FASEB bioAdvances最新文献

Peripheral arterial disease progression to critical limb ischemia remains a significant burden in the aged, necessitating revascularization. Therapies to enhance neovascularization, such as angiogenesis or arteriogenesis, may provide an option for patients not suitable for surgery. The thrombospondins (TSPs) are secreted matricellular glycoproteins, with TSP-1, TSP-2, and TSP-5 implicated in neovascularization. Currently, there is little data regarding the effects of TSP-2, TSP-5, sex, and aging on angiogenesis and arteriogenesis. In vitro, the effect of TSP-2 or TSP-5 on early or late passage endothelial cell (EC) tubule formation or disruption was assessed. In vivo, angiogenesis, and arteriogenesis in male and female, young (14-16 weeks) and old (105-110 weeks) wild-type, TSP-2 and TSP-5 knockout mice were compared. To assess the effect of sex hormones, neovascularization was assessed in ovariectomized young female mice. After 14 days, angiogenesis and arteriogenesis were quantified using immunohistochemistry. Laser Doppler was used to confirm > 50% decrease in blood flow. In vitro: TSP-2 inhibited angiogenesis in early passage ECs and disrupted tubules in late passage ECs. TSP-5 prevented early passage tubule disruption. Late passage cells showed greater disruption than early passage. In vivo: TSP-2 was anti-angiogenic in young mice and anti-arteriogenic in old mice; TSP-5 had no effect on angiogenesis but largely negatively impacted arteriogenesis. Females showed reduced angiogenesis/arteriogenesis versus males, aging blunted both responses, and TSP-2/TSP-5 knockouts altered sex- and age-specific ischemic responses. In conclusion, we broadly elucidate the differential effects of TSP-2, TSP-5, sex and aging on neovascularization after inducing limb ischemia.

Mitochondrial function is essential for skeletal muscle health, and its disruption leads to atrophy and functional decline. This study examines the impact of denervation on skeletal muscle mitochondria in polymerase gamma (PolG)^(+/mut) mice, which accumulate mitochondrial DNA (mtDNA) mutations due to a partial deficiency in polymerase gamma proofreading. Using a 14-day denervation protocol, we assessed muscle mass, mtDNA copy number, oxidative stress and mitochondrial dynamics in wild-type (WT) and PolG^(+/mut) mice. Our findings reveal that while denervation significantly reduced muscle wet weight and mitochondrial enzyme activity, no genotype-specific differences in muscle atrophy were observed. However, PolG^(+/mut) mice displayed more disorganized mitochondrial cristae and elevated oxidative stress markers, indicating greater mitochondrial vulnerability. Despite these changes, the lack of significant differences in mitochondrial proteins and gene expression between genotypes may reflect an adaptive antioxidant response, including increased catalase expression, although the compensatory nature of this response cannot be conclusively determined. These results suggest that oxidative stress-related responses are involved in mitochondrial adaptations during denervation-induced muscle atrophy. The increased expression of antioxidant enzymes, such as catalase, in PolG^(+/mut) mice suggests that antioxidant mechanisms are activated in response to increased oxidative stress. These findings underscore the importance of controlling oxidative stress for maintaining muscle health.

The cellular and molecular complexity of acne pathogenesis has hindered progress toward effective targeted therapies. While keratinocytes are known to influence skin inflammation, their precise transcriptional programs and regulatory circuitry in acne remain unclear. We developed an integrative computational framework that combines single-cell RNA sequencing (scRNA-seq), gene co-expression network analysis (WGCNA), and two complementary machine learning algorithms (SVM-RFE, LASSO) to identify disease-relevant biomarkers. We mapped acne lesion cellular composition, reconstructed keratinocyte differentiation trajectories, and integrated miRNA-transcription factor-drug interaction networks to link molecular signatures to potential interventions. We uncovered marked keratinocyte heterogeneity and enriched late-stage pro-inflammatory states in acne lesions, accompanied by increased macrophage/monocyte and T cell infiltration. Six keratinocyte-associated biomarkers (PYGL, C10orf99, C12orf75, S100A2, PI3, CARD18) were identified, achieving high diagnostic accuracy (AUC > 0.85). Functional enrichment connected these genes to cytokine and chemokine signaling, while regulatory analysis revealed upstream modulators (hsa-let-7b-5p, FOXC1). Drug-gene network mapping suggested repurposing potential for cyclosporin A and valproic acid. In conclusion, our study delineates a keratinocyte-centered molecular signature that shapes acne pathogenesis and provides potential therapeutic biomarkers.

Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system (CNS). Many aspects of GABAergic neurotransmission, including the densities of GABAergic neurons, the synthesis of GABA and its interaction with the respective receptors, are believed to be altered during aging, contributing to increased neuronal excitability seen in multiple neurodegenerative conditions, such as dementias, Alzheimer's disease, and traumatic brain injury (TBI). Oral administration of a nuclear fraction extract of the bovine thymus gland (thymus nuclear fraction-TNF) to rats was recently reported to improve their functional recovery from controlled cortical impact (CCI)-an animal model of TBI. Given that individual thymic peptides and mixed thymus fractions were also found to have broad neuroprotective effects and anti-neuroinflammatory activity, we sought to investigate the impact of TNF on GABAergic neurotransmission in the aging mouse brain. Using biochemical investigation, electrophysiological recordings, obtained using electroencephalography (EEG), and power spectral density analysis, we evaluated GABAergic protein expression and cortical neuronal activity in aged control mice and in mice supplemented with a low dose (LD) or a high dose of TNF for 14 weeks. We uncovered increased expression of two isoforms of glutamic acid decarboxylase, GAD65 and GAD67, and increased levels of β2/β3 subunits of GABA_A receptor in the brains of TNF-supplemented mice compared to the control group, suggesting possible enhancement of inhibitory neurotransmission. Decreased neuronal excitability, evidenced by reduced EEG amplitudes, power spectral densities, and peak amplitudes of high-frequency cortical oscillations, further confirmed a dose-dependent attenuation of neuronal excitability by TNF. Our results suggest that TNF supplementation may have the potential to mitigate age-related alterations in GABAergic neurotransmission, thereby modulating neuronal excitability.

Gasping respiration enhances survival chances during cardiac arrest by activating the suprahyoid muscles (SHMs), which are crucial for airway dilation. We previously reported that the high concentration of sevoflurane (6.5%: 2.0 minimum alveolar concentration, MAC) leads to gasping-like respiration in mice. Here, to understand the molecular mechanisms of this phenomenon, we compared the hypothalamic transcriptome profiles among control, 2.3% sevoflurane (0.7 MAC; eupnea), and 2.0 MAC groups and identified the differentially expressed genes (DEGs), in which hypocretin (orexin) precursor (Hcrt) gene expression was significantly elevated in the 2.0 MAC group. Notably, the intracerebroventricular administration of orexin enhanced SHM activity at 0.7 MAC. Our findings suggest that the 2.0 MAC sevoflurane-induced increases in orexin enhance activation of SHMs resulting in the involvement of gasping respiration.

Diabetic retinopathy (DR) is a major complication of diabetes mellitus. Growing evidence shows that hyperglycemia causes not only microvascular damage but also retinal neural dysfunction. Although different metabolic pathways have been implicated, the exact mechanism behind retinal degeneration remains unclear. Hyperglycemic stimuli have been shown to reduce the function of the retinal blood–barrier (BRB) in both diabetic humans and animals. As part of the BRB, the retinal pigment epithelium (RPE) plays a key role in retinal function by regulating the flow of metabolites and ions between the choroidal blood supply and the outer retina, and by supporting photoreceptor cell functions. Therefore, RPE dysfunction can lead to retinal injury. To understand the role of RPE in DR, we studied oxidative stress in the RPE at the early onset of streptozotocin-induced diabetes in rats. We found a 60% increase in lipoperoxidation at 45 days of diabetes, along with a 50% reduction in ascorbic acid content. Oxidized proteins were significantly increased after 20 and 45 days of diabetes induction, and changes in cell–cell contacts were observed. Despite these findings, superoxide dismutase activity was greatly increased at 45 days of diabetes, while Nrf2 expression and levels of total and reduced glutathione, key regulators of cellular antioxidant capacity, were similar in control and diabetic rat RPE. Moreover, the increase in oxidized proteins was not affected by the antioxidant quercetin nor by the NOS inhibitor L-NAME. These findings suggest that protein carbonylation may impair protein function or turnover, which in turn leads to RPE damage.

The brain relies on interoceptive feedback signals to regulate bodily functions. Female mice with low serum IGF-1 levels (LID mice) exhibit reduced spontaneous running compared to control females, an effect not seen in males. Reduced activity normalized after sustained systemic IGF-1 treatment. This observation led us to hypothesize that circulating IGF-1—a key regulator of skeletal muscle and bone mass that crosses the blood–brain barrier during physical activity—may convey body vigor information to the brain. Since hypothalamic orexin neurons, which are involved in regulating physical activity, express IGF-1 receptors (IGF-1R) and are modulated by this growth factor, we hypothesized that these neurons might gauge circulating IGF-1 levels to modulate physical activity. Indeed, inactivation of IGF-1R in mouse orexin neurons (Firoc mice) was associated with less time spent in free running. These mice maintain physical fitness but display altered mood and are less sensitive to the rewarding actions of exercise. Further, in response to exercise, Firoc mice showed limited c-fos activation of hypothalamic orexin neurons and monoaminergic neurons of the ventro-tegmental area (VTA) in the brainstem. This area is involved in the rewarding component of exercise that seems to be modulated by IGF-1, as mice receiving systemic IGF-1 showed increased c-fos expression in VTA neurons, while mice with reduced IGF-1R expression in VTA neurons showed no improved mood after exercise. Collectively, these results suggest that circulating IGF-1 is gauged by orexin neurons to modulate physical activity, and that VTA neurons convey the rewarding properties of exercise through direct actions of IGF-1 on them. Hence, serum IGF-1 may constitute an interoceptive signal acting on orexin/VTA neurons to modulate physical activity according to physical vigor (muscle and bone mass).

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related mortality, characterized by intrinsic resistance to conventional therapies and limited effective treatment options. In this study, we investigated the role of the CXCR2 axis in PDAC therapy resistance. CXCR2, a chemokine receptor, is actively involved in inflammation, tumor angiogenesis, and metastasis. Our working hypothesis is that CXCR2 contributes to PDAC chemotherapy resistance. To test this, we generated gemcitabine-resistant (GemR) lines using T3M4 and CD18/HPAF (CD18) cell lines. Baseline expression of CXCL1, CXCL5, and CXCL8 ligands was higher in GemR cells compared to parental cells. Upon gemcitabine treatment, parental cells exhibited a greater increase in CXCL1 and CXCL8 expression than GemR cells. Further analysis in T3M4 cells revealed a dose- and time-dependent increase in CXCL1 and CXCL8 expression following gemcitabine exposure. Next, we assessed whether targeting CXCR2 could enhance the therapeutic response. We treated parental and GemR cell lines with gemcitabine in combination with a CXCR2 antagonist, Navarixin. Notably, lower concentrations of gemcitabine combined with Navarixin were more effective than higher concentrations of gemcitabine alone in GemR cell lines. In both parental and GemR xenograft models, combination therapy with Navarixin and gemcitabine demonstrated superior antitumor and antimetastatic activity compared to either treatment alone. In conclusion, these findings highlight the critical role of the CXCR2 axis in PDAC therapy resistance. Targeting CXCR2 enhances gemcitabine efficacy, offering a potential therapeutic strategy to overcome resistance in PDAC.

The spleen is one of the key organs of the immune system that is involved in both innate and adaptive immunity. Splenectomy (SE) is surgery with many risks, including sepsis, thrombosis, and malignancy. In this regard, studies into the potential regeneration of the spleen and restoring its structure and functions are important. As in the past, heterotopic spleen transplantation regenerates the spleen structure after 30 days. This study assessed the impact of heterotopic spleen regeneration on tumor growth. We used two animal models. In the first, animals had SE. In the second, animals had SE and subcutaneous transplantation (ST) of spleen fragments. These animals, as well as intact animals, were transplanted under the skin with tumor cells to obtain a subcutaneous model of tumor growth. The results showed that while there was no significant effect on tumor growth at 15 days, there was a decrease in tumor cell proliferation rate. Spleen regeneration stimulated early occupancy of the tumor niche by macrophages, as well as influx of CD4+ T-lymphocytes and B-lymphocytes into the tumor, while infiltration of CD8+ T-lymphocytes was suppressed. Thus, the effects of regenerating spleen on tumor growth that we have demonstrated require further investigation at longer follow-up periods.

Emerging evidence highlights the pivotal role of the gut microbiota (GM) in regulating host metabolism and contributing to the development of insulin resistance (IR). Gut dysbiosis alters the production of critical metabolites, including short-chain fatty acids (SCFAs), bile acids, indole derivatives, and trimethylamine N-oxide (TMAO), which influence intestinal barrier integrity, inflammatory pathways, and glucose homeostasis. Recent clinical and translational studies indicate that SCFAs can improve fasting insulin and HOMA-IR, although the magnitude of benefit varies substantially across individuals, highlighting ongoing controversy surrounding their metabolic effects. Altered microbial regulation of bile-acid metabolism has also been implicated in impaired lipid and glucose signaling, reinforcing the relevance of FXR- and TGR5-mediated pathways in IR. Elevated TMAO levels have further been associated with adverse metabolic outcomes, though debate persists regarding its causal role versus its function as a diet-dependent biomarker. Microbiota-targeted strategies, including dietary fiber, probiotics, and fecal microbiota transplantation (FMT), show potential to modulate these metabolic pathways, yet clinical results remain inconsistent. This narrative review synthesizes recent mechanistic discoveries and clinical findings on microbiota-derived metabolites in IR, highlights key controversies, and outlines future priorities for translating microbiome science into effective and personalized interventions for metabolic disease prevention and management.