Phloretin is protective in a murine salmonella enterica serovar typhimurium infection model

Phloretin@cyclodextrin/natural silk protein/polycaprolactone nanofiber wound dressing with antioxidant and antibacterial activities promotes diabetic wound healing

In patients with diabetes, chronic hyperglycemia impairs immune function at wound sites, increasing susceptibility to infections, prolonging inflammation, and delaying healing. This study aimed to develop wound dressings that control bacterial infections and accelerate healing. Phloretin (PHL), which has antibacterial and anti-inflammatory properties, was encapsulated with γ-cyclodextrin (γ-CD) to form a PHL@CD complex with enhanced bioavailability. This complex was incorporated into nanofiber wound dressings composed of polycaprolactone and natural silk protein. The resulting dressings exhibited favorable physical and chemical properties, including nutrient transport and gas exchange, which are essential for wound healing. The nanofiber membranes exhibited antibacterial activity against Staphylococcus aureus (90.31 ± 4.41 % inhibition), with high antioxidant capacity (91.48 ± 0.33 % ABTS scavenging) and blood compatibility. The membranes also promoted cell viability. Importantly, the nanofiber dressings accelerated wound healing in a diabetic mouse model by reducing the duration of inflammation. The novel nanofiber wound dressing can significantly improve the treatment of diabetic wounds.

The gut microbiota contributes to the infection of bovine viral diarrhea virus in mice

Bovine viral diarrhea virus (BVDV) is prevalent worldwide and causes significant economic losses. Gut microbiota is a large microbial community and has a variety of biological functions. However, whether there is a correlation between gut microbiota and BVDV infection and what kind of relation between them have not been reported. Here, we found that gut microbiota composition changed in normal mice after infecting with BVDV, but mainly the low abundance microbe was affected. Interestingly, BVDV infection significantly reduced the diversity of gut microbiota and changed its composition in gut microbiota-dysbiosis mice. Furthermore, compared with normal mice of BVDV infection, there were more viral loads in the duodenum, jejunum, spleen, and liver of the gut microbiota-dysbiosis mice. However, feces microbiota transplantation (FMT) reversed these effects. The data above indicated that the dysbiosis of gut microbiota was a key factor in the high infection rate of BVDV. It is found that the IFN-I signal was involved by investigating the underlying mechanisms. The inhibition of the proliferation and increase in the apoptosis of peripheral blood lymphocytes (PBL) were also observed. However, FMT treatment reversed these changes by regulating PI3K/Akt, ERK, and Caspase-9/Caspase-3 pathways. Furthermore, the involvement of butyrate in the pathogenesis of BVDV was also further confirmed. Our results showed for the first time that gut microbiota acts as a key endogenous defense mechanism against BVDV infection; moreover, targeting regulation of gut microbiota structure and abundance may serve as a new strategy to prevent and control the disease.IMPORTANCEWhether the high infection rate of BVDV is related to gut microbiota has not been reported. In addition, most studies on BVDV focus on in vitro experiments, which limits the study of its prevention and control strategy and its pathogenic mechanism. In this study, we successfully confirmed the causal relationship between gut microbiota and BVDV infection as well as the potential molecular mechanism based on a mouse model of BVDV infection and a mouse model of gut microbiota dysbiosis. Meanwhile, a mouse model which is more susceptible to BVDV provided in this study lays an important foundation for further research on prevention and control strategy of BVDV and its pathogenesis. In addition, the antiviral effect of butyrate, the metabolites of butyrate-producing bacteria, has been further revealed. Overall, our findings provide a promising prevention and control strategy to treat this infectious disease which is distributed worldwide.

Dietary pectin attenuates Salmonella typhimurium-induced colitis by modulating the TLR2-NF-κB pathway and intestinal microbiota in mice

The role of dietary pectin on microbial-induced colitis, oxidative status, barrier function, and microbial composition, as well as the underlying mechanisms, is scarce. In this study, we aimed to investigate whether dietary pectin alleviates Salmonella typhimurium-induced colitis in mice. Male C57BL/6J mice fed an isocaloric and isofibrous diet with 7% pectin or cellulose were administered sterile water or Salmonella typhimurium to induce colitis, which is equal to a human food dose of 0.57% (5.68 g/kg). Dietary pectin alleviated Salmonella typhimurium-induced colitis and oxidative stress as shown by the reduced disease activity index score, decreased colon shortening and histological damage score, colonic hydrogen peroxide, malondialdehyde concentrations, and relative mRNA expressions of coenzyme Q-binding protein COQ10 homologue B (Coq10b), Ccl-2, Ccl-3, Ccl-8, Tnf-α, Il-1β, Ifn-γ, Ifn-β, and serum TNF-α protein level. Moreover, pectin administration ameliorated the downregulated colonic abundances of occludin, zonula occludens-1, zonula occludens-2, and the upregulated abundances of TLR2 and p-NF-κB in Salmonella-infected mice. Additionally, 16S rRNA analysis demonstrated that pectin altered the microbial beta-diversity and reduced Salmonella levels. Collectively, pectin ameliorated Salmonella typhimurium-induced colitis, oxidative stress, and tight junction, which may be related to the inactivation of TLR2-NF-κB signalling and reduced abundance of Salmonella.

The Molecular Pharmacology of Phloretin: Anti-Inflammatory Mechanisms of Action

The isolation of phlorizin from the bark of an apple tree in 1835 led to a flurry of research on its inhibitory effect on glucose transporters in the intestine and kidney. Using phlorizin as a prototype drug, antidiabetic agents with more selective inhibitory activity towards glucose transport at the kidney have subsequently been developed. In contrast, its hydrolysis product in the body, phloretin, which is also found in the apple plant, has weak antidiabetic properties. Phloretin, however, displays a range of pharmacological effects including antibacterial, anticancer, and cellular and organ protective properties both in vitro and in vivo. In this communication, the molecular basis of its anti-inflammatory mechanisms that attribute to its pharmacological effects is scrutinised. These include inhibiting the signalling pathways of inflammatory mediators' expression that support its suppressive effect in immune cells overactivation, obesity-induced inflammation, arthritis, endothelial, myocardial, hepatic, renal and lung injury, and inflammation in the gut, skin, and nervous system, among others.

Phloretin Protects Bovine Rumen Epithelial Cells from LPS-Induced Injury

Lipopolysaccharide (LPS) is an endotoxin that induces immune and inflammatory responses in the rumen epithelium of dairy cows. It is well-known that flavonoid phloretin (PT) exhibits anti-oxidative, anti-inflammatory and antibacterial activity. The aim of this research was to explore whether PT could decrease LPS-induced damage to bovine rumen epithelial cells (BRECs) and its molecular mechanisms of potential protective efficacy. BRECs were pretreated with PT for 2 h and then stimulated with LPS for the assessment of various response indicators. The results showed that 100 µM PT had no significant effect on the viability of 10 µg/mL LPS-induced BRECs, and this dose was used in follow-up studies. The results showed that PT pre-relieved the decline in LPS-induced antioxidant indicators (T-AOC and GSH-PX). PT pretreatment resulted in decreased interleukin-1β (IL-1β), IL-6, IL-8, tumor necrosis factor-α (TNF-α) and chemokines (CCL2, CCL5, CCL20) expression. The underlying mechanisms explored reveal that PT may contribute to inflammatory responses by regulating Toll-like receptor 4 (TLR4), nuclear transcription factor-κB p65 (NF-κB p65), and ERK1/2 (p42/44) signaling pathways. Moreover, further studies found that LPS-induced BRECs showed decreased expression of claudin-related genes (ZO-1, Occludin); these were attenuated by pretreatment with PT. These results suggest that PT enhances the antioxidant properties of BRECs during inflammation, reduces gene expression of pro-inflammatory cytokines and chemokines, and enhances barrier function. Overall, the results suggest that PT (at least in vitro) offers some protective effect against LPS-induced ruminal epithelial inflammation. Further in vivo studies should be conducted to identify strategies for the prevention and amelioration of short acute rumen acidosis (SARA) in dairy cows using PT.