Population genomics study of Vibrio alginolyticus.

Vibrio alginolyticus is a Gram-negative bacillus that causes vibriosis to human and aquatic products, including fish, shrimp and shellfish. It poses a threat to public health and causes enormous economic losses to the aquaculture industry. However, research on genetic diversity and pathogenicity-related genetic elements based on whole genome is still lacking. In this study, sixty-eight strains of V. alginolyticus were collected from four provinces of China and the whole genome sequences were obtained. Combined with 113 publicly available genome sequences downloaded from NCBI, we inferred the population structure of V. alginolyticus by using fineSTRUCTURE software, and identified the virulence and antibiotic resistance factors using the VFDB, CARD and ResFinder database. The results indicated that V. alginolyticus included two main lineages, named Lineage 1 and Lineage 2. Both lineages distributed in America and Asia, but all the European genomes were classified into Lineage 1. A single cross-ocean transmission event was inferred from one of the 12 identified clonal groups in our dataset. V. alginolyticus genome contains a variety of virulence factors, such as tlh, OmpU, and IlpA, etc. The distribution of virulence factors revealed no lineage-specificity, but some of which revealed differences in their geographical distribution. A lower frequency of VP1611, vcrD, vopD, fleR/flrC and a higher frequency of IlpA were observed in genomes of Europe than other continents. In China, a lower frequency of fleR/flrC, and no IlpA were observed in genomes from Guangxi province. Among the identified antibiotic resistance genes, TxR and fos are significantly enriched in Lineage 2. In addition, TxR is more common in genomes from Asia, compared with the American and European genomes. But in China, the frequency of TxR in Sichuan genomes is much lower than in other provinces. We also found that large fragments of plasmids or ICEs that carried multiple drug resistance genes were present in five V. alginolyticus genomes (VA24, VA28, 2014V-1011, ZJ-T and Vb1833). Based on population genomics analysis, our study delineated the population structure, distribution of virulence and antibiotic resistance related factors of V. alginolyticus, which lays a foundation for future study of genetic characters and pathogenesis mechanism of this pathogen and will improve the works on monitoring, prevention and control of this pathogen.

Recirculating Th2 cells induce severe thymic dysfunction via IL-4/STAT6 signaling pathway.

Thymic involution happened early in life, but a certain ratio of activated CD4+ T cells will persistently recirculate into the thymus from the periphery and it have been suggested to be able to inhibit the development of embryonic thymocytes. Our present study was aimed to elucidate the specific mechanism how activated CD4+ T cells could influence upon developing thymocytes by using fetal thymic organ culture (FTOC) and kidney capsule transplantation. Our results demonstrated that Th2 cells were found to play a fundamental role in the inhibition of embryonic thymocyte development since a very low concentration of Th2 cells could obviously reduce the total number of thymocytes. And this effect was not tenable in other Th cell type. Notably, IL-4, the major cytokine secreted by Th2 cells, was suggested the key factor playing the inhibition role. In addition to reduced cell population, the proportion of double positive (DP) T cells was also heavily decreased. Furthermore, we demonstrated that it was the downstream effector signal transducer and activator of transcription 6 (STAT6) of IL-4 partially manipulate this inhibition. Together, these findings reveal a novel influence of Th2 cells re-entering the thymus on thymic involution.

The Survey of Cronobacter spp. (formerly Enterbacter sakazakii) in Infant and Follow-up Powdered Formula in China in 2012.

OBJECTIVE: To determine Cronobacter spp. contamination in infant and follow-up powdered formula in China. METHODS: All of 2282 samples were collected from the retail markets in China from January 2012 to December 2012, and analyzed for Cronobacter spp. by the Chinese National Food Safety Standard. Characterization of the isolates was analyzed by pulsed-field gel electrophoresis (PFGE) with XbaI and SpeI restriction enzymes. RESULTS: Cronobacter spp. strains were isolated from 25 samples, and the positive rates in infant powdered formulas and follow-up powdered formulas were 0.90% (10/1011) and 1.18% (15/1271), respectively. Analysis of variable data regarding different purchasing store formats, seasonality, and production locations as well as comparison of infant versus follow-up formulas did not reveal statistically significant factors. During the sampling period, one of six surveillance zones did exhibit a statistically significant trend towards higher positive rate. PFGE characterization of Cronobacter spp. to elucidate genetic diversity revealed only three pairs of Cronobacter spp. out of 25 having the same PFGE patterns. CONCLUSION: The current investigation indicated a lower positive rate of Cronobacter spp. in the powdered formula in China. This evidence suggested contamination originating from multiple different sources during the manufacturing process.

Suspension of thymic emigration promotes the maintenance of antigen-specific memory T cells and the recall responses.

Thymic involution is evolutionarily conserved and occurs early in life. However, the physiological significance remains elusive of this seemingly detrimental process. The present study investigated the potential impact of altered thymic output on T cell memory using ovalbumin (OVA) expressed by Listeria monocytogenes as a model antigen. Suspension of thymic emigration by thymectomy was shown to lead to a marked increase in the frequency and total number of OVA-specific memory T cells. In contrast, oversupply of thymic emigrants through thymic grafting caused a significant decrease of such cells. When rechallenged with L. monocytogenes expressing OVA, the thymectomized mice mounted a more potent recall response as evidenced by the enlarged population of OVA-specific tetramer⁺ cells and the accelerated clearance of the bacteria. Notably, the memory-enhancing effect of thymectomy was abrogated following weekly adoptive transfer of naive T cells. Together, data from the present study indicate that reduced thymic output favors the maintenance of the memory T cell pool.

Asiaticoside improves diabetic nephropathy by reducing inflammation, oxidative stress, and fibrosis: An in vitro and in vivo study.

BACKGROUND: Diabetic nephropathy (DN) is a severe microvascular complication of diabetes characterized by inflammation, oxidative stress, and renal fibrosis. Asiaticoside (AC) exhibits anti-inflammatory, antioxidant, and anti-fibrotic properties, suggesting potential therapeutic benefits for DN. This study aimed to investigate the protective effects of AC against DN and elucidate the underlying mechanisms involving the nuclear factor erythroid 2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) antioxidant pathway. AIM: To investigate the renoprotective effects of AC against DN and elucidate the role of the NRF2/HO-1 pathway. METHODS: The effects of AC on high glucose (HG)-induced proliferation, inflammation, oxidative stress, and fibrosis were evaluated in rat glomerular mesangial cells (HBZY-1) in vitro. A streptozotocin-induced DN rat model was established to assess the in vivo impact of AC on renal injury, inflammation, oxidative stress, and fibrosis. The involvement of the NRF2/HO-1 pathway was examined using pharmacological inhibition studies in the cell model. RESULTS: AC inhibited HG-induced HBZY-1 cell proliferation and significantly improved various indicators of DN in rats, including reduced body weight, and elevated blood glucose, serum creatinine, blood urea nitrogen, and 24-h urine protein. Both in vitro and in vivo studies demonstrated that AC decreased inflammation and oxidative stress by reducing interleukin (IL)-6, IL-8, tumor necrosis factor-alpha, reactive oxygen species, and malondialdehyde levels while increasing superoxide dismutase activity. Additionally, AC suppressed the expression of fibrogenic markers such as collagen I, collagen IV, and fibronectin. AC activated NRF2 expression in the nucleus and increased HO-1 and NAD(P)H dehydrogenase (Quinone) 1 protein expression in renal tissues and HG-induced HBZY-1 cells. CONCLUSION: AC improves DN by reducing inflammation, oxidative stress, and fibrosis through the activation of the NRF2/HO-1 signaling pathway. These findings not only highlight AC as a promising therapeutic candidate for DN but also underscore the potential of targeting the NRF2/HO-1 pathway in developing novel treatments for other chronic kidney diseases characterized by oxidative stress and inflammation.

[Prevalence and antibiogram distribution of Salmonella isolated from broiler production and processing course in four provinces, China].

OBJECTIVE: To determine the contamination condition of Salmonella in broiler breeding and slaughter processing in China and to investigate the distribution of antimicrobial resistance profiles. METHODS: Five large-scale broiler holdings and fourteen slaughterhouses were chosen to detect Salmonella in Henan, Jiangsu, Sichuan and Shandong provinces in 2010. A total of 835 anal swabs and 744 chicken carcasses were sampled to compare the difference of Salmonella contamination rate.Salmonella isolates were identified by serotyping according to Kauffmann-White scheme.The antimicrobial susceptibilities of Salmonella isolates were determined by broth microdilution method and sixteen antimicrobial agents were chosen and examined. RESULTS: In total, Salmonella isolates were recovered in 56 (6.7%) specimens among 835 collected anal swabs and 122 (16.4%) specimens among 744 broiler carcasses. Positive rate of Salmonella in broiler carcasses was higher than anal swabs (χ(2) = 36.94, P < 0.05). The dominant Salmonella serovars isolated from broiler anal swabs were S.enterica serovar Indiana and S.enterica serovar Enteritidis, accounting for 58.9% (33/56) and 32.1% (18/56) respectively. The prevalent serovars in broiler carcasses were also the two serovars and occupied 29.8% (37/124), 32.2% (40/124) respectively. Nearly 95.0% (171/180) Salmonella isolates were resistant to at least one antimicrobial, 78.3% (141/180) Salmonella strains were multi-drug resistant isolates and 20 (11.1%) Salmonella isolates were resistant to 14 antimicrobials. CONCLUSION: Our findings indicated that Salmonella contamination was common and serious in commercial broiler production and processing course in China. Salmonella contamination rate in broiler slaughter processing performance was higher than broiler flocks. Additionally, antibiotic resistance of Salmonella was in serious situation.

The changes in peripheral blood Th17 and Treg ratios in Hashimoto's thyroiditis are accompanied by differential PD-1/PD-L1 expression.

Objective: The aim of this study was to analyze the percentages of T helper 17 cells (Th17s) and T regulatory cells (Tregs) in autoimmune Hashimoto's thyroiditis (HT), and the expression of the checkpoint molecules programmed death receptor 1/programmed death ligand 1 (PD-1/PD-L1) on these cells. Methods: This is a case-control study involving 53 initially diagnosed HT patients (HT group) and 21 normal controls (NC group). The peripheral blood mononuclear cells from the individuals of the two groups were isolated and restimulated ex vivo; the percentage of Th17s, Tregs, PD-1+ Th17s, PD-L1+ Th17s, PD-1+ Tregs, and PD-L1+ Tregs was assessed by flow cytometric analysis. Results: (1) The percentage of Th17s in the peripheral blood of the HT group was significantly higher than that of the NC group [(6.38 ± 1.32)% versus (3.12 ± 0.66)%; t = 14.110, P < 0.001], while the percentage of peripheral blood Tregs was significantly lower [(3.82 ± 1.48)% versus (5.61 ± 1.60)%; t = -4.599, P < 0.001]. (2) HT patients' Th17s expressed PD-1 at a significantly lower frequency than their counterparts in the NC [(6.46 ± 2.77)% versus (18.51 ± 3.96)%; t = -14.842, P < 0.001], while no difference was observed for PD-L1 between the two groups. (3) In contrast, both PD-1 and PD-L1 were expressed at significantly higher frequency on HT patients' Tregs than on NC [respectively: (17.01 ± 3.04)% versus (10.23 ± 2.77)%; t = 8.850, P < 0.001 for PD-1; (16.60 ± 9.58)% versus (11.36 ± 10.14)%; t = 2.089, P < 0.005, for PD-L1]. Conclusion: (1) The increased percentage of Th17s and decreased percentage of PD-1+ Th17s in the HT group suggest that a loss of control on Th17 activity through the checkpoint inhibitory axis PD-1/PD-L1 may participate in disease pathogenesis. (2) While the decreased percentage of Tregs in HT patients may explain a lack of regulatory functions able to prevent the autoimmune destruction of the thyroid, the significance of the increased frequency of Tregs expressing PD-1 and PD-L1, previously reported to boost Tregs differentiation, remains to be established. Elucidating this apparent contradiction may reveal important mechanisms underlying HT pathogenesis.

[Virulent gene prevalence of foodborne Listeria monocytogenes in China in 2005].

OBJECTIVE: To study the virulent gene prevalence of foodborne Listeria monocytogenes (LM) isolated from China. METHODS: 78 LM isolates derived from raw meat, cooked food, aquatic products and vegetables of 13 provinces and cities.LM isolates were investigated for prevalence of virulence genes (LIPI-1 (prfA, plcA, hly, mpl, actA, plcB); LIPI-2 (inlA, inlB), and iap) by PCR method. RESULTS: 87.2% (68/78) of the isolates were prfA positive, 98.7% (77/78) of the isolates were plcA, actA and plcB positive, 97.4% (76/78) of the isolates were hly positive, 87.2% (68/78) of the isolates were mpl positive, 92.3% (72/78) of the isolates were inlA positive, 100% (78/78) of the isolates were inlB positive, 98.7% (77/78) of the isolates were iap positive. Among 21 virulent gene negative isolates, there was 7 isolates lack of two or more virulence genes. The rate of virulence genes deletion isolates from cooked meat was 31.3% (10/32), the rate of virulence genes deletion isolates from raw meat was 16.1% (5/31), the rate of virulence genes deletion isolates from vegetables was 36.4% (4/11) and rate of virulence genes deletion isolates from seafood was 50% (2/4). No significant difference was found (χ(2) = 3.721, P > 0.05). The virulence gene array-1 strains were dominant among these isolates. CONCLUSION: Among 78 LM isolates, prevalent of virulent genes were different except inlB, virulence genes of LIP-1 were deleted prevalently among isolates, virulence gene deletion patterns were diverse.

[Study on the automatic ribotyping for Enterobacter sakazakii].

OBJECTIVE: To analyze the ribotyping fingerprint of Enterobacter sakazakii (E. sakazakii) isolated from food and its typing power. METHODS: Two standard strains and twenty-eight isolates of E.sakazakii were analyzed by the DuPont Riboprinter(TM) microbial characterization system. The relevant database was established and the fingerprint patterns were analyzed with BioNumerics software. RESULTS: This system grouped two standard strains and twenty-eight E.sakazakii isolates into 26 ribotypes, and four ribotypes included two strains respectively, the other twenty-two strains showed different ribotypes. The lowest similarity was 31.58%. The number of bands by ribotyping was approximately ten and the molecular weight of these bands ranged from 1 to 50 kb. By the clustering program in BioNumerics, these isolates could be grouped into four clusters. CONCLUSION: The automatic ribotyping method is convenient and fast in E.sakazakii typing.

Thymic homing of activated CD4+ T cells induces degeneration of the thymic epithelium through excessive RANK signaling.

Activated T cells have been shown to be able to recirculate into the thymus from the periphery. The present study was aimed to elucidate the functional consequences of thymic homing of activated T cells upon developing thymocytes and thymic epithelial cells (TEC). In the presence of activated T cells, especially CD4+ T cells, T cell development was found to be inhibited in thymic organ cultures with markedly reduced cellularity. Thymic transplantation demonstrated that the inhibitory effect was most likely due to a defective microenvironment. As the major component of the thymic stroma, the TEC compartment was severely disturbed after prolonged exposure to the activated T cells. In addition to reduced cell proliferation, TEC differentiation was heavily skewed to the mTEC lineage. Furthermore, we demonstrated that RANKL highly expressed by activated CD4+ T cells was primarily responsible for the detrimental effects. Presumably, excessive RANK signaling drove overproduction of mTECs and possibly exhaustion of epithelial progenitors, thereby facilitating the deterioration of the epithelial structures. These findings not only reveal a novel activity of activated T cells re-entering the thymus, but also provide a new perspective for understanding the mechanism underlying thymic involution.