Hong Shi

Objective: Adipose tissue inflammation in obesity promotes insulin resistance and metabolic disease. The Duffy Antigen Receptor for Chemokines (DARC), a non-signaling receptor expressed on erythrocytes and on other cell types, modulates inflammation by regulating chemokine levels. Gene variants that affect DARC expression on erythrocytes are common in people of African descent. Here, we disrupted DARC expression in hematopoietic cells and adipocytes to determine the impact on obesity. Methods: DARC floxed mice were bred with vav1-Cre mice to disrupt DARC expression in hematopoietic cells (DARC^Δhemato), and with adipoq-Cre mice to disrupt DARC expression in adipocytes (DARC^Δadipo). Mice were fed a chow diet (CD) versus a high-fat diet (HFD) and studied in vivo. In vitro studies were conducted on preadipocytes isolated from wild-type (WT) and global DARC knockout mice. Results: HFD-fed DARC^Δhemato mice exhibited impaired glucose tolerance compared with WT littermates, independent of weight gain. This was associated with increased adipose tissue inflammation and systemic oxidative stress. DARC^Δadipo mice exhibited similar glucose tolerance but had subtle differences in adipose depot mass and adipocyte size compared with WT littermates. Deletion of DARC in preadipocytes had no impact on adipogenic differentiation or lipid accumulation in vitro. Similarly, endothelial-specific DARC KO mice also showed no differences in glucose tolerance compared with WT. Conclusions: DARC disruption in hematopoietic cells is associated with adipose tissue inflammation and alters glucose homeostasis during diet-induced obesity, accompanied by reduced circulating levels of several DARC-binding chemokines. The relevance of these findings to human DARC genetic variants and obesity-related metabolic disease warrants further investigation.

Background: Sarcopenia, characterized by age-related loss of skeletal muscle mass and function, poses a significant challenge to lifelong health and wellbeing. Currently, no effective therapeutic interventions exist. In previous work, we developed specialized muscle progenitor cells (MPCs), termed Givi-MPC, from human induced pluripotent stem cells (hiPSCs). These cells demonstrated robust regenerative capacity in both sarcopenic and dystrophic muscle models. However, the potential of extracellular vesicles (EVs) derived from Givi-MPC to rejuvenate aged muscle stem cells (MuSCs) and their niche remains unexplored. This study investigates the therapeutic efficacy of EVs derived from Givi-MPC in sarcopenia. Methods: Givi-MPC were generated from hiPSCs using CHIR990021 and givinostat. EVs were isolated from Givi-MPC or primary human myoblast via size exclusion chromatography and characterized by transmission electron microscopy (TEM), Western blotting, and tandem mass tag (TMT)-based mass spectrometry. Aged C57BL/6J mice (24–25 months old) received intramuscular administration of EVs derived from Givi-MPC, and therapeutic efficacy was assessed through grip strength testing, immunohistochemistry, metabolic profiling, and spatial transcriptomics. To evaluate regenerative capacity, aged MuSCs treated with EVs-Givi-MPC or phosphate-buffered saline (PBS) were subjected to in vitro myogenic differentiation and transplanted into mdx/scid mice following cardiotoxin-induced muscle injury. Results: Proteomic analysis revealed that EVs derived from Givi-MPC were enriched in proteins associated with regeneration, angiogenesis, axonal repair, and cellular homeostasis compared to EVs from primary human myoblasts. Treatment with EVs-Givi-MPC significantly increased muscle mass and strength, reduced muscle degeneration, enhanced angiogenesis and reprogrammed the metabolic landscape of aged muscle. EVs-Givi-MPC treatment enhanced clonal expansion and myogenic differentiation of isolated aged MuSCs. Upon transplantation, MuSCs pretreated with EVs-Givi-MPC generated more dystrophin⁺/Myh3⁺ cells at day 5 and a greater number of dystrophin⁺ fibers at day 30 compared to PBS treated controls. Spatial transcriptomics and immunostaining indicated that Givi-MPC EVs reversed MuSCs senescence and reprogrammed their transcriptomic profile toward self-renewal and differentiation, while restoring niche signaling to a more youthful state. Conclusions: EVs derived from Givi-MPC improve muscle mass, fiber cross-sectional area, and grip strength, effectively rejuvenate aged MuSCs and their microenvironment. These findings support the potential of EV-based therapies as a novel approach for treating sarcopenia.

Background: Patients with systemic lupus erythematosus (SLE) face markedly increased cardiovascular disease (CVD) risk driven by mechanisms beyond traditional risk factors. Thoracic aortic perivascular adipose tissue (tPVAT) is dysfunctional in lupus and exacerbates endothelial dysfunction, yet the molecular basis of this dysfunction remains poorly defined. Methods: Integrated multi-omics profiling, including bulk RNA-seq, untargeted proteomics, lipidomics, and high-dimensional spectral flow cytometry, was performed on tPVAT from 15-week-old MRL/lpr mice (active lupus, n = 4–6) and MRL control mice (n = 5–6). Adipogenic differentiation capacity of tPVAT adipose stromal and progenitor cells (ASPCs) from MRL/lpr was assessed by Oil Red O staining at 5 (pre-dieasea) and 15 weeks (active disease), with subcutaneous ASPCs used as depot controls. Results: Transcriptomic profiling of tPVAT from MRL/lpr mice identified 2,742 upregulated and 1,494 downregulated genes (adjusted p < 0.001, |log2FC| > 1), with strong activation of interferon, IL6-JAK-STAT3, and TNFA signaling pathways together with suppression of fatty acid metabolism, oxidative phosphorylation, and adipogenic pathways. Proteomic and lipidomic analyses were concordant, revealing broad downregulation of mitochondrial bioenergetic machinery, depletion of cardiolipin and acylcarnitines, and enrichment of ceramide phosphoinositols and lysophosphatidylcholines. Cardiolipin strongly correlated with the mitochondrial/metabolic protein module (r = 0.95) and inversely with the immune/inflammatory protein module (r = −0.92). Spectral flow cytometry confirmed marked CD45+ leukocyte infiltration dominated by T cells, together with a significantly reduced Treg/CD4+ ratio indicating loss of local immunoregulatory balance. ASPCs derived from PVAT of 15-week-old MRL/lpr mice exhibited impaired white and beige adipogenic differentiation, while APCs from PVAT of 5-week-old MRL/lpr mice, and from subcutaneous adipose tissues of 15-week-old MRL/lpr mice, had normal white and beige differentiation, consistent with an acquired, depot-specific, disease-stage-dependent progenitor defect in PVAT of MRL/lpr mice. Conclusions: Lupus tPVAT undergoes a concordant cross-platform molecular reprogramming of mitochondrial bioenergetic genes coupled with establishment of an interferon-dominant immune niche and acquired loss of ASPC adipogenic capacity. These findings provide a molecular framework for lupus PVAT dysfunction and identify restoration of mitochondrial function, suppression of interferon-driven inflammation, and renewal of progenitor differentiation as potential therapeutic strategies for lupus vasculopathy.

Cellular senescence and mitochondrial dysfunction are prevalent in adipose tissues and disrupt metabolic homeostasis during aging, but the mechanisms are poorly understood. Here, we investigated the role of histone deacetylase 9 (HDAC9), an epigenetic regulator of adipogenic differentiation, in aging‐related adipose tissue senescence and mitochondrial dysfunction. HDAC9 expression correlated positively with age in mouse adipose tissues. Compared to age‐matched wild‐type (WT) mice, Hdac9 knockout (KO) mice gained less weight and had reduced fat mass during aging, in conjunction with reduced senescence‐associated beta‐galactosidase (SABG) staining and expression of senescence markers in adipose tissues. Additionally, preadipocytes isolated from Hdac9 KO mice exhibited reduced baseline and stress‐induced senescence compared to WT mice. Mechanistically, HDAC9 gene deletion resulted in coordinated upregulation of mitochondria‐associated genes, in association with increased mitochondrial DNA content and adipose tissue mitochondrial oxygen consumption parameters (e.g., increased basal respiration, proton leak). Furthermore, thiosulfate sulfurtransferase (TST), whose downregulation is associated with mitochondrial dysfunction, was reduced in adipose tissues of aging mice and upregulated by HDAC9 gene deletion. Finally, silencing TST in preadipocytes upregulated expression of senescence markers and increased SABG staining. We conclude that deletion of HDAC9 ameliorates the development of adipose tissue senescence and mitochondrial dysfunction with aging, at least in part via upregulation of TST, suggesting that targeting HDAC9 may be a promising strategy to maintain healthy adipose tissue during aging.

Background: Neointimal proliferation (NP) is a major cause of stenosis and occlusion in arteries and veins. Human saphenous veins (HSV), often used for coronary artery bypass grafting, frequently fail in part due to NP. Long non-coding RNAs (lncRNAs) have emerged as critical regulators of vascular smooth muscle cell (VSMC) phenotype, yet lncRNAs governing NP in human veins remain largely uncharacterized. Methods and Results: Using an ex vivo model of NP in human SV, we performed bulk RNA sequencing on SV tissues with and without NP. Among differentially expressed lncRNAs, we identified a previously uncharacterized transcript, Bromodomain Adjacent to Zinc Finger A1 antisense 1 ( BAZ1A-AS1 ), and its predicted cis -regulatory partner gene BAZ1A , as markedly upregulated during NP and predominantly enriched in VSMCs. Both transcripts were induced by genotoxic stimuli, with BAZ1A-AS1 showing transient induction preceding sustained BAZ1A upregulation, consistent with a priming role in the DNA damage response. Silencing of either BAZ1A-AS1 or BAZ1A attenuated VSMC proliferation and migration, accompanied by upregulation of contractile markers and suppression of proliferative and inflammatory transcriptional programs. ChIRP-qPCR demonstrated that BAZ1A-AS1 physically interacts with 3′ distal exons of BAZ1A at the DNA level while selectively engaging CNN1 , CCND1 , and IL6 mRNAs, indicating mechanistically distinct chromatin- and RNA-level regulatory functions. Baz1a haploinsufficiency attenuated neointima formation and preserved VSMC contractile identity in a mouse carotid artery ligation model. Conclusions: We identify BAZ1A-AS1 and BAZ1A as stress-responsive regulators of VSMC phenotype, operating through dual mechanisms of cis-regulatory chromatin interaction and selective mRNA engagement, and demonstrate a novel role for the BAZ1A - AS1 / BAZ1A axis in promoting NP.

Inflammatory arthritis encompasses a group of autoimmune diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) (Hammaker and Firestein, 2018). Although the exact etiology remains elusive, these conditions are thought to result from an overactive immune response to an unknown antigen, leading to joint pain, swelling, and deformity. Among these, RA is the most prevalent, affecting approximately 1% of the world’s population (Di Matteo et al, 2023). A hallmark of RA is its association with elevated rates of cardiovascular disease (CVD), which significantly increases morbidity and mortality and shortens patients’ life expectancy and quality of life (Semb et al, 2020). Although the prognosis for RA has improved markedly over the past two decades due to advanced treatment options, the lack of targeted therapies for CVD complications in RA patients remains a critical clinical challenge. Finally, guideline-based therapies for CVD are based on the etiology of the disease, which is hypertension or coronary artery disease. How well these therapies work in patients with cardiac complications of RA is incompletely understood.

Aging is associated with a decline in cardiac function. Exercise has been shown to effectively reduce the risks of cardiovascular diseases. Here whether a combination of endurance and resistance exercises can improve cardiac function in aged mice during late life is investigated. Through transcriptome analysis, several signaling pathways activated in the hearts of 22‐month‐old mice after combined exercise, including cardiac muscle contraction, mitophagy, and longevity regulation are identified. Combined exercise training mitigated age‐associated pathological cardiac hypertrophy, reduced oxidative stress, cardiac senescence, and enhanced cardiac function. Upstream stimulatory factor 2 (Usf2) is upregulated in the aged mouse hearts with combined exercise compared to sedentary mice. In the human cardiomyocytes senescent model, overexpression of Usf2 led to anti‐senescence effects, while knockdown of Usf2 exacerbated cellular senescence. The results suggest that a combination of endurance and resistance exercises, such as swimming and resistance running, can mitigate age‐related pathological cardiac remodeling and cardiac dysfunction in late life. These cardioprotective effects are likely due to the activation of Usf2 and its anti‐senescence effect. Therefore, Usf2 can potentially be a novel therapeutic target for mitigating age‐related cardiac dysfunction.

Histone deacetylase (HDAC) 9 is a negative regulator of adipogenic differentiation, which is required for maintenance of healthy adipose tissues. We reported that HDAC9 expression is upregulated in adipose tissues during obesity, in conjunction with impaired adipogenic differentiation, adipocyte hypertrophy, insulin resistance, and hepatic steatosis, all of which were alleviated by global genetic deletion of Hdac9. Here, we developed a novel transgenic (TG) mouse model to test whether overexpression of Hdac9 is sufficient to induce adipocyte hypertrophy, insulin resistance, and hepatic steatosis in the absence of obesity. HDAC9 TG mice gained less body weight than wild-type (WT) mice when fed a standard laboratory diet for up to 40 weeks, which was attributed to reduced fat mass (primarily inguinal adipose tissue). There was no difference in insulin sensitivity or glucose tolerance in 18-week-old WT and HDAC9 TG mice; however, at 40 weeks of age, HDAC9 TG mice exhibited impaired insulin sensitivity and glucose intolerance. Tissue histology demonstrated adipocyte hypertrophy, along with reduced numbers of mature adipocytes and stromovascular cells, in the HDAC9 TG mouse adipose tissue. Moreover, increased lipids were detected in the livers of aging HDAC9 TG mice, as evaluated by oil red O staining. In conclusion, the experimental aging HDAC9 TG mice developed adipocyte hypertrophy, insulin resistance, and hepatic steatosis, independent of obesity. This novel mouse model may be useful in the investigation of the impact of Hdac9 overexpression associated with metabolic and aging-related diseases.

Objective: Impaired adipogenic differentiation exacerbates metabolic disease in obesity. This study reported that high‐fat diet (HFD)‐fed mice housed at thermoneutrality exhibited impaired adipogenic differentiation, attributed to increased expression of histone deacetylase 9 (HDAC9). However, the impact of HFD on adipogenic differentiation is reportedly variable, possibly reflecting divergent environmental conditions such as housing temperature.Methods: C57BL/6J (wild‐type [WT]) mice were housed at either thermoneutral (28–30°C) or ambient (20–22°C) temperature and fed HFD or chow diet (CD) for 12 weeks. For acute exposure experiments, WT or transient receptor potential cation channel subfamily M member 8 (TRPM8) knockout mice housed under thermoneutrality were acutely exposed to ambient temperature for 6 to 24 h.Results: WT mice fed HFD and housed at thermoneutrality, compared with ambient temperature, gained more weight despite reduced food intake. They likewise exhibited increased inguinal adipose tissue HDAC9 expression and reduced adipogenic differentiation in vitro and in vivo compared with CD‐fed mice. Conversely, HFD‐fed mice housed at ambient temperature exhibited minimal change in adipose HDAC9 expression or adipogenic differentiation. Acute exposure of WT mice to ambient temperature reduced adipose HDAC9 expression independent of sympathetic β‐adrenergic signaling via a TRPM8‐dependent mechanism.Conclusions: Adipose HDAC9 expression is temperature sensitive, regulating adipogenic differentiation in HFD‐fed mice housed under thermoneutrality.