The impact of the intestinal microbiome on bone health

High-fat diet-induced osteoporosis in mice under hypoxic conditions

In the context of global aging, osteoporosis has emerged as a significant public health concern, with a relatively high prevalence observed in plateau regions. This study aimed to investigate the effects and underlying mechanisms of high-fat diet (HFD) and hypoxic conditions on bone metabolism in mice. The mice were subjected to different dietary regimens (a HFD versus a normal diet) and placed in a hypoxic environment. This study explored relevant mechanisms through comprehensive assessments, including body and bone morphological indices, pathological examinations, biochemical analyses, evaluation of gut microbiota diversity, and metabolomics approaches. The results indicated that, compared with those in the control group, the body weight, Lee's index, body mass index (BMI), and body fat percentage of the HFD-fed group were significantly greater. Additionally, the femoral microstructure was compromised, bone metabolic markers were disrupted, inflammatory responses were heightened, gut microbiota diversity was altered, and specific intestinal metabolites such as Anserine were downregulated, whereas L-carnosine was upregulated. Spearman correlation analysis and network visualization elucidated the multifactorial influence mechanism of a HFD on bone metabolism under hypoxic conditions. These factors interconnect to form a complex network that drives osteoporosis development. Notably, L-carnosine occupies a central position within this network, serving as a key hub for interactions among various factors. Under the dual stressors of hypoxia and a HFD, this network becomes imbalanced, leading to bone metabolic disorders and osteoporosis. This study provides insights into the multifactorial mechanisms of osteoporosis induced by a HFD and hypoxia in mice, offering a foundation for subsequent research and preventive strategies for osteoporosis in plateau areas.

Non-starch polysaccharides and health: gut-target organ axis influencing obesity

Obesity is recognized as a global epidemic that can result in changes in the human body and metabolism. Accumulating evidence indicates that gut microbiota (GM) can affect the development of obesity. The GM not only plays a crucial role in digesting and absorbing nutrients, but also in maintaining the overall health of the host. Dietary supplements such as non-starch polysaccharides are mainly fermented by the GM in the colon. Recent findings suggest that shaping the GM through the prebiotic function of non-starch polysaccharides may be a viable strategy against obesity. In this paper, the effects of non-starch polysaccharides on host health, together with their prebiotic function influencing the GM to control obesity via the gut-target organ axis, are reviewed. Potential perspectives of non-starch polysaccharides exhibiting anti-obesity effects via the gut-target organ axis are proposed for future research.

Graphical abstract

Interruptins Extracted from Cyclosorus terminans Protect Gut Pathologies Induced by High-Fat Diet in Rats

BACKGROUND/OBJECTIVES

The fern "Cyclosorus terminans" (C. terminans) or "Maiden Fern" contains interruptin A and interruptin B. This plant could attenuate obesity, insulin resistance, and fatty liver in rats fed a high-fat/calorie diet. However, the benefits of C. terminans to the gut remain unknown. We investigated the protective effect of C. terminans extract against gut dysfunction in rats exposed to a high-fat/calorie diet.

METHODS

Male Wistar rats were assigned to receive either (1) a normal diet treated with vehicle, (2) a high-fat/calorie diet treated with vehicle, (3) a high-fat/calorie diet treated with 100 mg per kg per day (mg·kg-1·day-1) of C. terminans extract, or (4) a high-fat/calorie diet treated with 200 mg·kg-1·day-1 of C. terminans extract. The rats were euthanized after 12 weeks of treatment to enable feces and colon tissue collection.

RESULTS

Both 100 and 200 mg·kg-1·day-1 of C. terminans extract reduced body weight (-10.49%; p = 0.030 and -10.54%; p = 0.037, respectively) and ameliorated gut inflammation, gut barrier disruption, changes in short-chain fatty acid levels, and gut dysbiosis caused by high-fat/calorie diet.

CONCLUSIONS

C. terminans extract attenuated an increase in body weight and exerted prophylactic effects against gut pathologies induced by high-fat/calorie diet.

Gut microbiota alterations in adolescent idiopathic scoliosis: a comparison study with healthy control and congenital scoliosis

PURPOSE

This study aims to compare the composition of GM isolated from individuals with AIS or congenital scoliosis (CS) and age-matched control (Ctr).

METHODS

A total of 48 patients with AIS, 24 patients with CS, and 31 healthy individuals were recruited as the discovery cohort, and 9 pairs of siblings where one was affected by AIS were recruited as the validation cohort. The GM profile was determined with 16S rRNA sequencing, and the alpha-diversity and beta-diversity metrics were performed with Mothur. Linear discriminant analysis (LDA) analysis was performed to identify the enriched species.

RESULTS

The α diversity (Chao1 index) was significantly lower in AIS patients with low BMI (< 18.5) than those with normal BMI. The PcoA analysis showed a trend of clustering of GM in AIS compared to that in Ctr and CS groups (r2 = 0.0553, p = 0.001). METASTAT analysis showed Cellulomonadaceae was significantly enriched in AIS groups compared to CS and Ctr. LDA analysis showed 9 enriched species in AIS patients. Compared to Ctr, two species including Hungatella genus and Bacteroides fragilis were significantly enriched, while the Firmicutes versus Bacteroidetes (F/B) ratio and the Ruminococcus genus were significantly decreased in AIS but not CS groups. The significantly reduced F/B ratio and Ruminococcus genus in AIS were replicated in the validation cohort.

CONCLUSIONS

Our study elucidated an association between low BMI and GM diversity in AIS patients. The reduced F/B ratio and Ruminococcus genus in AIS patients were identified and validated in 9 pairs of AIS patients and their unaffected siblings. Our pilot results may help understand the anthropometric discrepancy in these patients and support a possible role of GM in the pathogenesis of AIS.

Effects of traditional Chinese medicine Zuo-Gui-Wan on gut microbiota in an osteoporotic mouse model

BACKGROUND

The target and mechanism of oral traditional Chinese medicine (TCM) have been important research directions for a long time. The close relationship between osteoporosis and gut microbiota (GM) has been confirmed. However, the relevance of oral TCM and the "Gut-Bone Axis" is still poorly understood.

METHODS

Twenty-one SPF C57BL/6J female mice were divided into sham (Sham), ovariectomized (OVX), and Zuo-Gui-Wan-treated (ZGW, 1.4 g/kg) groups. The osteoporosis mouse model was established through ovariectomy. After eight weeks of Zuo-Gui-Wan treatment via gavage, serum calcium, phosphorus, ALT, AST, CREA, and other biochemical indicators were measured. Subsequently, Micro-CT, HE staining, and analysis of gut microbiota were conducted to further explore the potential mechanism.

RESULTS

The anti-osteoporotic effects of ZGW were confirmed through micro-CT, histological, and biochemical tests in an OVX-induced osteoporosis mouse model. ZGW treatment also alters the diversity and composition of the gut microbiota and altered the Firmicutes/Bacteroidetes ratio. Further analysis reveals a correlation between specific bacterial groups and serum indicators. Mfuzz clustering analysis and metagenomeSeq analysis identified important microbiota species that were rescued or modulated by ZGW treatment.

CONCLUSION

These findings suggest that changes in gut microbiota abundance may be linked to ZGW's ability to improve osteoporosis. This study provides new insights into how ZGW treats osteoporosis, though further research is needed to clarify the mechanisms by which specific gut microbiota influence bone health.

Association Between Self-Reported Lactose Intolerance, Additional Environmental Factors, and Bone Mineral Density in Young Adults

OBJECTIVES

This study examines the relationship between self-reported lactose intolerance (LI), environmental factors, and their effects on bone mineral density (BMD) in young adults from Slovakia.

METHODS

We assessed 985 adults aged 18-30 years, with an average age of 21.61 ± 2.32 years, who were enrolled in this pilot cross-sectional study during the period 2019-2023. Individual environmental factors (smoking status, alcohol consumption, physical activity, milk and milk product intake, and calcium intake) and self-reported LI were assessed using a detailed questionnaire. BMD was analyzed using the QUS device (Sunlight MiniOmni), and total weight was measured with the InBody 770 bioimpedance analyzer.

RESULTS

Linear regression analysis showed the independent influence of age, total weight, and the presence of LI on the speed of sound in meters per second (SOS; m/s) and Z-score parameters in women (p < 0.05), whereas in men, age and smoking status were significant predictors of SOS (p < 0.05), and age and LI status significantly influenced the Z-score (p < 0.05).

CONCLUSIONS

In the present study of young Slovak adults, the presence of self-reported LI and smoking had a negative effect on BMD, resulting in lower BMD in the radius.

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.

The Lachnospiraceae-butyric acid axis and its role in glucocorticoid-associated osteonecrosis

Glucocorticoids (GCs) are key inducers of osteonecrosis, yet not all patients treated with GCs develop glucocorticoid-associated osteonecrosis (GAON). The factors mediating this relationship are unclear. Studies have shown that gut microbiota and their metabolites influence bone metabolism, but their role in GAON is unclear. This study aimed to explore the connection between GAON and gut microbiota. Through bidirectional Mendelian randomization analysis, we identified 14 gut microbial taxa, including Lachnospiraceae (IVW, P = 0.011), associated with GAON. RNA-seq analysis revealed that GAON differentially expressed genes (DEGs) were enriched for intestinal inflammatory response mechanisms. We then compared patients who developed GAON (17 cases), those who did not (GAnON, 15 cases), and those untreated with GCs (Blank, 15 cases) for gut microbiota composition, short-chain fatty acids (SCFAs), and serum inflammatory factors. Our findings indicated a decrease in Lachnospiraceae abundance (GAON 17.13%, GAnON 12.51%, Blank 24.52%) in GC-treated patients. Serum inflammatory factors (IL-17 A, IL-33, and TNF-α) associated with GAON (59.603 ± 12.147, 89.337 ± 20.714, 42.584 ± 9.185) showed significant differences between Blank (1.446 ± 0.683, 11.534 ± 4.705, 4.682 ± 1.48) and GAnON (25.353 ± 8.181, 32.527 ± 7.352, 12.49 ± 3.217) groups, with a negative correlation between these factors and Lachnospiraceae levels. Butyric acid levels in SCFAs varied among groups (P<0.01) and correlated with Lachnospiraceae and inflammatory factors. Controlled experiments in GAON rats demonstrated butyric acid's osteoprotective role in GAON development (P<0.01). In conclusion, our study suggests that reduced Lachnospiraceae and butyric acid levels, along with increased inflammation due to GCs use, contribute to GAON. Butyric acid may mediate the effects of Lachnospiraceae and inflammation. Butyrate supplementation could potentially reduce GAON incidence, offering a novel approach for its clinical management.

The Link Between the Gut Microbiome and Bone Metastasis

The gut microbiome is essential for regulating host metabolism, defending against pathogens, and shaping the host's immune system. Mounting evidence highlights that disruption in gut microbial communities significantly impacts cancer development and treatment. Moreover, tumor-associated microbiota, along with its metabolites and toxins, may contribute to cancer progression by promoting epithelial-to-mesenchymal transition, angiogenesis, and metastatic spread to distant organs. Bones, in particular, are common sites for metastasis due to a rich supply of growth and neovascularization factors and extensive blood flow, especially affecting patients with thyroid, prostate, breast, lung, and kidney cancers, where bone metastases severely reduce the quality of life. While the involvement of the gut microbiome in bone metastasis formation is still being explored, proposed mechanisms suggest that intestinal dysbiosis may alter the bone microenvironment via the gut-immune-bone axis, fostering a premetastatic niche and immunosuppressive milieu suitable for cancer cell colonization. Disruption in the delicate balance of bone modeling and remodeling may further create a favorable environment for metastatic growth. This review focuses on the link between beneficial or dysbiotic microbiome composition and bone homeostasis, as well as the role of the microbiome in bone metastasis development. It also provides an overview of clinical trials evaluating the impact of gut microbial community structure on bone parameters across various conditions or health-related issues. Dietary interventions and microbiota modulation via probiotics, prebiotics, and fecal microbiota transplantation help support bone health and might offer promising strategies for addressing bone-related complications in cancer.

Blackcurrant Anthocyanins Attenuate Estrogen -Deficiency-Induced Bone Loss through Modulating Microbial-Derived Short-Chain Carboxylic Acids and Phytoestrogen Metabolites in Peri- and Early Postmenopausal Women

OBJECTIVES

The present study aimed to assess the effects of blackcurrant (BC) anthocyanins on concentrations of microbial-derived short-chain carboxylic acids (SCCAs) and metabolites of phytoestrogens. We then examined their associations with six-month changes in whole-body bone mineral density (BMD) and biomarkers of bone metabolism.

METHODS

Fecal and blood samples from a pilot randomized controlled trial were collected and analyzed from 37 eligible peri- and early postmenopausal women aged 45-60 years who were randomized into one of three treatment groups consuming one placebo capsule (control), 392 mg BC (low BC) or 784 mg BC (high BC) daily for six months.

RESULTS

Significant differences were observed between groups at baseline in acetic, propionic, valeric, caproic and heptanoic acids (p < 0.05). Isobutyric acid significantly decreased from baseline (0 months) to six months in the control group (p < 0.05) and the high BC group had a significantly greater concentration than the control group at six months (p < 0.05). Butyric acid was significantly greater in the high BC group than low BC at six months (p < 0.05). Six-month changes in caproic and isobutyric acids showed weak correlations with changes in whole-body BMD (r = 0.3519, p < 0.05 and r = 0.3465, p < 0.05, respectively). Isovaleric and valeric acids displayed weak correlations with BALP (r = 0.3361, p < 0.05) and OPG (r = 0.3593, p < 0.05), respectively. Enterodiol was positively correlated with BALP (r = 0.6056, p < 0.01) while enterolactone was positively correlated with osteocalcin (r = 0.5902, p < 0.001) and negatively correlated with sclerostin (r = -0.3485, p < 0.05).

CONCLUSIONS

The results suggest that BC may be a potential dietary agent to reduce postmenopausal bone loss through modulating microbially-derived SCCAs and phytoestrogen metabolites.

Microbiota-bone axis in ageing-related bone diseases

Bone homeostasis in physiology depends on the balance between bone formation and resorption, and in pathology, this homeostasis is susceptible to disruption by different influences, especially under ageing condition. Gut microbiota has been recognized as a crucial factor in regulating host health. Numerous studies have demonstrated a significant association between gut microbiota and bone metabolism through host-microbiota crosstalk, and gut microbiota is even an important factor in the pathogenesis of bone metabolism-related diseases that cannot be ignored. This review explores the interplay between gut microbiota and bone metabolism, focusing on the roles of gut microbiota in bone ageing and aging-related bone diseases, including osteoporosis, fragility fracture repair, osteoarthritis, and spinal degeneration from different perspectives. The impact of gut microbiota on bone metabolism during aging through modification of endocrinology system, immune system and gut microbiota metabolites are summarized, facilitating a better grasp of the pathogenesis of aging-related bone metabolic diseases. This review offers innovative insights into targeting the gut microbiota for the treatment of bone ageing-related diseases as a clinical therapeutic strategy.

The Role of Traditional Chinese Medicines in the Treatment of Osteoporosis

Osteoporosis (OP) represents a substantial public health issue and is associated with increasing rates of morbidity and mortality. It is characterized by reduced bone mineral density, deterioration of bone tissue quality, disruption of the microarchitecture of bones, and compromised bone strength. These changes may be attributed to the following factors: intercellular communication between osteoblasts and osteoclasts; imbalanced bone remodeling; imbalances between osteogenesis and adipogenesis; imbalances in hormonal regulation; angiogenesis; chronic inflammation; oxidative stress; and intestinal microbiota imbalances. Treating a single aspect of the disease is insufficient to address its multifaceted nature. In recent decades, traditional Chinese medicine (TCM) has shown great potential in the treatment of OP, and the therapeutic effects of Chinese patent drugs and Chinese medicinal herbs have been scientifically proven. TCMs, which contain multiple components, can target the diverse pathogeneses of OP through a multitargeted approach. Herbs such as XLGB, JTG, GSB, Yinyanghuo, Gusuibu, Buguzhi, and Nvzhenzi are among the TCMs that can be used to treat OP and have demonstrated promising effects in this context. They exert their therapeutic effects by targeting various pathways involved in bone metabolism. These TCMs balance the activity of osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells), and they exhibit anti-inflammatory, immunomodulatory, anti-oxidative, and estrogen-like functions. These multifaceted mechanisms underlie the efficacy of these herbs in the management and treatment of OP. Herein, we examine the efficacy of various Chinese herbs and Chinese patent drugs in treating OP by reviewing previous clinical trials and basic experiments, and we examine the potential mechanism of these therapies to provide evidence regarding the use of TCM for treating OP.

Understanding Osteoporosis: Human Bone Density, Genetic Mechanisms, Gut Microbiota, and Future Prospects

Osteoporosis is a systemic condition of the skeleton that leads to diminished bone mass, a breakdown in the bone tissue's microscopic architecture, and an elevated risk of breaking a bone. The elderly and women particularly after menopause are disproportionately affected, and the condition generally stays undiagnosed until a broken bone causes severe pain and immobility. Causes of osteoporosis include low bone mass, more than normal bone loss, changes in hormone levels (decreased estrogen or testosterone), certain diseases and therapies, and lifestyle factors like smoking and inactivity. The spine, hip, and forearm are particularly vulnerable to osteoporosis-related fractures. The purpose of this article is to present a thorough understanding of osteoporosis, including the disease's connection to bone density in humans, and the major part played by genetic pathways and gut flora. The causes of osteoporosis, the effects of aging on bone density, and why some groups experience a higher incidence of the disease than others are investigated. The paper also includes animal and human experiments investigating the link between gut flora and osteoporosis. Finally, it looks to the future and speculates on possible developments in osteoporosis prevention and therapy.

Microbiota metabolites in bone: Shaping health and Confronting disease

The intricate interplay between the gut microbiota and bone health has become increasingly recognized as a fundamental determinant of skeletal well-being. Microbiota-derived metabolites play a crucial role in dynamic interaction, specifically in bone homeostasis. In this sense, short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate, indirectly promote bone formation by regulating insulin-like growth factor-1 (IGF-1). Trimethylamine N-oxide (TMAO) has been found to increase the expression of osteoblast genes, such as Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein-2 (BMP2), thus enhancing osteogenic differentiation and bone quality through BMP/SMADs and Wnt signaling pathways. Remarkably, in the context of bone infections, the role of microbiota metabolites in immune modulation and host defense mechanisms potentially affects susceptibility to infections such as osteomyelitis. Furthermore, ongoing research elucidates the precise mechanisms through which microbiota-derived metabolites influence bone cells, such as osteoblasts and osteoclasts. Understanding the multifaceted influence of microbiota metabolites on bone, from regulating homeostasis to modulating susceptibility to infections, has the potential to revolutionize our approach to bone health and disease management. This review offers a comprehensive exploration of this evolving field, providing a holistic perspective on the impact of microbiota metabolites on bone health and diseases.

Alteration in the gut microbiome is associated with changes in bone metabolism after laparoscopic sleeve gastrectomy

Laparoscopic sleeve gastrectomy (LSG), the most common bariatric surgical procedure, leads to durable weight loss and improves obesity-related comorbidities. However, it induces abnormalities in bone metabolism. One unexplored potential contributor is the gut microbiome, which influences bone metabolism and is altered after surgery. We characterized the relationship between the gut microbiome and skeletal health in severe obesity and after LSG. In a prospective cohort study, 23 adults with severe obesity underwent skeletal health assessment and stool collection preoperatively and 6 mo after LSG. Gut microbial diversity and composition were characterized using 16S rRNA gene sequencing, and fecal concentrations of short-chain fatty acids (SCFA) were measured with LC-MS/MS. Spearman's correlations and PERMANOVA analyses were applied to assess relationships between the gut microbiome and bone health measures including serum bone turnover markers (C-terminal telopeptide of type 1 collagen [CTx] and procollagen type 1 N-terminal propeptide [P1NP]), areal BMD, intestinal calcium absorption, and calciotropic hormones. Six months after LSG, CTx and P1NP increased (by median 188% and 61%, P < .01) and femoral neck BMD decreased (mean -3.3%, P < .01). Concurrently, there was a decrease in relative abundance of the phylum Firmicutes. Although there were no change in overall microbial diversity or fecal SCFA concentrations after LSG, those with greater within-subject change in gut community microbial composition (β-diversity) postoperatively had greater increases in P1NP level (ρ = 0.48, P = .02) and greater bone loss at the femoral neck (ρ = -0.43, P = .04). In addition, within-participant shifts in microbial richness/evenness (α-diversity) were associated with changes in IGF-1 levels (ρ = 0.56, P < .01). The lower the postoperative fecal butyrate concentration, the lower the IGF-1 level (ρ = 0.43, P = .04). Meanwhile, the larger the decrease in butyrate concentration, the higher the postoperative CTx (ρ = -0.43, P = .04). These findings suggest that LSG-induced gut microbiome alteration may influence skeletal outcomes postoperatively, and microbial influences on butyrate formation and IGF-1 are possible mechanisms.

Microbiome Dynamics: A Paradigm Shift in Combatting Infectious Diseases

Infectious diseases have long posed a significant threat to global health and require constant innovation in treatment approaches. However, recent groundbreaking research has shed light on a previously overlooked player in the pathogenesis of disease-the human microbiome. This review article addresses the intricate relationship between the microbiome and infectious diseases and unravels its role as a crucial mediator of host-pathogen interactions. We explore the remarkable potential of harnessing this dynamic ecosystem to develop innovative treatment strategies that could revolutionize the management of infectious diseases. By exploring the latest advances and emerging trends, this review aims to provide a new perspective on combating infectious diseases by targeting the microbiome.

Effects of flora deficiency on the structure and function of the large intestine

The significant anatomical changes in large intestine of germ-free (GF) mice provide excellent material for understanding microbe-host crosstalk. We observed significant differences of GF mice in anatomical and physiological involving in enlarged cecum, thinned mucosal layer and enriched water in cecal content. Furthermore, integration analysis of multi-omics data revealed the associations between the structure of large intestinal mesenchymal cells and the thinning of the mucosal layer. Increased Aqp8 expression in GF mice may contribute to enhanced water secretion or altered hydrodynamics in the cecum. In addition, the proportion of epithelial cells, nutrient absorption capacity, immune function and the metabolome of cecum contents of large intestine were also significantly altered. Together, this is the first systematic study of the transcriptome and metabolome of the cecum and colon of GF mice, and these findings contribute to our understanding of the intricate interactions between microbes and the large intestine.

The impact of gut microbial signals on hematopoietic stem cells and the bone marrow microenvironment

Hematopoietic stem cells (HSCs) undergo self-renewal and differentiation in the bone marrow, which is tightly regulated by cues from the microenvironment. The gut microbiota, a dynamic community residing on the mucosal surface of vertebrates, plays a crucial role in maintaining host health. Recent evidence suggests that the gut microbiota influences HSCs differentiation by modulating the bone marrow microenvironment through microbial products. This paper comprehensively analyzes the impact of the gut microbiota on hematopoiesis and its effect on HSCs fate and differentiation by modifying the bone marrow microenvironment, including mechanical properties, inflammatory signals, bone marrow stromal cells, and metabolites. Furthermore, we discuss the involvement of the gut microbiota in the development of hematologic malignancies, such as leukemia, multiple myeloma, and lymphoma.

Association between Dysbiosis in the Gut Microbiota of Primary Osteoporosis Patients and Bone Loss

In recent decades, gut microbiome research has experienced significant growth, driven by technological advances that enable quantifying bacterial taxa with greater precision. Age, diet, and living environment have emerged as three key factors influencing gut microbes. Dysbiosis, resulting from alterations in these factors, may lead to changes in bacterial metabolites that regulate pro- and anti-inflammatory processes and consequently impact bone health. Restoration of a healthy microbiome signature could mitigate inflammation and potentially reduce bone loss associated with osteoporosis or experienced by astronauts during spaceflight. However, current research is hindered by contradictory findings, insufficient sample sizes, and inconsistency in experimental conditions and controls. Despite progress in sequencing technology, defining a healthy gut microbiome across global populations remains elusive. Challenges persist in identifying accurate gut bacterial metabolics, specific taxa, and their effects on host physiology. We suggest greater attention be directed towards this issue in Western countries as the cost of treating osteoporosis in the United States reaches billions of dollars annually, with expenses projected to continue rising.

From Cells to Environment: Exploring the Interplay between Factors Shaping Bone Health and Disease

The skeletal system is an extraordinary structure that serves multiple purposes within the body, including providing support, facilitating movement, and safeguarding vital organs. Moreover, it acts as a reservoir for essential minerals crucial for overall bodily function. The intricate interplay of bone cells plays a critical role in maintaining bone homeostasis, ensuring a delicate balance. However, various factors, both intrinsic and extrinsic, can disrupt this vital physiological process. These factors encompass genetics, aging, dietary and lifestyle choices, the gut microbiome, environmental toxins, and more. They can interfere with bone health through several mechanisms, such as hormonal imbalances, disruptions in bone turnover, direct toxicity to osteoblasts, increased osteoclast activity, immune system aging, impaired inflammatory responses, and disturbances in the gut-bone axis. As a consequence, these disturbances can give rise to a range of bone disorders. The regulation of bone's physiological functions involves an intricate network of continuous processes known as bone remodeling, which is influenced by various intrinsic and extrinsic factors within the organism. However, our understanding of the precise cellular and molecular mechanisms governing the complex interactions between environmental factors and the host elements that affect bone health is still in its nascent stages. In light of this, this comprehensive review aims to explore emerging evidence surrounding bone homeostasis, potential risk factors influencing it, and prospective therapeutic interventions for future management of bone-related disorders.

Osteoimmunology: A Link between Gastrointestinal Diseases and Skeletal Health in Chickens

Bone serves as a multifunctional organ in avian species, giving structural integrity to the body, aiding locomotion and flight, regulating mineral homeostasis, and supplementing calcium for eggshell formation. Furthermore, immune cells originate and reside in the bone marrow, sharing a milieu with bone cells, indicating a potential interaction in functions. In avian species, the prevalence of gastrointestinal diseases can alter the growth and the immune response, which costs a great fortune to the poultry industry. Previous studies have shown that coccidiosis and necrotic enteritis can dramatically reduce bone quality as well. However, possible mechanisms on how bone quality is influenced by these disease conditions have not yet been completely understood, other than the reduced feed intake. On the other hand, several mediators of the immune response, such as chemokines and cytokines, play a vital role in the differentiation and activation of osteoclasts responsible for bone resorption and osteoblasts for bone formation. In the case of Eimeria spp./Clostridium perfringens coinfection, these mediators are upregulated. One possible mechanism for accelerated bone loss after gastrointestinal illnesses might be immune-mediated osteoclastogenesis via cytokines-RANKL-mediated pathways. This review article thus focuses on osteoimmunological pathways and the interaction between host immune responses and bone biology in gastrointestinal diseases like coccidiosis and necrotic enteritis affecting skeletal health.

Dietary Fiber Intake Influences Changes in Ankylosing Spondylitis Disease Status

The objectives of this study were to characterize dietary fiber (DF) intake in patients with ankylosing spondylitis (AS), to assess whether DF intake affects disease activity in AS, and to investigate the effect of DF intake on disease activity in AS in the context of functional bowel disease (FBD) symptoms. We recruited 165 patients with AS and divided them into two groups according to whether they had a high DF intake > 25 g/d to investigate the characteristics of people with high DF intake. Some 72 of the 165 AS patients (43%) met the criteria for high DF intake, which was more common in patients with negative FBD symptoms (68%). Data analysis revealed that DF intake was negatively associated with AS disease activity and did not differ statistically significantly from FBD symptoms. Multivariate adjusted models were used to explore the effect of DF intake on AS disease activity. ASDAS-CRP and BASDAI were stable and negatively correlated across models in both groups with and without FBD symptoms. Thus, DF intake positively affected disease activity in patients with AS. ASDAS-CRP and BASDAI were negatively correlated with DF intake.

One-year supplementation with Lactobacillus reuteri ATCC PTA 6475 counteracts a degradation of gut microbiota in older women with low bone mineral density

Recent studies have shown that probiotic supplementation has beneficial effects on bone metabolism. In a randomized controlled trial (RCT) we demonstrated that supplementation of Lactobacillus reuteri ATCC PTA 6475 reduced bone loss in older women with low bone mineral density. To investigate the mechanisms underlying the effect of L. reuteri ATCC PTA 6475 on bone metabolism, 20 women with the highest changes (good responders) and the lowest changes (poor responders) in tibia total volumetric BMD after one-year supplementation were selected from our previous RCT. In the current study we characterized the gut microbiome composition and function as well as serum metabolome in good responders and poor responders to the probiotic treatment as a secondary analysis. Although there were no significant differences in the microbial composition at high taxonomic levels, gene richness of the gut microbiota was significantly higher (P < 0.01 by the Wilcoxon rank-sum test) and inflammatory state was improved (P < 0.05 by the Wilcoxon signed-rank test) in the good responders at the end of the 12-month daily supplementation. Moreover, detrimental changes including the enrichment of E. coli (adjusted P < 0.05 by DESeq2) and its biofilm formation (P < 0.05 by GSA) observed in the poor responders were alleviated in the good responders by the treatment. Our results indicate that L. reuteri ATCC PTA 6475 supplementation has the potential to prevent a deterioration of the gut microbiota and inflammatory status in elderly women with low bone mineral density, which might have beneficial effects on bone metabolism.

Roles of Gut Microbiome in Bone Homeostasis and Its Relationship with Bone-Related Diseases

The extended microbial genome-the gut microbiome (GM)-plays a significant role in host health and disease. It is able to influence a number of physiological functions. During dysbiosis, GM is associated with the development of various chronic diseases with impaired bone quality. In general, GM is important for bone homeostasis and can affect it via several mechanisms. This review describes the roles of GM in bone homeostasis through influencing the immune and endocrine functions, short-chain fatty acids production, calcium absorption and the gut-brain axis. The relationship between GM composition and several bone-related diseases, specifically osteoporosis, osteoarthritis, rheumatoid arthritis, diabetes mellitus, obesity and bone cancer, is also highlighted and summarized. GM manipulation may become a future adjuvant therapy in the prevention of many chronic diseases. Therefore, the beneficial effects of probiotic therapy to improve the health status of individuals with aforementioned diseases are provided, but further studies are needed to clearly confirm its effectiveness. Recent evidence suggests that GM is responsible for direct and indirect effects on drug efficacy. Accordingly, various GM alterations and interactions related to the treatment of bone-related diseases are mentioned as well.

Prebiotic to Improve Calcium Absorption in Postmenopausal Women After Gastric Bypass: A Randomized Controlled Trial

CONTEXT

The adverse skeletal effects of Roux-en-Y gastric bypass (RYGB) are partly caused by intestinal calcium absorption decline. Prebiotics, such as soluble corn fiber (SCF), augment colonic calcium absorption in healthy individuals.

OBJECTIVE

We tested the effects of SCF on fractional calcium absorption (FCA), biochemical parameters, and the fecal microbiome in a post-RYGB population.

METHODS

Randomized, double-blind, placebo-controlled trial of 20 postmenopausal women with history of RYGB a mean 5 years prior; a 2-month course of 20 g/day SCF or maltodextrin placebo was taken orally. The main outcome measure was between-group difference in absolute change in FCA (primary outcome) and was measured with a gold standard dual stable isotope method. Other measures included tolerability, adherence, serum calciotropic hormones and bone turnover markers, and fecal microbial composition via 16S rRNA gene sequencing.

RESULTS

Mean FCA ± SD at baseline was low at 5.5 ± 5.1%. Comparing SCF to placebo, there was no between-group difference in mean (95% CI) change in FCA (+3.4 [-6.7, +13.6]%), nor in calciotropic hormones or bone turnover markers. The SCF group had a wider variation in FCA change than placebo (SD 13.4% vs 7.0%). Those with greater change in microbial composition following SCF treatment had greater increase in FCA (r2 = 0.72, P = 0.05). SCF adherence was high, and gastrointestinal symptoms were similar between groups.

CONCLUSION

No between-group differences were observed in changes in FCA or calciotropic hormones, but wide CIs suggest a variable impact of SCF that may be due to the degree of gut microbiome alteration. Daily SCF consumption was well tolerated. Larger and longer-term studies are warranted.

Role of Dietary Supplements and Probiotics in Modulating Microbiota and Bone Health: The Gut-Bone Axis

Osteoporosis is characterized by an alteration of bone microstructure with a decreased bone mineral density, leading to the incidence of fragility fractures. Around 200 million people are affected by osteoporosis, representing a major health burden worldwide. Several factors are involved in the pathogenesis of osteoporosis. Today, altered intestinal homeostasis is being investigated as a potential additional risk factor for reduced bone health and, therefore, as a novel potential therapeutic target. The intestinal microflora influences osteoclasts’ activity by regulating the serum levels of IGF-1, while also acting on the intestinal absorption of calcium. It is therefore not surprising that gut dysbiosis impacts bone health. Microbiota alterations affect the OPG/RANKL pathway in osteoclasts, and are correlated with reduced bone strength and quality. In this context, it has been hypothesized that dietary supplements, prebiotics, and probiotics contribute to the intestinal microecological balance that is important for bone health. The aim of the present comprehensive review is to describe the state of the art on the role of dietary supplements and probiotics as therapeutic agents for bone health regulation and osteoporosis, through gut microbiota modulation.

L-Theanine mediates the p38MAPK signaling pathway to alleviate heat-induced oxidative stress and inflammation in mice

L-Theanine, an active ingredient in the tea plant (Camellia sinensis) associated with calming, is widely used as a functional ingredient and dietary supplement. In this study, a heat stress mouse model was used to evaluate the anti-heat stress effect of L-theanine and its possible mechanism of action. Mice subjected to heat stress (40 °C) that were administered L-theanine at various doses (100, 200, and 400 mg kg-1 d-1) had reduced oxidative stress and inflammatory factors when L-theanine was administered both long-term and as a preventative treatment. Our L-theanine intervention countered the reduction in growth and feed intake of mice under heat stress and reversed liver and jejunum tissue damage. Moreover, L-theanine countered the increase in inflammatory factors TNF-α, IL-6, and IL-1β and antioxidant enzymes SOD and CAT; it also counteracted GSH-Px inactivation, the upregulation of AST and ALT enzyme activity, and MDA production. The mechanism of action may involve mediation of the P38 signaling pathway, inhibition of MK2 overexpression, and downregulation of p-P65/P65 caused by the overexpression of downstream HSP27. This would inhibit the heat stress-induced imbalance in oxidative stress and inflammatory responses.

Pueraria lobata Targeted Preparation Improves the Clinical Symptoms of Cervical Spondylosis by Regulating the Balance of Gut Microbiota

BACKGROUND

Nanotargeted preparations can enhance the safety and effectiveness of medication by altering the pharmacokinetic behavior of drugs in the human body, and Pueraria lobata is shown to be effective in the treatment of neck and back pain.

PURPOSE

This study prepared a nano-Pueraria targeted preparation, in order to analyze its effect on improving the clinical symptoms of cervical spondylosis by adjusting the balance of intestinal flora.

METHODS

A total of 200 patients with cervical spondylosis admitted to the Affiliated Hospital of Nanjing University of Chinese Medicine were enrolled and divided into an observation group and a control group. The control group was given Tuina therapy, and the observation group was given nano-Pueraria targeted preparation + Tuina therapy. The clinical symptoms and intestinal microflora of the two groups were examined before intervention.

RESULTS

It was found that the markedly effective of treatment efficacy of the observation group (98%) was higher than that of the control group (78%) after 15 days of intervention, and the clinical symptoms were obviously fewer than those of the control group. The distribution of gut microbiota showed that there were significant differences in the composition of gut microbiota between the two groups. Compared with the control group, the abundance of Firmicutes in the observation group was significantly higher, while the abundance of Bacteroidetes and Proteobacteria was significantly lower.

CONCLUSION

The targeted preparation of nano-Pueraria can improve the clinical symptoms of patients with cervical spondylosis by adjusting the balance of gut microbiota.

Bacterial infections exacerbate myeloma bone disease

Multiple myeloma is characterized by osteolytic lesions caused by reduced bone formation and activated bone resorption. An important feature of myeloma is a failure of bone healing after successful treatment. In this work, clinical studies indicated a highly positive correlation between bone marrow bacteria abundance and bone lesion numbers of myeloma patients in complete remission. Coculture experiments demonstrated that marrow Escherichia coli (E. coli) promotes osteoclast differentiation and inhibits osteoblast differentiation. Mechanism studies showed that E. coli lipopolysaccharides (LPS) activated NF-κB p65 signaling and reduced phosphorylated smad1/5/9 binding ability with RUNX2 promoter, leading to decreased RUNX2 expression in osteoblast progenitors. Additionally, LPS enhanced phosphorylated NF-κB p65 binding ability with NFATc1 promoter, leading to increased NFATc1 expression in osteoclast progenitors. In vivo studies revealed E. coli contributes to osteolytic bone lesion, and elimination of E. coli infection assists healing of bone lesion in mouse model of myeloma in complete remission. These findings establish a heretofore unrecognized effect for E. coli in the genesis of myeloma bone disease and suggest a new treatment strategy.

Structural Changes in Trabecular Bone, Cortical Bone and Hyaline Cartilage as Well as Disturbances in Bone Metabolism and Mineralization in an Animal Model of Secondary Osteoporosis in Clostridium perfringens Infection

There is no information regarding whether changes in the microbiological balance of the gastrointestinal tract as a result of an infection with Clostridium perfringens influence the development of metabolic bone disorders. The experiment was carried out on male broiler chickens divided into two groups: control (n = 10) and experimental (n = 10). The experimental animals were infected with Clostridium perfringens between 17 and 20 days of age. The animals were euthanized at 42 days of age. The structural parameters of the trabecular bone, cortical bone, and hyaline cartilage as well as the mineralization of the bone were determined. The metabolism of the skeletal system was assessed by determining the levels of bone turnover markers, hormones, and minerals in the blood serum. The results confirm that the disturbed composition of the gastrointestinal microflora has an impact on the mineralization and metabolism of bone tissue, leading to the structural changes in cortical bone, trabecular bone, and hyaline cartilage. On the basis of the obtained results, it can be concluded that changes in the microenvironment of the gastrointestinal tract by infection with C. perfringens may have an impact on the earlier development of osteoporosis.

The Effect of Lactobacillus gasseri BNR17 on Postmenopausal Symptoms in Ovariectomized Rats

Clinical and preclinical studies have reported that Lactobacillus gasseri BNR17, a probiotic bacterial strain isolated from human breast milk, reduces body weight and white adipose tissue volume. In order to further explore the actions of L. gasseri BNR17, we investigated the anti-menopausal effects of L. gasseri BNR17 in an ovariectomized (OVX) rat model. The serum alanine aminotransferase levels of the rats in the OVX-BNR17 group were lower than those of the rats in the OVX-vehicle only (OVX-Veh) group. Upon administration of L. gasseri BNR17 after ovariectomy, calcitonin and Serotonin 2A levels increased significantly, whereas serum osteocalcin levels showed a decreasing tendency. Compared to the rats in the OVX-Veh group, those in the OVX-BNR17 group showed lower urine deoxypyridinoline levels, lower pain sensitivity, and improved vaginal cornification. Furthermore, L. gasseri BNR17 administration increased bone mineral density in the rats with OVX-induced femoral bone loss. These results suggest that L. gasseri BNR17 administration could alleviate menopausal symptoms, indicating that this bacterium could be a good functional probiotic for managing the health of older women.

An out of box thinking: the changes of iron-porphyrin during meat processing and gastrointestinal tract and some methods for reducing its potential health hazard

Iron-porphyrin is a very important substance in organisms, especially in animals. It is not only the source of iron in human body, but is also the catalytic center of many reactions. Previous studies suggested that adequate intake of iron was important for the health of human, especially for children and pregnant women. However, associated diseases caused by iron over-intake and excessive meat consumption suggested its potential harmfulness for human health. During meat processing, Iron-porphyrin will cause the oxidation of proteins and fatty acids. In the gastrointestinal tract, iron-porphyrin can induce the production of malondialdehyde, fats oxidation, and indirectly cause oxidation of amino acids and nitrates etc. Iron-porphyrin enters the intestinal tract and disturbs the balance of intestinal flora. Finally, some common measures for inhibiting its activity are introduced, including the use of chelating agent, antioxidants, competitive inhibitor, etc., as well as give the hypothesis that sodium chloride increases the catalytic activity of iron-porphyrin. The purpose of this review is to present an overview of current knowledge about the changes of iron-porphyrin in the whole technico- and gastrointesto- processing axis and to provide ideas for further research in meat nutrition.

The associations of gut microbiota and fecal short-chain fatty acids with bone mass were largely mediated by weight status: a cross-sectional study

PURPOSE

We aimed to investigate whether the gut microbiota and fecal short-chain fatty acids (SCFAs) are associated with bone mass in healthy children aged 6-9 years.

METHODS

In this study, 236 healthy children including 145 boys and 91 girls were enrolled. 16S rRNA gene sequencing was used to characterize the composition of their gut microbiota. Total and 10 subtypes of SCFAs in the fecal samples were determined by high-performance liquid chromatography. Dual X-ray absorptiometry was used to measure the bone mineral density (BMD) and bone mineral content (BMC) for total body (TB) and total body less head (TBLH). Z score of TBLH BMD was calculated based on the recommended reference.

RESULTS

Four gut microbiota principal components (PCs) were identified by the compositional principal component analysis at the genus level. After adjustment of covariates and controlling for the false discovery rate, multiple linear regression analysis showed that PC3 score (positive loadings on genera Lachnoclostridium and Blautia) was significantly negatively associated with TBLH BMD/BMC/Z score, TB BMC and pelvic BMD (β: - 0.207 to - 0.108, p: 0.002-0.048), whereas fecal total and several subtypes of SCFAs were correlated positively with TBLH BMD/Z score and pelvic BMD (β: 0.118-0.174, p: 0.038-0.048). However, these associations disappeared after additional adjustment for body weight. Mediation analysis suggested that body weight significantly mediated 60.4% and 78.0% of the estimated association of PC3 score and SCFAs with TBLH BMD Z score, respectively.

CONCLUSIONS

The associations of gut microbiota composition and fecal SCFA concentrations with bone mass in children were largely mediated by body weight.

Gut microbial-derived short-chain fatty acids and bone: a potential role in fracture healing

Bone healing complications such as delayed healing or non-union affect 5-10 % of patients with a long-bone fracture and lead to reduced quality of life and increased health-care costs. The gut microbiota and the metabolites they produce, mainly short-chain fatty acids (SCFAs), have been shown to impact nearly all organs of the human body including bone. SCFAs show broad activity in positively influencing bone healing outcomes either by acting directly on cell types involved in fracture healing, such as osteoblasts, osteoclasts, chondrocytes and fibroblasts, or indirectly, by shaping an appropriate anti-inflammatory and immune regulatory response. Due to the ability of SCFAs to influence osteoblast and osteoclast differentiation, SCFAs may also affect the integration of orthopaedic implants in bone. In addition, SCFA-derivatives have already been used in a variety of tissue engineering constructs to reduce inflammation and induce bone tissue production. The present review summarises the current knowledge on the role of the gut microbiota, in particular through the action of SCFAs, in the individual stages of bone healing and provides insights into how SCFAs may be utilised in a manner beneficial for fracture healing and surgical reconstruction.

The influence of gut microbiome on bone health and related dietary strategies against bone dysfunctions

The link between the gut microbiome and bone health has begun to attract widespread interest in recent years. The gut microbiome are vital in many diseases involving bone loss. Probiotics, prebiotics, and dietary supplements have been suggested to protect bone health by altering the composition of the gut microbiota. Notably, studying the relationship between the gut microbiome and bone health can provide a basis for the prevention and treatment of bone diseases. This review focuses on the link between the gut microbiome and bone diseases, exploring current knowledge of the mechanisms by which gut bacteria affect bone health. In addition, the influences of dietary supplements on the interactions between the gut microbiome and bone health are discussed. This knowledge will promote new ideas for gut microbiota-mediated dietary interventions in patients with bone diseases.

Metabolic Alterations in Older Women With Low Bone Mineral Density Supplemented With Lactobacillus reuteri

Osteoporosis and its associated fractures are highly prevalent in older women. Recent studies have shown that gut microbiota play important roles in regulating bone metabolism. A previous randomized controlled trial (RCT) found that supplementation with Lactobacillus reuteri ATCC PTA 6475 (L.reuteri) led to substantially reduced bone loss in older women with low BMD. However, the total metabolic effects of L. reuteri supplementation on older women are still not clear. In this study, a post hoc analysis (not predefined) of serum metabolomic profiles of older women from the previous RCT was performed to investigate the metabolic dynamics over 1 year and to evaluate the effects of L. reuteri supplementation on human metabolism. Distinct segregation of the L. reuteri and placebo groups in response to the treatment was revealed by partial least squares‐discriminant analysis. Although no individual metabolite was differentially and significantly associated with treatment after correction for multiple testing, 97 metabolites responded differentially at any one time point between L. reuteri and placebo groups (variable importance in projection score >1 and p value <0.05). These metabolites were involved in multiple processes, including amino acid, peptide, and lipid metabolism. Butyrylcarnitine was particularly increased at all investigated time points in the L. reuteri group compared with placebo, indicating that the effects of L. reuteri on bone loss are mediated through butyrate signaling. Furthermore, the metabolomic profiles in a case (low BMD) and control population (high BMD) of elderly women were analyzed to confirm the associations between BMD and the identified metabolites regulated by L. reuteri supplementation. The amino acids, especially branched‐chain amino acids, showed association with L. reuteri treatment and with low BMD in older women, and may serve as potential therapeutic targets. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Does the Intestinal Microbiome Impact Athletic Performance?

PURPOSE OF REVIEW

To analyze current research involving elite athletes and the gut microbiome, with the goal to expand knowledge of potential sports performance strategies and interventions.

RECENT FINDINGS

Most of the current research focuses on theoretical applications from microbiome research and known characteristics of performance, as few studies have actually been conducted in elite athletes. However, of the studies that have been conducted, the research is promising that dietary strategies may provide targeted interventions in the future. The majority of sports nutrition takes an external approach to diet: manipulating macronutrient intake based on type of training and performance goals. However, shifting to an internal focus, prioritizing the health of the gut microbiome, could be a new frontier for a competitive edge in athletics.

The role of gut microbiota metabolite trimethylamine N-oxide in functional impairment of bone marrow mesenchymal stem cells in osteoporosis disease

Background

Osteoporosis (OP) is a prevalent metabolic bone disease characterized by bone loss and structural deterioration, which increases the risk of fracture especially in older people. Recent research has shown that gut microbes play an important role in OP. Trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, has been implicated in the pathogenesis of diseases, including Alzheimer’s and cerebrovascular disease. This study aimed to examine the effect of TMAO in OP.

Methods

In this study, we firstly investigated the relationship between TMAO and OP. Serum samples were collected from patients with OP (n=10), and healthy participants (n=10), and the TMAO level in the serum was detected by ELISA assay. Then, bone marrow mesenchymal stem cells (BMSCs) were treated with TMAO, and we observed its effect on adipogenic and osteogenic differentiation, cell proliferation, reactive oxygen species (ROS) release, and inflammatory cytokine[interleukin (IL)-1β, IL-6 and tumor necrosis factor-alpha (TNF-α)] levels. Finally, we illustrated the underlying mechanism through which TMAO influenced BMSCs functions.

Results

Compared to the healthy group, highly significant TMAO levels were observed in the serum of the OP patients. When studied in vitro, TMAO treatment significantly promoted BMSCs adipogenesis and attenuated osteogenesis, increased ROS release and pro-inflammatory cytokine IL-1β, IL-6 and TNF-α production, and inhibited cell proliferation. Furthermore, we found that activation of the nuclear factor-κB (NF-κB) signaling pathway was necessary for TMAO to induce pro-inflammatory cytokine production, ROS release, and adipogenic and osteogenic differentiation in BMSCs.

Conclusions

Elevated TMAO levels have a strong negative correlation with the degree of bone mineral density (BMD) in OP. TMAO regulates BMSCs cell function by activating the NF-κB signaling pathway, which affects the balance of bone metabolism, leading to acceleration of bone loss and further progression of OP.

Bacteriocin PJ4 from probiotic lactobacillus reduced adipokine and inflammasome in high fat diet induced obesity

One of the characteristic features of obesity is increased body weight and accumulation of adipose tissue. It is associated with low grade inflammation and gut dysbiosis. Probiotics and its products could be an ideal strategy to prevent or treat diabetes. In the present study, animals were induced obesity by providing them with high fat diet. Three purified bacteriocins i.e., DT24, PJ4 and TSU4, previously isolated and purified from various probiotic strains, were given as treatment strategies, following the induction of obesity. Upon the completion of the study, animals were sacrificed and were checked for their tissue expression of inflammatory mediators and adipokines. Serum hormone and cytokines analysis were performed to check their inflammatory state. Treatment with purified bacteriocin DT24 did not show any therapeutic effect in any of the parameter studied. Bacteriocin TSU4 on the other hand showed better reversal compared to DT24. Bacteriocin PJ4 showed the most promising results by reversing all the altered parameters significantly. It significantly reversed all the biochemical, immunological in terms of serum cytokines as well as altered morphological characteristics. PJ4 can be further explored to determine its mode of action. The anti-microbial proteins or to be more specific, bacteriocins, which shows broad spectrum efficacy, could be a better alternative in modulating gut microflora for the treatment of obesity and diabetes characteristics. The efficacy of bacteriocin PJ4 may also be due to the source of the host of Lactobacillus.

Gut-organ axis: a microbial outreach and networking

Human gut microbiota (GM) includes a complex and dynamic population of microorganisms that are crucial for well-being and survival of the organism. It has been reported as diverse and relatively stable with shared core microbiota, including Bacteroidetes and Firmicutes as the major dominants. They are the key regulators of body homeostasis, involving both intestinal and extra-intestinal effects by influencing many physiological functions such as metabolism, maintenance of barrier homeostasis, inflammation and hematopoiesis. Any alteration in GM community structures not only trigger gut disorders but also influence other organs and cause associated diseases. In recent past, the GM has been defined as a 'vital organ' with its involvement with other organs; thus, establishing a link or a bi- or multidirectional communication axis between the organs via neural, endocrine, immune, humoral and metabolic pathways. Alterations in GM have been linked to several diseases known to humans; although the exact interaction mechanism between the gut and the organs is yet to be defined. In this review, the bidirectional relationship between the gut and the vital human organs was envisaged and discussed under several headings. Furthermore, several disease symptoms were also revisited to redefine the communication network between the gut microbes and the associated organs.

The Effect of Lactobacillus acidophilus YT1 (MENOLACTO) on Improving Menopausal Symptoms: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

This study evaluated the efficacy of Lactobacillus acidophilus YT1 (MENOLACTO) for alleviating menopausal symptoms. This study was a multi-center, randomized, double-blinded, placebo-controlled clinical trial involving female subjects (ages: 40-60 years) with menopausal symptoms and a Kupperman index (KMI) score ≥ 20. Subjects were administered 1 × 108 CFU/day MENOLACTO or placebo, with the primary endpoint being total KMI score, and the effect of secondary endpoints on alleviating menopausal symptoms according to individual categories of the modified KMI, as well as a quality of life questionnaire (MENQOL questionnaire). After 12 weeks, total KMI scores decreased significantly, demonstrating improved menopausal symptoms relative to placebo along with improved modified KMI scores. Additionally, quality of life, according to the MENQOL questionnaire, significantly improved in all four symptoms-physical, psychosocial, vasomotor, and sexual symptoms. Moreover, we observed no significant difference between the two groups or significant changes in blood follicle-stimulating hormone and estradiol levels or endometrial thickness. These results demonstrated that MENOLACTO alleviated menopausal symptoms without notable side effects and improved quality of life, suggesting its efficacy as an alternative supplement to alleviate menopausal symptoms in women ineligible for hormonal therapy.

The role of gut microbiota in bone homeostasis

The gut microbiota (GM) is referred to as the second gene pool of the human body and a commensal, symbiotic, and pathogenic microorganism living in our intestines. The knowledge of the complex interaction between intestinal microbiota and health outcomes is a novel and rapidly expanding the field. Earlier studies have reported that the microbial communities affect the cellular responses and shape many aspects of physiology and pathophysiology within the body, including muscle and bone metabolism (formation and resorption). GM influences the skeletal homeostasis via affecting the host metabolism, immune function, hormone secretion, and the gut-brain axis. The premise of this review is to discuss the role of GM on bone homeostasis and skeletal muscle mass function. This review also opens up new perspectives for pathophysiological studies by establishing the presence of a 'microbiota-skeletal' axis and raising the possibility of innovative new treatments for skeletal development.

Probiotics Can Boost the Antitumor Immunity of CD8+T Cells in BALB/c Mice and Patients with Colorectal Carcinoma

Background

The drug resistance and the immune suppression in the tumor microenvironment are important factors affecting tumor progression. Reversing drug resistance and changing tumor suppression microenvironment are ideal ways to inhibit tumor progression.

Objective

The aim of the study is to verify antitumor immune response of probiotics in patients with colorectal carcinoma and to explore its mechanism.

Methods

To detect the tumor samples of 122 patients with colorectal carcinoma after surgery, analyze the effect of probiotics on enhancing tumor-infiltrating CD8⁺T cells to inhibit colorectal carcinoma, and further verify the mechanism of probiotics on enhancing the antitumor immune response of CD8⁺T cells through animal experiments.

Results

The results of immunohistochemistry showed that the proportion of CD8⁺T cells in the patients treated with probiotics before surgery was increased significantly than that in other patients (P = 0.033). The results of flow cytometry also showed that the proportion of CD8⁺T cells in the probiotics group was higher than that in the nonprobiotics group (P = 0.029). Kaplan-Meier survival estimates also showed that the CD8⁺T cells, TNM stage, pathology grade, lymphatic metastasis, and probiotic treatment were significantly associated with the progression-free survival (PFS) (χ ² = 9.684, P = 0.002 for CD8⁺T cells; χ ² = 5.878, P = 0.015 for TNM stage; χ ² = 7.398, P = 0.004 for pathology grade; χ ² = 8.847, P = 0.003 for Lymphatic metastasis; and χ ² = 4.622, P = 0.032 for the group (group A was treated with probiotics before surgery; group B was not treated with probiotics)). The experimental results in mice showed that probiotics could inhibit tumor growth and increase the proportion of CD8⁺T cells in mice; the difference was statistically significant (P = 0.037). It was also found that probiotic feeding could upregulate the expression of T-cell immunoglobulin mucin receptor 1(TIM-1) in CD8⁺T cells of mice and also found that probiotic feeding could downregulate the expression of programmed cell death protein 1 (PD-1) in CD8⁺T cells of mice, compared with the nonfeeding group; the difference was statistically significant (P = 0.045 for TIM-1 and P = 0.02 for PD-1, respectively). In order to further understand the functional status of CD8⁺T cells, we analyzed interferon-gamma (IFN-γ)⁺ T cells and tumor necrosis factor-α (TNF-α)⁺CD8⁺T cells by flow cytometry. The results showed that the proportion of IFN-γ ⁺ T cells and TNF-α ⁺CD8⁺T cells significantly increased after probiotic treatment, compared with the nonprobiotic treatment group; the difference was statistically significant (P = 0.040 for IFN-γ ⁺ T cells and P = 0.014 for TNF-α ⁺CD8⁺T, respectively).

Conclusions

Probiotics can enhance the antitumor immune response of CD8⁺T cells. It can play a synergistic antitumor role. On the one hand, its mechanism is through regulating intestinal flora, and on the other hand, through regulating the antitumor immune function of CD8⁺T cells.

Probiotics and bone disorders: the role of RANKL/RANK/OPG pathway

The skeleton is the framework and in charge of body configuration preservation. As a living tissue, bones are constantly being formed and absorbed. Osteoblasts and osteoclasts are the main bone cells and balance between their activities indicates bone health. Several mechanisms influence the bone turnover and RANKL/RANK/OPG pathway is one of them. This system, whose components are part of the tumor necrosis factor (TNF) superfamily, exists in many organs and could play a role in bone modeling and remodeling. RANKL/RANK pathway controls osteoclasts activity and formation. In addition, they are identified as key factors on bone turnover in different pathological situations. At the same time, OPG (RANKL's decoy receptor) plays role as a bone-protective factor by binding to RANKL and prevention of extra resorption. The lack of balance between RANKL and OPG could result in excessive bone resorption. Probiotics, the beneficial microorganisms for human health, entail bones in their advantages. Recent studies suggest that probiotics could reduce inflammatory factors (for example TNF-α and IL-1β) and increase bone OPG expression. In addition, probiotics have shown to maintain bones in various ways. Although current evidence is not enough for definitive approval of probiotics' efficacy on RANKL/RANK/OPG, its positive responses from conducted studies are significant. Understanding of the probiotics' effects on RANKL/RANK/OPG pathway will help focus future studies, and assist in developing efficient treatment strategies.

Is It Time to Use Probiotics to Prevent or Treat Obesity?

In recent years, attention has been given to the role potentially played by gut microbiota in the development of obesity. Several studies have shown that in individuals with obesity, the gut microbiota composition can be significantly different from that of lean individuals, that faecal bacteria can exert a fundamental role in modulating energy metabolism, and that modifications of gut microbiota composition can be associated with increases or reductions of body weight and body mass index. Based on this evidence, manipulation of the gut microbiota with probiotics has been considered a possible method to prevent and treat obesity. However, despite a great amount of data, the use of probiotics to prevent and treat obesity and related problems remains debated. Studies have found that the probiotic effect on body weight and metabolism is strain specific and that only some of the species included in the Lactobacillus and Bifidobacterium genera are effective, whereas the use of other strains can be deleterious. However, the dosage, duration of administration, and long-term effects of probiotics administration to prevent overweight and obesity are not known. Further studies are needed before probiotics can be rationally prescribed for the prevention or treatment of obesity. Control of the diet and environmental and life-style factors that favour obesity development remain the best solution to problems related to weight gain.