Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

Effects of Guizhi and Erxian Decoction on menopausal hot flashes: insights from the gut microbiome and metabolic profiles

AIMS

To examine the influence of GED on the gut microbiota and metabolites using a bilateral ovariectomized (OVX) rat model. We tried to elucidate the underlying mechanisms of GED in the treatment of menopausal hot flashes.

METHODS AND RESULTS

16S rRNA sequencing, metabonomics, molecular biological analysis, and fecal microbiota transplantation (FMT) were conducted to elucidate the mechanisms by which GED regulates the gut microbiota. GED significantly reduced OVX-induced hot flashes and improved disturbances in the gut microbiota metabolites. Moreover, FMT validated that the gut microbiota can trigger hot flashes, while GED can alleviate hot flash symptoms by modulating the composition of the gut microbiota. Specifically, GED upregulated the abundance of Blautia, thereby increasing l(+)-ornithine levels for the treatment of menopausal hot flashes. Additionally, GED affected endothelial nitric oxide synthase and heat shock protein 70 (HSP70) levels in the hypothalamic preoptic area by changing the gut microbiota composition.

CONCLUSIONS

Our study illuminated the underlying mechanisms by which GED attenuated the hot flashes through modulation of the gut microbiota and explored the regulatory role of the gut microbiota on HSP70 expression in the preoptic anterior hypothalamus, thereby establishing a foundation for further exploration of the role of the gut-brain axis in hot flashes.

Heat shock response during the resolution of inflammation and its progressive suppression in chronic-degenerative inflammatory diseases

The heat shock response (HSR) is a crucial biochemical pathway that orchestrates the resolution of inflammation, primarily under proteotoxic stress conditions. This process hinges on the upregulation of heat shock proteins (HSPs) and other chaperones, notably the 70 kDa family of heat shock proteins, under the command of the heat shock transcription factor-1. However, in the context of chronic degenerative disorders characterized by persistent low-grade inflammation (such as insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases) a gradual suppression of the HSR does occur. This work delves into the mechanisms behind this phenomenon. It explores how the Western diet and sedentary lifestyle, culminating in the endoplasmic reticulum stress within adipose tissue cells, trigger a cascade of events. This cascade includes the unfolded protein response and activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome, leading to the emergence of the senescence-associated secretory phenotype and the propagation of inflammation throughout the body. Notably, the activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome not only fuels inflammation but also sabotages the HSR by degrading human antigen R, a crucial mRNA-binding protein responsible for maintaining heat shock transcription factor-1 mRNA expression and stability on heat shock gene promoters. This paper underscores the imperative need to comprehend how chronic inflammation stifles the HSR and the clinical significance of evaluating the HSR using cost-effective and accessible tools. Such understanding is pivotal in the development of innovative strategies aimed at the prevention and treatment of these chronic inflammatory ailments, which continue to take a heavy toll on global health and well-being.

The macrophage senescence hypothesis: the role of poor heat shock response in pulmonary inflammation and endothelial dysfunction following chronic exposure to air pollution

INTRODUCTION

Cardiovascular diseases (CVD) have been associated with high exposure to fine particulate air pollutants (PM_2.5). Alveolar macrophages are the first defense against inhaled particles. As soon as they phagocytize the particles, they reach an inflammatory phenotype, which affects the surrounding cells and associates with CVD. Not coincidentally, CVD are marked by a depleted heat shock response (HSR), defined by a deficit in inducing 70-kDa heat shock protein (HSP70) expression during stressful conditions. HSP70 is a powerful anti-inflammatory chaperone, whose reduced levels trigger a pro-inflammatory milieu, cellular senescence, and a senescence-associated secretory phenotype (SASP). However, whether macrophage senescence is the main mechanism by which PM_2.5 propagates low-grade inflammation remains unclear.

OBJECTIVE AND DESIGN

In this article, we review evidence supporting that chronic exposure to PM_2.5 depletes HSR and determines the ability to solve the initial stress.

RESULTS AND DISCUSSION

When exposed to PM_2.5, macrophages increase the production of reactive oxygen species, which activate nuclear factor-kappa B (NF-κB). NF-κB is naturally a pro-inflammatory factor that drives prostaglandin E2 (PGE2) synthesis and causes fever. PGE2 can be converted into prostaglandin A2, a powerful inducer of HSR. Therefore, when transiently activated, NF-κB can trigger the anti-inflammatory response through negative feedback, by inducing HSP70 expression. However, when chronically activated, NF-κB heads a set of pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, unfolded protein response, inflammasome activation, and apoptosis. During chronic exposure to PM_2.5, cells cannot properly express sirtuin-1 or activate heat shock factor-1 (HSF-1), which delays the resolution phase of inflammation. Since alveolar macrophages are the first immune defense against PM_2.5, we suppose that the pollutant impairs HSR and, consequently, induces cellular senescence. Accordingly, senescent macrophages change its secretory phenotype to a more inflammatory one, known as SASP. Finally, macrophages' SASP would propagate the systemic inflammation, leading to endothelial dysfunction and atherosclerosis.

Increased eHSP70-to-iHSP70 ratio in prediabetic and diabetic postmenopausal women: a biomarker of cardiometabolic risk

Decreased estrogen levels in menopause are associated with anthropometric, metabolic, and inflammatory impairments, predisposing women to cardiometabolic risk factors such as diabetes. Menopause and type two diabetes (DM2) are marked by altered heat shock response (HSR), shown by decreased expression of the 70-kDa heat shock protein in the intracellular milieu (iHSP70). While iHSP70 plays an anti-inflammatory role, extracellular HSP70 (eHSP70) may mediate pro-inflammatory pathways and has been associated with insulin resistance in DM2. Considering the roles of these proteins according to localization, the eHSP70-to-iHSP70 ratio (H-index) has been proposed as a biomarker for HSR. We, therefore, evaluated whether this biomarker is associated with glycemic and inflammatory status in postmenopausal women. In this transversal study, 36 postmenopausal women were grouped according to fasting glycemia status as either the control group (normoglycemic, ≤ 99 mg/dL) or DM2 (prediabetic and diabetic, glycemia ≥ 100 mg/dL). DM2 group showed higher triglyceride/glucose (TyG) index and plasma atherogenic index (PAI), both of which are indicators of cardiometabolic risk. In addition, we found that the eHSP70-to-iHSP70 ratio (plasma/peripheral blood mononuclear cells-PBMC ratio) was higher in the DM2 group, compared with the control group. Furthermore, blood leukocyte and glycemia levels were positively correlated with the eHSP70-to-iHSP70 ratio in women that presented H-index values above 1.0 (a.u.). Taken together, our results highlight the eHSP70-to-iHSP70 ratio as a biomarker of altered HSR in DM2 postmenopausal women.

Chaperone duality: the role of extracellular and intracellular HSP70 as a biomarker of endothelial dysfunction in the development of atherosclerosis

The 70-kDa heat shock proteins (HSP70) may provide relevant information about the endothelial dysfunction in cardiovascular diseases. Located in the intracellular milieu (iHSP70), they are essential chaperones that inhibit nuclear factor kappa B activation, stimulate nitric oxide production and superoxide dismutase activity, and inhibit apoptosis. However, under stressful conditions, HSP70 can be released into the extracellular medium (eHSP70) and act as an inflammatory mediator. Although studies have reported the vasoprotective role of iHSP70, the evidence regarding eHSP70 is contradictory. eHSP70 can activate NFκB and activator protein-1, thus stimulating the release of inflammatory cytokines and production of reactive oxygen species. Due to the antagonistic nature of HSP70 according to its location, the eHSP70/iHSP70 ratio (Heck index) has been proposed as a better marker of inflammatory status; however, more studies are required to confirm this hypothesis. Therefore, this review summarises studies that, together, describe the role of HSP70 in endothelial dysfunction.

Inflammation, oxidative stress and altered heat shock response in type 2 diabetes: the basis for new pharmacological and non-pharmacological interventions

Type 2 diabetes mellitus (DM2) is a chronic disease characterised by variable degrees of insulin resistance and impaired insulin secretion. Besides, several pieces of evidence have shown that chronic inflammation, oxidative stress, and 70 kDa heat shock proteins (HSP70) are strongly involved in DM2 and its complications, and various pharmacological and non-pharmacological treatment alternatives act in these processes/molecules to modulate them and ameliorate the disease. Besides, uncontrolled hyperglycaemia is related to several complications as diabetic retinopathy, neuropathy and hepatic, renal and cardiac complications. In this review, we address discuss the involvement of different inflammatory and pro-oxidant pathways related to DM2, and we described molecular targets modulated by therapeutics currently available to treat DM2.

Harnessing the Immunogenic Potential of Gold Nanoparticle-Based Platforms as a Therapeutic Strategy in Breast Cancer Immunotherapy: A Mini Review

Breast cancer remains the most common malignancy among women worldwide. Although the implementation of mammography has dramatically increased the early detection rate, conventional treatments like chemotherapy, radiation therapy, and surgery, have significantly improved the prognosis for breast cancer patients. However, about a third of treated breast cancer patients are known to suffer from disease recurrences and progression to metastasis. Immunotherapy has recently gained traction due to its ability to establish long-term immune surveillance, and response for the prevention of disease recurrence and extension of patient survival. Current research findings have revealed that gold nanoparticles can enhance the safety and efficacy of cancer immunotherapy, through their unique intrinsic properties of good biocompatibility, durability, convenient surface modification, as well as enhanced permeability and retention effect. Gold nanoparticles are also able to induce innate immune responses through the process of immunogenic cell death, which can lead to the establishment of lasting adaptive immunity. As such gold nanoparticles are considered as good candidates for next generation immunotherapeutic strategies. This mini review gives an overview of gold nanoparticles and their potential applications in breast cancer immunotherapeutic strategies.

Effects of prebiotic-rich yogurt on menopausal symptoms and metabolic indices in menopausal women: a triple-blind randomised controlled trial

This study aimed to investigate the effects of prebiotics on metabolic indices and menopausal symptoms. This triple-blind randomised controlled trial was conducted on 60 menopausal women. The participants were assigned to two groups based on block randomisation. Over 6 weeks, the experimental group received 100 g of prebiotic-rich yogurt daily after lunch and the control group received regular yogurt. Menopausal symptoms and metabolic indices were assessed before and after the treatment. The mean total score of menopausal symptoms (p < 0.001), anxiety (p < 0.001), depression (p = 0.003), vasomotor (p < 0.001), and low-density lipoprotein (p = 0.028) was statistically lower in the experimental group than the control group. Moreover, the serum insulin level was statistically higher among those in the experimental group (p = 0.011). The study results demonstrated the positive effects of prebiotic-rich yogurt on menopausal symptoms and some metabolic indices. Trial registration: Iranian Registry of Clinical Trials (IRCT): IRCT20120718010324N52; Date of registration: 12/4/2019. URL: https://en.irct.ir/user/trial/41105/view; Date of first registration: 12/5/2019.

HSP70 as a biomarker of the thin threshold between benefit and injury due to physical exercise when exposed to air pollution

Physical exercise has acute and chronic effects on inflammatory balance, metabolic regulation, and redox status. Exercise-induced adaptations are mediated by enhanced 70-kDa heat shock protein (HSP70) levels and an improved heat shock response (HSR). Therefore, exercise could be useful against disease conditions [obesity, diabetes mellitus (DM), and exposure to atmospheric pollutants] marked by an impaired HSR. However, exercise performed by obese or diabetic subjects under pollution conditions might also be dangerous at certain intensities. Intensity correlates with an increase in HSP70 levels during physical exercise until a critical point at which the effort becomes harmful and impairs the HSR. Establishing a unique biomarker able to indicate the exercise intensity on metabolism and cellular fatigue is essential to ensure adequate and safe exercise recommendations for individuals with obesity or DM who require exercise to improve their metabolic status and live in polluted regions. In this review, we examined the available evidence supporting our hypothesis that HSP70 could serve as a biomarker for determining the optimal exercise intensity for subjects with obesity or diabetes when exposed to air pollution and establishing the fine threshold between anti-inflammatory and pro-inflammatory exercise effects.

Gold Compounds and the Anticancer Immune Response

Gold compounds are not only well-explored for cytotoxic effects on tumors, but are also known to interact with the cancer immune system. The immune system deploys innate and adaptive mechanisms to protect against pathogens and prevent malignant transformation. The combined action of gold compounds with the activated immune system has shown promising results in cancer therapy through in vivo and in vitro experiments. Gold compounds are known to induce innate immune responses; however, these responses may contribute to adaptive immune responses. Gold compounds play the role of a major hapten that acts synergistically in innate immunity. Gold compounds support cancer cell antigenicity and promote anti-tumor immune response by inducing the release of CRT, ATP, HMGB1, HSP, and NKG2D to enhance immunogenicity. Gold compounds affect various immune cells (including suppressor regulatory T cells), inhibit myeloid derived suppressor cells, and enhance the function and number of dendritic cells. Gold nanoparticles (AuNPs) have potential for improving the effect of immunotherapy and reducing the toxicity and side effects of the treatment process. Thus, AuNPs provide an ideal opportunity for exploring the combination of anticancer gold compounds and immunotherapeutic interventions.

Innate immunity, inflammation activation and heat-shock protein in COVID-19 pathogenesis

SARS-CoV-2-induced COVID-19 is a serious pandemic of the 21st century, which has caused a devastating loss of lives and a global economic catastrophe. A successful vaccine against SARS-CoV-2 has suffered a delay due to lack of substantial knowledge about its mechanisms of action. Understanding the innate immune system against SARS-CoV-2 and the role of heat shock proteins' (HSP) inhibiting and resolution of inflammatory pathways may provide information to the low SARS-CoV-2 mortality rates in Africa. In addition, bats being a host to different viruses, including SARS-CoV-2 possess a well specialized IFN-innate antiviral inflammatory response, showing no signs of disease or pro-inflammatory cytokine storm. We discuss the molecular pathways in COVID-19 with a focus on innate immunity, inflammation, HSP responses, and suggest appropriate candidates for therapeutic targets and The contribution of the innate immune system to the efficacy of mRNA or vector based Corona immunizations.

Ovariectomy reduces the cardiac cytoprotection in rats exposed to particulate air pollutant

Fine particulate matter (PM_2.5) has been considered a risk factor for cardiovascular diseases by inducing an oxidative and inflammatory phenotype. Besides, the reduction of 17β-estradiol (E2) levels during menopause is a natural risk for cardiovascular outcomes. During the E2 downfall, there is a high requirement of the 70-kDa heat shock proteins (HSP70), which present essential antioxidant, anti-inflammatory, and anti-senescence roles. We investigated if the ovariectomy, an animal model for menopause, could induce additional effects in cardiac health by impairing oxidative and heat shock response parameters of female rats chronically exposed to residual oil fly ash (ROFA; an inorganic fraction of PM_2.5). Thus, ROFA was obtained from São Paulo (Brazil) and solubilized it in saline. Further, female Wistar rats were exposed to 50 μL of saline (control group) or ROFA solution (250 μg) (polluted) by intranasal instillation, 5 days/week, 12 weeks. At the 12th week, animals were subdivided into four groups (n = 6 p/group): control, OVX, polluted, and polluted + OVX. Control and polluted were submitted to false surgery, while OVX and polluted + OVX were ovariectomized. ROFA or saline exposure continued for 12 weeks. Ovariectomy reduced the cardiac catalase activity and iHSP70 expression in female rats exposed to ROFA. Neither plasma eHSP72 levels nor H-index (eHSP72 to cardiac iHSP70 ratio) was affected. In conclusion, ovariectomy reduces the cardiac cytoprotection and antioxidant defense, and enhances the susceptibility to premature cellular senescence in rats exposed to ROFA.

Plasma heat shock protein response to euglycemia in type 2 diabetes

INTRODUCTION

Glucose variability is associated with mortality and macrovascular diabetes complications. The mechanisms through which glucose variability mediates tissue damage are not well understood, although cellular oxidative stress is likely involved. As heat shock proteins (HSPs) play a role in the pathogenesis of type 2 diabetes (T2D) complications and are rapidly responsive, we hypothesized that HSP-related proteins (HSPRPs) would differ in diabetes and may respond to glucose normalization.

RESEARCH DESIGN AND METHODS

A prospective, parallel study in T2D (n=23) and controls (n=23) was undertaken. T2D subjects underwent insulin-induced blood glucose normalization from baseline 7.6±0.4 mmol/L (136.8±7.2 mg/dL) to 4.5±0.07 mmol/L (81±1.2 mg/dL) for 1 hour. Control subjects were maintained at 4.9±0.1 mmol/L (88.2±1.8 mg/dL). Slow Off-rate Modified Aptamer-scan plasma protein measurement determined a panel of HSPRPs.

RESULTS

At baseline, E3-ubiquitin-protein ligase (carboxyl-terminus of Hsc70 interacting protein (CHIP) or HSPABP2) was lower (p=0.03) and ubiquitin-conjugating enzyme E2G2 higher (p=0.003) in T2D versus controls. Following glucose normalization, DnaJ homolog subfamily B member 1 (DNAJB1 or HSP40) was reduced (p=0.02) in T2D, with HSP beta-1 (HSPB1) and HSP-70-1A (HSP70-1A) (p=0.07 and p=0.09, respectively) also approaching significance relative to T2D baseline levels.

CONCLUSIONS

Key HSPRPs involved in critical protein interactions, CHIP and UBE2G2, were altered in diabetes at baseline. DNAJB1 fell in response to euglycemia, suggesting that HSPs are reacting to basal stress that could be mitigated by tight glucose control with reduction of glucose variability.

Meta-analysis: Early Age at Natural Menopause and Risk for All-Cause and Cardiovascular Mortality

Aims

The aim of this meta-analysis was to comprehensively evaluate the association of early age at natural menopause with the risk for all-cause and cardiovascular mortality.

Methods

Literature retrieval was done on August 4, 2020. Article selection and data extraction were completed independently and in duplicate. Early age at natural menopause was grouped into premature menopause (<40 years), early menopause (40-44 years), and relatively early menopause (45-49 years). Effect-size estimates are summarized as hazard ratio (HR) or relative risk (RR) with 95% confidence interval (CI).

Results

Sixteen articles involving 321,233 women were meta-analyzed. Overall analyses revealed a statistically significant association of early age at natural menopause with all-cause mortality risk (HR_adjusted = 1.08, 95% CI: 1.03 to 1.14, P = 0.002; RR_adjusted = 1.05, 95% CI 1.01 to 1.08, P = 0.005), but not with cardiovascular mortality risk. In dose-response analyses, the association with all-cause mortality was significant for premature menopause with (HR_adjusted = 1.10; 95% CI: 1.01 to 1.21; P = 0.034) and without (RR_adjusted = 1.34; 95% CI: 1.08 to 1.66; P = 0.007) considering follow-up intervals. As for cardiovascular mortality, marginal significance was noted for premature menopause after considering follow-up intervals (HR = 1.09; 95% CI: 1.00-1.19; P = 0.045). Subgroup analyses indicated that gender, country, and follow-up periods were possible causes of heterogeneity. There was an overall low probability of publication bias.

Conclusions

Our findings indicate that premature menopause is a promising independent risk factor for both all-cause and cardiovascular mortality.

A-family anti-inflammatory cyclopentenone prostaglandins: A novel class of non-statin inhibitors of HMG-CoA reductase

Disruption of the intracellular lipid balance leading to cholesterol accumulation is one of the features of cells that participate in the development of atherosclerotic lesions. Evidence form our laboratory indicates that anti-inflammatory cyclopentenone prostaglandins (cyPGs) of A- and J-family deviate lipid metabolism from the synthesis of cholesterol and cholesteryl esters to the synthesis of phospholipids in foam-cell macrophages. cyPGs possessing an α,β-unsaturated cyclopentane ring are highly electrophilic substances able to promptly react with reactive cysteines of intracellular molecules through Michael addition. On the other hand, HMG-CoA reductase (HMGCR), the enzyme responsible for the rate-limiting step in cholesterol biosynthesis, presents critically reactive cysteines at the entry of catalytic domain, particularly Cys561, that could be target of cyPG inhibition. In the present study, we showed that cyPGs (but not other non-α,β-unsaturated PGs) physically interact with HMGCR, in a dithiothreitol- and β-mercaptoethanol-sensitive way, and block the activity of the catalytic subunit of the enzyme (IC₅₀ for PGA₂ = 0.17 μM). PGA₂ inhibits HMGCR activity in cultured rat and human macrophages/macrophage-foam cells and leads to enhanced expression of HMGCR protein, as observed with statins. In cell culture models, PGA₂ effectively inhibits the reductase at non-toxic doses (e.g., 1 μM) that block cell proliferation thus suggesting that part of the well-known antiproliferative effect of PGA₂ may be due to its ability of blocking HMGCR activity, as cells cannot proliferate without a robust cholesterogenesis. Therefore, besides the powerfully anti-inflammatory and antiproliferative effects, the anticholesterogenic effects of PGA₂ should be exploited in atherosclerosis therapeutics.

Oxidative and Cellular Stress Markers in Postmenopause Women with Diabetes: The Impact of Years of Menopause

Women live approximately one-third of their lives in postmenopause. Among postmenopausal women, type 2 diabetes mellitus (DM2) is one of the most prevalent chronic diseases. These conditions promote alterations in the oxidative, metabolic, and immune-inflammatory profiles marked by higher extracellular 72 kDa-heat shock protein (eHSP72). Here, we investigated whether the time of menopause is associated with oxidative cellular stress marker levels in postmenopausal women with DM2. Sixty-four women were recruited (56.7 ± 12.6 years old) in the pre- (n = 22) and postmenopause (n = 42) period, with (n = 19) or without DM2 (n = 45), and a fasting blood collection was made for the evaluation of metabolic, oxidative, and inflammatory markers. We found that menopause and DM2 influenced metabolic and oxidative parameters and presented synergistic effects on the plasma lipoperoxidation levels. Also, postmenopausal women had the highest eHSP72 concentration levels associated with the years in postmenopause. We conclude that the time of menopause impacts the markers of cellular stress and increases the risk of oxidative stress, mainly when it is associated with DM2.

Ovariectomy enhances female rats' susceptibility to metabolic, oxidative, and heat shock response effects induced by a high-fat diet and fine particulate matter

Obesity and exposure to fine particulate matter (air pollutant PM_2.5) are important risk factors for metabolic and cardiovascular diseases. They are also related to early menopause. The reduction of 17β-estradiol (E2) levels during female climacteric, marked by menopause, is of significant concern because of its imminent influence on metabolism, redox and inflammatory status. This complex homeostasis-threatening scenario may induce a heat shock response (HSR) in cells, enhancing the expression of the 70 kDa heat shock protein (HSP70). A failure in this mechanism could predispose women to cardiovascular diseases. In this study, we evaluated if the climacteric could represent an additional risk among obese rats exposed to PM_2.5 by worsening lipid, oxidative, and inflammatory parameters and HSP70 in cardiac tissue. We induced obesity in female Wistar rats using a high-fat diet (HFD) (58.3% as fats) and exposed them to 50 μL of saline 0.9% (control, n = 15) or 250 μg residual oil fly ash (ROFA, the inorganic portion of PM_2.5) (polluted, n = 15) by intranasal instillation, 5 days/w for 12 weeks. At the 12th week, we subdivided these animals into four groups: control (n = 6), OVX (n = 9), polluted (n = 6) and polluted + OVX (n = 9). OVX and polluted + OVX were submitted to a bilateral ovariectomy (OVX), a surgical model for menopause, while control and polluted received a false surgery (sham). ROFA exposure and HFD consumption were continued for 12 additional weeks, after which the animals were euthanized. ROFA enhanced the susceptibility to ovariectomy-induced dyslipidemia, while ovariectomy predisposed female rats to the ROFA-induced decrease of cardiac iHSP70 expression. Ovariectomy also decreased the IL-6 levels and IL-6/IL-10 in obese animals, reinforcing a metabolic impairment and a failure to respond to unfavorable conditions. Our results support the hypothesis that obese ovariectomized animals are predisposed to a metabolic worsening under polluted conditions and are at higher risk of cardiovascular diseases.

The association of subchronic exposure to low concentration of PM2.5 and high-fat diet potentiates glucose intolerance development, by impairing adipose tissue antioxidant defense and eHSP72 levels

The subchronic exposure to fine particulate matter (PM2.5) and high-fat diet (HFD) consumption lead to glucose intolerance by different mechanisms involving oxidative stress and inflammation. Under stressful conditions, the cells exert a heat shock response (HSR), by releasing the 72-kDa heat shock proteins (eHSP72), fundamental chaperones. The depletion of the HSR can exacerbate the chronic inflammation. However, there are few studies about the early effects of the association of HFD consumption and exposure to low concentrations of PM2.5 in the oxidative stress and HSR, in the genesis of glucose intolerance. Thus, we divided 23 male B6129SF2/J mice into control (n = 6), polluted (n = 6), HFD (n = 6), and high-fat diet + polluted (HFD + polluted) (n = 5) groups. Control and polluted received a standard diet (11.4% of fats), while HFD and HFD + polluted received HFD (58.3% of fats). Simultaneously, polluted and HFD + polluted received 5 μg/10 μL of PM2.5, daily, 7×/week, while control and HFD were exposed to 10 μL of saline solution 0.9% for 12 weeks. At the 12th week, animals were euthanized. We collected the metabolic tissues to analyze oxidative parameters, total blood to the hematological parameters, and plasma to eHSP72 measurement. The association of HFD and PM2.5 impaired glucose tolerance in the 12th week. Besides, it triggered an antioxidant defense by the adipose tissue, which was negatively correlated with eHSP72 levels. In conclusion, a low concentration of PM2.5 exposure associated with HFD consumption leads to glucose intolerance, by impairing adipose tissue antioxidant defense and systemic eHSP72 levels.

Suppressed anti-inflammatory heat shock response in high-risk COVID-19 patients: lessons from basic research (inclusive bats), light on conceivable therapies

The major risk factors to fatal outcome in COVID-19 patients, i.e., elderliness and pre-existing metabolic and cardiovascular diseases (CVD), share in common the characteristic of being chronic degenerative diseases of inflammatory nature associated with defective heat shock response (HSR). The molecular components of the HSR, the principal metabolic pathway leading to the physiological resolution of inflammation, is an anti-inflammatory biochemical pathway that involves molecular chaperones of the heat shock protein (HSP) family during homeostasis-threatening stressful situations (e.g., thermal, oxidative and metabolic stresses). The entry of SARS coronaviruses in target cells, on the other hand, aggravates the already-jeopardized HSR of this specific group of patients. In addition, cellular counterattack against virus involves interferon (IFN)-mediated inflammatory responses. Therefore, individuals with impaired HSR cannot resolve virus-induced inflammatory burst physiologically, being susceptible to exacerbated forms of inflammation, which leads to a fatal "cytokine storm". Interestingly, some species of bats that are natural reservoirs of zoonotic viruses, including SARS-CoV-2, possess an IFN-based antiviral inflammatory response perpetually activated but do not show any sign of disease or cytokine storm. This is possible because bats present a constitutive HSR that is by far (hundreds of times) more intense and rapid than that of human, being associated with a high core temperature. Similarly in humans, fever is a physiological inducer of HSR while antipyretics, which block the initial phase of inflammation, impair the resolution phase of inflammation through the HSR. These findings offer a rationale for the reevaluation of patient care and fever reduction in SARS, including COVID-19.

A single dose of eHSP72 attenuates sepsis severity in mice

High levels of extracellular 72 kDa heat shock protein (eHSP72) can be detected in the serum of septic patients and are associated with increased oxidative profiles and elevated rates of mortality among these patients. However, a possible immunomodulatory role for this protein, resulting in tissue protection during sepsis, has never been assessed. In this study, we investigated whether eHSP72 administration could attenuate the severity of sepsis in a mouse peritonitis model. Animals (90-day-old male C57BL/6J mice) were divided into Sepsis (n = 8) and Sepsis + eHSP72 (n = 9) groups, which both received injections of 20% fecal solution [1 mg/g body weight (wt), intraperitoneal (i.p.)], to trigger peritonitis induced-sepsis, whereas a Control group (n = 7) received a saline injection. eHSP72 was administered (1.33 ng/g body wt) to the Sepsis+eHSP72 group, 12 h after sepsis induction. All animals were evaluated for murine sepsis score (MSS), hemogram, core temperature, and glycemia (before and 4, 12, and 24 h after sepsis induction). Treatment with eHSP72 promoted reduced sepsis severity 24 h after sepsis induction, based on MSS scores (Control = 1.14 ± 1.02; Sepsis = 11.07 ± 7.24, and Sepsis + eHSP72 = 5.62 ± 1.72, P < 0.001) and core temperatures (°C; Control = 37.48 ± 0.58; Sepsis = 35.17 ± 2.88, and Sepsis + eHSP72 = 36.94 ± 2.02; P = 0.006). eHSP72 treatment also limited the oxidative profile and respiratory dysfunction in mice with sepsis. Although sepsis modified glycemic levels and white and red blood cell counts, these variables were not influenced by eHSP72 treatment (P > 0.05). Finally, eHSP72 improved the survival rate after sepsis (P = 0.0371). Together, our results indicated that eHSP72 may ameliorate sepsis severity and possibly improve some sepsis indices in mice.

Chronic heat treatment positively impacts metabolic profile of ovariectomized rats: association with heat shock response pathways

Low estrogen levels may predispose women to increased bodyweight and dyslipidemia. Previous studies from our laboratory suggest an involvement of depressed heat shock response (HSR) in this scenario because estrogen potently stimulates HSR. As heat treatment induces the expression of the anti-inflammatory heat shock proteins of the 70-kDa family (HSP70) and its accompanying HSR, we aimed to investigate whether chronic heat treatment promotes beneficial effects on biometric, lipid profile, oxidative stress, and HSR in ovariectomized rats. Wistar adult female rats (n = 32) were divided into four groups: control (C, n = 7), ovariectomized (OVX, n = 9), heat-treated (HT, n = 9), and heat-treated ovariectomized rats (OVX+HT, n = 7). HT and OVX+HT rats were anesthetized and submitted to heat treatment (once a week for 12 weeks) in a water bath (41 °C) to increase rats' rectal temperature up to 41 °C for 15 min, while C and OVX animals were submitted to a 36 °C water bath. HT attenuated the weight gain induced by OVX and increased HDL cholesterol and triglyceride serum levels. Also, OVX rats showed increased total cholesterol and LDL cholesterol levels that were not influenced by HT. Interestingly, it was found that an overall trend for HT to decrease tissue catalase and superoxide dismutase antioxidant activities was paralleled by a decrease in malondialdehyde levels (indicative of lower lipoperoxidation), especially in the skeletal muscle. Surprisingly, OVX was not able to depress intracellular HSP70 expression in the skeletal muscle, as expected, and this remained unchanged with HT. However, chronic HT did enhance intracellular HSP70 contents in white adipose tissue of OVX animals. As both glucose and insulin tolerance tests were not affected by OVX, which was not modified by HT, we suppose that estrogen absence alone is not sufficient to determine a state of insulin resistance associated with low intramuscular HSP70 content.

Heat shock response to exercise in pancreatic islets of obese mice

Chronic obesity imposes an organismal state of low-grade inflammation because the physiological resolution of inflammation is progressively repressed giving rise to cellular senescence and its accompanying Senescence-Associated Secretory Phenotype (SASP), which avoids apoptosis but perpetuates the relay of inflammatory signals from adipose tissue toward the rest of the body. Conversely, resolution of inflammation depends on the integrity of heat shock response (HSR) pathway that leads to the expression of cytoprotective and anti-inflammatory protein chaperones of the 70 kDa family (HSP70). However, chronic exposure to the aforementioned injuring factors leads to SASP, which, in turn, suppresses the HSR. A main metabolic tissue severely jeopardized by obesity-related dysfunctions is the endocrine pancreas, particularly β-cells of the islets of Langerhans. Because exercise is a powerful inducer of HSR and predicted to alleviate negative health outcomes of obesity, we sought whether obesity influence HSP70 expression in pancreatic islets and other metabolic tissues (adipose tissue and skeletal muscle) of adult B6.129SF2/J mice fed on a high-fat diet (HFD) for 13 weeks since the weaning and whether acute exercise as well as moderate-intensity exercise training (8 weeks) could interfere with this scenario. We showed that acute exercise of moderate intensity protects pancreatic islets against cytokine-induced cell death. In addition, acute exercise challenge time-dependently increased islet HSP70 that peaked at 12 h post-exercise in both trained and untrained mice fed on a control diet, suggesting an adequate HSR to exercise training. Unexpectedly, however, neither exercise training nor acute exercise challenges were able to increase islet HSP70 contents in trained mice submitted to HFD, but only in untrained HFD animals. In parallel, HFD disrupted glycemic status which is accompanied by loss of muscular mass resembling sarcopenic obesity that could not be rescued by exercise training. These results suggest that exercise influences HSR in pancreatic islets but obesity undermines islet, muscle and adipose tissue HSR, which is associated with metabolic abnormalities observed in such tissues.

Ovariectomy predisposes female rats to fine particulate matter exposure's effects by altering metabolic, oxidative, pro-inflammatory, and heat-shock protein levels

The reduction of estrogen levels, as a result of menopause, is associated with the development of metabolic diseases caused by alterations in oxidative stress (OS), inflammatory biomarkers, and 70-kDa heat-shock protein (HSP70) expression. Additionally, exposure to fine particulate matter air pollution modifies liver OS levels and predisposes organisms to metabolic diseases, such as type 2 diabetes (T2DM). We investigated whether ovariectomy affects hepatic tissue and alters glucose metabolism in female rats exposed to particulate air pollution. First, 24 female Wistar rats received an intranasal instillation of saline or particles suspended in saline 5 times per week for 12 weeks. The animals then received either bilateral ovariectomy (OVX) or false surgery (sham) and continued to receive saline or particles for 12 additional weeks, comprising four groups: CTRL, Polluted, OVX, and Polluted+OVX. Ovariectomy increased body weight and adiposity and promoted edema in hepatic tissue, hypercholesterolemia, glucose intolerance, and a pro-inflammatory profile (reduced IL-10 levels and increased IL-6/IL-10 ratio levels), independent of particle exposure. The Polluted+OVX group showed an increase in neutrophils and neutrophil/lymphocyte ratios, decreased antioxidant defense (SOD activity), and increased liver iHSP70 levels. In conclusion, alterations in the reproductive system predispose female organisms to particulate matter air pollution effects by affecting metabolic, oxidative, pro-inflammatory, and heat-shock protein expression.

Detectable levels of eHSP72 in plasma are associated with physical activity and antioxidant enzyme activity levels in hypertensive subjects

Previous studies reported that extracellular HSP72 (eHSP72) correlates with poor prognosis, markers of vascular dysfunction, and the severity of cardiovascular diseases, associated with a systemic oxidative and inflammatory profile. On the other hand, eHSP72 may represent immune-regulatory signaling that is related to exercise benefits, but the association between physical activity levels and eHSP72 levels is not established. Thus, since regular physical activity may avoid oxidative stress and inflammation, we investigate whether detectable levels of eHSP72 in plasma are associated with physical activity and antioxidant enzyme activity levels in hypertensive subjects. Physical activity levels of hypertensive subjects (n = 140) were measured by tri-axial movement sensor pedometer for 24 h during 5 consecutive days. One day after, blood was collected into heparinized tubes for oxidative stress analyses (catalase-CAT and superoxide dismutase-SOD activities and malondialdehyde levels) or in disodium EDTA tubes for eHSP72 assays. Thus, hypertensive subjects were classified as physically inactive (< 10,000 footsteps/day) or active (> than 10,000 footsteps/day) and according detectable or not detectable eHSP72 levels in plasma, performing the inactive/eHSP72-, active/eHSP72-, inactive/eHSP72+, and active/eHSP72+ groups. We found that detectable levels of eHSP72 in plasma were associated with physical activity levels and low oxidative stress profile (Higher CAT and SOD activities and low malondialdehyde levels). eHSP72 levels can be used as a biomarker of the amount of physical activity necessary to improve antioxidant defense and thus cardiovascular health in hypertensive subjects.

Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review

Introduction

Many health benefits are claimed by individuals and facilities promoting sauna bathing; however the medical evidence to support these claims is not well established. This paper aims to systematically review recent research on the effects of repeated dry sauna interventions on human health.

Methods

A systematic search was made of medical databases for studies reporting on the health effects of regular dry sauna bathing on humans from 2000 onwards. Risk of bias was assessed according to the Cochrane Collaboration guidelines.

Results

Forty clinical studies involving a total of 3855 participants met the inclusion criteria. Only 13 studies were randomized controlled trials and most studies were small (n < 40). Reported outcome measures were heterogeneous with most studies reporting beneficial health effects. Only one small study (n = 10) reported an adverse health outcome of disrupted male spermatogenesis, demonstrated to be reversible when ceasing sauna activity.

Conclusions

Regular dry sauna bathing has potential health benefits. More data of higher quality is needed on the frequency and extent of adverse side effects. Further study is also needed to determine the optimal frequency and duration of distinct types of sauna bathing for targeted health effects and the specific clinical populations who are most likely to benefit.

Exercise Training under Exposure to Low Levels of Fine Particulate Matter: Effects on Heart Oxidative Stress and Extra-to-Intracellular HSP70 Ratio

Fine particulate matter (PM_2.5) promotes heart oxidative stress (OS) and evokes anti-inflammatory responses observed by increased intracellular 70 kDa heat shock proteins (iHSP70). Furthermore, PM_2.5 increases the levels of these proteins in extracellular fluids (eHSP70), which have proinflammatory roles. We investigated whether moderate and high intensity training under exposure to low levels of PM_2.5 modifies heart OS and the eHSP70 to iHSP70 ratio (H-index), a biomarker of inflammatory status. Male mice (n = 32), 30 days old, were divided into six groups for 12 weeks: control (CON), moderate (MIT) and high intensity training (HIT), exposure to 5 μg of PM_2.5 daily (PM_2.5), and moderate and high intensity training exposed to PM_2.5 (MIT + PM_2.5 and HIT + PM_2.5 groups). The CON and PM_2.5 groups remained sedentary. The MIT + PM_2.5 group showed higher heart lipid peroxidation levels than the MIT and PM_2.5 groups. HIT and HIT + PM_2.5 showed higher heart lipid peroxidation levels and lower eHSP70 and H-index levels compared to sedentary animals. No alterations were found in heart antioxidant enzyme activity or iHSP70 levels. Moderate exercise training under exposure to low levels of PM_2.5 induces heart OS but does not modify eHSP70 to iHSP70 ratio (H-index). High intensity exercise training promotes anti-inflammatory profile despite exposure to low levels of PM_2.5.