Xiaohuan Guo

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.

Induction of Innate Lymphoid Cell-Derived Interleukin-22 by the Transcription Factor STAT3 Mediates Protection against Intestinal Infection

Inhibitors of the transcription factor STAT3 target STAT3-dependent tumorigenesis but patients often develop diarrhea from unknown mechanisms. Here we showed that STAT3 deficiency increased morbidity and mortality after Citrobacter rodentium infection with decreased secretion of cytokines including IL-17 and IL-22 associated with the transcription factor RORγt. Administration of the cytokine IL-22 was sufficient to rescue STAT3-deficient mice from lethal infection. Although STAT3 was required for IL-22 production in both innate and adaptive arms, by using conditional gene-deficient mice, we observed that STAT3 expression in RORγt(+) innate lymphoid cells (ILC3s), but not T cells, was essential for the protection. However, STAT3 was required for RORγt expression in T helper cells, but not in ILC3s. Activated STAT3 could directly bind to the Il22 locus. Thus, cancer therapies that utilize STAT3 inhibitors increase the risk for pathogen-mediated diarrhea through direct suppression of IL-22 from gut ILCs.

Innate Lymphoid Cells Control Early Colonization Resistance against Intestinal Pathogens through ID2-Dependent Regulation of the Microbiota

Microbiota-mediated effects on the host immune response facilitate colonization resistance against pathogens. However, it is unclear whether and how the host immune response can regulate the microbiota to mediate colonization resistance. ID2, an essential transcriptional regulator for the development of innate lymphoid cell (ILC) progenitors, remains highly expressed in differentiated ILCs with unknown function. Using conditionally deficient mice in which ID2 is deleted from differentiated ILC3s, we observed that these mutant mice exhibited greatly impaired gut colonization resistance against Citrobacter rodentium. Utilizing gnotobiotic hosts, we showed that the ID2-dependent early colonization resistance was mediated by interleukin-22 (IL-22) regulation of the microbiota. In addition to regulating development, ID2 maintained homeostasis of ILC3s and controlled IL-22 production through an aryl hydrocarbon receptor (AhR) and IL-23 receptor pathway. Thus, ILC3s can mediate immune surveillance, which constantly maintains a proper microbiota, to facilitate early colonization resistance through an ID2-dependent regulation of IL-22.

CD160 is essential for NK-mediated IFN-γ Production

Tu et al. generated a novel CD160-deficient mouse and showed impaired NK cell–mediated tumor elimination and IFN-γ production. CD160+ NK cells are functionally distinct in secretion of IFN-γ from their CD160− NK cell counterparts.

The ETS1 transcription factor is required for the development and cytokine-induced expansion of ILC2.

Zook et al. use a novel mouse model to demonstrate a requirement for the transcription factor ETS1 in the development and function of group 2 innate lymphoid cells.

A novel 3p22.3 gene CMTM7 represses oncogenic EGFR signaling and inhibits cancer cell growth

Deletion of 3p12-22 is frequent in multiple cancer types, indicating the presence of critical tumor-suppressor genes (TSGs) at this region. We studied a novel candidate TSG, CMTM7, located at the 3p22.3 CMTM-gene cluster, for its tumor-suppressive functions and related mechanisms. The three CMTM genes, CMTM6, 7 and 8, are broadly expressed in human normal adult tissues and normal epithelial cell lines. Only CMTM7 is frequently silenced or downregulated in esophageal and nasopharyngeal cell lines, but uncommon in other carcinoma cell lines. Immunostaining of tissue microarrays for CMTM7 protein showed its downregulation or absence in esophageal, gastric, pancreatic, liver, lung and cervix tumor tissues. Promoter CpG methylation and loss of heterozygosity were both found contributing to CMTM7 downregulation. Ectopic expression of CMTM7 in carcinoma cells inhibits cell proliferation, motility and tumor formation in nude mice, but not in immortalized normal cells, suggesting a tumor inhibitory role of CMTM7. The tumor-suppressive function of CMTM7 is associated with its role in G1/S cell cycle arrest, through upregulating p27 and downregulating cyclin-dependent kinase 2 (CDK2) and 6 (CDK6). Moreover, CMTM7 could promote epidermal growth factor receptor (EGFR) internalization, and further suppress AKT signaling pathway. Thus, our findings suggest that CMTM7 is a novel 3p22 tumor suppressor regulating G1/S transition and EGFR/AKT signaling during tumor pathogenesis.

The CKLF1-C19 peptide attenuates allergic lung inflammation by inhibiting CCR3- and CCR4-mediated chemotaxis in a mouse model of asthma.

To cite this article: Tian L, Li W, Wang J, Zhang Y, Zheng Y, Qi H, Guo X, Zhang Y, Ma D, Shen H, Wang Y. The CKLF1‐C19 peptide attenuates allergic lung inflammation by inhibiting CCR3‐ and CCR4‐mediated chemotaxis in a mouse model of asthma. Allergy 2011; 66: 287–297.

VSTM1-v2, a novel soluble glycoprotein, promotes the differentiation and activation of Th17 cells

Cytokines are soluble proteins that mediate immune reactions and are responsible for communication among immune cells. CD4(+) T cells are the principle sources of cytokines of adaptive immunity. Cytokines play critical roles in the differentiation and effector function of CD4(+) T cells. They also play key roles in diseases, and some of them have been developed into drugs in the forms of recombinant cytokines, soluble receptors and neutralizing antibodies. Therefore, identifying novel potential cytokines is necessary and beneficial for better understanding immunology and enhancing human health. To find novel potential cytokines, we carried out an integrated bioinformatics analysis on the whole human genome. Cytokine candidates were selected for cDNA cloning, sub-cloning, secretion verification, expression profile analysis and functional study. Here, we report a novel soluble protein, VSTM1-v2, which is a classical secretory glycoprotein mainly expressed in immune tissues, and can promote the differentiation and activation of Th17 cells.

CMTM5-v1 induces apoptosis in cervical carcinoma cells

CMTM5 (CKLF-like MARVEL transmembrane domain-containing member 5) exhibits tumor inhibition activity with frequent epigenetic inactivation in various tumor cell lines including cervical carcinoma (CC) cells. In this paper, we examined the function of CMTM5-v1 (the primary RNA splicing form) in both HeLa and SiHa cells. Overexpression of CMTM5-v1 in both cells can induce apoptosis, but the effects are more obvious in SiHa than that in HeLa. In SiHa cells, restoration of CMTM5-v1 caused disruption of mitochondrial transmembrane potential, release of cytochrome c, activation of caspase3 and cleavage of PARP. General caspase inhibitor almost prevented apoptosis of SiHa cells, suggesting that CMTM5-v1 induces apoptosis mainly through caspase-dependent pathway. These findings verify that CMTM5-v1 inhibits the growth of CC cell lines via inducing apoptosis.

Aberrant expression of CKLF-like MARVEL transmembrane member 5 (CMTM5) by promoter methylation in myeloid leukemia

CMTM5 has been shown to exhibit tumor suppressor activities, however, its role in leukemia is unclear. Herein we firstly reported the expression and function of CMTM5 in myeloid leukemia. CMTM5 was down-regulated, or undetectable, in leukemia cell lines and bone marrow cells from leukemia patients with promoter methylation. Ectopic expression of CMTM5-v1 strongly inhibited the proliferation of K562 and MEG-01 cells. In addition, significant negative correlations were observed between CMTM5 and three leukemia-specific fusion genes (AML1-ETO, PML-RARα and BCR/ABL1). CMTM5 expression was up-regulated in patients who had undergone treatment. Therefore, CMTM5 may be involved in the pathomechanism of myeloid leukemias.