Low-Dose rIL-15 Protects from Nephrotoxic Serum Nephritis via CD8+ T Cells.

Rapid progressive glomerulonephritis (GN) often leads to end-stage kidney disease, driving the need for renal replacement therapy and posing a global health burden. Low-dose cytokine-based immunotherapies provide a new strategy to treat GN. IL-15 is a strong candidate for the therapy of immune-mediated kidney disease since it has proven to be tubular-protective before. Therefore, we set out to test the potential of low-dose rIL-15 treatment in a mouse model of nephrotoxic serum nephritis (NTS), mimicking immune complex-driven GN in humans. A single low-dose treatment with rIL-15 ameliorated NTS, reflected by reduced albuminuria, less tissue scarring, fewer myeloid cells in the kidney, and improved tubular epithelial cell survival. In addition, CD8+ T cells, a primary target of IL-15, showed altered gene expression and function corresponding with less cytotoxicity mediated by rIL-15. With the use of transgenic knock-out mice, antibody depletion, and adoptive cell transfer studies, we here show that the beneficial effects of rIL-15 treatment in NTS depended on CD8+ T cells, suggesting a pivotal role for them in the underlying mechanism. Our findings add to existing evidence of the association of IL-15 with kidney health and imply a potential for low-dose rIL-15 immunotherapies in GN.

Brain motor and fear circuits regulate leukocytes during acute stress.

The nervous and immune systems are intricately linked1. Although psychological stress is known to modulate immune function, mechanistic pathways linking stress networks in the brain to peripheral leukocytes remain poorly understood2. Here we show that distinct brain regions shape leukocyte distribution and function throughout the body during acute stress in mice. Using optogenetics and chemogenetics, we demonstrate that motor circuits induce rapid neutrophil mobilization from the bone marrow to peripheral tissues through skeletal-muscle-derived neutrophil-attracting chemokines. Conversely, the paraventricular hypothalamus controls monocyte and lymphocyte egress from secondary lymphoid organs and blood to the bone marrow through direct, cell-intrinsic glucocorticoid signalling. These stress-induced, counter-directional, population-wide leukocyte shifts are associated with altered disease susceptibility. On the one hand, acute stress changes innate immunity by reprogramming neutrophils and directing their recruitment to sites of injury. On the other hand, corticotropin-releasing hormone neuron-mediated leukocyte shifts protect against the acquisition of autoimmunity, but impair immunity to SARS-CoV-2 and influenza infection. Collectively, these data show that distinct brain regions differentially and rapidly tailor the leukocyte landscape during psychological stress, therefore calibrating the ability of the immune system to respond to physical threats.

B Cell Composition Is Altered After Kidney Transplantation and Transitional B Cells Correlate With SARS-CoV-2 Vaccination Response.

BACKGROUND: The COVID-19 pandemic has major implications on kidney transplant recipients (KTRs) since they show increased mortality due to impaired immune responses to SARS-CoV-2 infection and a reduced efficacy of SARS-CoV-2 vaccination. Surprisingly, dialysis patients have shown superior seroconversion rates after vaccination compared to KTRs. Therefore, we investigated peripheral blood B cell (BC) composition before and after kidney transplantation (KT) and aimed to screen the BC compartment to explain impaired antibody generation. METHODS: A total of 105 patients were recruited, and multicolor flow cytometric phenotyping of peripheral venous blood BC subpopulations was performed before and 1 year after KT. Complete follow-up was available for 71 individuals. Anti-SARS-CoV-2 antibodies were collected retrospectively and were available for 40 subjects, who had received two doses of an mRNA-based vaccine (BNT162b2 or mRNA-1273). RESULTS: Overall, relative BC frequencies within lymphocytes decreased, and their absolute counts trended in the same direction 1 year after KT as compared to CKD G5 patients. Frequencies and absolute numbers of naïve BCs remained stable. Frequencies of double negative BCs, a heterogeneous subpopulation of antigen experienced BCs lacking CD27 expression, were increased after KT, yet their absolute counts were similar at both time points. Transitional BCs (TrBCs) and plasmablasts were significantly reduced after KT in absolute and relative terms. Memory BCs were affected differently since class-switched and IgM-only subsets decreased after KT, but unswitched and IgD-only memory BCs remained unchanged. CD86+ and CD5+ expression on BCs was downregulated after KT. Correlational analysis revealed that TrBCs were the only subset to correlate with titer levels after SARS-CoV-2 vaccination. Responders showed higher TrBCs, both absolute and relative, than non-responders. CONCLUSION: Together, after 1 year, KTRs showed persistent and profound compositional changes within the BC compartment. Low TrBCs, 1 year after KT, may account for the low serological response to SARS-CoV-2 vaccination in KTRs compared to dialysis patients. Our findings need confirmation in further studies as they may guide vaccination strategies.

Agonism of Prostaglandin E2 Receptor 4 Ameliorates Tubulointerstitial Injury in Nephrotoxic Serum Nephritis in Mice.

Selectively targeting the E-type prostanoid receptor 4 (EP4) might be a new therapeutic option in the treatment of glomerulonephritis (GN), since the EP4 receptor is expressed on different immune cells, resident kidney cells, and endothelial cells, which are all involved in the pathogenesis of immune-complex GN. This study aimed to evaluate the therapeutic potential and to understand the mode of action of EP4 agonist in immune-complex GN using the murine model of nephrotoxic serum nephritis (NTS). In vivo, NTS mice were treated two times daily with two different doses of an EP4 agonist ONO AE1-329 or vehicle for 14 days total. The effect of PGE2 and EP4 agonism and antagonism was tested on murine distal convoluted tubular epithelial cells (DCT) in vitro. In vivo, the higher dose of the EP4 agonist led to an improved NTS phenotype, including a reduced tubular injury score and reduced neutrophil gelatinase-associated lipocalin (NGAL) and blood urea nitrogen (BUN) levels. EP4 agonist treatment caused decreased CD4+ T cell infiltration into the kidney and increased proliferative capacity of tubular cells. Injection of the EP4 agonist resulted in dose-dependent vasodilation and hypotensive episodes. The low-dose EP4 agonist treatment resulted in less pronounced episodes of hypotension. In vitro, EP4 agonism resulted in cAMP production and increased distal convoluted tubular (DCT) proliferation. Taken together, EP4 agonism improved the NTS phenotype by various mechanisms, including reduced blood pressure, decreased CD4+ T cell infiltration, and a direct effect on tubular cells leading to increased proliferation probably by increasing cAMP levels.

Blockade of tumor necrosis factor superfamily members CD30 and OX40 abrogates disease activity in murine immune-mediated glomerulonephritis.

Co-stimulation is a prerequisite for pathogenic activity in T cell-mediated diseases and has been demonstrated to achieve tolerance in organ-specific autoimmunity as a therapeutic target. Here, we evaluated the involvement of the tumor necrosis factor family members CD30 and OX40 in immune-complex mediated kidney disease. In vitro stimulation and proliferation studies were performed with CD4+ cells from wild type and CD30/OX40 double knock-out (CD30OX40-/-) mice. In vivo studies were performed by induction of nephrotoxic serum nephritis in wild type, CD30OX40- /- , CD30-/-, OX40-/-, reconstituted Rag1-/- and C57Bl/6J mice treated with αCD30L αOX40L antibodies. CD30, OX40 and their ligands were upregulated on various leukocytes in nephrotoxic serum nephritis. CD30OX40-/- mice, but not CD30-/- or OX40-/- mice were protected from nephrotoxic serum nephritis. Similar protection was found in Rag1-/- mice injected with CD4+ T cells from CD30OX40-/- mice compared to Rag1-/- mice injected with CD4+ T cells from wild type mice. Furthermore, CD4+ T cells deficient in CD30OX40-/- displayed decreased expression of CCR6 in vivo. CD30OX40-/- cells were fully capable of differentiating into disease mediating T helper cell subsets, but showed significantly decreased levels of proliferation in vivo and in vitro compared to wild type cells. Blocking antibodies against CD30L and OX40L ameliorated nephrotoxic serum nephritis without affecting pan-effector or memory T cell populations. Thus, our results indicate disease promotion via CD30 and OX40 signaling due to facilitation of exaggerated T cell proliferation and migration of T helper 17 cells in nephrotoxic serum nephritis. Hence, co-stimulation blockade targeting the CD30 and OX40 signaling pathways may provide a novel therapeutic strategy in autoimmune kidney disease.

Glucagon-Like Peptide-1 Receptor Agonism Improves Nephrotoxic Serum Nephritis by Inhibiting T-Cell Proliferation.

Glucagon-like peptide (GLP)-1 analogs such as liraglutide improved albuminuria in patients with type 2 diabetes in large randomized controlled trials. One of the suspected mechanisms is the anti-inflammatory potential of GLP-1 receptor (Glp1r) agonism. Thus, the anti-inflammatory action of Glp1r agonism was tested in a nondiabetic, T-cell-mediated murine model of nephrotoxic serum nephritis (NTS). The role of Glp1r in NTS was evaluated by using Glp1r-/- mice or C57BL/6 mice treated with liraglutide. In vitro, murine T cells were stimulated in the presence of liraglutide or vehicle. Glp1r-/- mice displayed increased renal infiltration of neutrophils and T cells after induction of NTS. Splenocyte proliferation and TH1 cytokine transcription were increased in spleen and lymph nodes of Glp1r-/- mice. Liraglutide treatment significantly improved the renal outcome of NTS in C57BL/6 mice by decreasing renal infiltration and proliferation of T cells, which resulted in decreased macrophage infiltration. In vitro, T cells stimulated in the presence of liraglutide showed decreased proliferation of TH1 and TH17 cells. Liraglutide blocked glycolysis in T cells and decreased their Glut1 mRNA expression. Together, Glp1r agonism protects mice from a T-cell-dependent glomerulonephritis model by inhibition of T-cell proliferation, possibly by interacting with their metabolic program. This mechanism may explain in part the renoprotective effects of Glp1r agonism in diabetic nephropathy.

MicroRNA-142-3p improves vascular relaxation in uremia.

BACKGROUND AND AIMS: Chronic kidney disease (CKD) is strongly associated with a high burden of cardiovascular morbidity and mortality. Therefore, we aimed to characterize the putative role of microRNAs (miR)s in uremic vascular remodelling and endothelial dysfunction. METHODS: We investigated the expression pattern of miRs in two independent end-stage renal disease (ESRD) cohorts and in the animal model of uremic DBA/2 mice via quantitative RT-PCR. Moreover, DBA/2 mice were treated with intravenous injections of synthetic miR-142-3p mimic and were analysed for functional and morphological vascular changes by mass spectrometry and wire myography. RESULTS: The expression pattern of miRs was regulated in ESRD patients and was reversible after kidney transplantation. Out of tested miRs, only blood miR-142-3p was negatively associated with carotid-femoral pulse-wave velocity in CKD 5D patients. We validated these findings in a murine uremic model and found similar suppression of miR-142-3p as well as decreased acetylcholine-mediated vascular relaxation of the aorta. Therefore, we designed experiments to restore bioavailability of aortic miR-142-3p in vivo via intravenous injection of synthetic miR-142-3p mimic. This intervention restored acetylcholine-mediated vascular relaxation. CONCLUSIONS: Taken together, we provide compelling evidence, both in humans and in mice, that miR-142-3p constitutes a potential pharmacological agent to prevent endothelial dysfunction and increased arterial stiffness in ESRD.

Blockade of prostaglandin E2 receptor 4 ameliorates nephrotoxic serum nephritis.

Prostaglandin E2 (PGE2) signaling is known to modulate inflammation and vascular resistance. Receptors of PGE2 [E-type prostanoid receptors (EP)] might be an attractive pharmacological target in immune-mediated diseases such as glomerulonephritis. We hypothesized that selective EP4 antagonism improves nephrotoxic serum nephritis (NTS) by its anti-inflammatory properties. Mice were subjected to NTS and treated with the EP4 antagonist ONO AE3-208 (10 mg·kg body wt-1·day-1] or vehicle starting from disease initiation. In one set of experiments, treatment was started 4 days after NTS induction. Tubular epithelial cells were evaluated in vitro under starving conditions. EP4 antagonist treatment significantly improved the NTS phenotype without affecting blood pressure levels. Remarkably, the improved NTS phenotype was also observed when treatment was started 4 days after NTS induction. EP4 antagonism decreased tubular chemokine (C-X-C motif) ligand ( Cxcl) 1 and Cxcl-5 expression and thereby subsequently reduced interstitial neutrophil infiltration into the kidney. In vitro, tubular epithelial cells increasingly expressed Cxcl-5 mRNA and Cxcl-5 protein when treated with PGE2 or an EP4 agonist under starving conditions, which was blunted by EP4 antagonist treatment. Together, EP4 antagonism improves the NTS phenotype, probably by decreasing mainly Cxcl-5 production in tubular cells, thereby reducing renal neutrophil infiltration.

Frequent IgG subclass and mannose binding lectin deficiency in patients with chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a severe disease characterized by various symptoms of immune dysfunction. CFS onset is typically with an infection and many patients suffer from frequently recurrent viral or bacterial infections. Immunoglobulin and mannose binding lectin (MBL) deficiency are frequent causes for increased susceptibility to infections. In this study we retrospectively analysed 300 patients with CFS for immunoglobulin and MBL levels, and B-cell subset frequencies. 25% of the CFS patients had decreased serum levels of at least one antibody class or subclass with IgG3 and IgG4 subclass deficiencies as most common phenotypes. However, we found elevated immunoglobulin levels with an excess of IgM and IgG2 in particular in another 25% of patients. No major alteration in numbers of B cells and B-cell subsets was seen. Deficiency of MBL was found in 15% of the CFS patients in contrast to 6% in a historical control group. In a 2nd cohort of 168 patients similar frequencies of IgG subclass and MBL deficiency were found. Thus, humoral immune defects are frequent in CFS patients and are associated with infections of the respiratory tract.