Molecular epidemiology and characterization of antimicrobial-resistant Staphylococcus haemolyticus strains isolated from dairy cattle milk in Northwest, China.

Introduction: Non-aureus Staphylococcus (NAS) species are currently the most commonly identified microbial agents causing sub-clinical infections of the udder and are also deemed as opportunistic pathogens of clinical mastitis in dairy cattle. More than 10 NAS species have been identified and studied but little is known about S. haemolyticus in accordance with dairy mastitis. The present study focused on the molecular epidemiology and genotypic characterization of S. haemolyticus isolated from dairy cattle milk in Northwest, China. Methods: In this study, a total of 356 milk samples were collected from large dairy farms in three provinces in Northwest, China. The bacterial isolation and presumptive identification were done by microbiological and biochemical methods following the molecular confirmation by 16S rRNA gene sequencing. The antimicrobial susceptibility testing (AST) was done by Kirby-Bauer disk diffusion assay and antibiotic-resistance genes (ARGs) were identified by PCR. The phylogenetic grouping and sequence typing was done by Pulsed Field Gel Electrophoresis (PFGE) and Multi-Locus Sequence Typing (MLST) respectively. Results: In total, 39/356 (11.0%) were identified as positive for S. haemolyticus. The overall prevalence of other Staphylococcus species was noted to be 39.6% (141/356), while the species distribution was as follows: S. aureus 14.9%, S. sciuri 10.4%, S. saprophyticus 7.6%, S. chromogenes 4.2%, S. simulans 1.4%, and S. epidermidis 1.1%. The antimicrobial susceptibility of 39 S. haemolyticus strains exhibited higher resistance to erythromycin (92.3%) followed by trimethoprim-sulfamethoxazole (51.3%), ciprofloxacin (43.6%), florfenicol (30.8%), cefoxitin (28.2%), and gentamicin (23.1%). All of the S. haemolyticus strains were susceptible to tetracycline, vancomycin, and linezolid. The overall percentage of multi-drug resistant (MDR) S. haemolyticus strains was noted to be 46.15% (18/39). Among ARGs, mphC was identified as predominant (82.05%), followed by ermB (33.33%), floR (30.77%), gyrA (30.77%), sul1 (28.21%), ermA (23.08%), aadD (12.82%), grlA (12.82%), aacA-aphD (10.26%), sul2 (10.26%), dfrA (7.69%), and dfrG (5.13%). The PFGE categorized 39 S. haemolyticus strains into A-H phylogenetic groups while the MLST categorized strains into eight STs with ST8 being the most predominant while other STs identified were ST3, ST11, ST22, ST32, ST19, ST16, and ST7. Conclusion: These findings provided new insights into our understanding of the epidemiology and genetic characteristics of S. haemolyticus in dairy farms to inform interventions limiting the spread of AMR in dairy production.

Duan-Nai-An, A Yeast Probiotic, Improves Intestinal Mucosa Integrity and Immune Function in Weaned Piglets.

Post-weaning diarrhea commonly occurs in piglets and results in significant economic loss to swine producers. Non-antibiotic measures for managing post-weaning diarrhea are critically needed. Duan-Nai-An, a probiotic produced from the yeast fermentation of egg whites, was previously shown to optimize intestinal flora and reduce the incidence of clinical diarrhea in weaning piglets. To study the effects of Duan-Nai-An on mucosal integrity and immunity in pig intestine, we examined the microstructure and ultrastructure of the intestines of weaned pigs with or without Duan-Nai-An as a feed supplement. The piglets of the Duan-Nai-An-fed group developed intestines with intact columnar epithelia covered by tightly packed microvilli on the apical surface. However, piglets of the control group (no supplement) showed villous atrophy and thinning, microvillus slough, and in the severe cases, damage of intestinal epithelia and exposure of the underlying lamina propria. Moreover, piglets of the Duan-Nai-An-fed group showed apparent plasmocyte hyperplasia, increased lymphoid nodule numbers, well-developed Peyer's Patchs, and apparent germinal centers. The lymphoid tissues of the control group were far less developed, showing lymph node atrophy, lymphocyte reduction, degeneration, and necrosis. These results indicate that Duan-Nai-An improves the development of the intestinal structures and lymphoid tissues and promotes intestinal health in weaned piglets.

Tumor-associated macrophages increase the proportion of cancer stem cells in lymphoma by secreting pleiotrophin.

Tumor-associated macrophages (TAMs) are closely related to the occurrence and development of lymphoma, but their mechanism is still unclear. Here we collected peripheral blood and lymphoma tissue from patients with diffuse large B lymphoma. Results showed that the proportion of TAMs in high-risk group was significantly higher than that in low-risk group. Moreover, the expressions of pleiotrophin (PTN), PTPRZ1 (PTN receptor) and ß-catenin in lymphoma tissues of high-risk group were also significantly higher than those in low-risk group. Correlation analysis showed that the proportion of TAMs in lymphocyte was positively correlated with the expression of PTN and PTPRZ1 in lymphoma tissue. In vitro experimental results showed that TAM promoted the invasion and proliferation of lymphoma cells by secreting PTN. We also found that TAMs increased the proportion of cancer stem cells in lymphoma. Animal experiments showed that TAMs promoted lymphoma growth. Both Ki-67 proliferation index and CD44+cancer stem cells increased significantly in TAM group. Blocking PTN or ß-catenin partly inhibited these effects of TAMs. In conclusion, TAMs increased the proportion of cancer stem cells through PTN/ß-catenin pathway in lymphoma.

Melatonin enhances arsenic trioxide-induced cytotoxicity by modulating autophagy in an acute promyelocytic leukemia cell line.

BACKGROUND: Arsenic trioxide (ATO)-containing therapeutic strategies are widely used in the treatment of acute promyelocytic leukemia (APL). Growing evidence has shown that melatonin enhances the radio- or chemo-sensitivity of numerous cancer cells. However, whether melatonin is capable of enhancing the cytotoxic effects of ATO in APL cells remains unknown. METHODS: The present study conducted a 24 h melatonin exposure followed by additional 12, 24 or 48 h ATO exposure in the APL cell line NB4 with or without autophagy-related protein 7 (ATG7) silencing by RNA interference. Cell cytotoxicity was evaluated by Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase (LDH) assays. Cell apoptosis was assessed by Annexin-V/propidium iodide assay and western blotting against cleaved caspase 3, Bax and Bcl-2. Autophagy was evaluated by western blotting against LC3. RESULTS: Pre-treatment with a non-cytotoxic dose of melatonin significantly enhanced ATO-mediated reduced cell viability and increased LDH release. Furthermore, melatonin pre-treatment also enhanced ATO-mediated increase in early and late apoptosis, as well as the expression of Bax and cleaved caspase 3, while further decreasing ATO-mediated reduced expression of Bcl-2. Concomitantly, melatonin pre-treatment increased LC3II expression and enhanced the ATO-mediated elevation in LC3II expression. However, autophagy inhibition by ATG7 silencing blocked the enhancing effects of melatonin on ATO-induced apoptosis and cytotoxicity. These findings indicated that melatonin pre-treatment enhances ATO-induced cytotoxicity by modulating ATG7-mediated autophagy. CONCLUSIONS: Melatonin could represent a valuable adjuvant to ATO in APL treatment, particularly in patients with ATO-resistant APL.

Establishment of a method for culturing cynomolgus T lymphocytes induced by human CD3Ab / 中国肿瘤生物治疗杂志

@#[Abstract] Objective: To establish a method for in vitro isolation and culture of T lymphocytes from peripheral blood of cynomolgus monkeys that induced by human CD3 antibody based on the foundation of protein homology of CD3 from human, cynomolgus monkey and porcine. Methods: The amino acid sequences of human, cynomolgus monkeys and porcine CD3 proteins were obtained from NCBI, and the sequence, homology and phylogenetic tree were analyzed by DNAMAN software. Western blotting was used to detect the expression of CD3 protein on T cell membranes from the three species. PBMCs of healthy cynomolgus were isolated and divided into three groups: group A was stimulated with anti-human CD3Ab alone, group B was stimulated with IL-2 alone, and group C was costimulated with human CD3Ab and IL-2. Cell morphology and growth status were observed under inverted microscope and the cell growth curve was plotted. Cell viability was detected by trypan blue staining and the expressions of CD3, CD4 and CD8 on T cell surface were detected by flow cytometry. Results: The homology of the amino acid sequence of human CD3 protein to cynomolgus monkey and porcine were 86.9% and 65.6% respectively. The expression levels of CD3 protein on cynomolgus and porcine T cell membrane were 79% and 17% contrast to human, respectively. Cells of group A did not proliferate. Proliferation, viability and CD3 expression [(93.8±3.6)% vs (70.3±4.7)%, P<0.01] in T cells of group C were significantly higher than those in group B. Growth curve of T cells in group C showed an S-shape, which is consistent with Logistic growth curve. T cells in group C exhibited high purity and expressed high level CD3; moreover, the CD8+T cell took a high proportion. Conclusion: The membrane of T lymphocytes from peripheral blood of cynomolgus can express CD3 protein that highly homological to human. Co-stimulation of human CD3Ab, IL-2 and 1% PHAcan induce the proliferation and differentiation of T lymphocytes of cynomolgus, and obtain T lymphocytes with good growth status, high proliferation ability and high purity.