Advances in Immunology最新文献

Reversible lysine acetylation of histones is a key epigenetic regulatory process controlling gene expression. Reversible histone acetylation is mediated by two opposing enzyme families: histone acetyltransferases (HATs) and histone deacetylases (HDACs). Moreover, many non-histone targets of HATs and HDACs are known, suggesting a crucial role for lysine acetylation as a posttranslational modification on the cellular proteome and protein function far beyond chromatin-mediated gene regulation. The HDAC family consists of 18 members and pan-HDAC inhibitors (HDACi) are clinically used for the treatment of certain types of cancer. HDACi or individual HDAC member-deficient (cell lineage-specific) mice have also been tested in a large number of preclinical mouse models for several autoimmune and autoinflammatory diseases and in most cases HDACi treatment results in an attenuation of clinical disease severity. A reduction of disease severity has also been observed in mice lacking certain HDAC members. This indicates a high therapeutic potential of isoform-selective HDACi for immune-mediated diseases. Isoform-selective HDACi and thus targeted inactivation of HDAC isoforms might also overcome the adverse effects of current clinically approved pan-HDACi. This review provides a brief overview about the fundamental function of HDACs as epigenetic regulators, highlights the roles of HDACs beyond chromatin-mediated control of gene expression and summarizes the studies showing the impact of HDAC inhibitors and genetic deficiencies of HDAC members for the outcome of autoimmune and autoinflammatory diseases with a focus on rheumatoid arthritis, inflammatory bowel disease and experimental autoimmune encephalomyelitis (EAE) as an animal model of multiple sclerosis.

The innate immune system represents the first defense line of the host following viral infection. The infection triggers the recognition of pathogen-associated molecular patterns (PAMPs) from the viruses by pattern recognition receptors (PRRs) of the host cell. The interaction between viral PAMPs and PRRs evokes a sophisticated signal transduction system and eventually promotes the expression of type I interferons (IFNs) and proinflammatory cytokines. Ubiquitination plays an indispensable role in fine-tuning almost every single step of this signaling cascade given on its versatile functions. Ubiquitin ligases and deubiquitinases (DUBs), which cooperatively and accurately regulate the dynamic and reversible ubiquitination process, are the master regulators of antiviral signaling. In this review, we concentrate on summarizing the ubiquitin ligases and DUBs that modulate the central signaling molecules in antiviral innate immunity. Especially, we emphasize the ones that were identified by the immunologists from China.

Mast cells and IgE are most familiar as the effectors of type I hypersensitivity reactions including anaphylaxis. It is becoming clear however that this pair has important immunomodulatory effects on innate and adaptive cells of the immune system. In this purview, they act as endogenous adjuvants to ignite evolving immune responses, promote the transition of allergic disease into chronic illness and disrupt the development of active mechanisms of tolerance to ingested foods. Suppression of IgE-mediated mast cell activation can be exerted by molecules targeting IgE, FcɛRI or signaling kinases including Syk, or by IgG antibodies acting via inhibitory Fcγ receptors. In 2015 we reviewed the evidence for the adjuvant functions of mast cells. This update includes the original text, incorporates some important developments in the field over the past five years and discusses how interventions targeting these pathways might have promise in the development of strategies to treat allergic disease.

Natural killer cells are lymphocytes that respond rapidly to intracellular pathogens or cancer/stressed cells by producing pro-inflammatory cytokines or chemokines and by killing target cells through direct cytolysis. NK cells are distinct from B and T lymphocytes in that they become activated through a series of broadly expressed germ line encoded activating and inhibitory receptors or through the actions of inflammatory cytokines. They are the founding member of the innate lymphoid cell family, which mirror the functions of T lymphocytes, with NK cells being the innate counterpart to CD8 T lymphocytes. Despite the functional relationship between NK cells and CD8 T cells, the mechanisms controlling their specification, differentiation and maturation are distinct, with NK cells emerging from multipotent lymphoid progenitors in the bone marrow under the control of a unique transcriptional program. Over the past few years, substantial progress has been made in understanding the developmental pathways and the factors involved in generating mature and functional NK cells. NK cells have immense therapeutic potential and understanding how to acquire large numbers of functional cells and how to endow them with potent activity to control hematopoietic and non-hematopoietic malignancies and autoimmunity is a major clinical goal. In this review, we examine basic aspects of conventional NK cell development in mice and humans and discuss multiple transcription factors that are known to guide the development of these cells.

Class switch recombination (CSR) plays an important role in humoral immunity by generating antibodies with different effector functions. CSR to a particular antibody isotype is induced by external stimuli, and occurs between highly repetitive switch (S) sequences. CSR requires transcription across S regions, which generates long non-coding RNAs and secondary structures that promote accessibility of S sequences to activation-induced cytidine deaminase (AID). AID initiates DNA double-strand breaks (DSBs) intermediates that are repaired by general DNA repair pathways. Switch transcription is controlled by various regulatory elements, including enhancers and insulators. The current paradigm posits that transcriptional control of CSR involves long-range chromatin interactions between regulatory elements and chromatin loops-stabilizing factors, which promote alignment of partner S regions in a CSR centre (CSRC) and initiation of CSR. In this review, we focus on the role of IgH transcriptional control elements in CSR and the chromatin-based mechanisms underlying this control.

Over the last decade, the interplay between the gut microbiota, the consortium of intestinal microbes that colonizes intestinal mucosal barriers, and its host immune system has been increasingly better understood. Disruption of the delicate balance between beneficial and pathogenic commensals, known as dysbiosis, contributes to a variety of chronic immunologic and metabolic diseases. Complicating this paradigm are bacterial strains that can operate paradoxically both as instigators and attenuators of inflammatory responses, depending on host background. Here, we review the role of several strains in the genus Lactobacillus within the context of autoimmune and other chronic disorders with a predominant focus on L. reuteri. While strains within this species have been shown to provide immune health benefits, they have also been demonstrated to act as a pathobiont in autoimmune-prone hosts. Beneficial functions in healthy hosts include competing with pathogenic microbes, promoting regulatory T cell development, and protecting the integrity of the gut barrier. On the other hand, certain strains can also break through a dysfunctional gut barrier, colonize internal tissues such as the spleen or liver and promote inflammatory responses in host tissues that lead to autoimmune disease. This review summarizes the manifold roles that these commensals play in the context of health and disease.