Enterococcus faecium HDRsEf1 Promotes Systemic Th1 Responses and Enhances Resistance to SalmonellaTyphimurium Infection.

The gut microbiota is known to regulate the immune system and thereby influence susceptibility to infection. In this study, we observed that the administration of Enterococcus faecium HDRsEf1 (HDRsEf1) led to an improvement in the development of the immune system. This was evidenced by an increase in both the spleen index and the area of spleen white pulp. Specifically, the proportion of T helper (Th) 1 cells and the production of IFN-γ and IL-12 were significantly increased in the spleens of mice treated with HDRsEf1. In agreement with the in vivo results, we found that Th1-related cytokines, including IFN-γ and IL-12p70, were strongly induced in splenocytes treated with HDRsEf1. In addition, Th1 cell activation and high-level secretion of IL-12p70 were also confirmed by coculture of CD4+ T cells with bone marrow-derived dendritic cells treated with HDRsEf1. Moreover, the employment of HDRsEf1 was identified to augment resilience against systemic infection provoked by S. Typhimurium and stimulate the expression of the genes for TNFα and iNOS in the initial stage of infection, signifying that reinforced Th1 cells and IL-12 might activate macrophages for antibacterial safeguards. In summary, our study suggests that HDRsEf1 could act as an effective immunobiotic functional agent, promoting systemic Th1 immunological responses and priming defenses against infection.

Prevalence, drug resistance spectrum and virulence gene analysis of Campylobacter jejuni in broiler farms in central Shanxi, China.

This study collected 324 chicken cloacal swabs from 6 broiler farms in 4 different areas in Shanxi Province, China (i.e., Lvliang, Taiyuan, Jinzhong, and Yangquan), and analyzed the antimicrobial resistance and virulence-associated genes of the isolates to investigate the prevalence, drug resistance, and virulence gene data of Campylobacter jejuni in broilers. The population structure of C. jejuni and genetic evolutionary relationships among isolates from broiler farms in different regions were studied by using multilocus sequence typing. A total of 35 C. jejuni isolates with an infection rate of 10.8% (35/324) were obtained. The isolates were most resistant to ampicillin (85.7%) and were most sensitive to erythromycin (14.3%). Isolates with multidrug resistance accounted for 88.6% of the total isolates. In this experiment, 15 distinct sequence types were identified and included 9 new unique sequence types. cadF was present in all isolates, and ciaB had the lowest prevalence (51.4%). C. jejuni collected from broiler farms in central Shanxi had varied infection rates, and their overall positive rate was lower than of C. jejuni collected from other regions of the country. The isolates had high resistance to quinolones and ß-lactams, and multidrug resistance was prevalent. The isolates were genotypically diverse and carried 5 virulence-associated genes at high rates. Therefore, the importance of source contamination control in broiler farms is emphasized and may have considerable effects on human and animal health.

The inflammatory cytokine IL-6 induces FRA1 deacetylation promoting colorectal cancer stem-like properties.

Colorectal cancer (CRC) has long been known for its tight association with chronic inflammation, thought to play a key role in tumor onset and malignant progression through the modulation of cancer stemness. However, the underlying molecular and cellular mechanisms are still largely elusive. Here we show that the IL-6/STAT3 inflammatory signaling axis induces the deacetylation of FRA1 at the Lys-116 residue located within its DNA-binding domain. The HDAC6 deacetylase underlies this key modification leading to the increase of FRA1 transcriptional activity, the subsequent transactivation of NANOG expression, and the acquisition of stem-like cellular features. As validated in a large (n = 123) CRC cohort, IL-6 secretion was invariably accompanied by increased FRA1 deacetylation at K116 and an overall increase in its protein levels, coincident with malignant progression and poor prognosis. Of note, combined treatment with the conventional cytotoxic drug 5-FU together with Tubastatin A, a HDAC6-specific inhibitor, resulted in a significant in vivo synergistic inhibitory effect on tumor growth through suppression of CRC stemness. Our results reveal a novel transcriptional and posttranslational regulatory cross-talk between inflammation and stemness signaling pathways that underlie self-renewal and maintenance of CRC stem cells and promote their malignant behavior. Combinatorial treatment aimed at the core regulatory mechanisms downstream of IL-6 may offer a novel promising approach for CRC treatment.

Colorectal cancer-derived small extracellular vesicles establish an inflammatory premetastatic niche in liver metastasis.

Liver metastases develop in more than half of the patients with colorectal cancer (CRC) and are associated with a poor prognosis. The factors influencing liver metastasis of CRC are poorly characterized, but this information is urgently needed. We have now discovered that small extracellular vesicles (sEVs; exosomes) derived from CRC can be specifically targeted to liver tissue and induce liver macrophage polarization toward an interleukin-6 (IL-6)-secreting proinflammatory phenotype. More importantly, we found that microRNA-21-5p (miR-21) was highly enriched in CRC-derived sEVs and was essential for creating a liver proinflammatory phenotype and liver metastasis of CRC. Silencing either miR-21 in CRC-sEVs or Toll-like receptor 7 (TLR7) in macrophages, to which miR-21 binds, abolished CRC-sEVs' induction of proinflammatory macrophages. Furthermore, miR-21 expression in plasma-derived sEVs was positively correlated with liver metastasis in CRC patients. Collectively, our data demonstrate a pivotal role of CRC-sEVs in promoting liver metastasis by inducing an inflammatory premetastatic niche through the miR-21-TLR7-IL-6 axis. Thus, sEVs-miR-21 represents a potential prognostic marker and therapeutic target for CRC patients with liver metastasis.

ATR-CHK1-E2F3 signaling transactivates human ribonucleotide reductase small subunit M2 for DNA repair induced by the chemical carcinogen MNNG.

BACKGROUND: N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), an alkylating agent and an environmental carcinogen, causes DNA lesions and even carcinomas. DNA damage responses induced by MNNG activate various DNA repair genes and related signaling pathways. The present study aimed to investigate the regulatory mechanisms of human RR small subunit M2 (hRRM2) in response to MNNG. RESULTS: In this study, we demonstrated that the RRM2 gene was transactivated by MNNG exposure more strongly than the other small subunit, p53R2. The upregulated RRM2 translocated to the nucleus for DNA repair. Further study showed that E2F3 transactivated RRM2 expression by directly binding to its promoter after MNNG exposure. The transactivation was enhanced by the upregulation of NFY, which bound to the RRM2 promoter adjacent to the E2F3 binding site and interacted with E2F3. In response to MNNG treatment, E2F3 accumulated mainly through its phosphorylation at S124 and was dependent on ATR-CHK1 signaling. In comparison, p53R2 played a relatively weaker role in the MNNG-induced DNA damage response, and its transcription was regulated by the ATR-CHK2-E2F1/p53 pathway. CONCLUSIONS: We suggest that MNNG-stimulated ATR/CHK1 signaling stabilizes E2F3 by S124 phosphorylation, and then E2F3 together with NFY co-transactivate RRM2 expression for DNA repair. GENERAL SIGNIFICANCE: We propose a new mechanism for RRM2 regulation to maintain genome stability in response to environmental chemical carcinogens.

Aberrantly expressed Fra-1 by IL-6/STAT3 transactivation promotes colorectal cancer aggressiveness through epithelial-mesenchymal transition.

The pro-inflammatory cytokine interleukin-6 (IL-6) in tumor microenvironment has been suggested to promote development and progression of colorectal cancer (CRC). However, the underlying molecular mechanisms remain elusive. In this study, we demonstrate that fos-related antigen-1 (Fra-1) plays a critical role in IL-6 induced CRC aggressiveness and epithelial-mesenchymal transition (EMT). In CRC cell lines, the expression of Fra-1 gene was found significantly upregulated during IL-6-driven EMT process. The Fra-1 induction occurred at transcriptional level in a manner dependent on signal transducer and activator of transcription 3 (STAT3), during which both phosphorylated and acetylated post-translational modifications were required for STAT3 activation to directly bind to the Fra-1 promoter. Importantly, RNA interference-based attenuation of either STAT3 or Fra-1 prevented IL-6-induced EMT, cell migration and invasion, whereas ectopic expression of Fra-1 markedly reversed the STAT3-knockdown effect and enhanced CRC cell aggressiveness by regulating the expression of EMT-promoting factors (ZEB1, Snail, Slug, MMP-2 and MMP-9). Furthermore, Fra-1 levels were positively correlated with the local invasion depth as well as lymph node and liver metastasis in a total of 229 CRC patients. Intense immunohistochemical staining of Fra-1 was observed at the tumor marginal area adjacent to inflammatory cells and in parallel with IL-6 secretion and STAT3 activation in CRC tissues. Together, this study proposes the existence of an aberrant IL-6/STAT3/Fra-1 signaling axis leading to CRC aggressiveness through EMT induction, which suggests novel therapeutic opportunities for the malignant disease.