Sestrin2 induction contributes to anti-inflammatory responses and cell survival by globular adiponectin in macrophages

The effect and application of adiponectin in hepatic fibrosis

Hepatic fibrosis, a degenerative liver lesion, significantly contributes to the deterioration and mortality among patients with chronic liver diseases. The condition arises from various factors including toxins, such as alcohol, infections like different types of viral hepatitis, and metabolic diseases. Currently, there are no effective treatments available for liver fibrosis. Recent research has shown that adiponectin (ADPN) exhibits inhibitory effects on hepatic fibrosis. ADPN, an adipocytokine secreted by mature adipocytes, features receptors that are widely distributed across multiple tissues, especially the liver. In the liver, direct effects of ADPN on liver fibrosis include reducing inflammation and regulating hepatic stellate cell proliferation and migration. And its indirect effects include alleviating hepatic endoplasmic reticulum stress and reducing inflammation in hepatic lobules, thereby mitigating hepatic fibrosis. This review aims to elucidate the regulatory role of ADPN in liver fibrosis, explore how ADPN and its receptors alleviate endoplasmic reticulum stress, summarize ADPN detection methods, and discuss its potential as a novel marker and therapeutic agent in combating hepatic fibrosis.

Adiponectin restores the obesity-induced impaired immunomodulatory function of mesenchymal stromal cells via glycolytic reprogramming

Obesity has been known to negatively modulate the life-span and immunosuppressive potential of mesenchymal stromal cells (MSC). However, it remains unclear what drives the compromised potency of obese MSC. In this study, we examined the involvement of adiponectin, an adipose tissue-derived hormone, in obesity-induced impaired therapeutic function of MSC. Diet-induced obesity leads to a decrease in serum adiponectin, accompanied by impairment of survival and immunomodulatory effects of adipose-derived MSC (ADSC). Interestingly, priming with globular adiponectin (gAcrp) improved the immunomodulatory potential of obese ADSC. Similar effects were also observed in lean ADSC. In addition, gAcrp potentiated the therapeutic effectiveness of ADSC in a mouse model of DSS-induced colitis. Mechanistically, while obesity inhibited the glycolytic capacity of MSC, gAcrp treatment induced a metabolic shift toward glycolysis through activation of adiponectin receptor type 1/p38 MAPK/hypoxia inducible factor-1α axis. These findings suggest that activation of adiponectin signaling is a promising strategy for enhancing the therapeutic efficacy of MSC against immune-mediated disorders.

Status of Research on Sestrin2 and Prospects for its Application in Therapeutic Strategies Targeting Myocardial Aging

Cardiac aging is accompanied by changes in the heart at the cellular and molecular levels, leading to alterations in cardiac structure and function. Given today's increasingly aging population, the decline in cardiac function caused by cardiac aging has a significant impact on quality of life. Antiaging therapies to slow the aging process and attenuate changes in cardiac structure and function have become an important research topic. Treatment with drugs, including metformin, spermidine, rapamycin, resveratrol, astaxanthin, Huolisu oral liquid, and sulforaphane, has been demonstrated be effective in delaying cardiac aging by stimulating autophagy, delaying ventricular remodeling, and reducing oxidative stress and the inflammatory response. Furthermore, caloric restriction has been shown to play an important role in delaying aging of the heart. Many studies in cardiac aging and cardiac aging-related models have demonstrated that Sestrin2 has antioxidant and anti-inflammatory effects, stimulates autophagy, delays aging, regulates mitochondrial function, and inhibits myocardial remodeling by regulation of relevant signaling pathways. Therefore, Sestrin2 is likely to become an important target for antimyocardial aging therapy.

The promotion of sestrin2/AMPK signaling by HIF-1α overexpression enhances the damage caused by acute myocardial infarction

OBJECTIVE

Acute myocardial infarction (AMI), is a serious form of coronary heart disease. The present study sought to investigate the impact of HIF-1α on AMI, along with its fundamental mechanism.

METHODS

Sprague-Dawley (SD) rats were used to conduct an AMI model. 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) staining was used examine the region of myocardial infract area at various time intervals. Protein expression levels were detected using western blotting. The rats were randomly divided into sham, model, negative control (NC), HIF-1α overexpression (HIF-1α-OE), and HIF-1α-OE+ si-sestrin2 groups. We examined the impact of HIF-1α overexpression on AMI rats using Haematoxylin-Eosin (H&E) staining, TTC staining, enzyme-linked immunosorbent assay (ELISA), TdT-mediated dUTP Nick-End Labeling (TUNEL) assay, and immunohistochemistry (IHC) staining.

RESULTS

According to the TTC findings, the region affected by myocardial infarction reached its peak at day 14. Based on the results from the western blot analysis, the levels of HIF-1α and sestrin2 were found the minimum on day 28. Subsequently, we discovered that the overexpression of HIF-1α rescued the cardiac function parameters, improved the morphology of myocardial tissue, and mitigated inflammation. Furthermore, the overexpression of HIF-1α led to a reduction in the levels of MDA and an increase in the levels of SOD. Moreover, the overexpression of HIF-1α resulted in a decrease in cellular apoptosis. This result was confirmed by the expression levels of Bcl-2 and Bax. Nevertheless, the defensive impact of elevated HIF-1α expression was somewhat counteracted by the suppression of sestrin2. In terms of mechanism, the overexpression of HIF-1α enhanced the levels of sestrin2 and the protein adenosine monophosphate activated kinase (AMPK).

CONCLUSION

Our research suggests that the overexpression of HIF-1α may rescue the damage to myocardial tissue, and this effect is associated with the sestrin2/AMPK signaling pathway. Our study provides a novel comprehension of the protective effects of HIF-1α overexpression on AMI.

Modulation of miR-146b Expression during Aging and the Impact of Physical Activity on Its Expression and Chondrogenic Progenitors

The finding of molecules associated with aging is important for the prevention of chronic degenerative diseases and for longevity strategies. MicroRNAs (miRNAs) are post-transcriptional regulators involved in many biological processes and miR-146b-5p has been shown to be involved in different degenerative diseases. However, miR-146b-5p modulation has not been evaluated in mesenchymal stem cells (MSCs) commitment or during aging. Therefore, the modulation of miR-146b-5p in the commitment and differentiation of mesenchymal cells as well as during maturation and aging in zebrafish model were analyzed. In addition, circulating miR-146b-5p was evaluated in human subjects at different age ranges. Thus, the role of physical activity in the modulation of miR-146b-5p was also investigated. To achieve these aims, RT (real-time)-PCR, Western blot, cell transfections, and three-dimensional (3D) culture techniques were applied. Our findings show that miR-146b-5p expression drives MSCs to adipogenic differentiation and increases during zebrafish maturation and aging. In addition, miR-146b-5p expression is higher in females compared to males and it is associated with the aging in humans. Interestingly, we also observed that the physical activity of walking downregulates circulating miR-146b-5p levels in human females and increases the number of chondroprogenitors. In conclusion, miR-146b-5p can be considered an age-related marker and can represent a useful marker for identifying strategies, such as physical activity, aimed at counteracting the degenerative processes of aging.

A cross-talk between sestrins, chronic inflammation and cellular senescence governs the development of age-associated sarcopenia and obesity

The rapid increase in both the lifespan and proportion of older adults is accompanied by the unprecedented rise in age-associated chronic diseases, including sarcopenia and obesity. Aging is also manifested by increased susceptibility to multiple endogenous and exogenous stresses enabling such chronic conditions to develop. Among the main physiological regulators of cellular adaption to various stress stimuli, such as DNA damage, hypoxia, and oxidative stress, are sestrins (Sesns), a family of three evolutionarily conserved proteins, Sesn1, 2, and 3. Age-associated sarcopenia and obesity are characterized by two key processes: (i) accumulation of senescent cells in the skeletal muscle and adipose tissue and (ii) creation of a systemic, chronic, low-grade inflammation (SCLGI). Presumably, failed SCLGI resolution governs the development of these chronic conditions. Noteworthy, Sesns activate senolytics, which are agents that selectively eliminate senescent cells, as well as specialized pro-resolving mediators, which are factors that physiologically provide inflammation resolution. Sesns reveal clear beneficial effects in pre-clinical models of sarcopenia and obesity. Based on these observations, we propose a novel treatment strategy for age-associated sarcopenia and obesity, complementary to the conventional therapeutic modalities: Sesn activation, SCLGI resolution, and senescent cell elimination.

Modulation of NLRP3 inflammasomes activation contributes to improved survival and function of mesenchymal stromal cell spheroids

Mesenchymal stem cells (MSCs) are ubiquitous multipotent cells that exhibit significant therapeutic potentials in a variety of disorders. Nevertheless, their clinical efficacy is limited owing to poor survival, low rate of engraftment, and impaired potency upon transplantation. Spheroidal three-dimensional (3D) culture of MSCs (MSC3D) has been proven to better preserve their in vivo functional properties. However, the molecular mechanisms underlying the improvement in MSC function by spheroid formation are not clearly understood. NLRP3 inflammasomes, a key component of the innate immune system, have recently been shown to play a role in cell fate decision of MSCs. The present study examined the role of NLRP3 inflammasomes in the survival and potency of MSC spheroids. We found that MSC3D led to decreased activation of NLRP3 inflammasomes through alleviation of ER stress in an autophagy-dependent manner. Importantly, downregulation of NLRP3 inflammasomes signaling critically contributes to the enhanced survival rate in MSC3D through modulation of pyroptosis and apoptosis. The critical role of NLRP3 inflammasome suppression in the enhanced therapeutic efficacy of MSC spheroids was further confirmed in an in vivo mouse model of DSS-induced colitis. These findings suggest that 3D culture confers survival and functional advantages to MSCs by suppressing NLRP3 inflammasome activation.

Cathepsin B maturation plays a critical role in leptin-induced hepatic cancer cell growth through activation of NLRP3 inflammasomes

Leptin, an adipose tissue-derived hormone, exhibits potent tumor promoting effects through various mechanisms. Cathepsin B, a member of the lysosomal cysteine proteases, has been shown to modulate the growth of cancer cells. In this study, we have investigated the role of cathepsin B signaling in leptin-induced hepatic cancer growth. Leptin treatment caused significant increase in the levels of active cathepsin B through the axis of endoplasmic reticulum stress and autophagy induction without significant effects on pre- and pro-forms of cathepsin B. Interestingly, inhibition of cathepsin B signaling by gene silencing or treatment with a selective pharmacological inhibitor (CA-074) prevented leptin-enhanced viability of hepatic cancer cell and suppressed progression of cell cycle, indicating the critical role of cathepsin B in leptin-induced hepatic cancer growth. We have further observed that maturation of cathepsin B is required for NLRP3 inflammasomes activation, which is implicated in the growth of hepatic cancer cell. The crucial roles of cathepsin B maturation in leptin-induced hepatic cancer growth and NLRP3 inflammasomes activation were confirmed in an in vivo HepG2 tumor xenograft model. Taken together, these results demonstrate that cathepsin B signaling plays a pivotal role in leptin-induced hepatic cancer cell growth by activating NLRP3 inflammasomes.

Effects of PEG-Linker Chain Length of Folate-Linked Liposomal Formulations on Targeting Ability and Antitumor Activity of Encapsulated Drug

Introduction

Ligand-conjugated liposomes are promising for the treatment of specific receptor-overexpressing cancers. However, previous studies have shown inconsistent results because of the varying properties of the ligand, presence of a polyethylene glycol (PEG) coating on the liposome, length of the linker, and density of the ligand.

Methods

Here, we prepared PEGylated liposomes using PEG-linkers of various lengths conjugated with folate and evaluated the effect of the PEG-linker length on the nanoparticle distribution and pharmacological efficacy of the encapsulated drug both in vitro and in vivo.

Results

When folate was conjugated to the liposome surface, the cellular uptake efficiency in folate receptor overexpressed KB cells dramatically increased compared to that of the normal liposome. However, when comparing the effect of the PEG-linker length in vitro, no significant difference between the formulations was observed. In contrast, the level of tumor accumulation of particles in vivo significantly increased when the length of the PEG-linker was increased. The tumor size was reduced by >40% in the Dox/FL-10K-treated group compared to that in the Dox/FL-2K- or 5K-treated groups.

Discussion

Our study suggests that as the length of PEG-linker increases, the tumor-targeting ability can be enhanced under in vivo conditions, which can lead to an increase in the antitumor activity of the encapsulated drug.

Sestrin2: multifaceted functions, molecular basis, and its implications in liver diseases

Sestrin2 (SESN2), a highly conserved stress-responsive protein, can be triggered by various noxious stimuli, such as hypoxia, DNA damage, oxidative stress, endoplasmic reticulum (ER) stress, and inflammation. Multiple transcription factors regulate SESN2 expression, including hypoxia-inducible factor 1 (HIF-1), p53, nuclear factor E2-related factor 2 (Nrf2), activating transcription factor 4 (ATF4), ATF6, etc. Upon induction, SESN2 generally leads to activation of adenosine monophosphate-activated protein kinase (AMPK) and inhibition of mechanistic target of rapamycin complex 1 (mTORC1). To maintain cellular homeostasis, SESN2 and its downstream molecules directly scavenge reactive oxygen species or indirectly influence the expression patterns of key genes associated with redox, macroautophagy, mitophagy, ER stress, apoptosis, protein synthesis, and inflammation. In liver diseases including acute liver injury, fatty liver diseases, hepatic fibrosis, and hepatocellular carcinoma (HCC), SESN2 is abnormally expressed and correlated with disease progression. In NAFLD, SESN2 helps with postponing disease progression through balancing glycolipid metabolism and macroautophagy (lipophagy), and rectifying oxidative damage and ER stress. During hepatic fibrosis, SESN2 represses HSCs activation and intrahepatic inflammation, hindering the occurrence and progress of fibrogenesis. However, the role of SESN2 in HCC is controversial due to its paradoxical pro-autophagic and anti-apoptotic effects. In conclusion, this review summarizes the biological functions of SESN2 in hypoxia, genotoxic stress, oxidative stress, ER stress, and inflammation, and specifically emphasizes the pathophysiological significance of SESN2 in liver diseases, aiming to providing a comprehensive understanding for SESN2 as a potential therapeutic target in liver diseases.

Mitophagy Induction and Aryl Hydrocarbon Receptor-Mediated Redox Signaling Contribute to the Suppression of Breast Cancer Cell Growth by Taloxifene via Regulation of Inflammasomes Activation

Aims: Raloxifene, a selective estrogen receptor (ER) modulator, has been reported to exert the tumor-suppressive effects in both ER-positive and ER-negative cancer cells; however, the mechanisms underlying its ER-independent anti-cancer effects are poorly understood. The NLRP3 inflammasome, a critical component of the innate immune system, has recently received growing attention owing to its multifaceted roles in various aspects of cancer development. The present study aimed at examining the involvement of NLRP3 inflammasomes in the anti-breast cancer effects of raloxifene and its underlying mechanisms. Results: Raloxifene significantly inhibited the activation of NLRP3 inflammasomes in various breast cancer cell lines. Importantly, forced expression of a gain-of-function variant of NLRP3 rescued breast cancer cells from growth arrest by raloxifene, suggesting that the suppression of NLRP3 inflammasomes activation mediates the raloxifene-induced inhibition of breast cancer growth. Mechanistically, raloxifene suppressed NLRP3 inflammasomes activation by lowering the cellular levels of reactive oxygen species (ROS) through the modulation of redox signaling mediated via aryl hydrocarbon receptor (AhR)-nuclear factor erythroid 2-related factor 2 (Nrf2)-heme oxygenase-1 (HO-1) axis or the impaired generation of mitochondrial ROS in a mitophagy-dependent manner. Further, the blockage of AhR signaling or inhibition of mitophagy abolished the tumor-suppressive effect of raloxifene in a human breast tumor xenograft model. Innovation: We elucidate a novel molecular mechanism underlying the breast tumor suppressing effect of raloxifene. Conclusion: The results observed in this study suggest that the modulation of NLRP3 inflammasomes activation is a critical event in the inhibition of breast tumor growth by raloxifene. Antioxid. Redox Signal. 37, 1030-1050.

Combining NMR and MS to Describe Pyrrole-2-Carbaldehydes in Wheat Bran of Radiation

Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) are indispensable analytical tools to provide chemical fingerprints in metabolomics studies. The present study evaluated radiation breeding wheat lines for chemical changes by non-targeted NMR-based metabolomics analysis of bran extracts. Multivariate analysis following spectral binning suggested pyrrole-2-carbaldehydes as chemical markers of four mutant lines with distinct NMR fingerprints in a δ_H range of 9.28-9.40 ppm. Further NMR and MS data analysis, along with chromatographic fractionation and synthetic preparation, aimed at structure identification of marker metabolites and identified five pyrrole-2-carbaldehydes. Quantum-mechanical driven ¹H iterative full spin analysis (QM-HiFSA) on synthetic pyrrole-2-carbaldehydes provided a precise description of complex peak patterns. Biological evaluation of pyrrole-2-carbaldehydes was performed with nine synthetic products, and six compounds showed hepatoprotective effects via modulation of reactive oxygen species production. Given that three out of five identified in wheat bran of radiation were described for hepatoprotective activity, the value of radiation mutation to greatly enhance pyrrole-2-carbaldehyde production was supported.

Inhibitory effects of 6'-sialyllactose on angiotensin II-induced proliferation, migration, and osteogenic switching in vascular smooth muscle cells

Excessive production and migration of vascular smooth muscle cells (VSMCs) are associated with vascular remodeling that causes vascular diseases, such as restenosis and hypertension. Angiotensin II (Ang II) stimulation is a key factor in inducing abnormal VSMC function. This study aimed to investigate the effects of 6'-sialyllactose (6'SL), a human milk oligosaccharide, on Ang II-stimulated cell proliferation, migration and osteogenic switching in rat aortic smooth muscle cells (RASMCs) and human aortic smooth muscle cells (HASMCs). Compared with the control group, Ang II increased cell proliferation by activating MAPKs, including ERK1/2/p90RSK/Akt/mTOR and JNK pathways. However, 6'SL reversed Ang II-stimulated cell proliferation and the ERK1/2/p90RSK/Akt/mTOR pathways in RASMCs and HASMCs. Moreover, 6'SL suppressed Ang II-stimulated cell cycle progression from G0/G1 to S and G2/M phases in RASMCs. Furthermore, 6'SL effectively inhibited cell migration by downregulating NF-κB-mediated MMP2/9 and VCAM-1 expression levels. Interestingly, in RASMCs, 6'SL attenuated Ang II-induced osteogenic switching by reducing the production of p90RSK-mediated c-fos and JNK-mediated c-jun, leading to the downregulation of AP-1-mediated osteopontin production. Taken together, our data suggest that 6'SL inhibits Ang II-induced VSMC proliferation and migration by abolishing the ERK1/2/p90RSK-mediated Akt and NF-κB signaling pathways, respectively, and osteogenic switching by suppressing p90RSK- and JNK-mediated AP-1 activity.

Anti-inflammatory effect of a triterpenoid from Balanophora laxiflora: results of bioactivity-guided isolation

Balanophora laxiflora, a medicinal plant traditionally used to treat fever, pain, and inflammation in Vietnam, has been reported to possess prominent anti-inflammatory activity. This study examined the active constituents and molecular mechanisms underlying these anti-inflammatory effects using bioactivity-guided isolation in combination with cell-based assays and animal models of inflammation. Among the isolated compounds, the triterpenoid (21α)-22-hydroxyhopan-3-one (1) showed the most potent inhibitory effect on COX-2 expression in LPS-stimulated Raw 264.7 macrophages. Furthermore, 1 suppressed the expression of the inflammatory mediators iNOS, IL-1β, INFβ, and TNFα in activated Raw 264.7 macrophages and alleviated the inflammatory response in carrageenan-induced paw oedema and a cotton pellet-induced granuloma model. Mechanistically, the anti-inflammatory effects of 1 were mediated via decreasing cellular reactive oxygen species (ROS) levels by inhibiting NADPH oxidases (NOXs) and free radical scavenging activities. By downregulating ROS signalling, 1 reduced the activation of MAPK signalling pathways, leading to decreased AP-1-dependent transcription of inflammatory mediators. These findings shed light on the chemical constituents that contribute to the anti-inflammatory actions of B. laxiflora and suggest that 1 is a promising candidate for treating inflammation-related diseases.