The role of exercise-and high fat diet-induced bone marrow extracellular vesicles in stress hematopoiesis

The influence of high-fat diet and energy-restricted diet on hematopoietic stem cells: mechanisms and implications

Increasing evidence demonstrates a close relationship between daily diet and homeostasis of the body's internal environment, particularly hematopoietic system homeostasis. Hematopoietic stem cells (HSCs) are located at the top of the hematopoietic system and have the ability to self-renew and differentiate into various types of immune cells. They play an important role in maintaining body stability and health. Studies have shown that different diets can lead to changes in HSC homeostasis, thereby affecting immune function and overall health status of the body. However, there is a scarcity of comprehensive reviews on how different diets affects HSC function. Therefore, this review summarizes the current progression in research on the effects of a high-fat diet (HFD) and energy-restricted diet on HSC function. HFD has a predominantly negative effect on HSCs, as does severe energy-restricted diet (SERD). Conversely, moderate energy-restricted diet (dietary restriction, DR) promotes the repopulation of HSCs but seriously impairs the differentiation of HSCs into lymphoid lineage. Further study of the influence of different diets on HSCs may aid in designing rational dietary guidelines to optimize the hematopoietic and immune functions of the body, which has significant implications for clinical medical practices.

Weight-adjusted waist index is associated with risk of poor bone quality rather than low bone mass in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes (T2D) correlates with an elevated risk of osteoporotic fractures. However, factors influencing bone mineral density (BMD) and trabecular bone score (TBS) in Chinese individuals with T2D remain unclear. This study aimed to investigate the clinical and biochemical determinants of BMD and TBS in patients with T2D, with a focus on elucidating the role of weight-adjusted waist index (WWI) in modulating bone mass and quality in this cohort.

METHODS

Data of 161 women and 153 men with T2D collected between July 2022 and March 2023 in Shenzhen, China, were analyzed in our cross-sectional study. Lumbar spine BMD and TBS of all participants were obtained using dual-energy X-ray absorptiometry. WWI was defined as waist circumference over the square root of weight.

RESULTS

Multivariate regression analysis demonstrated that lumbar spine TBS was inversely correlated with age, menopausal status, and WWI in women (p < 0.05). In men, TBS was negatively associated with age and WWI (p < 0.05). For women, glycated hemoglobin A1c positively influenced BMD (p < 0.05), whereas age, diabetic retinopathy, and N-mid osteocalcin were negatively associated. No significant predictors of BMD were identified in the male cohort. For predicting degraded TBS, the optimal WWI cut-offs were 11.257 cm/√kg (S: 61.1%, E: 80.7%) in males and 11.247 cm/√kg (S: 70.3%, E: 71.1%) in females.

CONCLUSIONS

Our findings highlight WWI as a novel and potentially more precise indicator of body fat, associated with diminished bone quality rather than solely low bone mass in patients with T2D in China. These results suggest that evaluating bone health in individuals with higher WWI may require more than just bone mass assessment. The results also suggest that the optimal WWI cut-off points for predicting degraded TBS are approximately 11.25 cm/√kg, highlighting thresholds for fracture risk.

High-fat diets promote hematopoietic stem cell expansion and exercise reduces myeloid skewing during maintenance hematopoiesis

High-fat diets (HFD) and exercise (EX) exert differential impacts on hematopoietic stem and progenitor cell (HSPC) differentiation during stress hematopoiesis, in part, through alterations in the HSPC niche. However, how HFDs and EX alter HSPC differentiation during maintenance conditions remains unknown. Therefore, we examined HSPC and niche cell concentrations during maintenance hematopoiesis following a HFD and EX training intervention. Male CBA mice (n = 40) underwent 8 wk of HFD or control (CON) diet consumption with the latter 4 wk involving sedentary (SED) or EX training interventions. Bone marrow cells were quantified by flow cytometry, and marrow-derived HSPCs were magnetically isolated for a colony-forming unit assay. HFD mice had higher body weight, body fat percentage, and lean body mass compared with CON mice without any effect of exercise. HFD promoted HSPC and myeloid progenitor cell expansion without impacting lymphoid progenitor cells. HSPCs derived from HFD mice displayed enhanced myeloid colony formation, which was inhibited by EX. EX reduced mesenchymal stromal cell concentrations. Together, these results suggest that during maintenance hematopoiesis, EX inhibits myeloid and mesenchymal stromal cell expansion, whereas HFD opposes these effects, which is similar to their effects during stress hematopoiesis.NEW & NOTEWORTHY We are the first to show that exercise inhibits myeloid progenitor cell expansion and mesenchymal stromal cell concentration with high-fat diet consumption during maintenance hematopoiesis in vivo. Further, we show that exercise prevents high-fat diet-induced hematopoietic stem and progenitor cell myeloid differentiation priming. Together, our findings show an important role for exercise in regulating the maintenance of hematopoiesis under high-fat diet conditions.

Obesity Promotes Marrow-Derived Myeloid Cell Accumulation While Exercise Reduces Proliferative Signaling in Colon Cancer

PURPOSE

Obesity increases colon cancer risk that has been previously linked to marrow-derived myeloid cells. We previously demonstrated that exercise training (EX) prevents colon cancer initiation, potentially through reduced myelopoiesis. However, it remains unknown whether early myeloid cell accumulation and inflammation in the colon precedes carcinogenesis with high-fat diet (HFD)-induced obesity, and if EX can attenuate these effects. We hypothesized that obesity would promote colon carcinogenesis that was preceded by myeloid cell accumulation and inflammation that would be attenuated by EX.

METHODS

C57BL/6 mice were randomized to a HFD or control (CON) diet for 8 weeks. The HFD mice switched to CON diet and all mice were given intraperitoneal injections of azoxymethane (AOM) to induce colon cancer and randomized into EX or sedentary (SED) conditions.

RESULTS

HFD mice developed more aberrant crypt foci (ACF), a marker for early carcinogenesis, compared with CON ( P < 0.01), and EX developed fewer ACF compared with SED ( P < 0.0001). Marrow-derived ( P < 0.001) CD206 + macrophages were elevated in HFD compared with CON at study week 16 ( P < 0.01). Marrow-derived CD206 - macrophages ( P < 0.05) and marrow-derived ( P < 0.05) CD206 + macrophages were more abundant in HFD compared with CON at study week 42. EX did not alter colon immune cell populations. β-catenin protein was higher in HFD compared with CON at study week 42 ( P < 0.05), and STAT3 protein content was lower at study week 28 with EX compared with SED ( P < 0.05).

CONCLUSIONS

The results suggest that obesity promotes colon ACF formation, potentially through early inflammatory myeloid cell accumulation. Despite attenuating ACF, EX did not alter myeloid cell accumulation in the colon, suggesting that EX inhibits ACF formation through alternative mechanisms which may include reduced β-catenin and STAT3 signaling.

Weight-adjusted waist index associated with bone mineral density in rheumatoid arthritis patients: a cross-sectional study

The research examined the association between weight-adjusted waist index (WWI) and bone mineral density (BMD) in individuals with rheumatoid arthritis, considering the impact of obesity on bone health. The association between WWI and BMD was examined utilizing weighted linear regression and smoothed curve fitting with data from NHANES 2005-2010, 2013-2014, and 2017-2018. Subgroup analysis verified the stability of the results. The study included a cohort of 983 rheumatoid arthritis patients. A significant negative correlation was found between WWI and BMD at the total femur, femoral neck, and lumbar spine (β = -0.03, 95% CI (-0.04, -0.02), p < 0.001; β = -0.02, 95% CI (-0.04, -0.01), p = 0.001; β = -0.04, 95% CI (-0.06, -0.02), p < 0.001). This negative association was not significantly influenced by factors like age, gender, race, education, PIR, diabetes, hypertension, sleep disorders, alcohol consumption, or smoking status (p > 0.05 for interaction). The findings indicate a negative correlation between WWI and BMD in the rheumatoid arthritis population. Key Points •A negative correlation was found between WWI and BMD at the total femur, femoral neck, and lumbar spine in the rheumatoid arthritis population.

The association between weight-adjusted-waist index and total bone mineral density in adolescents: NHANES 2011-2018

Introduction

The weight-adjusted waist index (WWI) serves as an innovative obesity measure, seemingly surpassing body mass index (BMI) and waist circumference (WC) in evaluating lean and fat mass. This study aimed to explore the relationship between WWI and total bone mineral density (BMD) in US adolescents.

Methods

This population-based study investigated adolescents aged 8-19 years with comprehensive WWI and total BMD data from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. WWI was computed by dividing WC by the square root of body weight. Weighted multivariate linear regression and smoothed curve fitting were employed to examine linear and non-linear associations. Threshold effects were determined using a two-part linear regression model. Additionally, subgroup analyses and interaction tests were conducted.

Results

Multivariate linear regression analysis revealed a significant negative association between WWI and total BMD in 6,923 US adolescents aged 8-19 years [β = -0.03, 95% CI: (-0.03, -0.03)]. This negative correlation remained consistent across all subcategories, with the exception of age, encompassing gender,ethnicity, and diabetes status subgroups. Furthermore, a non-linear relationship and saturation effect between WWI and total BMD were identified, with an inflection point at 9.88 cm/√kg.

Conclusions

Our research demonstrated a notable negative relationship and saturation effect between WWI and total BMD among US adolescents.