Two novel genes (pwtsB and pwtsC) encoding lipases were isolated by screening the soil metagenomic library. Sequence analysis revealed that pwtsB encodes a protein of 301 amino acids with a predicted molecular weight of 33 kDa, and pwtsC encodes a protein of 323 amino acids with a predicted molecular weight of 35 kDa. Furthermore, both genes were cloned and expressed in Escherichia coli BL21 (DE3) using pET expression system. The expressed recombinant enzymes were purified by Ni-nitrilotriacetic acid affinity chromatography and characterized by spectrophotometric with different p-nitrophenyl esters. The results showed that PWTSB displayed a high degree of activity and stability at 20 degrees C with an optimal pH of around 8.0, and PWTSC at 40 degrees C with an optimal pH of around 7.0. P-nitrophenyl palmitate (p-NPP) was identified as the best substrate of PWTSB and PWTSC. The specific activities of PWTSB and PWTSC were 150 and 166 U/mg, respectively toward p-NPP at 30 degrees C, about 20-fold higher than that toward p-nitrophenyl butyrate (C4) and caprylate (C8). In conclusion, our results suggest that PWTSB is a cold adapt lipase and PWTSC is a thermostable lipase to long-chain p-nitrophenyl esters.

The dissemination of drug-resistant bacteria into different environments has posed a grave threat to public health, but data on the spread of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) from animal farms to the receiving river are limited. Here, 57 ESBL-producing E. coli isolated from a pig farm and the receiving river were analyzed in terms of drug resistance, ESBL genes, and enterobacterial repetitive intergenic consensus (ERIC). The results showed that ESBL-producing E. coli from swine feces and downstream water of the pig farm outfall overlapped substantially in drug resistance and ESBL genes. Additionally, six ESBL-producing E. coli from the downstream water exhibited 100 % genetic similarity with strains from the swine feces. In conclusion, effluents of animal farms are a likely contributor to the presence of ESBL-producing E. coli in aquatic environments.

Inflammatory bowel disease (IBD) refers to inflammatory disorders of the gut with unclear pathogenesis. miR155 expression was increased in IBDs by upregulated Th1/Th17 cell response and proinflammatory factors to promote intestinal inflammation. Dendritic cell (DC) is a heterogeneous subsets in the intestine, and plays important roles in maintaining intestinal homeostasis. However, it is unclear whether miR155 regulate the differentiation and function of intestinal DC subsets to orchestrate inflammation in the intestinal microenvironment. Here, we found defiency of miR155 led to a significantly decreased number of CD103+CD11b+DC in the lamina propria (LP) of intestine at steady state, moreover, the yield of bone marrow-derived CD103+CD11b+DC induced by GM-CSF and Flt3L in vitro was also decreased compared to that of wild type (WT) mice. Further study showed that differency of miR155 had no effect on turnover rate and migration. Interestingly, we found the percentage and number of pre-cDC1 (CD103+DC precursor) in the BM were reduced significantly in the bone marrow of miR155-deficient mice compared to that of WT mice, and the transcriptor IRF4 and Notch2 expression of CD103+CD11b+DC in the LP was also decreased in miR155-deficient mice. In addition, CD103+DC and CD103+CD11b+DC in the LP of miR155-deficient mice exhibited a poor pro-inflammatory phenotype. Taken together, our results identifies a role of miR155 as a critical regular of intestinal homeostasis, which will be helpful for seeking a potential therapeutic target for the treatment of IBD.

Numerous studies have been suggested that ILC2s play a critical role in the initiation of allergic asthmatic airway inflammation, but their property and role in chronic allergic lung inflammation has not been well established. Our study found that purified allergen-experienced ILC2s produce more cytokines than naive ILC2s when stimulated by suboptimal amounts of IL-33 and IL-2 in vitro. Furthermore, upon allergen intranasal re-challenge, allergen-experienced ILC2s proliferate more vigorously and produce much greater amounts of type 2 cytokines than naive ILC2s. These results suggested that allergen-experienced ILC2s showed some memory-like properties in allergic asthma. To further characterize these memory-like ILC2s, we analyzed the expression of some activation surface markers, such as KLRG1, CD62L, CD69, ST2, ICOS, NKG2D, CD44, CD25 and CD122 on ILC2s in the lungs of naive and IL-33-treated mice at different time point. The results showed that during the initial expansion phase, IL-33 treatment resulted in a rapid increase in the number of CD25− ILC2s cells, which peaked at d6. And then the CD25− ILC2 population in the lung started to contract, the number of CD25− ILC2s cells was rapidly declined at d14, a time point that the numbers of CD25+ ILC2s reached their peak. Both of CD25− and CD25+ ILC2s rapidly declined at d30, however, the numbers of CD25+ ILC2s was much higher than CD25− ILC2. Thus, these results suggested that allergen-experienced ILC2s could differentiate into two different memory potential ILC2 subsets, namely CD25− short-term surviving effector ILC2s cells an CD25+ long-term surviving memory ILC2s cells. This work was supported by grants (2015CB943203, 31300730, 81272315, 2016GCC09)

The generation of RORγt+ regulatory T cells (Tregs), which regulate type 2 immune respond, is dependent on dendritic cells and microbiota, but mechanisms are poorly understood. Here we show that the differentiation of RORγt+ Tregs was critically dependented on integrin αvβ8 expressed in DCs. In mice, lack of αvβ8 in DCs resulted in loss of RORγt+ Tregs in the small intestine and mesenteric lymph nodes. Moreover, we also report that the maintenance of RORγt+ Tregs needs the existence of commensal bacteria but not DCs in small intestine. The percentage and the proliferation of RORγt+ Tregs were decreased after treated with antibiotic while these were unaffected by the absence of DCs in a short time. These date demonstrate that αvβ8 expressed in small intestinal DCs play a critical role in the induction of RORγt+ Tregs and microbiota act as a key factor on maintenance of RORγt+ Tregs, respectively. Our results may help to explain the mechanisms of oral tolerance via αvβ8 in DCs and commensal microbiota regulate the generation of RORγt+ Tregs to suppress type 2 immune respond.