Antimicrobial resistance of Streptococcus uberis isolated from bovine mastitis: Systematic review and meta-analysis.

Streptococcus uberis is one of the most common pathogens associated with bovine mastitis, commonly treated with antimicrobials (AM), favoring the appearance of antimicrobial resistance (AMR). The objective of this work was to determine the proportion of phenotypic AMR among S. uberis isolated worldwide from bovine intramammary infections between the years 1983-2022, and to assess the variables associated by means of a systematic review and metanalysis. Sixty articles were eligible for quantitative review. Ninety-four independent studies were obtained. The antimicrobials evaluated in more S. uberis strains were penicillin (21,987 strains), oxacillin (21,727 strains), erythromycin (20,013 strains), and ampicillin (19,354 strains). Most of the studies included in this meta-analysis were from Europe (44), followed by America (25), Africa (10), Asia (10), and Oceania (5). Among the included articles, 22 were published from 1983 to 2006, 23 from 2007 to 2012, 25 from 2013 to 2015, and the remaining 24 after 2016. Penicillin, erythromycin, and tetracycline were the antimicrobials with >25 studies. Therefore, the following analyses were performed only for these antimicrobials, presenting a high heterogeneity index (I2). The variability observed for penicillin and tetracycline was only explained, partially, by continent of origin. The variability observed for erythromycin was not explained by any of the potential explanatory variables included in this study. The S. uberis proportion of resistance to antimicrobials is highly variable and probably influenced by many factors other than those studied in this meta-analysis, where it was not possible to inform a unique average proportion of resistance.

Interplay between estrogen and Stat3/NF-κB-driven immunomodulation in lung cancer.

K-ras mutant lung adenocarcinoma (LUAD) is the most common type of lung cancer, displays abysmal prognosis and is tightly linked to tumor-promoting inflammation, which is increasingly recognized as a target for therapeutic intervention. We have recently shown a gender-specific role for epithelial Stat3 signaling in the pathogenesis of K-ras mutant LUAD. The absence of epithelial Stat3 in male K-ras mutant mice (LR/Stat3Δ/Δ mice) promoted tumorigenesis and induced a nuclear factor-kappaB (NF-κB)-driven pro-tumor immune response while reducing tumorigenesis and enhancing anti-tumor immunity in female counterparts. In the present study, we manipulated estrogen and NF-κB signaling to study the mechanisms underlying this intriguing gender-disparity. In LR/Stat3Δ/Δ females, estrogen deprivation by bilateral oophorectomy resulted in higher tumor burden, an induction of NF-κB-driven immunosuppressive response, and reduced anti-tumor cytotoxicity, whereas estrogen replacement reversed these changes. On the other hand, exogenous estrogen in males successfully inhibited tumorigenesis, attenuated NF-κB-driven immunosuppression and boosted anti-tumor immunity. Mechanistically, genetic targeting of epithelial NF-κB activity resulted in reduced tumorigenesis and enhanced the anti-tumor immune response in LR/Stat3Δ/Δ males, but not females. Our data suggest that estrogen exerts a context-specific anti-tumor effect through inhibiting NF-κB-driven tumor-promoting inflammation and provide insights into developing novel personalized therapeutic strategies for K-ras mutant LUAD.

Preconditioning in an Inflammatory Milieu Augments the Immunotherapeutic Function of Mesenchymal Stromal Cells.

Multipotent mesenchymal stromal cells (MSCs) have emerged as potent therapeutic agents for multiple indications. However, recent evidence indicates that MSC function is compromised in the physiological post-injury milieu. In this study, bone marrow (BM)- and adipose-derived (AD)-MSCs were preconditioned in hypoxia with or without inflammatory mediators to potentiate their immunotherapeutic function in preparation for in vivo delivery. Human MSCs were cultured for 48 hours in either normoxia (21% O2) or hypoxia (2% O2) with or without the addition of Cytomix, thus creating 4 groups: 1) normoxia (21%); 2) Cytomix-normoxia (+21%); 3) hypoxia (2%); and 4) Cytomix-hypoxia (+2%). The 4 MSC groups were subjected to comprehensive evaluation of their characteristics and function. Preconditioning did not alter common MSC surface markers; nonetheless, Cytomix treatment triggered an increase in tissue factor (TF) expression. Moreover, the BM-MSCs and AD-MSCs from the +2% group were not able to differentiate to chondrocytes and osteoblasts, respectively. Following Cytomix preconditioning, the metabolism of MSCs was significantly increased while viability was decreased in AD-MSCs, but not in BM-MSCs. MSCs from both tissues showed a significant upregulation of key anti-inflammatory genes, increased secretion of IL-1 receptor antagonist (RA), and enhanced suppression of T-cell proliferation following the Cytomix treatment. Similarly, following a lipopolysaccharide challenge, the Cytomix-treated MSCs suppressed TNF-α secretion, while promoting the production of IL-10 and IL-1RA. These preconditioning approaches facilitate the production of MSCs with robust anti-inflammatory properties. AD-MSCs preconditioned with Cytomix under normoxia appear to be the most promising therapeutic candidates; however, safety concerns, such as thrombogenic disposition of cells due to TF expression, should be carefully considered prior to clinical translation.

Short-term physiological hypoxia potentiates the therapeutic function of mesenchymal stem cells.

BACKGROUND: In the bone marrow, MSCs reside in a hypoxic milieu (1-5% O2) that is thought to preserve their multipotent state. Typically, in vitro expansion of MSCs is performed under normoxia (~ 21% O2), a process that has been shown to impair their function. Here, we evaluated the characteristics and function of MSCs cultured under hypoxia and hypothesized that, when compared to normoxia, dedicated hypoxia will augment the functional characteristics of MSCs. METHODS: Human and porcine bone marrow MSCs were obtained from fresh mononuclear cells. The first study evaluated MSC function following both long-term (10 days) and short-term (48 h) hypoxia (1% O2) culture. In our second study, we evaluated the functional characteristics of MSC cultured under short-term 2% and 5% hypoxia. MSCs were evaluated for their metabolic activity, proliferation, viability, clonogenicity, gene expression, and secretory capacity. RESULTS: In long-term culture, common MSC surface marker expression (CD44 and CD105) dropped under hypoxia. Additionally, in long-term culture, MSCs proliferated significantly slower and provided lower yields under hypoxia. Conversely, in short-term culture, MSCs proliferated significantly faster under hypoxia. In both long-term and short-term cultures, MSC metabolic activity was significantly higher under hypoxia. Furthermore, MSCs cultured under hypoxia had upregulated expression of VEGF with concomitant downregulation of HMGB1 and the apoptotic genes BCL-2 and CASP3. Finally, in both hypoxia cultures, the pro-inflammatory cytokine, IL-8, was suppressed, while levels of the anti-inflammatories, IL-1ra and GM-CSF, were elevated in short-term hypoxia only. CONCLUSIONS: In this study, we demonstrate that hypoxia augments the therapeutic characteristics of both porcine and human MSCs. Yet, short-term 2% hypoxia offers the greatest benefit overall, exemplified by the increase in proliferation, self-renewing capacity, and modulation of key genes and the inflammatory milieu as compared to normoxia. These data are important for generating robust MSCs with augmented function for clinical applications.