Th17 cells are most abundant in the gut, where their presence depends on the intestinal microbiota. Here, we examined whether intestinal Th17 cells contribute to extra-intestinal Th17 responses in ...autoimmune kidney disease. We found high frequencies of Th17 cells in the kidneys of patients with antineutrophil cytoplasmatic antibody (ANCA)-associated glomerulonephritis. We utilized photoconversion of intestinal cells in Kaede mice to track intestinal T cell mobilization upon glomerulonephritis induction, and we found that Th17 cells egress from the gut in a S1P-receptor-1-dependent fashion and subsequently migrate to the kidney via the CCL20/CCR6 axis. Depletion of intestinal Th17 cells in germ-free and antibiotic-treated mice ameliorated renal disease, whereas expansion of these cells upon Citrobacter rodentium infection exacerbated pathology. Thus, in some autoimmune settings, intestinal Th17 cells migrate into target organs, where they contribute to pathology. Targeting the intestinal Th17 cell “reservoir” may present a therapeutic strategy for these autoimmune disorders.
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•Pathogenic TH17 cells migrate from the gut to the kidney in autoimmunity•TH17 cells egress the intestine in a S1PR1-dependent manner in glomerulonephritis•Targeting microbiota-induced TH17 cells ameliorates extraintestinal TH17 responses
By photolabelling intestinal cells, Krebs and colleagues provide direct evidence that microbiota-induced TH17 cells egress from the gut S1PR1-dependently and infiltrate the kidney via CCL20/CCR6 in immune-mediated diseases. This finding will build the basis for therapies targeting the intestinal TH17 cell “reservoir” to treat extraintestinal TH17 autoimmunity.
A Mechanism for Cancer-Associated Membranous Nephropathy Hoxha, Elion; Wiech, Thorsten; Stahl, Phillip R ...
New England journal of medicine/The New England journal of medicine,
2016-May-19, Letnik:
374, Številka:
20
Journal Article
IL-6 is required for the response of mice against Listeria monocytogenes. Control of infection depends on classical IL-6 signaling via membrane IL-6Rα, but IL-6 target cells and protective mechanisms ...remain unclear. We used mice with IL-6Rα-deficiency in T cells (Il6rafl/fl×CD4cre) or myeloid cells (Il6rafl/fl×LysMcre) to define the role of these cells in IL-6-mediated protection. Abrogation of IL-6Rα in T cells did not interfere with bacteria control and induction of TH1 and CD8+ T-cell responses. IL-6Rα-deficiency in myeloid cells caused significant defects in listeria control. This defect was not associated with reduced recruitment of granulocytes and inflammatory monocytes, and both cell populations were activated and not impaired in cytokine production. However, IL-6Rα-deficient inflammatory monocytes displayed diminished expression of IL-4Rα and of CD38, a protein required for phagocytosis and innate control of listeria. In vitro studies revealed that IL-4 and IL-6 cooperated in induction of CD38. In listeria-infected mice, phagocytic activity of inflammatory monocytes correlated with CD38 expression levels on cells and inflammatory monocytes of Il6rafl/fl×LysMcre mice were significantly impaired in phagocytosis. In conclusion, we demonstrate that inhibition of classical IL-6 signaling in myeloid cells causes alterations in differentiation and function of these cells, which subsequently prevent effective control of L. monocytogenes.
IL-6 can mediate proinflammatory effects, and IL-6 receptor (IL-6R) blockade as a treatment for inflammatory diseases has entered clinical practice. However, opposing effects of IL-6 have been ...observed in models of GN. Although IL-6 is proinflammatory in murine lupus nephritis, protective effects have been observed for IL-6 in the nephrotoxic nephritis (NTN) model of acute crescentic GN. In light of the potential dangers of IL-6-directed treatment, we studied the mechanisms underlying the contradictory findings in GN. IL-6 can signal through the membrane-bound IL-6R, which is expressed only on hepatocytes and certain leukocytes (classic), or through the soluble IL-6R, which binds the ubiquitously expressed gp130 (alternative). Preemptive treatment of mice with anti-IL-6R or anti-IL-6 worsened NTN, whereas selective blockade of alternative IL-6 signaling by the fusion protein sgp130Fc did not. FACS analysis of mouse spleen cells revealed proinflammatory macrophages express the highest levels of IL-6Rα, and in vitro treatment with IL-6 blocked macrophage proliferation. Furthermore, proinflammatory macrophages were expanded during inflammation in IL-6(-/-) mice. Late application of anti-IL-6 after establishment of adaptive nephritogenic immunity was sufficient to aggravate NTN within 2.5 days, a period when macrophages are active. Finally, NTN was aggravated in mice with macrophage-specific impairment of IL-6 classic signaling, coincident with enhanced macrophage proliferation and accumulation in the kidney. Our data thus reveal a novel mechanism in which IL-6-mediated dampening of macrophage activation protects tissues from overshooting immune responses. This finding has important implications for potential IL-6-directed therapies and supports the careful choice of recipient patients and timing.
Recent studies have identified the EGF receptor (EGFR) ligand amphiregulin (AREG) as an important mediator of inflammatory diseases. Both pro- and anti-inflammatory functions have been described, but ...the role of AREG in GN remains unknown.
The nephrotoxic nephritis model of GN was studied in AREG
mice after bone marrow transplantation, and in mice with myeloid cell-specific EGFR deficiency. Therapeutic utility of AREG neutralization was assessed. Furthermore, AREG's effects on renal cells and monocytes/macrophages (M/M) were analyzed. Finally, we evaluated AREG expression in human renal biopsies.
Renal AREG mRNA was strongly upregulated in murine GN. Renal resident cells were the most functionally relevant source of AREG. Importantly, the observation that knockout mice showed significant amelioration of disease indicates that AREG is pathogenic in GN. AREG enhanced myeloid cell responses
inducing chemokine and colony stimulating factor 2 (CSF2) expression in kidney resident cells. Furthermore, AREG directly skewed M/M to a proinflammatory M1 phenotype and protected them from apoptosis. Consequently, anti-AREG antibody treatment dose-dependently ameliorated GN. Notably, selective abrogation of EGFR signaling in myeloid cells was sufficient to protect against nephritis. Finally, strong upregulation of AREG expression was also detected in kidneys of patients with two forms of crescentic GN.
AREG is a proinflammatory mediator of GN
(
) enhancing renal pathogenic myeloid cell infiltration and (
) direct effects on M/M polarization, proliferation, and cytokine secretion. The AREG/EGFR axis is a potential therapeutic target for acute GN.
The discovery of interleukin (IL)-17-producing CD4+ T (Th17) cells as a unique T-helper cell lineage has revised our understanding of T-cell-mediated tissue injury. Recent data from studies in humans ...and mice indicate that autoimmune diseases such as multiple sclerosis and rheumatoid arthritis, classically believed to be Th1-mediated, are predominantly driven by a Th17 immune response. IL-17 (IL-17A), IL-17F, IL-21, IL-22, and possibly also IL-9 produced by Th17 cells promote inflammation by directly causing tissue injury and enhancing secretion of pro-inflammatory cytokines and chemokines by resident cells. This results in augmented infiltration of leukocytes, in particular neutrophils, to the affected tissue where they induce organ inflammation and injury. Recent studies have highlighted the potential importance of the Th17 immune response also in renal inflammatory disease. This includes the identification and characterization of IL-17-producing T cells in nephritic kidneys of mice and humans, as well as evidence for the contribution of IL-17 and the IL-23/Th17 axis to renal tissue injury in glomerulonephritis. In this review, we will briefly summarize general characteristics of Th17 cells and discuss in detail the potential role of the Th17 immune response in human and experimental renal inflammation with a special focus on glomerulonephritis.
Multiple studies have identified CD4+ T cells as central players of glomerulonephritis (GN). Cells of the Th1 and Th17 responses cause renal tissue damage, while Tregs mediate protection. Recently, a ...high degree of plasticity among these T cell lineages was proposed. During inflammation, Th17 cells were shown to have the potential of transdifferentiation into Th1, Th2, or alternatively anti-inflammatory Tr1 cells. Currently available data from studies in GN, however, do not indicate relevant Th17 to Th1 or Th2 conversion, leaving the Th17 cell fate enigmatic. Tregs, on the other hand, were speculated to transdifferentiate into Th17 cells. Again, data from GN do not support this concept. Rather, it seems that previously unrecognized subspecialized effector Treg lineages exist. These include Th1 specific Treg1 as well as Th17 directed Treg17 cells. Furthermore, a bifunctional Treg subpopulation was recently identified in GN, which secrets IL-17 and coexpresses Foxp3 together with the Th17 characteristic transcription factor RORγt. Similarities between these different and highly specialized effector Treg subpopulations with the corresponding T helper effector cell lineages might have resulted in previous misinterpretation as Treg transdifferentiation. In summary, Th17 cells have a relatively stable phenotype during GN, while, in the case of Tregs, currently available data suggest lineage heterogeneity rather than plasticity.
T cells infiltrate the kidney in both human and experimental glomerulonephritis, and several lines of evidence indicate that T cell-mediated tissue damage plays an important role in the ...immunopathogenesis of renal inflammatory diseases. However, the functions of the different T cell subsets, particularly the recently identified interleukin-17 (IL-17)-producing T cells (Th17 cells), are incompletely understood in glomerulonephritis. Here, we identified renal IL-17-producing T cells in the T cell-mediated model of nephrotoxic nephritis in mice. In vitro, IL-17 enhanced the production of the proinflammatory chemokines CCL2/MCP-1, CCL3/MIP-1alpha, and CCL20/LARC, which are implicated in the recruitment of T cells and monocytes, in mouse mesangial cells. To determine the function of Th17 cells in renal inflammation, we induced nephrotoxic nephritis in IL-23 p19(-/-) mice, which have reduced numbers of Th17 cells, and in IL-17(-/-) mice, which are deficient in the effector cytokine IL-17 itself. In comparison with nephritic wild-type mice, IL-23 p19(-/-) mice demonstrated less infiltration of Th17 cells, and both IL-23 p19(-/-) and IL-17(-/-) mice developed less severe nephritis as measured by renal function, albuminuria, and frequency of glomerular crescent formation. These results demonstrate that the IL-23/IL-17 pathway significantly contributes to renal tissue injury in experimental glomerulonephritis. Targeting the IL-23/Th17 axis may be a promising therapeutic strategy for the treatment of proliferative and crescentic glomerulonephritis.
In acute kidney injury, which is a significant cause of morbidity and mortality, cytokines and leukocytes promote inflammation and injury. We examined the pathogenic role of IL-17A in ...cisplatin-induced acute kidney injury. Intrarenal IL-17A mRNA transcription and protein expression were increased in wild-type mice after cisplatin-induced renal injury. An important role for IL-17A in the nephrotoxicity of cisplatin was demonstrated by observing protection from cisplatin-induced functional and histological renal injury in Il17a−/− and Rorγt−/− mice, as well as in mice treated pre-emptively with anti–IL-17A antibodies. Both renal injury and renal IL-1β and IL-17A production were attenuated in Asc−/− and Tlr2 −/− mice, suggesting that cisplatin induces endogenous TLR2 ligand production and activates the ASC-dependent inflammasome complex, resulting in IL-1β and injurious IL-17A production. Neutrophils and natural killer cells are the likely targets of these pathways, because combined depletion of these cells was strongly protective; anti–IL-17A antibodies had no additional effect in this setting. Although IL-17A can also be produced by CD4+ and γδ T cells, IL-17A from those cells does not contribute to renal injury. Cisplatin-induced injury was unchanged in γδ T-cell–deficient mice, whereas Il17a−/− CD4+ T cells induced similar injury as did wild-type CD4+ T cells on transfer to cisplatin-injected Rag1−/− mice. These studies demonstrate an important role for TLR2, the ASC inflammasome, and IL-17A in innate leukocytes in cisplatin-induced renal injury.
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