The coagulation system has gained much interest again as new anticoagulatory substances have been introduced into clinical practice. Especially patients with renal failure are likely candidates for such a therapy as they often experience significant comorbidity including cardiovascular diseases that require anticoagulation. Patients with renal failure on new anticoagulants have experienced excessive bleeding which can be related to a changed pharmacokinetic profile of the compounds. However, the coagulation system itself, even without any interference with coagulation modifying drugs, is already profoundly changed during renal failure. Coagulation disorders with either episodes of severe bleeding or thrombosis represent an important cause for the morbidity and mortality of such patients. The underlying reasons for these coagulation disorders involve the changed interaction of different components of the coagulation system such as the coagulation cascade, the platelets and the vessel wall in the metabolic conditions of renal failure. Recent work provides evidence that new factors such as microparticles (MPs) can influence the coagulation system in patients with renal insufficiency through their potent procoagulatory effects. Interestingly, MPs may also contain microRNAs thus inhibiting the function of platelets, resulting in bleeding episodes. This review comprises the findings on the complex pathophysiology of coagulation disorders including new factors such as MPs and microRNAs in patients with renal insufficiency.

Tubular damage following ischemic renal injury is often reversible, and tubular epithelial cell (TEC) proliferation is a hallmark of tubular repair. Macrophages have been implicated in tissue repair, and CSF-1, the principal macrophage growth factor, is expressed by TECs. We therefore tested the hypothesis that CSF-1 is central to tubular repair using an acute renal injury and repair model, ischemia/reperfusion (I/R). Mice injected with CSF-1 following I/R exhibited hastened healing, as evidenced by decreased tubular pathology, reduced fibrosis, and improved renal function. Notably, CSF-1 treatment increased TEC proliferation and reduced TEC apoptosis. Moreover, administration of a CSF-1 receptor-specific (CSF-1R-specific) antibody after I/R increased tubular pathology and fibrosis, suppressed TEC proliferation, and heightened TEC apoptosis. To determine the contribution of macrophages to CSF-1-dependent renal repair, we assessed the effect of CSF-1 on I/R in mice in which CD11b + cells were genetically ablated and determined that macrophages only partially accounted for CSF-1-dependent tubular repair. We found that TECs expressed the CSF-1R and that this receptor was upregulated and coexpressed with CSF-1 in TECs following renal injury in mice and humans. Furthermore, signaling via the CSF-1R stimulated proliferation and reduced apoptosis in human and mouse TECs. Taken together, these data suggest that CSF-1 mediates renal repair by both a macrophage-dependent mechanism and direct autocrine/paracrine action on TECs.

Anti Jo-1 antibodies are the main markers of the antisynthetase syndrome (ASSD), an autoimmune disease clinically characterized by the occurrence of arthritis, myositis, and interstitial lung disease (ILD). These manifestations usually co-occur (for practical purpose complete forms) in the same patient, but cases with only 1 or 2 of these findings (for practical purpose incomplete forms) have been described. In incomplete forms, the ex novo occurrence of further manifestations is possible, although with frequencies and timing not still defined. The aim of this international, multicenter, retrospective study was to characterize the clinical time course of anti Jo-1 positive ASSD in a large cohort of patients. Included patients should be anti Jo-1 positive and with at least 1 feature between arthritis, myositis, and ILD. We evaluated the differences between complete and incomplete forms, timing of clinical picture appearance and analyzed factors predicting the appearance of further manifestations in incomplete ASSD. Finally, we collected 225 patients (58 males and 167 females) with a median follow-up of 80 months. At the onset, complete ASSD were 44 and incomplete 181. Patients with incomplete ASSD had frequently only 1 of the classic triad findings (110 cases), in particular, isolated arthritis in 54 cases, isolated myositis in 28 cases, and isolated ILD in 28 cases. At the end of follow-up, complete ASSD were 113, incomplete 112. Only 5 patients had an isolated arthritis, only 5 an isolated myositis, and 15 an isolated ILD. During the follow-up, 108 patients with incomplete forms developed further manifestations. Single main feature onset was the main risk factor for the ex novo appearance of further manifestation. ILD was the prevalent ex novo manifestation (74 cases). In conclusion, ASSD is a condition that should be carefully considered in all patients presenting with arthritis, myositis, and ILD, even when isolated. The ex novo appearance of further manifestations in patients with incomplete forms is common, thus indicating the need for an adequate clinical and instrumental follow-up. Furthermore, the study clearly suggested that in ASSD multidisciplinary approach involving Rheumatology, Neurology, Pneumology, and Internal Medicine specialists is mandatory.

MRL/MpJ-Faslpr (MRL-Faslpr) mice develop a spontaneous T cell and macrophage-dependent autoimmune disease that shares features with human lupus. Interactions via the programmed death 1/programmed death ligand 1 (PD-1/PD-L1) pathway down-regulate immune responses and provide a negative regulatory checkpoint in mediating tolerance and autoimmune disease. Therefore, we tested the hypothesis that the PD-1/PD-L1 pathway suppresses lupus nephritis and the systemic illness in MRL-Faslpr mice. For this purpose, we compared kidney and systemic illness (lymph nodes, spleen, skin, lung, glands) in PD-L1 null (−/−) and PD-L1 intact (wild type, WT) MRL-Faslpr mice. Unexpectedly, PD-L1−/−;MRL-Faslpr mice died as a result of autoimmune myocarditis and pneumonitis before developing renal disease or the systemic illness. Dense infiltrates, consisting of macrophage and T cells (CD8+ > CD4+), were prominent throughout the heart (atria and ventricles) and localized specifically around vessels in the lung. In addition, once disease was evident, we detected heart specific autoantibodies in PD-L1−/−;MRL-Faslpr mice. This unique phenotype is dependent on MRL-specific background genes as PD-L1−/−;MRL+/+ mice lacking the Faslpr mutation developed autoimmune myocarditis and pneumonitis. Notably, the transfer of PD-L1−/−;MRL+/+ bone marrow cells induced myocarditis and pneumonitis in WT;MRL+/+ mice, despite a dramatic up-regulation of PD-L1 expression on endothelial cells in the heart and lung of WT;MRL+/+ mice. Taken together, we suggest that PD-L1 expression is central to autoimmune heart and lung disease in lupus-susceptible (MRL) mice.

IL-6 is a strong promoter of lupus nephritis and may be a promising new therapeutic target in the treatment of human lupus nephritis.

Objective. MRL-FasConclusion. Taken together, our findings suggest that IL-18-producing TECs may directly be involved in the pathogenesis of lupus nephritis.

Macrophages mediate kidney disease and are prominent in a mouse model (MRL-Fas lpr ) of lupus nephritis. Colony stimulating factor-1 (CSF-1) is the primary growth factor for macrophages, and CSF-1 deficiency protects MRL-Fas lpr mice from kidney disease and systemic illness. Whether this renoprotection derives from a reduction of macrophages and whether systemic CSF-1, as opposed to intrarenal CSF-1, promotes macrophage-dependent lupus nephritis remain unclear. Here, we found that increasing systemic CSF-1 hastened the onset of lupus nephritis in MRL-Fas lpr mice. Using mutant MRL-Fas lpr strains that express high, moderate, or no systemic CSF-1, we detected a much higher tempo of kidney disease in mice with the highest level of CSF-1. Furthermore, we uncovered a multistep CSF-1-dependent systemic mechanism central to lupus nephritis. CSF-1 heightened monocyte proliferation in the bone marrow (SSC low CD11b ϩ ), and these monocytes subsequently seeded the circulation. Systemic CSF-1 skewed the frequency of monocytes toward "inflammatory" (SSC low CD11b ϩ Ly6C high ) and activated populations that homed to sites of inflammation, resulting in a more rapid accumulation of intrarenal macrophages (CD11b ϩ CSF-1R ϩ or CD68 ϩ ) that induced apoptosis of tubular epithelial cells, damaging the kidney. In humans, we found increased levels of CSF-1 in the serum, urine, and kidneys of patients with lupus compared with healthy controls. Furthermore, serum and urine CSF-1 levels correlated with lupus activity, and intrarenal CSF-1 expression correlated with the histopathology activity index of lupus nephritis. Taken together, circulating CSF-1 is a potential therapeutic target for lupus nephritis.

Chemokines are instrumental in macrophage-and T cell-dependent diseases. The chemokine CCL2 promotes kidney disease in two models of immune-mediated nephritis (MRL-Fas lpr mice and the nephrotoxic serum nephritis model), but evidence suggests that multiple chemokines are involved. For identification of additional therapeutic targets for immune-mediated nephritis, chemokine ligands and receptors in CCL2Ϫ/Ϫ and wild-type (WT) MRL-Fas lpr kidneys were profiled. The focus was on intrarenal chemokine ligand/receptor pairs that were highly upregulated downstream of CCL2; the chemokine CXCL10 and its cognate receptor, CXCR3, stood out as potential therapeutic targets. However, renal disease was not suppressed in CXCL10Ϫ/Ϫ MRL-Fas lpr mice, and CXCL10 Ϫ/Ϫ C57BL/6 mice were not protected from nephrotoxic serum nephritis compared with WT mice. Because CXCR3 engages with the ligand CXCL9, CXCR3 Ϫ/Ϫ , CXCL9 Ϫ/Ϫ , and CXCL10 Ϫ/Ϫ B6 mice were compared with WT mice with nephrotoxic serum nephritis. Kidney disease, measured by loss of renal function and histopathology, was suppressed in both CXCR3 Ϫ/Ϫ and CXCL9 Ϫ/Ϫ mice but not in CXCL10 Ϫ/Ϫ mice. With nephrotoxic serum nephritis, CXCR3 Ϫ/Ϫ and CXCL9 Ϫ/Ϫ mice had fewer intrarenal activated T cells and activated macrophages. Both IgG glomerular deposits and antigen-specific IgG in serum were reduced in these mice, suggesting that although CXCR3 and CXCL9 initiate nephritis through cell-mediated events, renal inflammation may be sustained by their regulation of IgG. It is concluded that specific blockade of CXCL9 or CXCR3 may be a potential therapeutic target for human immune-mediated kidney diseases.