It has been shown that gut dysbiosis can be associated with the development of type 2 diabetes mellitus (T2DM). Consequently, intervention with probiotics may be a useful approach to improve metabolic variables in diabetes. The present study aimed to evaluate the efficacy of L. paracasei HII01 on glycemia in T2DM patients. In a randomized, double-blind, placebo-controlled study, 50 participants were allocated to receive L. paracasei HII01 (50 × 10⁹ CFU/day) or a placebo (corn starch 10 mg/day). Blood and fecal samples were assessed at baseline and at the end of the trial. After 12 weeks of intervention, fasting blood glucose level had significantly decreased in the probiotic group compared with the placebo group. Importantly, probiotic supplementation significantly decreased the plasma levels of LPS, TNF-α, IL-6 and hsCRP compared the placebo group. Additionally, an increase in beneficial bacteria and a decrease in pathogenic bacteria, which related to the improvement of SCFAs, was found following L. paracasei HII01 supplementation. These findings demonstrated that L. paracasei HII01 improved hyperglycemia and inflammatory markers by favorably modifying gut microbiota and subsequently ameliorating the leaky gut and endotoxemia, thereby suggesting a potential role as an adjuvant treatment in type 2 diabetes.

Despite the updated knowledge of the impact of gut dysbiosis on diabetes, investigations into the beneficial effects of individual bacteria are still required. This study evaluates the antihyperglycemic efficacy of Lactobacillus paracasei HII01 and its possible mechanisms in diabetic rats. Diabetic rats were assigned to receive vehicle, L. paracasei HII01 (10⁸ CFU/day), metformin 30 (mg/kg) or a combination of L. paracasei HII01 and metformin. Normal rats given vehicle and L. paracasei HII01 were included. Metabolic parameters, including in vitro hemi-diaphragm glucose uptake, skeletal insulin-signaling proteins, plasma lipopolysaccharide (LPS), gut permeability, composition of gut microbiota and its metabolites, as well as short-chain fatty acids (SCFAs), were assessed after 12 weeks of experiment. The results clearly demonstrated that L. paracasei HII01 improved glycemic parameters, glucose uptake, insulin-signaling proteins including pAkt^Ser473, glucose transporter 4 (GLUT4) and phosphorylation of AMP-activated protein kinase (pAMPK^Thr172), tumor necrosis factor (TNF-α) and nuclear factor-κB (NF-kB) in diabetic rats. Modulation of gut microbiota was found together with improvement in leaky gut, endotoxemia and SCFAs in diabetic rats administered L. paracasei HII01. In conclusion, L. paracasei HII01 alleviated hyperglycemia in diabetic rats primarily by modulating gut microbiota along with lessening leaky gut, leading to improvement in endotoxemia and inflammation-disturbed insulin signaling, which was mediated partly by PI3K/Akt signaling and AMPK activation.

Transforming growth factor beta (TGF-β) is a key factor mediating the intercellular crosstalk between the hematopoietic stem cells and their microenvironment. Here, we investigated the skeletal phenotype of transgenic mice expressing constitutively active TGF-β receptor type I under the control of Mx1-Cre (Mx1;TβRI^CA mice). μCT analysis showed decreased cortical thickness, and cancellous bone volume in both femurs and mandibles. Histomorphometric analysis confirmed a decrease in cancellous bone volume due to increased osteoclast number and decreased osteoblast number. Primary osteoblasts showed decreased ALP and mineralization. Constitutive TβRI activation increased osteoclast differentiation. qPCR analysis showed that Tnfsf11/Tnfrsf11b ratio, Ctsk, Sufu, and Csf1 were increased whereas Runx2, Ptch1, and Ptch2 were decreased in Mx1;TβRI^CA femurs. Interestingly, Gli1, Wnt3a, Sp7, Alpl, Ptch1, Ptch2, and Shh mRNA expression were reduced whereas Tnfsf11/Tnfrsf11b ratio was increased in Mx1;TβRI^CA mandibles. Similarly, osteoclast-related genes were increased in Mx1;TβRI^CA osteoclasts whereas osteoblast-related genes were reduced in Mx1;TβRI^CA osteoblasts. Western blot analysis indicated that SMAD2 and SMAD3 phosphorylation was increased in Mx1;TβRI^CA osteoblasts, and SMAD3 phosphorylation was increased in Mx1;TβRI^CA osteoclasts. CTSK was increased while RUNX2 and PTCH1 was decreased in Mx1;TβRI^CA mice. Microindentation analysis indicated decreased hardness in Mx1;TβRI^CA mice. Our study indicated that Mx1;TβRI^CA mice were osteopenic by increasing osteoclast number and decreasing osteoblast number, possibly by suppressing Hedgehog signaling pathways.

Transforming growth factor beta (TGF-β) is ubiquitously found in bone and plays a key role in bone turnover. Mice expressing constitutively active TGF-β receptor type I (Mx1;TβRI^CA mice) are osteopenic. Here, we identified the candidate genes involved in bone turnover in Mx1;TβRI^CA mice using RNA sequencing analysis. A total of 285 genes, including 87 upregulated and 198 downregulated genes, were differentially expressed. According to the KEGG analysis, some genes were involved in osteoclast differentiation (Fcgr4, Lilrb4a), B cell receptor signaling (Cd72, Lilrb4a), and neutrophil extracellular trap formation (Hdac7, Padi4). Lilrb4 is related to osteoclast inhibition protein, whereas Hdac7 is a Runx2 corepressor that regulates osteoblast differentiation. Silencing Lilrb4 increased the number of osteoclasts and osteoclast marker genes. The knocking down of Hdac7 increased alkaline phosphatase activity, mineralization, and osteoblast marker genes. Therefore, our present study may provide an innovative idea for potential therapeutic targets and pathways in TβRI-associated bone loss.

Chronic inflammation contributes to the development of skeletal disorders in patients with systemic lupus erythematosus (SLE). Activation of the host immune response stimulates osteoclast activity, which in turn leads to bone loss. Regenerating bone in the inflammatory microenvironments of SLE patients with critical bone defects remains a great challenge. In this study, we utilized lipopolysaccharide (LPS) to imitate locally and systemically pathogenic bacterial infection and examined the bone regeneration performance of LPS-associated mandibular and tibial bone regeneration impairment in FcγRIIB^−/− mice. Our results indicated that a loss of FcγRIIB alleviates bone regeneration in both mandibles and tibiae. After LPS induction, FcγRIIB^−/− mice were susceptible to impaired fracture healing in tibial and mandibular bones. LPS decreased the mineralization to collagen ratio in FcγRIIB^−/− mice, indicating a mineralization defect during bone repair. An osteoblast-associated gene (Col1a1) was attenuated in FcγRIIB-deficient mice, whereas Bglap, Hhip, and Creb5 were further downregulated with LPS treatment in FcγRIIB^−/− mice compared to FcγRIIB^−/− mice. Alpl and Bglap expression was dcreased in osteoblasts derived from bone chips. An osteoclast-associated gene, Tnfsf11/Tnfrsf11 ratio, ewas increased in LPS-induced FcγRIIB^−/− mice and in vitro. Furthermore, systemic LPS was relatively potent in stimulating production of pro-inflammatory cytokines including TNF-α, IL-6, and MCP-1 in FcγRIIB^−/− mice compared to FcγRIIB^−/− mice. The levels of TNF-α, IFN-β, IL-1α, and IL-17A were increased, whereas IL-10 and IL-23 were decreased in FcγRIIB^−/− mice treated locally with LPS. These findings suggest that both local and systemic LPS burden can exacerbate bone regeneration impairment, delay mineralization and skeletal repair, and induce inflammation in SLE patients.

Transforming growth factor beta (TGF-β), a master regulator of renal fibrosis, is the hallmark of chronic kidney disease (CKD) progression, and CKD worsens bone remodeling. However, the effects of the dysregulation of TGF-β signaling on bone remodeling during CKD have not been investigated. Here, we determined the effects of TGF-β receptor I (TβRI) overexpression under the control of Mx1-Cre on bone remodeling in CKD mice (Mx1;TβRI^CA-CKD mice). Our results demonstrated that kidney fibrosis and serum urea nitrogen levels were elevated in Mx1;TβRI^CA-CKD mice compared to WT-CKD, indicating that TβRI overexpression exacerbated renal injury during CKD. Serum calcium was decreased, while PTH was enhanced, in Mx1;TβRI^CA-CKD mice. Mx1;TβRI^CA-CKD mice displayed severe osteopenia as assessed by uCT in both femurs and mandibles. An histomorphometric analysis showed that tibial cancellous bone volume was decreased in Mx1;TβRI^CA-CKD. Likewise, mRNA expression levels of an osteoclastogenesis marker, Tnfsf11/Tnfrsf11b, was increased, and osteoblast marker genes Runx2 and Sp7 were decreased in Mx1;TβRI^CA-CKD mice. Mx1;TβRI^CA-CKD mice displayed increased inflammatory cytokines levels. Together, our results indicated that in the setting of CKD, TβRI overexpression induced both CKD progression and the dysregulation of bone remodeling, leading to severe bone loss. As such, these data provide an avenue for the future development of therapeutics for CKD-induced osteoporosis.