Ectopic lymphoid-like structures often develop at sites of inflammation where they influence the course of infection, autoimmune disease, cancer and transplant rejection. These lymphoid aggregates ...range from tight clusters of B cells and T cells to highly organized structures that comprise functional germinal centres. Although the mechanisms governing ectopic lymphoid neogenesis in human pathology remain poorly defined, the presence of ectopic lymphoid-like structures within inflamed tissues has been linked to both protective and deleterious outcomes in patients. In this Review, we discuss investigations in both experimental model systems and patient cohorts to provide a perspective on the formation and functions of ectopic lymphoid-like structures in human pathology, with particular reference to the clinical implications and the potential for therapeutic targeting.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Randomized tests of quality-improvement interventions were embedded within an existing health care system. Quality and efficiency were improved by abandoning ineffective interventions and continuing ...successful quality-improvement strategies.
The successful treatment of certain autoimmune conditions with the humanized anti-IL-6 receptor (IL-6R) antibody tocilizumab has emphasized the clinical importance of cytokines that signal through ...the β-receptor subunit glycoprotein 130 (gp130). In this Review, we explore how gp130 signaling controls disease progression and examine why IL-6 has a special role among these cytokines as an inflammatory regulator. Attention will be given to the role of the soluble IL-6R, and we will provide a perspective into the clinical blockade of IL-6 activity in autoimmunity, inflammation, and cancer.
Appropriate control of leukocyte recruitment and activation is a fundamental requirement for competent host defense and resolving inflammation. A pivotal event that defines the successful outcome of ...any inflammatory event is the transition from innate to acquired immunity. In IL-6 deficiency, this process appears defective, and a series of in vivo studies have documented important roles for IL-6 in both the resolution of innate immunity and the development of acquired immune responses. Within this review, particular attention will be given to the regulatory properties of the soluble IL-6 receptor and how its activity may affect chronic disease progression.
Fibrosis in response to tissue damage or persistent inflammation is a pathological hallmark of many chronic degenerative diseases. By using a model of acute peritoneal inflammation, we have examined ...how repeated inflammatory activation promotes fibrotic tissue injury. In this context, fibrosis was strictly dependent on interleukin-6 (IL-6). Repeat inflammation induced IL-6-mediated T helper 1 (Th1) cell effector commitment and the emergence of STAT1 (signal transducer and activator of transcription-1) activity within the peritoneal membrane. Fibrosis was not observed in mice lacking interferon-γ (IFN-γ), STAT1, or RAG-1. Here, IFN-γ and STAT1 signaling disrupted the turnover of extracellular matrix by metalloproteases. Whereas IL-6-deficient mice resisted fibrosis, transfer of polarized Th1 cells or inhibition of MMP activity reversed this outcome. Thus, IL-6 causes compromised tissue repair by shifting acute inflammation into a more chronic profibrotic state through induction of Th1 cell responses as a consequence of recurrent inflammation.
•Repeated acute resolving inflammation leads to excessive tissue damage•IL-6 regulates profibrotic IFN-γ-secreting T cells•IFN-γ increases detrimental STAT1 signaling in stromal tissue•STAT1 activity alters homeostatic control of extracellular matrix to promote fibrosis
Tissue-resident macrophages are heterogeneous as a consequence of anatomical niche–specific functions. Many populations self-renew independently of bone marrow in the adult, but the molecular ...mechanisms of this are poorly understood. We determined a transcriptional profile for the major self-renewing population of peritoneal macrophages in mice. These cells specifically expressed the transcription factor Gata6. Selective deficiency of Gata6 in myeloid cells caused substantial alterations in the transcriptome of peritoneal macrophages. Gata6 deficiency also resulted in dysregulated peritoneal macrophage proliferative renewal during homeostasis and in response to inflammation, which was associated with delays in the resolution of inflammation. Our investigations reveal that the tissue macrophage phenotype is under discrete tissue-selective transcriptional control and that this is fundamentally linked to the regulation of their proliferation renewal.
Cytokine receptors, which exist in membrane‐bound and soluble forms, bind their ligands with comparable affinity. Although most soluble receptors are antagonists and compete with their ...membrane‐associated counterparts for the ligands, certain soluble receptors are agonists. In these cases, complexes of ligand and soluble receptor bind on target cells to second receptor subunits and initiate intracellular signaling. The soluble receptors of the interleukin (IL)‐6 family of cytokines (sIL‐6R, sIL‐11R, soluble ciliary neurotrophic factor receptor) are agonists capable of transmitting signals through interaction with the universal signal‐transducing receptor for all IL‐6 family cytokines, gp130. In vivo, the IL‐6/sIL‐6R complex stimulates several types of cells, which are unresponsive to IL‐6 alone, as they do not express the membrane IL‐6R. We have named this process trans‐signaling. The generation of soluble cytokine receptors occurs via two distinct mechanisms—limited proteolysis and translation—from differentially spliced mRNA. We have demonstrated that a soluble form of the IL‐6 family signaling receptor subunit gp130, which is generated by differential splicing, is the natural inhibitor of IL‐6 trans‐signaling responses. We have shown that in many chronic inflammatory diseases, including chronic inflammatory bowel disease, peritonitis, rheumatoid arthritis, asthma, as well as colon cancer, IL‐6 trans‐signaling is critically involved in the maintenance of a disease state, by promoting transition from acute to chronic inflammation. Moreover, in all these models, the course of the disease can be disrupted by specifically interfering with IL‐6 trans‐signaling using the soluble gp130 protein. The pathophysiological mechanisms by which the IL‐6/sIL‐6R complex regulates the inflammatory state are discussed.
Ectopic lymphoid-like structures (ELSs) reminiscent of secondary lymphoid organs often develop at sites of chronic inflammation where they contribute to immune-mediated pathology. Through evaluation ...of synovial tissues from rheumatoid arthritis (RA) patients, we now show that low interleukin-27 (IL-27) expression corresponds with an increased incidence of ELS and gene signatures associated with their development and activity. The presence of synovial ELS was also noted in mice deficient in the IL-27 receptor (IL-27R) after the onset of inflammatory arthritis. Here, pathology was associated with increased synovial expression of pro-inflammatory cytokines, homeostatic chemokines, and transcriptional regulators linked with lymphoid neogenesis. In both clinical and experimental RA, synovial ELS coincided with the heightened local expression of cytokines and transcription factors of the Th17 and T follicular helper (Tfh) cell lineages, and included podoplanin-expressing T cells within lymphoid aggregates. IL-27 inhibited the differentiation of podoplanin-expressing Th17 cells, and an increased number of these cells were observed in IL-27R-deficient mice with inflammatory arthritis. Thus, IL-27 appears to negatively regulate ELS development in RA through control of effector T cells. These studies open new opportunities for patient stratification and treatment.
The introduction of biologic agents to clinical practice has had a major bearing on the treatment of patients with chronic inflammatory diseases such as rheumatoid arthritis. These drugs have the ...potential to improve the outcome of disease and the quality of life for patients. However, clinical criteria alone are inadequate for determining which therapy is most appropriate for an individual patient. Furthermore, why a particular drug is effective in a particular patient, or indeed in any patient, but is ineffective for other individuals, is often unknown. In this Review, we provide an overview of biologic therapies currently available for patients with rheumatoid arthritis, and discuss why certain immunological regulators represent potential targets for intervention. Current agents can be clustered into three major types: cytokine blockers, lymphocyte-targeting agents, and small-molecule inhibitors of signal transduction pathways. We differentiate among the modes of action of each of these types of therapy and consider the challenges associated with their use in clinical practice.
Immuno-surveillance networks operating at barrier sites are tuned by local tissue cues to ensure effective immunity. Site-specific commensal bacteria provide key signals ensuring host defense in the ...skin and gut. However, how the oral microbiome and tissue-specific signals balance immunity and regulation at the gingiva, a key oral barrier, remains minimally explored. In contrast to the skin and gut, we demonstrate that gingiva-resident T helper 17 (Th17) cells developed via a commensal colonization-independent mechanism. Accumulation of Th17 cells at the gingiva was driven in response to the physiological barrier damage that occurs during mastication. Physiological mechanical damage, via induction of interleukin 6 (IL-6) from epithelial cells, tailored effector T cell function, promoting increases in gingival Th17 cell numbers. These data highlight that diverse tissue-specific mechanisms govern education of Th17 cell responses and demonstrate that mechanical damage helps define the immune tone of this important oral barrier.
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•Distinct signals shape the Th17 cell network at the oral barrier•Oral barrier Th17 cells develop independently of commensal microbe colonization•Physiologic damage through mastication promotes the generation of oral Th17 cells•Barrier damage triggers oral Th17-cell-mediated protective immunity and inflammation
The signals regulating immunity at the gingiva, a key oral barrier, remain unclear. Dutzan et al. show that oral barrier Th17 cells are induced in response to mastication rather than commensal colonization, identifying physiologic mechanical damage as a unique tissue-specific cue conditioning local immunity and inflammation at the oral barrier.
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