T-cell phenotype (Tconv) that secretes pro-inflammatory cytokines. In contrast, HLA-DR1-α3135-145 tetramer+ T cells in HLA-DR1 and HLA-DR15/DR1 transgenic mice are predominantly CD4+Foxp3+ regulatory T cells (Treg cells) expressing tolerogenic cytokines. HLA-DR1-induced Treg cells confer resistance to disease in HLA-DR15/DR1 transgenic mice. HLA-DR15+ and HLA-DR1+ healthy human donors display altered α3135-145-specific T-cell antigen receptor usage, HLA-DR15-α3135-145 tetramer+ Foxp3- Tconv and HLA-DR1-α3135-145 tetramer+ Foxp3+CD25hiCD127lo Treg dominant phenotypes. Moreover, patients with Goodpasture disease display a clonally expanded α3135-145-specific CD4+ T-cell repertoire. Accordingly, we provide a mechanistic basis for the dominantly protective effect of HLA in autoimmune disease, whereby HLA polymorphism shapes the relative abundance of self-epitope specific Treg cells that leads to protection or causation of autoimmunity.

The use of belimumab in three cases of refractory lupus nephritis.

In recent trials for the treatment of systemic lupus erythematosus (SLE), belimumab (BLM), in addition to standard immunosuppression, has been shown to improve renal and nonrenal outcomes. We report our experience using BLM in three cases of refractory lupus nephritis (LN), where renal remission was not achieved using cyclophosphamide, mycophenolate mofetil and other immunosuppressive medications. In two of the three cases, BLM therapy led to a partial remission of LN, improvement in serological markers of SLE and disease activity, which permitted a reduction in prednisolone dosing. Treatment with efficacious therapies early in the course of LN is a desirable therapeutic strategy, to achieve early remission of proteinuria and curtail the development of irreversible chronic renal damage. Further studies are needed to provide information on the effectiveness of BLM for maintenance of remission, prevention of flares and monitoring for long-term complications of B-cell modulation.