Innate lymphoid cells promote lung-tissue homeostasis after infection with influenza virus

Innate lymphoid cells (ILCs), a heterogeneous cell population, are critical in orchestrating immunity and inflammation in the intestine, but whether ILCs influence immune responses or tissue homeostasis at other mucosal sites remains poorly characterized. Here we identify a population of lung-resident ILCs in mice and humans that expressed the alloantigen Thy-1 (CD90), interleukin 2 (IL-2) receptor a-chain (CD25), IL-7 receptor a-chain (CD127) and the IL-33 receptor subunit T1-ST2. Notably, mouse ILCs accumulated in the lung after infection with influenza virus, and depletion of ILCs resulted in loss of airway epithelial integrity, diminished lung function and impaired airway remodeling. These defects were restored by administration of the lung ILC product amphiregulin. Collectively, our results demonstrate a critical role for lung ILCs in restoring airway epithelial integrity and tissue homeostasis after infection with influenza virus.     

Innate lymphoid cells are pivotal actors in allergic,inflammatory and autoimmune diseases

Innate lymphoid cells (ILCs) are lymphoid cells that do not express V(D)J-rearranged receptors and play a role in the innate immune system. ILCs are categorized into three groups with respect to their function in the immune system. ILC1 induces production of IFN-γ via T-box expressed on T cells, ILC2 promotes production of type 2 cytokines via GATA-binding protein-3 and ILC3 promotes IL-17 and IL-22 production via retinoic acid receptor-related orphan receptor-γt. ILCs can maintain homeostasis in epithelial surfaces by responding to locally produced cytokines or direct recognition of danger patterns. Altered epithelial barrier function seems to be a key point in inappropriate activation of ILCs to promote inflammatory and allergic responses. ILCs play an essential role in initiation and maintenance of defense against infections as well as immune-mediated diseases. In this paper, we discuss the role of ILCs in inflammatory, allergic and autoimmune diseases.     

Innate lymphoid cells in secondary lymphoid organs

The family of innate lymphoid cells (ILCs) has attracted attention in recent years as its members are important regulators of immunity, while they can also cause pathology. In both mouse and man, ILCs were initially discovered in developing lymph nodes as lymphoid tissue inducer (LTi) cells. These cells form the prototypic members of the ILC family and play a central role in the formation of secondary lymphoid organs (SLOs). In the absence of LTi cells, lymph nodes (LN) and Peyer's Patches (PP) fail to form in mice, although the splenic white pulp can develop normally. Besides LTi cells, the ILC family encompasses helper-like ILCs with functional distinctions as seen by T-helper cells, as well as cytotoxic natural killer (NK) cells. ILCs are still present in adult SLOs where they have been shown to play a role in lymphoid tissue regeneration. Furthermore, ILCs were implicated to interact with adaptive lymphocytes and influence the adaptive immune response. Here, we review the recent literature on the role of ILCs in secondary lymphoid tissue from the formation of SLOs to mature SLOs in adults, during homeostasis and pathology.     

The aryl hydrocarbon receptor regulates gut immunity through modulation of innate lymphoid cells

Innate lymphoid cells (ILCs) expressing the nuclear receptor RORγt are essential for gut immunity presumably through production of interleukin-22 (IL-22). The molecular mechanism underlying the development of RORγt(+) ILCs is poorly understood. Here, we have shown that the aryl hydrocarbon receptor (Ahr) plays an essential role in RORγt(+) ILC maintenance and function. Expression of Ahr in the hematopoietic compartment was important for accumulation of adult but not fetal intestinal RORγt(+) ILCs. Without Ahr, RORγt(+) ILCs had increased apoptosis and less production of IL-22. RORγt interacted with Ahr and promoted Ahr binding at the Il22 locus. Upon IL-23 stimulation, Ahr-deficient RORγt(+) ILCs had reduced IL-22 expression, consistent with downregulation of IL-23R in those cells. Ahr-deficient mice succumbed to Citrobacter rodentium infection, whereas ectopic expression of IL-22 protected animals from early mortality. Our data uncover a previously unrecognized physiological role for Ahr in promoting innate gut immunity by regulating RORγt(+) ILCs.     

Pivotal Roles of ILCs in Hepatic Diseases

Innate lymphoid cells (ILCs) are involved in the development of mucosal-associated lymphoid tissues and serve as a rapid and early source of the effector cytokines that are typically associated with the T helper cell subsets in response to pathogen-induced changes in the microenvironment. Recent research has implicated ILCs as potential contributing factors to the spectrum of inflammation-related hepatic diseases, particularly hepatitis, fibrosis and carcinoma. In this review, we summarize the current knowledge on the roles of ILCs in these hepatic pathogeneses, providing insights into the underlying cellular and signaling mechanisms to help guide the future research to elucidate the ILCs’ characters under normal and diseased conditions and provide interventional targets with therapeutic potential.     

Development and function of intestinal innate lymphoid cells

Innate lymphoid cells (ILCs) are generated from common lymphoid precursors, like lymphocytes, but do not express an antigen receptor. ILCs include Natural Killer (NK) cells, first described 38 years ago, as well as the more recently discovered lymphoid tissue inducer (LTi) cells, NK(22) cells and ILC2s. ILCs reflect many functions of CD4(+) T helper cells by expressing IFNγ, IL-17, IL-22 or IL-13. However, in contrast to T cells, they are not selected on the basis of antigen specificity, and expand and act shortly after stimulation. Therefore, ILCs play fundamental roles early in responses to infection and injury, in the maintenance of homeostasis, and possibly in the regulation of adaptive immunity. Here, we review the recent data on the development and role of RORγt(+) ILCs and ILC2s in intestinal homeostasis and defense.     

Classical-type invasive lobular carcinoma with HER2 overexpression: clinical, histologic, and hormone receptor characteristics

The majority of invasive lobular carcinomas (ILCs) express estrogen receptor (ER) and progesterone receptor (PR) but lack ERBB2 (HER2) amplification. HER2 overexpression is traditionally considered to occur in the pleomorphic variant of ILCs. We describe 12 cases of classical-type ILCs with HER2 overexpression in a 3-year period. All tumors displayed the characteristic morphologic features of classical ILC with uniform cells and discohesive growth patterns. The lobular phenotype was confirmed by the absence of E-cadherin staining. Multiple variables regarding clinical, histologic, and hormone receptor characteristics of tumors were evaluated and compared with a set of HER2- classical ILCs. The study identified 2 main pathologic features associated with HER2 overexpression in classical type ILC: histiocytoid morphologic features and absence of PR expression. ER is still expressed in HER2+ classical ILCs, although the level of expression is significantly reduced compared with the HER2- cases. The implications of the findings are discussed.     

The role of innate lymphoid cells in response to microbes at mucosal surfaces

Innate lymphoid cells (ILCs) are a lymphocyte population that is mostly resident at mucosal surfaces. They help to induce an appropriate immune response to the microbiome at homeostasis. In healthy people, the mucosal immune system works symbiotically with organisms that make up the microbiota. ILCs play a critical role in orchestrating this balance, as they can both influence and in turn be influenced by the microbiome. ILCs also are important regulators of the early response to infections by diverse types of pathogenic microbes at mucosal barriers. Their rapid responses initiate inflammatory programs, production of antimicrobial products and repair processes. This review will focus on the role of ILCs in response to the microbiota and to microbial infections of the lung and intestine.     

The interplay between innate lymphoid cells and T cells

ILCs and T cells are closely related functionally but they significantly differ in their ability to circulate, expand, and renew. Cooperation and reciprocal functional regulation suggest that these cell types are more complementary than simply redundant during immune responses. How ILCs shape T-cell responses is strongly dependent on the tissue and inflammatory context. Likewise, indirect regulation of ILCs by adaptive immunity is induced by environmental cues such as the gut microbiota. Here, we review shared requirements for the development and function of both cell types and divergences in the orchestration of prototypic immune functions. We discuss the diversity of functional interactions between T cells and ILCs during homeostasis and immune responses. Identifying the location and the nature of the tissue microenvironment in which these interactions are taking place may uncover the remaining mysteries of their close encounters.     

Immunotherapy targeting inhibitory checkpoints: The role of NK and other innate lymphoid cells

Monoclonal antibodies that target specific ligand-receptor signaling pathways and act as immune checkpoint inhibitors have been designed to remove the brakes in T cells and restore strong and long-term antitumor-immunity. Of note, many of these inhibitory receptors are also expressed by Innate Lymphoid Cells (ILCs), suggesting that also blockade of inhibitory pathways in innate lymphocytes has a role in the response to the treatment with checkpoint inhibitors. ILCs comprise cytotoxic NK cells and “helper” subsets and are important cellular components in the tumor microenvironment. In addition to killing tumor cells, ILCs release inflammatory cytokines, thus contributing to shape adaptive cell activation in the context of immunotherapy. Therefore, ILCs play both a direct and indirect role in the response to checkpoint blockade. Understanding the impact of ILC-mediated response on the treatment outcome would contribute to enhance immunotherapy efficacy, as still numerous patients resist or relapse.     

诱导人脐带MSCs分化为胰岛样细胞团的促成熟方案及机制

 [摘 要]目的:通过各种生物化学制剂的不同组合在体外诱导人脐带间充质干细胞（hUC-MSCs）向胰岛样细胞团（ILCs）分化,筛选出能表达激素原转化酶（PC）1和PC2的促成熟方案。方法:用胶原酶Ⅱ消化、过滤离心和不完全消化传代的方法从人的完整脐带中分离和纯化hUC-MSCs,流式细胞术、RT-PCR和免疫细胞荧光技术检测其干细胞标志物。选用A、B、C 3种方案诱导hUC-MSCs向ILCs分化：方案A为含10 μg/L 碱性成纤维细胞生长因子（bFGF）、10 μg/L 表皮生长因子（EGF）、10 mg/L银杏提取液（GBE）及2%胎牛血清（FCS）的高糖培养基IMDM;在方案A基础上加入10 μg/L尼克酰胺为方案B;在方案B基础上加入10 μg/L肝细胞生长因子（HGF）为方案C。在hUC-MSCs诱导前后,通过倒置显微镜观察其形态变化,采用RT-PCR、qPCR和Western blotting检测胰岛相关mRNA和蛋白,特别是PC1和 PC2的表达情况。结果:(1)细胞形态、表面相关抗原、干细胞特异基因的表达等情况表明hUC-MSCs可以从人脐带中被成功地分离和纯化;hUC-MSCs普遍表达nestin,轻微表达Isl1。(2) RT-PCR检测发现方案A诱导的ILCs有Glut-2和MafA mRNA表达,方案B诱导的ILCs有Glut-2、MafA、Nkx6.1和PC2 mRNA表达,方案C诱导的ILCs有Glut-2、MafA、Nkx6.1、PC2、Ngn3、Pdx1、PC1和胰岛素mRNA表达,提示A、B和C 3种方案诱导的细胞有逐渐成熟的趋势。qPCR检测也证实了PC1 mRNA仅在方案C中有表达,PC2 mRNA在方案B和方案C中均有表达,但方案C中PC2 mRNA的表达量显著高于方案B（P<0.01）;Western blotting结果也表明PC1蛋白只在方案C中有表达;PC2酶原（ProPC2）与PC2在方案B和方案C中都有表达,且它们在方案C中的表达量均显著高于方案B(P<0.01)。结论: （1）hUC-MSCs具有向胰岛祖细胞或胰岛细胞分化的潜能;(2)方案C中尼克酰胺和HGF可促进hUC-MSCs向ILCs分化,使ILCs表达PC1并上调PC2;相对于方案A和B,方案C是一种促成熟方案。