Cmtm4 deficiency exacerbates colitis by inducing gut dysbiosis and S100a8/9 expression

The dysfunction of innate immunity components is one of the major drivers for ulcerative colitis(UC),and increasing reports indicate that the gut microbiome serves as an intermediate between genetic mutations and UC development.Here,we find that the IL-17 receptor subunit,CMTM4,is reduced in UC patients and dextran sulfate sodium(DSS)-induced colitis.The deletion of CMTM4(Cmtm4^(-/-))in mice leads to a higher susceptibility to DSS-induced colitis than in wild-type,and the gut microbiome significantly changes in composition.The causal role of the gut microbiome is confirmed with a cohousing experiment.We further identify that S100a8/9 is significantly up-regulated in Cmtm4^(-/-)colitis,with the block of its receptor RAGE that reverses the phenotype associated with the CMTM4 deficiency.CMTM4 deficiency rather suppresses S100a8/9 expression in vitro via the IL17 pathway,further supporting that the elevation of S100a8/9 in vivo is most likely a result of microbial dysbiosis.Taken together,the results suggest that CMTM4 is involved in the maintenance of intestinal homeostasis,suppression of S100a8/9,and prevention of colitis development.Our study further shows CMTM4 as a crucial innate immunity component,confirming its important role in UC development and providing insights into potential targets for the development of future therapies.

FAM19A4 is a novel cytokine ligand of formyl peptide receptor I （FPR 1） and is able to promote the migration and phagocytosis of macrophages

FAM 19A4 is an abbreviation for family with sequence similarity 19 （chemokine （C-C motif）-Iike） member A4, which is a secretory protein expressed in low levels in normal tissues. The biological functions of FAM19A4 remain to be determined, and its potential receptor（s） is unclarified. In this study, we demonstrated that FAM 19A4 was a classical secretory protein and we verified for the first time that its mature protein is composed of 95 amino acids. We found that the expression of this novel cytokine was upregulated in lipopolysaccharide （LPS）-stimulated monocytes and macrophages and was typically in polarized M 1. FAM 19A4 shows chemotactic activities on macrophages and enhances the macrophage phagocytosis of zymosan both in vitro and in vivo with noticeable increases of the phosphorylation of protein kinase B （Akt）. FAM 19A4 can also increase the release of reactive oxygen species （ROS） upon zymosan stimulation. Furthermore, based on receptor internalization, radio ligand binding assays and receptor blockage, we demonstrated for the first time that FAM19A4 is a novel ligand of formyl peptide receptor 1 （FPR1）. The above data indicate that upon inflammatory stimulation, monocyte/macrophage-derived FAM 19A4 may play a crucial role in the migration and activation of macrophages during pathogenic infections.

Research progress in cytokines with chemokine-like function

Cytokines are small proteins secreted by a variety of cells,which regulate not only cell growth and differentiation but also immune function by binding to their corresponding receptors.1 Cytokines mainly include interleukin,colonystimulating factor(CSF),interferon,tumor necrosis factor,growth factor(GF)and chemokine.Chemokines are a class of cytokines with chemotactic activity and function by binding to G proteincoupled receptors.2 Chemokines and their receptors have important roles in inflammation and tumors by regulating chemotaxis,immunoregulation and the behavior of various cells.

LRRC25 plays a key role in all-trans retinoic acid-induced granulocytic differentiation as a novel potential leukocyte differentiation antigen

Leukocyte differentiation antigens （LDAs） play important roles in the immune system, by serving as surface markers and participating in multiple biological activities, such as recognizing pathogens, mediating membrane signals, interacting with other cells or systems, and regulating cell differentiation and activation. Data mining is a powerful tool used to identify novel LDAs from whole genome. LRRC25 （leucine rich repeat-containing 25） was predicted to have a role in the function of myeloid cells by a large-scale ＂omics＂ data analysis. Further experimental validation showed that LRRC25 is highly expressed in primary myeloid cells, such as granulocytes and monocytes, and lowly/intermediately expressed in B cells, but not in T cells and almost all NK cells. It was down-regulated in multiple acute myeloid leukemia （AML） cell lines and bone marrow cells of AML patients and up-regulated after all-trans retinoic acid （ATRA）-mediated granulocytic differentiation in AML cell lines and acute promyelocytic leukemia （APL; AML-M3, FAB classification） cells. Localization analysis showed that LRRC25 is a type I transmembrane molecule. Although ectopic LRRC25 did not promote spontaneous differentiation of NB4 cells, knockdown of LRRC25 by siRNA or shRNA and knockout of LRRC25 by the CRISPR-Cas9 system attenuated ATRA-induced termi- nal granulocytic differentiation, and restoration of LRRC25 in knockout cells could rescue ATRA-induced granulocytic differentiation. Therefore, LRRC25, a potential leukocyte differentiation antigen, is a key regulator of ATRA-induced granulocytic differentiation.

Secretory expression of the fusion protein composed of human IL-2 and PreS antigen of hepatitis B virus in mammalian cells

In order to make entire HBV preSAg secrete from mammalian cells, we constructed an eukaryotic expression vector by using leader sequence of human interleukin-2 (IL-2) as secretory signal peptide, and using high hydrophilic amino acids as the linker between IL-2 C end and preSAg N end. As a result, the IL-2preS fusing protein could be secreted from mammalian cells transfected with the reconstructed vector and the expression efficiency was identical to that of natural IL-2. It was considered that the retentive effect of preS1Ag could be successfully bypassed. The results not only laid a theoretical and practical foundation for constructing specific gene vaccine against HBV persistent infection, but also supplied experimental evidence for studying modulation of protein secretory expression.