Extracellular histones induce inflammation and senescence of vascular smooth muscle cells by activating the AMPK/FOXO4 signaling pathway

Emerging therapeutic strategies targeting extracellular histones for critical and inflammatory diseases: an updated narrative review

Extracellular histones are crucial damage-associated molecular patterns involved in the development and progression of multiple critical and inflammatory diseases, such as sepsis, pancreatitis, trauma, acute liver failure, acute respiratory distress syndrome, vasculitis and arthritis. During the past decade, the physiopathologic mechanisms of histone-mediated hyperinflammation, endothelial dysfunction, coagulation activation, neuroimmune injury and organ dysfunction in diseases have been systematically elucidated. Emerging preclinical evidence further shows that anti-histone strategies with either their neutralizers (heparin, heparinoids, nature plasma proteins, small anion molecules and nanomedicines, etc.) or extracorporeal blood purification techniques can significantly alleviate histone-induced deleterious effects, and thus improve the outcomes of histone-related critical and inflammatory animal models. However, a systemic evaluation of the efficacy and safety of these histone-targeting therapeutic strategies is currently lacking. In this review, we first update our latest understanding of the underlying molecular mechanisms of histone-induced hyperinflammation, endothelial dysfunction, coagulopathy, and organ dysfunction. Then, we summarize the latest advances in histone-targeting therapy strategies with heparin, anti-histone antibodies, histone-binding proteins or molecules, and histone-affinity hemoadsorption in pre-clinical studies. Finally, challenges and future perspectives for improving the clinical translation of histone-targeting therapeutic strategies are also discussed to promote better management of patients with histone-related diseases.

Sodium Tanshinone IIA Sulfonate alleviates vascular senescence in diabetic mice by modulating the A20-NFκB-NLRP3 inflammasome-catalase pathway

Diabetes accelerates vascular senescence, which is the basis for atherosclerosis and stiffness. The activation of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and oxidative stress are closely associated with the deteriorative senescence in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). For decades, Sodium Tanshinone IIA Sulfonate (STS) has been utilized as a cardiovascular medicine with acknowledged anti-inflammatory and anti-oxidative properties. Nevertheless, the impact of STS on vascular senescence remains unexplored in diabetes. Diabetic mice, primary ECs and VSMCs were transfected with the NLRP3 overexpression/knockout plasmid, the tumor necrosis factor alpha-induced protein 3 (TNFAIP3/A20) overexpression/knockout plasmid, and treated with STS to detect senescence-associated markers. In diabetic mice, STS treatment maintained catalase (CAT) level and vascular relaxation, reduced hydrogen peroxide probe (ROSgreen) fluorescence, p21 immunofluorescence, Senescence β-Galactosidase Staining (SA-β-gal) staining area, and collagen deposition in aortas. Mechanistically, STS inhibited NLRP3 phosphorylation (serine 194), NLRP3 dimer formation, NLRP3 expression, and NLRP3-PYCARD (ASC) colocalization. It also suppressed the phosphorylation of IkappaB alpha (IκBα) and NFκB, preserved A20 and CAT levels, reduced ROSgreen density, and decreased the expression of p21 and SA-β-gal staining in ECs and VSMCs under HG culture. Our findings indicate that STS mitigates vascular senescence by modulating the A20-NFκB-NLRP3 inflammasome-CAT pathway in hyperglycemia conditions, offering novel insights into NLRP3 inflammasome activation and ECs and VSMCs senescence under HG culture. This study highlights the potential mechanism of STS in alleviating senescence in diabetic blood vessels, and provides essential evidence for its future clinical application.

FGF21 overexpression alleviates VSMC senescence in diabetic mice by modulating the SYK-NLRP3 inflammasome-PPARγ-catalase pathway

Diabetes accelerates vascular senescence, which is the basis for atherosclerosis and stiffness. The activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and oxidative stress are closely associated with progressive senescence in vascular smooth muscle cells (VSMCs). The vascular protective effect of FGF21 has gradually gained increasing attention, but its role in diabetes-induced vascular senescence needs further investigation. In this study, diabetic mice and primary VSMCs are transfected with an FGF21 activation plasmid and treated with a peroxisome proliferator-activated receptor γ (PPARγ) agonist (rosiglitazone), an NLRP3 inhibitor (MCC950), and a spleen tyrosine kinase (SYK)-specific inhibitor, R406, to detect senescence-associated markers. We find that FGF21 overexpression significantly restores the level of catalase (CAT), vascular relaxation, inhibits the intensity of ROSgreen fluorescence and p21 immunofluorescence, and reduces the area of SA-β-gal staining and collagen deposition in the aortas of diabetic mice. FGF21 overexpression restores CAT, inhibits the expression of p21, and limits the area of SA-β-gal staining in VSMCs under high glucose conditions. Mechanistically, FGF21 inhibits SYK phosphorylation, the production of the NLRP3 dimer, the expression of NLRP3, and the colocalization of NLRP3 with PYCARD (ASC), as well as NLRP3 with caspase-1, to reverse the cleavage of PPARγ, preserve CAT levels, suppress ROSgreen density, and reduce the expression of p21 in VSMCs under high glucose conditions. Our results suggest that FGF21 alleviates vascular senescence by regulating the SYK-NLRP3 inflammasome-PPARγ-catalase pathway in diabetic mice.

PAMPs and DAMPs in Sepsis: A Review of Their Molecular Features and Potential Clinical Implications

Sepsis is a serious organ dysfunction caused by a dysregulated immune host reaction to a pathogen. The innate immunity is programmed to react immediately to conserved molecules, released by the pathogens (PAMPs), and the host (DAMPs). We aimed to review the molecular mechanisms of the early phases of sepsis, focusing on PAMPs, DAMPs, and their related pathways, to identify potential biomarkers. We included studies published in English and searched on PubMed® and Cochrane®. After a detailed discussion on the actual knowledge of PAMPs/DAMPs, we analyzed their role in the different organs affected by sepsis, trying to elucidate the molecular basis of some of the most-used prognostic scores for sepsis. Furthermore, we described a chronological trend for the release of PAMPs/DAMPs that may be useful to identify different subsets of septic patients, who may benefit from targeted therapies. These findings are preliminary since these pathways seem to be strongly influenced by the peculiar characteristics of different pathogens and host features. Due to these reasons, while initial findings are promising, additional studies are necessary to clarify the potential involvement of these molecular patterns in the natural evolution of sepsis and to facilitate their transition into the clinical setting.

AT1R autoantibody promotes phenotypic transition of smooth muscle cells by activating AT1R-OAS2

Phenotypic transition of vascular smooth muscle cells (VSMCs) is an early event in the onset and progression of several cardiovascular diseases. As an important mediator of the renin-angiotensin system (RAS), activation of the angiotensin II type 1 receptor (AT1R) induces phenotypic transition of VSMCs. AT1R autoantibodies (AT1-AAs), which are agonistic autoantibodies of AT1R, have been detected in the sera of patients with a variety of cardiovascular diseases associated with phenotypic transition. However, the effect of AT1-AA on phenotypic transition is currently unknown. In this study, AT1-AA-positive rat model was established by active immunization to detect markers of VSMCs phenotypic transition. The results showed that AT1-AA-positive rats showed phenotypic transition of VSMCs, which was evidenced by the decrease of contractile markers, while the increase of synthetic markers in the thoracic aorta. However, in AT1-AA-positive AT1R knockout rats, the phenotypic transition-related proteins were not altered. In vitro, after stimulating human aortic smooth muscle cells with AT1-AA for 48 h, 2'-5' oligoadenylate synthase 2 (OAS2) was identified as the key differentially expressed gene by RNA sequencing and bioinformatics analysis. Furthermore, high expression of OAS2 was found in aorta of AT1-AA-positive rats; knockdown of OAS2 by siRNA can reverse the phenotypic transition of VSMCs induced by AT1-AA. In summary, this study suggests that AT1-AA can promote phenotypic transition of VSMCs through AT1R-OAS2 pathway, and OAS2 might serve as a potential therapeutic target to prevent pathological phenotypic transition of smooth muscle cells.

The rules and regulatory mechanisms of FOXO3 on inflammation, metabolism, cell death and aging in hosts

The FOX family of transcription factors was originally identified in 1989, comprising the FOXA to FOXS subfamilies. FOXO3, a well-known member of the FOXO subfamily, is widely expressed in various human organs and tissues, with higher expression levels in the ovary, skeletal muscle, heart, and spleen. The biological effects of FOXO3 are mostly determined by its phosphorylation, which occurs in the nucleus or cytoplasm. Phosphorylation of FOXO3 in the nucleus can promote its translocation into the cytoplasm and inhibit its transcriptional activity. In contrast, phosphorylation of FOXO3 in the cytoplasm leads to its translocation into the nucleus and exerts regulatory effects on biological processes, such as inflammation, aerobic glycolysis, autophagy, apoptosis, oxidative stress, cell cycle arrest and DNA damage repair. Additionally, FOXO3 isoform 2 acts as an important suppressor of osteoclast differentiation. FOXO3 can also interfere with the development of various diseases, including inhibiting the proliferation and invasion of tumor cells, blocking the production of inflammatory factors in autoimmune diseases, and inhibiting β-amyloid deposition in Alzheimer's disease. Furthermore, FOXO3 slows down the aging process and exerts anti-aging effects by delaying telomere attrition, promoting cell self-renewal, and maintaining genomic stability. This review suggests that changes in the levels and post-translational modifications of FOXO3 protein can maintain organismal homeostasis and improve age-related diseases, thus counteracting aging. Moreover, this may indicate that alterations in FOXO3 protein levels are also crucial for longevity, offering new perspectives for therapeutic strategies targeting FOXO3.

Estrogen ameliorates sepsis-induced vascular hyporeactivity in thoracic aorta of female rats via permissive effect of GRα expression

OBJECTIVE

Estrogen is correlated to the lower mortality and disease severity of female than that of male, which indicates the potential therapeutic role of estrogen supplement therapy in sepsis. The structure of Daidzein is similar to that of 17β estradiol (E₂), an estrogen in human body, causing the exogenous Daidzein can interact with estrogen receptor as well as E₂ in the body. We aim to explore the therapeutic role of estrogen in sepsis-induced vascular dysfunction. Also, we wonder if estrogen regulates blood pressure via glucocorticoid-mediated vascular reactivity.

METHODS

Female SD rats received ovariectomy (OVX) to induce estrogen deficiency. After 12 weeks of administration, cecal ligation and puncture (CLP) was used to establish the in vivo model of sepsis. Lipopolysaccharide (LPS) was used to construct the in vitro model of sepsis in vascular smooth muscle cells (VSMCs). E₂ and Daidzein were used for estrogen supplement therapy.

RESULTS

E₂ and Daidzein significantly inhibited inflammation infiltration and histopathological injury in thoracic aorta in the rat model with CLP. E₂ and Daidzein improved carotid pressure and vascular hyporeactivity in sepsis rats with OVX. Importantly, E₂ and Daidzein promoted glucocorticoid permissive action and increased glucocorticoid receptor α (GRα) expression in thoracic aorta smooth muscle cells. E₂ and Daidzein upregulated GRα, and inhibits cytokine production, proliferative phenotype and cell migration in LPS-induced VSMCs.

CONCLUSION

Estrogen improved vascular hyporeactivity in thoracic aorta induced by sepsis via permissive effect of GRα expression.