Angiotensin II (Ang II) is the most active peptide hormone produced by the renin-angiotensin system (RAS). Genetic deletion of genes that ultimately restrict Ang II formation has been shown to result in marked anemia in mice. In this study, adult mice with a genetic deletion of the RAS precursor protein angiotensinogen (Agt-KO) were used. Experimental analyses included capillary hematocrit, hemogram, plasma and tissue iron quantifications, expression analyses of genes encoding relevant proteins for body iron homeostasis in different organs as well as plasma and urine hepcidin quantifications. As previously reported Agt-KO were anemic with reduced red blood cell counts. Interestingly, we found that they presented microcytic anemia based on the reduced red blood cell volume. In agreement, plasma quantification of iron revealed lower levels of circulating iron in Agt-KO. The major body iron stores namely in liver and spleen were also depleted in the RAS-deficient line. Hepatic hepcidin expression was reduced as well as the one of its major regulator, BMP6, as a result of the iron deficiency. However, plasma hepcidin levels were unexpectedly increased in Agt-KO. We confirm the typical morphological alterations and impaired renal function of Agt-KO and conclude that hepcidin accumulates in the circulation due to the reduced glomerular filtration in Agt-KO, and therefore identified the culprit of iron deficiency in Agt-KO. Collectively, the data demonstrated that the severe anemia developed in RAS-deficient mice is exacerbated by iron deficiency which is secondary to the renal damage-induced hepcidin accumulation in the circulation.

Neddylation is a process of attaching neuronal precursor cell-expressed developmentally downregulated protein 8 (NEDD8) to substrates for the protein function modulation via enzymatic cascades involving NEDD8-activating enzyme (E1), NEDD8-conjugating enzyme (E2), and NEDD8 ligase (E3). Defective in cullin neddylation 1 (DCN1) serves as a co-E3 ligase, that can simultaneously bind E2 UBE2M and cullin proteins to stabilize the catalytic center of the Cullin-Ring E3 ligase (CRL) complex, thereby promoting cullin neddylation. Neddylation is reported to be activated in diverse human diseases, and inhibition of protein neddylation has been regarded as a promising anticancer therapy. However, whether neddylation participates in renal fibrosis and whether blockade of neddylation through targeted inhibition of DCN1 play effects on renal fibrosis remains unknown. In this study, a NEDD8 overexpressed plasmid, DCN1 small interfering RNAs (siRNAs), DCN1 specific inhibitor NAcM-OPT, human renal tubular epithelial cells (HK-2), rat kidney fibroblasts (NRK-49F), RNA-sequencing (RNA-seq), unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion injury (UIRI) mouse renal fibrosis models were used. Herein, we first showed that neddylation was activated in renal fibrosis. Neddylation blockade through DCN1 deficiency alleviated TGFβ1-induced upregulation of fibronectin and α-SMA in HK-2 and NRK-49F cells. Importantly, DCN1 inhibition attenuated UUO and UIRI-induced mouse renal fibrosis. Further studies revealed that DCN1 loss selectively inhibited cullin3 neddylation and induced its substrate NRF2 accumulation, thereby inhibiting TGFβ-Smad2/3 signaling pathway. Overall, blockade of neddylation through targeted inhibition of DCN1 contributes to alleviating renal fibrosis in vitro and in vivo, which may constitute a novel therapeutic strategy for renal fibrosis.

Metabolic and insulin-resistant diseases, such as type 2 diabetes mellitus (T2DM), have become major health issues worldwide. The prevalence of insulin resistance in the general population ranges from 15.5% to 44.6%. Shockingly, the global T2DM population is anticipated to double by 2050 compared with 2021. Prior studies indicate that oxidative stress and inflammation are instrumental in causing insulin resistance and instigating metabolic diseases. Numerous methods and drugs have been designed to combat insulin resistance, including metformin, thiazolidinediones (TZDs), sodium-glucose cotransporter 2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor agonists (GLP1RA), and dipeptidyl peptidase 4 inhibitors (DPP4i). Bilirubin is an antioxidant with fat-burning actions by binding to the PPARα nuclear receptor transcription factor, improving insulin sensitivity, reducing inflammation, and reversing metabolic dysfunction. Potential treatment with antioxidants like bilirubin and increasing the enzyme that produces it, heme oxygenase (HMOX), has also gained attention. This review discusses the relationships between bilirubin, HMOX, and insulin sensitivity, how T2DM medications affect HMOX levels and activity, and potentially using bilirubin nanoparticles to treat insulin resistance. We explore the sex differences between these treatments in the HMOX system and how bilirubin levels are affected. We discuss the emerging concept that bilirubin bioconversion to urobilin may have a role in metabolic diseases. This comprehensive review summarizes our understanding of bilirubin functioning as a hormone, discusses the HMOX isoforms and their beneficial mechanisms, analyzes the sex differences that might cause a dichotomy in responses, and examines the potential use of HMOX and bilirubin nanoparticle therapies in treating metabolic diseases.

Salt sensitivity of blood pressure (SSBP) is a complex physiological trait characterized by changes in blood pressure in response to dietary salt intake. Aging introduces an additional layer of complexity to the pathophysiology of SSBP, with mitochondrial dysfunction, epigenetic modifications, and alterations in gut microbiota emerging as critical factors. Despite advancements in understanding these mechanisms, the processes driving increased salt sensitivity with age and their differential impacts across sexes remain unclear. This review explores the current understanding of salt sensitivity, delving into its underlying mechanisms, the role of inflammation, and the influence of aging and sex differences on these processes. We also aim to provide insights into the multifaceted nature of salt sensitivity and its implications for personalized treatment strategies in hypertension management.

Lactylation, a post-translational modification, has been linked to gene transcription regulation through epigenetic modulation in various pathophysiological processes. The lactylation regulatory proteins, known as writers, erasers, and readers, govern their dynamics by adding, removing, and recognizing lactyl groups on proteins. Macrophages, as cells of the immune system, maintain homeostasis, responding dynamically to diverse internal and external stimuli. Emerging researches unveil that lactylation, through inducing macrophage activation and polarization, affects their functionality in pathological conditions such as inflammation, tumor microenvironment, and fibrosis. Evidence progressively indicates that lactate-driven alterations in lactylation levels within macrophages can influence the pathogenesis of numerous diseases. This review aims to systematically summarize the research progress of lactylation in macrophages, explore its functions and mechanisms by which lactylation contributes to the pathology of different disease phenotypes, and propose future research directions along with potential diagnostic and therapeutic strategies.

Metabolic changes are an important characteristic of vascular complications in diabetes. The accumulation of lactate in the microenvironment can promote vascular smooth muscle cell (VSMC) calcification in diabetes, although the specific mechanism remains to be fully elucidated. In this study, we explored the characteristics of lactylation in diabetic arterial calcification and the underlying molecular mechanism. We found that in high-glucose calcified VSMC, the overall lactylation level was significantly increased. Mass spectrometry analysis revealed a significant up-regulation of H3 histone lactylation. After site-specific point-mutation at K18 to simulate the delactylation modification, VSMC calcification was significantly reduced. Through a combination of H3K18la ChIP-seq, RNA-seq, H3K18la ChIP-qPCR, and point-mutation experiments, we confirmed that H3K18la can up-regulate CHI3L1. CHI3L1 knockout significantly alleviated VSMC osteogenic phenotype transformation and mouse arterial calcification. RNA-seq analysis of the downstream molecular signaling showed that CHI3L1 activates the IL-13-IL-13Ra2-JAK1-STAT3 pathway. Targeted inhibition of IL-13Ra2 reduced VSMC calcification. We conclude that in a diabetic calcification environment, the H3 histone K18 site undergoes lactylation modification in VSMCs, upregulating CHI3L1, which, in turn, regulates the IL-13-IL-13Ra2-JAK1-STAT3 signaling pathway, ultimately exacerbating arterial calcification. Our study elucidates the epigenetic mechanism by which lactate promotes arterial calcification in diabetes.

Septic acute kidney injury (AKI) is an important risk factor for developing chronic kidney disease (CKD). Hu antigen R (HuR) is recognized as a crucial modulator in inflammation. We hypothesized that elevated HuR contributes to the transition from septic AKI to CKD by promoting persistent inflammation and fibrosis, and inhibition of HuR may reverse septic kidney injury. Mice subjected to lipopolysaccharide (LPS) injections every other day were concurrently treated without or with either KH39 or niclosamide (NCS) for 7 days. Control mice received saline injections. Repeated LPS injections led to a significant increase in HuR expression in the kidneys, which was effectively suppressed by KH39 or NCS treatment. LPS-induced kidney injury was characterized by elevated plasma blood urea nitrogen levels and urinary albuminuria, along with histological signs of inflammatory cell infiltration and fibrosis, as determined by periodic acid-Schiff and Masson's trichrome staining, and immunofluorescent staining for markers such as α-smooth muscle actin, fibronectin, collagen III, and F4/80. Treatment with either KH39 or NCS mitigated these changes observed in LPS-injured kidneys. Additionally, increased expression of CD147, a molecule implicated in inflammatory cell recruitment and tubular injury, was inhibited by KH39 or NCS treatment. These effects on HuR and CD147 expression were further validated in vitro in cultured macrophages and tubular cells. This study suggests that HuR elevation in LPS-stimulated macrophages and kidney cells contributes to the progression of septic kidney injury, possibly through HuR-CD147 interactions, underscoring the therapeutic potential of HuR inhibitors for this condition.

Genetic diagnostic testing of 325 pulmonary arterial hypertension (PAH) patients using a PAH specific gene panel including 18 known PAH genes revealed mutations in 23%. Further PAH candidate genes were sequenced in the remaining patients exposing two SMAD5 variants, which were clinically and functionally characterized. We first recorded familial cosegregation and clinical parameters. Functional tests were performed following transient over-expression of the two SMAD5 variants in pulmonary artery smooth muscle cells (PASMCs). Expression of these variants was confirmed by quantitative PCR, Sanger sequencing, and Western blotting. Cell viability was evaluated using cell counting kit 8, cell proliferation by bromodeoxyuridine (BrdU), and apoptosis by annexin V assay. Both SMAD5 missense variants were absent in healthy controls and predicted to be pathogenic. The variant c.1175T>C p.(Leu392Pro) was identified in a heritable PAH patient and her healthy son. The mother had died of suspected PAH at age 42. The expression of this variant in PASMCs led to significantly higher cell viability due to higher proliferation in comparison with SMAD5 wild-type cells. The second variant c.277T>A p.(Trp93Arg) was identified in a patient with congenital heart disease associated PAH with a surgically repaired ventricular septal defect. Its expression led to significantly lower cell viability due to increased apoptosis in comparison with wild-type SMAD5 cells. Taking into account familial aggregation, clinical findings, and functional evidence, both variants could be classified as likely pathogenic. This is the first description of SMAD5 as a potential novel PAH gene for genetic diagnostic testing.

Obesity is a significant global health challenge, increasing the risk of developing type 2 diabetes mellitus (T2DM) and cardiovascular disease. Research indicates that obese individuals, regardless of their diabetic status, have an increased risk of cardiovascular complications. Studies suggest that these patients experience impaired electrical conduction in the heart, although the underlying cause-whether due to obesity-induced fat toxicity or diabetes-related factors-remains uncertain. This study investigated ventricular action potential parameters, as well as sodium (INa) and calcium (ICa, L) currents, in Zucker fatty (ZF) rats and Zucker diabetic fatty (ZDF) rats, which serve as models for obesity and T2DM, respectively. Ventricular myocytes were isolated from 25- to 30-week-old Zucker rats. Resting and action potentials were recorded using a β-escin perforated patch clamp, while INa and ICa,L were assessed with whole-cell patch clamp methods. ZF rats exhibited higher excitability and faster upstroke velocity with greater INa density, whereas ZDF rats showed decreased INa and slower action potential upstroke. No differences in ICa,L density or voltage sensitivity were found among the groups. In summary, obesity, with or without accompanying T2DM, distinctly impacts the action potential waveform, INa density, and excitability of ventricular myocytes in this rat model of T2DM.

Transglutaminase 2 (TG2) is an enzyme with multiple conformations. In its open conformation, TG2 exhibits transamidase activity linked to fibrosis, arterial remodeling, and endothelial dysfunction, a process enhanced by high glucose in endothelial cells. However, the closed conformation of TG2 contributes to transmembrane signaling and nitric oxide (NO)-dependent vasorelaxation. LDN 27219, a reversible allosteric inhibitor, stabilizes TG2 in its closed conformation. We examined whether pharmacological modulation of TG2 into its closed conformation induces vasorelaxation and enhances endothelium-dependent and independent relaxation in resistance arteries from age-matched diabetic (n = 14) and non-diabetic patients (n = 14) (age 71 (Standard Error of the Mean: ± 2)). Subcutaneous arteries (diameter 133-1013 µm) were isolated from abdominal fat biopsies. TG2 mRNA expression and transamidase activity were assessed via RT-qPCR and 5-biotin(amido)pentylamine (5-BP) incorporation, while vascular reactivity was measured using wire myography. TG2 mRNA was highly expressed without significant differences between the groups and LDN 27219 induced concentration-dependent vasorelaxation in arteries from both groups. Sex-specific analysis revealed that potentiation of acetylcholine-induced vasorelaxation by LDN 27219 was driven by increased TG2 expression in non-diabetic females, whereas no effect was observed in arteries from non-diabetic males. Among diabetic patients, LDN 27219 increased maximal acetylcholine-induced vasorelaxation in males only. LDN 27219 did not affect endothelium-independent relaxation to sodium nitroprusside in either group. In conclusion, TG2 is expressed in human resistance arteries, and LDN 27219 induced vasorelaxation, selectively enhancing ACh relaxation in non-diabetic females, likely owing to increased TG2 expression. This finding underscores the importance of sex differences in TG2 modulation of vasorelaxation.

Anthracyclines, such as doxorubicin, are important anti-cancer therapies but are associated with arterial injury. Histopathological insights have been limited to small animal models, and the role of inflammation in the arterial toxic effects of anthracycline is unclear in humans. Our aims were (1) to evaluate aortic media fibrosis and injury in non-human primates treated with anthracyclines; (2) to assess the effect of anthracycline on aortic inflammation in patients treated for lymphoma. African Green monkeys (AGMs) received doxorubicin (30-60 mg/m2/biweekly intravenously, cumulative dose: 240 mg/m2). Blinded histopathologic analyses of the ascending aorta were performed 15 weeks after the last doxorubicin dose and compared to five age- and gender-matched healthy, untreated AGMs. Analysis of the thoracic aorta of patients with diffuse large B-cell lymphoma (DLBCL), at baseline and after doxorubicin exposure, was performed using 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in this observational study by maximal tissue-to-background ratio (TBRmax). In AGMs, doxorubicin exposure was associated with greater aortic fibrosis (collagen deposition: doxorubicin 6.23 ± 0.88% vs. controls 4.67 ± 0.54%; P=0.01) and intracellular vacuolization (doxorubicin 66.3 ± 10.1 vs. controls 11.5 ± 4.2 vacuoles/field, P<0.0001) than untreated controls. In 101 patients with DLBCL, there was no change in aortic TBRmax after anthracycline exposure (TBRmax 1.46 ± 0.16 vs. 1.44 ± 0.14, respectively, P=0.14). Univariate analyses yielded similar results. In a large animal model, anthracycline exposure was associated with aortic fibrosis. In patients with lymphoma, anthracycline exposure was not associated with aortic inflammation. Further research is required to elucidate the mechanisms of anthracycline-related vascular harm.

Sepsis and septic shock are global healthcare problems associated with high mortality rates. Activation of the renin-angiotensin-aldosterone system (RAAS) is an early event in sepsis, and elevated renin may be predictive of worse outcomes. In a subset of sepsis patients enrolled in the Vitamin C, Thiamine and Steroids in Sepsis (VICTAS) trial, elevated levels of active renin (median value > 189 pg/mL or 5.1 pM) at baseline (day 0) were strongly associated with mortality; however, corresponding plasma levels of the vasopressor hormone Angiotensin II were not substantially increased nor was Angiotensin II associated with disease severity. The current study assessed RAAS components that may impact the Angiotensin II response in control subjects, normal renin sepsis (NRS, renin < 5.1 pM) and high renin sepsis (HRS, renin > 5.1 pM) patients. NRS and HRS subjects exhibited a similar reduction in ACE (40%), but increased levels of ACE2 and DPP3. The ACE to DPP3 ratio was higher in controls but this relationship was reversed in both NRS and HRS subjects. Intact angiotensinogen was 50% lower in the HRS than control or NRS subjects, whereas the intact angiotensinogen to renin ratio was <10% of control or NRS subjects. We conclude that altered expression of ACE, ACE2, DPP3 and angiotensinogen may attenuate the expected increase in Angiotensin II, particularly in sepsis subjects with high renin concentrations.

Apelin, a (neuro) vasoactive peptide, plays a prominent role in controlling water balance and cardiovascular functions. Apelin and its receptor co-localize with vasopressin in magnocellular vasopressinergic neurons. Apelin receptors (Apelin-Rs) are also expressed in the collecting ducts of the kidney, where vasopressin type 2 receptors are also present. Apelin and vasopressin interact at the brain and renal levels to maintain body fluid homeostasis by regulating diuresis in opposite directions. Apelin and angiotensin II have opposite effects on the regulation of blood pressure (BP). Angiotensin II, by binding to AT1 receptors present in VSMCs, induces intracellular calcium mobilization and vasoconstriction, while apelin, by binding to Apelin-R present on vascular endothelium, increases nitric oxide production and induces vasodilation. Apelin also plays a crucial role in the regulation of cardiac function. Apelin-deficient and Apelin-R-deficient mice develop progressive myocardial dysfunction with ageing and are susceptible to heart failure in response to pressure overload. Since the half-life of apelin is very short in vivo (in the minute range), several metabolically stable apelin analogs and non-peptidic Apelin-R agonists have been developed, with potential applications in diverse diseases. In this review, we highlight the interaction between apelin and vasopressin in the regulation of water balance and that between apelin and angiotensin II in the regulation of BP. Additionally, we underline the protective effects of apelin in cardiac function. Lastly, we discuss the beneficial effects of Apelin-R activation in different pathological states such as hyponatremia, hypertension, and heart failure.

Chronic inflammatory diseases, e.g., obesity, cardiovascular disease and type-2 diabetes, progressively suppress the anti-inflammatory heat shock response (HSR) by impairing the synthesis of key components, perpetuating inflammation. Monitoring HSR progression offers predictive value for countering chronic inflammation. This study quantified HSR in high-fat diet (HFD) and normal chow (NC) mice by measuring 70 kDa heat shock protein (HSP70) expression after heat treatment of whole blood samples. To align with human translational relevance, animals were housed within their thermoneutral zone (TNZ). Whole blood was heat-challenged weekly at 42 °C for 1-2 hours over 22 weeks, and ΔHSP70 was calculated as the difference between HSP70 expressions at 42 °C and 37 °C. Results correlated with fasting glycaemia, oral glucose tolerance test, intraperitoneal insulin tolerance test and 2-hour post-glucose load glycaemia. ΔHSP70 levels >0.2250 indicated normal fasting glycaemia, while levels <0.2125 signalled insulin resistance and type-2 diabetes onset. A logistic model (five-parameter logistic) showed progressive HSR decline, with HFD mice exhibiting earlier ΔHSP70 reduction (t1/2 = 3.14 weeks) compared with NC mice (t1/2 = 8.24 weeks), highlighting compromised anti-inflammatory capacity in both groups of mice maintained at TNZ. Remarkably, even NC mice surpassed insulin resistance thresholds by week 22, relevant as control diets confronted interventions. Observed HSR decline mirrors tissue-level suppression in obese and type-2 diabetic individuals, underscoring HSR failure as a hallmark of obesity-driven inflammation. This study introduces a practical whole-blood assay to evaluate HSR suppression, allowing assessment of glycaemic status during obesity onset before any clinical manifestation.

Renin-expressing juxtaglomerular (JG) cells possess an intrinsic pressure-sensing mechanism(s) that regulates renin synthesis and release in response to changes in perfusion pressure. Although we recently described the structure of the nuclear mechanotransducer that controls renin transcription, the acute pressure-sensing mechanism that controls the rapid release of renin has not been identified. In JG cells there is an inverse relationship between intracellular calcium and renin release, the 'calcium paradox'. Since the discovery of Piezo2 as the 'touch' receptors, there has been a significant interest in exploring whether they are also involved in other tissues beyond the skin. Given that Piezo receptors are permeable to calcium upon mechanical stimuli, it would be reasonable to hypothesize that Piezo2 controls renin synthesis and/or release in JG cells. To test this hypothesis, we used a variety of novel mouse models and JG cell-specific techniques to define whether Piezo2 controls renin expression and/or release in JG cells. Our in vivo data using constitutive and inducible Cre driver mouse lines and a variety of novel experimental approaches indicate that Piezo2 channels are not necessary for renin synthesis or release in JG cells during normal conditions or when homeostasis is threatened by hypotension, sodium depletion, or inverse changes in blood pressure. Furthermore, Piezo1 channels do not compensate for the lack of Piezo2 in JG cells. Efforts should be devoted to identifying the acute mechanosensory mechanisms controlling renin release.

Over the past 20 years, basic research has robustly demonstrated the regulatory role of bile acids in physiological processes, primarily by the discovery and the study of their specific receptors and the understanding of the pathways they modulate. The dysregulation of the bile acid pool and the perturbation of bile acid signaling have been implicated in the pathophysiology of various clinical conditions, including cardiometabolic, cholestatic and inflammatory diseases. Consequently, bile acids have emerged as promising therapeutic targets, with compounds to modulate bile acid metabolism and signaling being actively investigated in pre-clinical and clinical settings. Despite these advancements, much remains to be understood before bile acid metabolism and bile acid-regulated pathways can be effectively manipulated for health protection. As a step forward in this direction, Clinical Science has curated a themed collection on the new discoveries in bile acids, gut microbiota and host interactions in health and diseases. This collection emphasizes mechanistic research papers, connecting basic science to disease mechanisms, aiming to enhance the understanding of the role of bile acids in physiological and pathophysiological conditions.

Vertical transmission of SARS-CoV-2 during human pregnancy remains highly controversial as most studies have focused on the third trimester or the peripartum period. Given the lack of early trimester data, determining the prevalence of vertical transmission during early pregnancy and assessing the potential risks for fetal morbidity and mortality poses a challenge. Therefore, we analyzed the impact of SARS-CoV-2 infection on an endometrial 3D spheroid model system. The 3D spheroids are capable of decidualization and express ACE2 as well as TMPRSS2, rendering them susceptible to SARS-CoV-2 infection. Employing this 3D cell model, we identified that SARS-CoV-2 can infect both non-decidualized and decidualized endometrial spheroids. Infection significantly increased the chemokine MCP-1 compared to non-infected spheroids. Decidualized spheroids exhibited upregulated chemokine IL-8 levels. Furthermore, RNA sequencing revealed dysregulation of several genes involved in tissue-specific immune response, Fc receptor signalling, angiotensin-activated signalling and actin function. Gene expression changes varied between SARS-CoV-2 infected non-decidualized and decidualized spheroids and genes associated with the innate immune system (CCL20, CD38, LCN2 and NR4A3) were dysregulated as a potential mechanism for immune evasion of SARS-CoV-2. Altogether, our study demonstrates that endometrial spheroids are a useful model to examine the clinical implications of SARS-CoV-2 vertical transmission, warranting further investigations.

Adipose tissue dysfunction leads to abnormal lipid metabolism and high inflammation levels. This research aims to explore the role of Serpina3c, which is highly expressed in adipocytes, in obesity-related hypertriglyceridemia and metaflammation. Serpina3c global knockout (KO) mice, adipocyte-specific Serpina3c overexpressing mice, Serpina3c knockdown (KD) mice, and hypoxia-inducible factor 1 alpha (Hif1α) KD mice were fed a high-fat diet (HFD) for 16 weeks to generate obesity-related hypertriglyceridemia mice models. In the present study, Serpina3c KO mice and adipocyte-specific Serpina3c KD mice exhibited more severe obesity-related hypertriglyceridemia and metaflammation under HFD conditions. Serpina3c KO epididymal white adipose tissue (eWAT) primary stromal vascular fraction (SVF)-derived adipocytes exhibited higher lipid (triglyceride and non-esterified fatty acid) levels and higher fatty acid synthase expression after palmitic acid stimulation. Adipocyte-specific Serpina3c overexpression in KO mice prevented the KO group phenotype. The RNA-seq and in vitro validation revealed that Hif1α and the glycolysis pathways were upregulated in Serpina3c KD adipocytes, which were all validated by in vitro and in vivo reverse experiments. Co-immunoprecipitation (co-IP) provided evidence that Serpina3c bound nuclear factor erythroid 2-related factor 2 (Nrf2) to regulate Hif1α. Nrf2 KD reduced Hif1α and Fasn expression, decreased lipid content, and reduced the extracellular acidification rate in Serpina3c KO adipocytes. Metabolomics revealed that lactic acid (LD) levels in eWAT were responsible for adipose-associated macrophage inflammation. In summary, Serpina3c inhibits the Hif1α-glycolysis pathway and reduces de novo lipogenesis and LD secretion in adipocytes by binding to Nrf2, thereby improving HFD-induced lipid metabolism disorders and alleviating adipose tissue macrophage inflammation.

The renin-angiotensin system (RAS) is a classically known circulatory regulatory system. In addition to the previously known multi-organ circulatory form of the RAS, the existence of tissue RASs in individual organs has been well established. Skeletal muscle has also been identified as an organ with a distinct RAS. In recent years, the effects of RAS activation on skeletal muscle have been elucidated from several perspectives: differences in motor function due to genetic polymorphisms of RAS components, skeletal muscle dysfunction under conditions of excessive RAS activation such as heart failure, and the effects of the use of RAS inhibitors on muscle strength. In addition, the concept of the RAS itself has recently been expanded with the discovery of a 'protective arm' of the RAS formed by factors such as angiotensin-converting enzyme 2 and angiotensin 1-7. This has led to a new understanding of the physiological function of the RAS in skeletal muscle. This review summarizes the diverse physiological functions of the RAS in skeletal muscle and considers the potential of future therapeutic strategies targeting the RAS to overcome problems such as sarcopenia and muscle weakness associated with chronic disease.