Microbiome-metabolomics analysis of the effects of decreasing dietary crude protein content on goat rumen mictobiota and metabolites.

OBJECTIVE: The objective of this study was to investigate the effects of decreasing dietary crude protein content on rumen fermentation, mictobiota, and metabolites in goats. METHODS: In an 84-day feeding trial, a total of twelve male Anhui white goat kids with initial body weight 15.9±1.13 kg were selected and randomly classified into two groups, feeding a normal crude protein diet (14.8% CP, NCP) or a low crude protein diet (12.0% CP, LCP). At the end of the experimental trial (on day 84), six animals were randomly selected from each group and were slaughtered to collect rumen fluid samples for the analysis of rumen fermentation parameters, microbiome, and metabolome. RESULTS: The concentrations of ammonia-nitrogen, total volatile fatty acid, acetate, and propionate were decreased (p<0.05) in the LCP group in comparison with those in the NCP group. The abundances of genera Prevotella, Campylobacter, Synergistetes, and TG5, which were associated with nitrogen metabolism, were lower (p<0.05) in the LCP group compared with those in the NCP group. The levels of 78 metabolites (74 decreased, 4 increased) in the rumen fluid were altered (p<0.05) by the treatment. Most of the ruminal metabolites that showed decreased levels in the LCP group were substrates for microbial protein synthesis. Metabolic pathway analysis showed that vitamin B6 metabolism was significantly different (p<0.05) in rumen fluid between the two treatments. CONCLUSION: Decreased dietary protein level inhibited rumen fermentation through microbiome and metabolome shifts in goat kids. These results enhance our understanding of ruminal bacteria and metabolites of goat fed a low protein diet.

The negative feedback regulation of microRNA-146a in human periodontal ligament cells after Porphyromonas gingivalis lipopolysaccharide stimulation.

OBJECTIVE: Toll-like receptors (TLRs) pathway has been demonstrated to play an important role in periodontitis. However, the regulatory mechanism of microRNAs (miRNAs) on TLRs pathway is still unclear. Hence, this study is to explore the function of miRNA-146a in inflammatory reaction induced by Porphyromonas gingivalis lipopolysaccharide (LPS) in human periodontal ligament cells (hPDLCs). METHODS: Cells were treated with 1 or 10 µg/ml P. gingivalis LPS. The expression of TLR2, TLR4 and miRNA-146a were measured by real-time polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay (ELISA) was applied to detect nuclear factor (NF)-κ B p65 nuclear activity, interleukin-1ß (IL-1ß), IL-6, IL-8 and tumor necrosis factor-α (TNF-α). To examine the underlying mechanisms, cells were exposed to anti-TLR2/4 mAb or miRNA-146a inhibitor/mimic and evaluated by real-time PCR and ELISA. RESULTS: 10 µg/ml P. gingivalis LPS increased the expressions of TLR2 (3.79 ± 0.31), TLR4 (2.21 ± 0.31), and miRNA-146a (4.91 ± 0.87), NF-κ B p65 nuclear activity (6.51 ± 0.77 fold) (p < 0.05). 1 µg/ml P. gingivalis LPS induced TLR2 (3.05 ± 0.23), miRNA-146a (3.66 ± 0.83) and NF-κ B p65 nuclear activity (4.06 ± 0.78 fold) (p < 0.05), except TLR4 (1.11 ± 0.30, p > 0.05). Also, cytokines production increased (p < 0.05). The up-regulation of miRNA-146a could be blocked by anti-TLR2/4 mAb (p < 0.05). After the blockage of miRNA-146a, TLR2, TLR4, NF-κ B p65 nuclear activity and proinflammatory cytokines increased. However, after application of miRNA-146a mimic, the levels of these indexes decreased obviously (p < 0.05). CONCLUSION: MiRNA-146a functions as a negative feedback regulator via down-regulating proinflammatory cytokine secretion and blocking TLRs signaling pathway in hPDLCs after P. gingivalis LPS stimulation.

High glucose induces inflammatory cytokine through protein kinase C-induced toll-like receptor 2 pathway in gingival fibroblasts.

Toll-like receptors (TLRs) play a key role in innate immune response and inflammation, especially in periodontitis. Meanwhile, hyperglycemia can induce inflammation in diabetes complications. However, the activity of TLRs in periodontitis complicated with hyperglycemia is still unclear. In the present study, high glucose (25 mmol/l) significantly induced TLR2 expression in gingival fibroblasts (p<0.05). Also, high glucose increased nuclear factor kappa B (NF-κB) p65 nuclear activity, tumor necrosis factor-α (TNF-α) and interleukin-lß (IL-1ß) levels. Protein kinase C (PKC)-α and δ knockdown with siRNA significantly decreased TLR2 and NF-κB p65 expression (p<0.05), whereas inhibition of PKC-ß had no effect on TLR2 and NF-κB p65 under high glucose (p<0.05). Additional studies revealed that TLR2 knockdown significantly abrogated high-glucose-induced NF-κB expression and inflammatory cytokine secretion. Collectively, these data suggest that high glucose stimulates TNF-α and IL-1ß secretion via inducing TLR2 through PKC-α and PKC-δ in human gingival fibroblasts.

Influence of electrolyte and poloxamer 188 on the aggregation kinetics of solid lipid nanoparticles (SLNs).

Solid lipid nanoparticles (SLNs) have attracted increasing attention as colloidal drug carriers due to theirs advantages including low toxicity, drug targeting and modified release. However, undesired particle aggregation in aqueous dispersions would limit the applicability of SLNs for drug delivery. The purpose of the present article is to investigate the aggregation behavior of the SLNs and quantitatively evaluate how the concentration of NaCl and F68 affect the stability of the SLNs. The early stage aggregation kinetics of the SLNs was investigated over a wide range of NaCl concentrations by employing dynamic light scattering (DLS). In the presence of the NaCl, aggregation kinetics of the SLNs exhibited reaction-limited (slow) and diffusion-limited (fast) regimes. These results indicated that the aggregation behavior of these new nanoparticles can be well explained by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The critical coagulation concentration (CCC) of SLNs containing 0.0%, 0.1%, 0.5%, 2.0%, and 4.0% of Poloxamer 188 (F68) was 416, 328, 519, 607, and 602 mM, respectively, suggesting that the F68 influences the aggregation behavior of the SLNs. F68 made the SLNs more sensitive to the electrolyte when its concentration is low (0.1%), the bush of the polymer F68 has a bridging effect that accelerated the aggregation process of the SLNs. However, at the high concentration, F68 can provide the steric repulsion to the nanoparticles, which effectively stabilized the SLNs dispersions.