Mild stimulatory effect of a probiotic mix on bone mass when treatment is initiated 1.5 weeks after ovariectomy in mice

Progress of research on the gut microbiome and its metabolite short-chain fatty acids in postmenopausal osteoporosis: a literature review

Postmenopausal osteoporosis (PMOP) is a systemic metabolic bone disease caused by the decrease in estrogen levels after menopause. It leads to bone loss, microstructural damage, and an increased risk of fractures. Studies have found that the gut microbiota and its metabolites can regulate bone metabolism through the gut-bone axis and the gut-brain axis. As research progresses, PMOP has been found to be associated with gut microbiota dysbiosis and Th17/Treg imbalance. The gut microbiota is closely related to the development and differentiation of Treg and Th17 cells. Among them, the metabolites of the gut microbiota such as short-chain fatty acids (SCFAs) can regulate the differentiation of effector T cells by acting on molecular receptors on immune cells, thereby regulating the bone immune process. The multifaceted relationship among the gut microbiota, SCFAs, Th17/Treg cell-mediated bone immunity, and bone metabolism is eliciting attention from researchers. Through a review of existing literature, we have comprehensively summarized the effects of the gut microbiota and SCFAs on PMOP, especially from the perspective of Th17/Treg balance. Regulating this balance may provide new opportunities for PMOP treatment.

Dietary index for gut microbiota and its inverse association with female infertility: evidence from NHANES 2013-2018

Background

Infertility has become a global health concern, especially as the aging population continues to grow. Previous studies suggest that gut microbiota plays a crucial role in female reproductive health. This study aimed to investigate the association between the Dietary Index for Gut Microbiota (DI-GM) and female infertility.

Methods

We analyzed data from 8,910 participants aged 20-45 years in the NHANES 2013-2018 cycles. DI-GM scores were calculated based on dietary recall interviews, including 14 foods and nutrients associated with gut health. Female infertility was identified through reproductive health questionnaires. Weighted logistic regression models were used to assess the relationship between DI-GM and infertility, with adjustments for demographic, lifestyle, and health-related covariates. Restricted cubic spline (RCS) analyses explored non-linear associations, and subgroup analyses ensured the robustness of the results.

Results

A significant negative association was observed between DI-GM and female infertility (adjusted OR = 0.89, 95% CI: 0.83-0.95, p < 0.001). Participants with DI-GM scores ≥6 had a 40% lower risk of infertility compared to those with scores 0-3 (OR = 0.60, 95% CI: 0.44-0.82, p = 0.001). RCS analyses revealed an L-shaped non-linear relationship, with a threshold at DI-GM = 5. Subgroup analyses indicated stronger associations in women with lower education levels and those with coronary heart disease (P for interaction <0.05).

Conclusion

Our findings demonstrate that a higher DI-GM score is associated with a reduced risk of female infertility, suggesting that dietary interventions targeting gut microbiota may offer a cost-effective strategy for improving reproductive health. Further longitudinal and interventional studies are warranted to confirm causality and elucidate underlying mechanisms.

The Impact of Fermented Dairy Products and Probiotics on Bone Health Improvement

The bone is an important body organ due to its role in locomotion, protection and mineral homeostasis. Bone health is affected by various intrinsic and extrinsic factors like genetics, diet, environment and immune status of an individual. Being a dynamic organ, bones are continuously being remodeled and the remodeling is mediated by an intricate balance of bone formation and resorption which, in turn, are regulated by environmental, genetic, hormonal and neural factors. Lack of balance in any of these factors leads to bone disorders such as osteoporosis. Fermented dairy products along with their probiotics content play a significant role in bone remodeling process ensuring the maintenance of intricate balance in bone forming cells (osteoblasts) and bone resorbing cells (osteoclasts). Proteins and various minerals are important constituents of bone. Dairy products, especially fermented ones, are significant because of being a good source of proteins and minerals required to make and maintain a healthy bone. In addition, these provide the body with probiotics which are involved in bone health improvement by enhancing the bioavailability of dietary constituents, production of short chain fatty acids and reducing the inflammatory components. Hence, fermented dairy products should be a regular part of our diet to keep our bone healthy.

The beneficial effects of a probiotic mix on bone and lean mass are dependent on the diet in female mice

Bone mass and lean mass decrease with age and these changes are associated with increased fracture risk and sarcopenia. Previous studies demonstrated that a probiotic mixture of Lacticaseibacillus paracasei DSM13434, Lactiplantibacillus plantarum DSM 15312 and DSM 15313 (L. Mix) prevents bone loss in ovariectomized (ovx) female mice. The purpose of the present study is to test if the beneficial effect of L. Mix is modified by the diet. Female mice were fed either a high-fat (HFD, 60% kcal from fat) or a low-fat (LFD, 10% kcal from fat) diet and subjected to either sham or ovx surgery and treated with L. Mix for 12 weeks. L. Mix treatment increased total body bone mineral density (p ≤ 0.01), by increasing cortical bone area, and total body lean mass (p = 0.035) in mice on LFD but not in mice on HFD. Metagenome sequencing of cecal content showed that L. Mix treatment increased the relative abundance of Lacticaseibacillus paracasei and, Lactiplantibacillus plantarum, demonstrating successful treatment. In addition, the probiotic treatment affected the overall gut microbiota composition and functionality. These findings demonstrate that the L. Mix in combination with a healthy diet is beneficial for musculoskeletal health in female mice.

Gut-bone axis perturbation: Mechanisms and interventions via gut microbiota as a primary driver of osteoporosis

A growing number of studies have highlighted the significance of human gut microbiota (GM) as a potential target for osteoporosis. In this review, we discuss the effect of GM to bone metabolism focusing on two aspects: the local alterations of the human gut permeability that modify how the GM interact with the gut-bone axis (e.g., intestinal leakage, nutrient absorption), and the alterations of the GM itself (e.g., changes in microbiota metabolites, immune secretion, hormones) that modify the events of the gut-bone axis. We then classify these changes as possible therapeutic targets of bone metabolism and highlight some associated promising microbiome-based therapies. We also extend our discussions into combinatorial treatments that incorporate conservative treatments, such as exercise. We anticipate our review can provide an overview of the current pathophysiological and therapeutic paradigms of the gut-bone axis, as well as the prospects of ongoing clinical trials for readers to gain further insights into better microbiome-based treatments to osteoporosis and other bone-degenerative diseases. The translational potential of this article: This paper reviewed the potential links between gut microbiota and osteoporosis, as well as the prospective therapeutic avenues targeting gut microbiota for osteoporosis management, presenting a thorough and comprehensive literature review.

A systematic review and meta-analysis of the effects of probiotics on bone outcomes in rodent models

Emerging evidence demonstrates an opportunity for using probiotics to support bone health, but findings in humans are limited. This systematic review investigated if probiotic supplementation improves bone mineral density (BMD) and bone structure in rodent models compared to no supplementation. Studies (n = 71) examining the effect of oral consumption of any probiotic strain on BMD or bone structure in rodents were included. Meta-analyses were conducted separately by study model (intact, ovariectomized) and bone site (femur, tibia, spine) to determine the probiotic effect (standardized mean difference, SMD) on volumetric BMD (vBMD), bone volume fraction (BV/TV), and cortical thickness (Ct.Th). Reasons for heterogeneity were explored (probiotic genus, sex, type of rodent). In intact rodents, probiotics resulted in greater vBMD (SMD = 0.43, 95% CI [0.13, 0.74], I2 = 3%, p < 0.05) and higher BV/TV (SMD = 0.63, 95% CI [0.25, 1.02], I2 = 57%, p < 0.05) at the femur without changes in cortical bone structure. In ovariectomized models, probiotic supplementation resulted in greater vBMD (femur: SMD = 1.28, 95% CI [1.01, 1.55], I2 = 3%, p < 0.05; tibia: SMD = 1.29, 95% CI [0.52, 2.05], I2 = 67%, p < 0.05; and spine: SMD = 1.47, 95% CI [0.97, 1.97], I2 = 26%, p < 0.05) as well as higher BV/TV (femur: SMD = 1.16, 95% CI [0.80, 1.52], I2 = 56%, p < 0.05; tibia: SMD = 2.13, 95% CI [1.09, 3.17], I2 = 79%, p < 0.05; spine: SMD = 2.04, 95% CI [1.17, 2.90], I2 = 76%, p < 0.05) and Ct.Th at the tibia (SMD = 2.35; 95% CI [0.72, 3.97], I2 = 82%, p < .0.05) but not at the femur versus control. The syntheses support probiotics as a strategy to improve bone outcomes in rodent models.

Probiotics Inhibit Cartilage Damage and Progression of Osteoarthritis in Mice

Increasing interest has focussed on the possible role of alterations in the microbiome in the pathogenesis of metabolic disease, inflammatory disease, and osteoporosis. Here we examined the role of the microbiome in a preclinical model of osteoarthritis in mice subjected to destabilisation of medical meniscus (DMM). The intestinal microbiome was depleted by broad-spectrum antibiotics from 1 week before birth until the age of 6 weeks when mice were subjected reconstitution of the microbiome with faecal microbial transplant (FMT) followed by the administration of a mixture of probiotic strains Lacticaseibacillus paracasei 8700:2, Lactiplantibacillus plantarum HEAL9 and L. plantarum HEAL19 or vehicle. All mice were subjected to DMM at the age of 8 weeks. The severity of osteoarthritis was evaluated by histological analysis and effects on subchondral bone were investigated by microCT analyses. The combination of FMT and probiotics significantly inhibited cartilage damage at the medial femoral condyle such that the OARSI score was 4.64 ± 0.32 (mean ± sem) in the FMT and probiotic group compared with 6.48 ± 0.53 in the FMT and vehicle group (p = 0.007). MicroCT analysis of epiphyseal bone from the femoral condyle showed that the probiotic group had higher BV/TV, increased Tb.Th, and moderately thicker subchondral bone plates than the control group. There was no difference between groups in joint inflammation or in serum concentrations of inflammatory cytokines and chemokines. We conclude that treatment with probiotics following FMT in mice where the microbiome has been depleted inhibits DMM-induced cartilage damage and impacts on the structure of subchondral bone particularly at the femoral condyle. While further studies are required to elucidate the mechanism of action, our research suggests that these probiotics may represent a novel intervention for the treatment of osteoarthritis.

New Advances in Improving Bone Health Based on Specific Gut Microbiota

The gut microbiota has been shown to play an important role in the pathogenesis of various diseases, including metabolic diseases, cardiovascular diseases, and cancer. Recent studies suggest that the gut microbiota is also closely associated with bone metabolism. However, given the high diversity of the gut microbiota, the effects of different taxa and compositions on bone are poorly understood. Previous studies demonstrated that the mechanisms underlying the effects of the gut microbiota on bone mainly include its modulation of nutrient absorption, intestinal permeability, metabolites (such as short-chain amino acids), immune responses, and hormones or neurotransmitters (such as 5-hydroxytryptamine). Several studies found that external interventions, such as dietary changes, improved bone health and altered the composition of the gut microbiota. This review summarises the beneficial gut bacteria and explores how dietary, natural, and physical factors alter the diversity and composition of the gut microbiota to improve bone health, thereby providing potential new insight into the prevention of osteoporosis.

Acute fat loss does not affect bone mass

Obesity has previously been thought to protect bone since high body weight and body mass index are associated with high bone mass. However, some more recent studies suggest that increased adiposity negatively impacts bone mass. Here, we aimed to test whether acute loss of adipose tissue, via adipocyte apoptosis, alters bone mass in age-related obese mice. Adipocyte apoptosis was induced in obese male FAT-ATTAC mice through AP20187 dimerizer-mediated activation of caspase 8 selectively in adipocytes. In a short-term experiment, dimerizer was administered to 5.5 month-old mice that were terminated 2 weeks later. At termination, the total fat mass weighed 58% less in dimerizer-treated mice compared with vehicle-treated controls, but bone mass did not differ. To allow for the detection of long-term effects, we used 9-month-old mice that were terminated six weeks after dimerizer administration. In this experiment, the total fat mass weighed less (− 68%) in the dimerizer-treated mice than in the controls, yet neither bone mass nor biomechanical properties differed between groups. Our findings show that adipose tissue loss, despite the reduced mechanical loading, does not affect bone in age-related obese mice. Future studies are needed to test whether adipose tissue loss is beneficial during more severe obesity.