Heat stress induces apoptosis through transcription-independent p53-mediated mitochondrial pathways in human umbilical vein endothelial cell

Technical pitfalls when collecting, cryopreserving, thawing, and stimulating human T-cells

The collection, cryopreservation, thawing, and culture of peripheral blood mononuclear cells (PBMCs) can profoundly influence T cell viability and immunogenicity. Gold-standard PBMC processing protocols have been developed by the Office of HIV/AIDS Network Coordination (HANC); however, these protocols are not universally observed. Herein, we have explored the current literature assessing how technical variation during PBMC processing can influence cellular viability and T cell immunogenicity, noting inconsistent findings between many of these studies. Amid the mounting concerns over scientific replicability, there is growing acknowledgement that improved methodological rigour and transparent reporting is required to facilitate independent reproducibility. This review highlights that in human T cell studies, this entails adopting stringent standardised operating procedures (SOPs) for PBMC processing. We specifically propose the use of HANC's Cross-Network PBMC Processing SOP, when collecting and cryopreserving PBMCs, and the HANC member network International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) PBMC Thawing SOP when thawing PBMCs. These stringent and detailed protocols include comprehensive reporting procedures to document unavoidable technical variations, such as delayed processing times. Additionally, we make further standardisation and reporting recommendations to minimise and document variability during this critical experimental period. This review provides a detailed overview of the challenges inherent to a procedure often considered routine, highlighting the importance of carefully considering each aspect of SOPs for PBMC collection, cryopreservation, thawing, and culture to ensure accurate interpretation and comparison between studies.

"Unravelling the impacts of climatic heat events on cardiovascular health in animal models"

Climate change has led to an increase in high ambient temperatures, causing extreme heat events worldwide. According to the World Meteorological Organization (WMO), July 2023 marked a historic milestone as the Earth reached its hottest recorded temperature, precisely hitting the critical threshold of 1.5 °C set by the Paris Agreement. This distressing development led to a stark warning from the United Nations, signaling the dawn of what they call "an era of global boiling". The increasing global temperatures can result in high heat stress which leads to various physiological and biochemical alterations in the human body. Given that cardiovascular diseases (CVDs) are a leading cause of morbidity and mortality globally, heat events exacerbate this public health issue. While clinical and in-vitro studies have suggested a range of pathophysiological and biochemical mechanisms underlying the body's response to heat stress, the complex nature of organ-system level interactions makes precise investigation challenging. To address this knowledge gap effectively, the use of animal models exposed to acute or chronic heat stress can be invaluable. These models can closely replicate the multifaceted effects observed in humans during heat stress conditions. Despite extensive independent reviews, limited focus has been shed on the high heat-induced cardiovascular complications and their mechanisms, particularly utilizing animal models. Therefore, in this comprehensive review, we highlight the crucial biomarkers altered during heat stress, contributing significantly to various CVDs. We explore potential mechanisms underlying heat-induced cardiovascular dysfunction and damage, delving into various animal models. While traditional rodent models are commonly employed, we also examine less conventional models, including ruminants, broilers, canines, and primates. Furthermore, we delve into various potential therapeutic approaches and preventive measures. These insights hold significant promise for the development of more effective clinical interventions against the effects of heat stress on the human cardiovascular system.

DNAJA1‑knockout alleviates heat stroke‑induced endothelial barrier disruption via improving thermal tolerance and suppressing the MLCK‑MLC signaling pathway

Endothelial barrier disruption plays a key role in the pathophysiology of heat stroke (HS). Knockout of DNAJA1 (DNAJA1‑KO) is thought to be protective against HS based on a genome‑wide CRISPR‑Cas9 screen experiment. The present study aimed to illustrate the function of DNAJA1‑KO against HS in human umbilical vein endothelial cells. DNAJA1‑KO cells were infected using a lentivirus to investigate the role of DNAJA1‑KO in HS‑induced endothelial barrier disruption. It was shown that DNAJA1‑KO could ameliorate decreased cell viability and increased cell injury, according to the results of Cell Counting Kit‑8 and lactate dehydrogenase assays. Moreover, HS‑induced endothelial cell apoptosis was inhibited by DNAJA1‑KO, as indicated by Annexin V‑FITC/PI staining and cleaved‑caspase‑3 expression using flow cytometry and western blotting, respectively. Furthermore, the endothelial barrier function, as measured by transepithelial electrical resistance and FITC‑Dextran, was sustained during HS. DNAJA1‑KO was not found to have a significant effect on the expression and distribution of cell junction proteins under normal conditions without HS. However, DNAJA1‑KO could effectively protect the HS‑induced decrease in the expression and distribution of cell junction proteins, including zonula occludens‑1, claudin‑5, junctional adhesion molecule A and occludin. A total of 4,394 proteins were identified using proteomic analysis, of which 102 differentially expressed proteins (DEPs) were activated in HS‑induced wild‑type cells and inhibited by DNAJA1‑KO. DEPs were investigated by enrichment analysis, which demonstrated significant enrichment in the 'calcium signaling pathway' and associations with vascular‑barrier regulation. Furthermore, the 'myosin light‑chain kinase (MLCK)‑MLC signaling pathway' was proven to be activated by HS and inhibited by DNAJA1‑KO, as expected. Moreover, DNAJA1‑KO mice and a HS mouse model were established to demonstrate the protective effects on endothelial barrier in vivo. In conclusion, the results of the present study suggested that DNAJA1‑KO alleviates HS‑induced endothelial barrier disruption by improving thermal tolerance and suppressing the MLCK‑MLC signaling pathway.

Thromboinflammation and microcirculation damage in heatstroke

Rising temperatures associated with climate change have significantly increased the risk of heatstroke. Unfortunately, the trend is anticipated to persist and increasingly threaten vulnerable populations, particularly older adults. According to Japan's environment ministry, over 1000 people died from heatstroke in 2021, and 86% of deaths occurred in those above 65. Since the precise mechanism of heatstroke is not fully understood, we examined the pathophysiology by focusing on the microcirculatory derangement. Online search of published medical literature through MEDLINE and Web of Science using the term "heatstroke," "heat-related illness," "inflammation," "thrombosis," "coagulation," "fibrinolysis," "endothelial cell," and "circulation." Articles were chosen for inclusion based on their relevance to heatstroke, inflammation, and thrombosis. Reference lists were reviewed to identify additional relevant articles. Other than preexisting conditions (genetic background, age, etc.), factors such as hydration status, acclimatization, dysregulated coagulation, and inflammation are the additional major factors that promote tissue malcirculation in heatstroke. The fundamental pathophysiologic mechanisms significantly overlap with those seen in the systemic inflammatory response to sepsis, and as a result, coagulation-predominant coagulopathy develops during heat stress. Although a bleeding tendency is not common, bleeding frequently occurs in the microcirculation, causing additional injury. Sterile inflammation is mediated by proinflammatory cytokines, chemokines, and other humoral mediators in concert with cellular factors, including monocytes, neutrophils, platelets, and endothelial cells. Excess inflammation results in inflammatory cell death, including pyroptosis and necroptosis, and the release of danger signals that further propagate systemic inflammation and coagulopathy. Consequently, thromboinflammation is the critical factor that induces microcirculatory disturbance in heatstroke.

Hyperthermia-induced changes in leukocyte survival and phagocytosis: a comparative study in bovine and buffalo leukocytes

Heat stress negatively affects health, welfare, and livestock productivity by impairing immune function, increasing disease incidence. In recent years, there has been increasing interest in understanding the immune system of water buffalo due to the growing economic impact of this species for the high quality and nutritional value of buffalo milk. While there are common responses across bovine and buffalo species, there are also some species-specific variations in the physiological responses to heat stress, mainly attributed to differences in metabolism and heat dissipation efficiency. At cellular level, the exposure to thermal stress induces several anomalies in cell functions. However, there is limited knowledge about the differential response of bovine and buffalo leucocytes to early and late exposure to different degrees of thermal exposure. The aim of this study was to compare the in vitro effect of hyperthermia on apoptosis and phagocytosis in leukocytes from bovine and buffalo species. For this, whole blood samples of six bovines and nine buffaloes were incubated at 39°C (mimicking normothermia condition) or 41°C (mimicking heat stress condition) for 1, 2, and 4 h. Two flow cytometric assays were then performed to evaluate apoptosis and determine functional capacity of phagocytic cells (neutrophils and monocytes). The results showed that the viability of bovine and buffalo leukocytes was differently affected by temperature and time of in vitro exposure. A higher percentage of apoptotic leukocytes was observed in bovines than in buffaloes at 39°C (3.19 vs. 1.51, p < 0.05) and 41°C (4.01 vs. 1.69, p < 0.05) and for all incubation time points (p < 0.05). In contrast, no difference was observed in the fraction of necrotic leukocytes between the two species. In both species, lymphocytes showed the highest sensitivity to hyperthermia, showing an increased apoptosis rates along with increased incubation time. In bovine, apoptotic lymphocytes increased from 5.79 to 12.7% at 39°C (p < 0.05), in buffalo, this population increased from 1.50 to 3.57% at 39°C and from 2.90 to 4.99% at 41°C (p < 0.05). Although no significant differences were found between the two species regarding the percentage of phagocytic neutrophils, lower phagocytosis capacity values (MFI, mean fluorescence intensity) were found in bovines compared with buffaloes at 41°C (27960.72 vs. 53676.45, p > 0.05). However, for monocytes, the differences between species were significant for both phagocytosis activity and capacity with lower percentages of bovine phagocytic monocytes after 2 h at 39°C and after 1 h at 41°C. The bovine monocytes showed lower MFI values for all temperature and time variations than buffaloes (37538.91 vs. 90445.47 at 39°C and 33752.91 vs. 70278.79 at 41°C, p < 0.05). In conclusion, the current study represents the first report on the comparative analysis of the effect of in vitro heat stress on bovine and buffalo leukocyte populations, highlighting that the leukocytes of buffalo exhibit relatively higher thermal adaptation than bovine cells.

Role of intrinsic apoptosis in environmental exposure health outcomes

Environmental exposures are linked to diseases of high public health concern, including cancer, neurodegenerative disorders, and autoimmunity. These diseases are caused by excessive or insufficient cell death, prompting investigation of mechanistic links between environmental toxicants and dysregulation of cell death pathways, including apoptosis. This review describes how legacy and emerging environmental exposures target the intrinsic apoptosis pathway to potentially drive pathogenesis. Recent discoveries reveal that dynamic regulation of apoptosis may heighten the vulnerability of healthy tissues to exposures in children, and that apoptotic signaling can guide immune responses, tissue repair, and tumorigenesis. Understanding how environmental toxicants dysregulate apoptosis will uncover opportunities to deploy apoptosis-modulating agents for the treatment or prevention of exposure-linked diseases.

Insect Peptide CopA3 Mitigates the Effects of Heat Stress on Porcine Muscle Satellite Cells

Heat stress inhibits cell proliferation as well as animal production. Here, we aimed to demonstrate that 9-mer disulfide dimer peptide (CopA3) supplementation stabilizes porcine muscle satellite cell (PMSC) proliferation and heat shock protein (HSP) expression at different temperatures. Therefore, we investigated the beneficial effects of CopA3 on PMSCs at three different temperatures (37, 39, and 41 °C). Based on temperature and CopA3 treatment, PMSCs were divided into six different groups including treatment and control groups for each temperature. Cell viability was highest with 10 µg/mL CopA3 and decreased as the concentration increased in a dose-dependent manner. CopA3 significantly increased the cell viability at all temperatures at 24 and 48 h. It significantly decreased apoptosis compared to that in the untreated groups. In addition, it decreased the apoptosis-related protein, Bcl-2-associated X (BAX), expression at 41 °C. Notably, temperature and CopA3 had no effects on the apoptosis-related protein, caspase 3. Expression levels of HSP40, HSP70, and HSP90 were significantly upregulated, whereas those of HSP47 and HSP60 were not affected by temperature changes. Except HSP90, CopA3 did not cause temperature-dependent changes in protein expression. Therefore, CopA3 promotes cell proliferation, inhibits apoptosis, and maintains stable HSP expression, thereby enhancing the heat-stress-tolerance capacity of PMSCs.

Identification of genes associated with abiotic stress tolerance in sweetpotato using weighted gene co-expression network analysis

Sweetpotato, Ipomoea batatas (L.), a key food security crop, is negatively impacted by heat, drought, and salinity stress. The orange-fleshed sweetpotato cultivar "Beauregard" was exposed to heat, salt, and drought treatments for 24 and 48 h to identify genes responding to each stress condition in leaves. Analysis revealed both common (35 up regulated, 259 down regulated genes in the three stress conditions) and unique sets of up regulated (1337 genes by drought, 516 genes by heat, and 97 genes by salt stress) and down regulated (2445 genes by drought, 678 genes by heat, and 204 genes by salt stress) differentially expressed genes (DEGs) suggesting common, yet stress-specific transcriptional responses to these three abiotic stressors. Gene Ontology analysis of down regulated DEGs common to both heat and salt stress revealed enrichment of terms associated with "cell population proliferation" suggestive of an impact on the cell cycle by the two stress conditions. To identify shared and unique gene co-expression networks under multiple abiotic stress conditions, weighted gene co-expression network analysis was performed using gene expression profiles from heat, salt, and drought stress treated 'Beauregard' leaves yielding 18 co-expression modules. One module was enriched for "response to water deprivation," "response to abscisic acid," and "nitrate transport" indicating synergetic crosstalk between nitrogen, water, and phytohormones with genes encoding osmotin, cell expansion, and cell wall modification proteins present as key hub genes in this drought-associated module. This research lays the groundwork for exploring to a further degree, mechanisms for abiotic stress tolerance in sweetpotato.

Heat stress combined with lipopolysaccharide induces pulmonary microvascular endothelial cell glycocalyx inflammatory damage in vitro

Heat stroke is a life-threatening disease with high mortality and complications. Endothelial glycocalyx (EGCX) is essential for maintaining endothelial cell structure and function as well as preventing the adhesion of inflammatory cells. Potential relationship that underlies the imbalance in inflammation and coagulation remains elusive. Moreover, the role of EGCX in heat stroke-induced organ injury remained unclear. Therefore, the current study aimed to illustrate if EGCX aggravates apoptosis, inflammation, and oxidative damage in human pulmonary microvascular endothelial cells (HPMEC). Heat stress and lipopolysaccharide (LPS) were employed to construct in vitro models to study the changes of glycocalyx structure and function, as well as levels of heparansulfate proteoglycan (HSPG), syndecan-1 (SDC-1), heparansulfate (HS), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, Von Willebrand factor (vWF), endothelin-1 (ET-1), occludin, E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and reactive oxygen species (ROS). Here, we showed that heat stress and LPS devastated EGCX structure, activated EGCX degradation, and triggered oxidative damage and apoptosis in HPMEC. Stimulation of heat stress and LPS decreased expression of HSPG, increased levels of SDC-1 and HS in culture supernatant, promoted the production and release of proinflammation cytokines (TNF-α and IL-6,) and coagulative factors (vWF and ET-1) in HPMEC. Furthermore, Expressions of E-selection, VCAM-1, and ROS were upregulated, while that of occludin was downregulated. These changes could be deteriorated by heparanase, whereas they meliorated by unfractionated heparin. This study indicated that EGCX may contribute to apoptosis and heat stroke-induced coagulopathy, and these effects may have been due to the decrease in the shedding of EGCX.

Heat stress-induced intestinal epithelial cells necroptosis via TLR3-TRIF-RIP3 pathway was dependent on p53

BACKGROUND

Heatstroke is a life-threatening disease. Present study was aimed to investigate the mechanism in heat induced intestinal epithelial cell death.

METHOD

Heat stress in vitro model was established on IEC cells with 42℃ for 2 h. Caspase-8 inhibitor, Caspase-3 inhibitor, RIP3 inhibitor, TLR3 agonist, poly(I:C) and p53 knockdown were used to determine the signaling pathway. Heatstroke in vivo model was established on C57BL/6 mice, with a temperature of 35.5℃±0.5℃ and a relative humidity of 60% ± 5%. The intestine necroptosis and inflammatory cytokines were measured. Pifithrin α (3 mg/kg) and p53 knockout mice were used to evaluate the role of p53.

RESULTS

Heat stress-induced reduction of cell viability was remarkable reversed by RIP3 inhibitor. Heat stress induced upregulation of TLR3 and facilitate the formation of TRIF-RIP3 complex. The heat stress induced upregulation of RIP3 and p-RIP3 were normalized by the deletion of p53. Meanwhile, p53 knockout decreased TLR3 expression and blocked the formation of TLR3-TRIF complex. The deletion of p53 blocked the decreased cell viability and restored the activation of RIP3-MLKL signaling after heat stress, however, which were abolished by re-expression of p53 via Tp53 OE. Increased the expression of TLR3 in the p53-deficient cells could not affect the heat stress induced necrotic cell death, which suggests that heat stress induced necroptosis via TLR3-TRIF-RIP3 signaling pathway is dependent on p53.

CONCLUSION

Heat stress promoted p53 phosphorylation, then upregulated TLR3 and enhanced the interaction of TRIF-RIP3, which would activate the RIP3-MLKL signaling pathway to mediate necroptosis in intestinal epithelial cells.

Blood Transcriptomic Analyses Reveal Functional Pathways Associated with Thermotolerance in Pregnant Ewes Exposed to Environmental Heat Stress

Environmental heat stress triggers a series of compensatory mechanisms in sheep that are dependent on their genetic regulation of thermotolerance. Our objective was to identify genes and regulatory pathways associated with thermotolerance in ewes exposed to heat stress. We performed next-generation RNA sequencing on blood collected from 16 pregnant ewes, which were grouped as tolerant and non-tolerant to heat stress according to a physiological indicator. Additional samples were collected to measure complete blood count. A total of 358 differentially expressed genes were identified after applying selection criteria. Gene expression analysis detected 46 GO terms and 52 KEGG functional pathways. The top-three signaling pathways were p53, RIG-I-like receptor and FoxO, which suggested gene participation in biological processes such as apoptosis, cell signaling and immune response to external stressors. Network analysis revealed ATM, ISG15, IRF7, MDM4, DHX58 and TGFβR1 as over-expressed genes with high regulatory potential. A co-expression network involving the immune-related genes ISG15, IRF7 and DXH58 was detected in lymphocytes and monocytes, which was consistent with hematological findings. In conclusion, transcriptomic analysis revealed a non-viral immune mechanism involving apoptosis, which is induced by external stressors and appears to play an important role in the molecular regulation of heat stress tolerance in ewes.

Effects of Cooling Interventions with Different Target Temperatures on Heat Stroke Rats

Purpose

To investigate the optimal target temperature of cooling intervention in heat stroke (HS) rats and explore the potential mechanisms of cooling intervention in alleviating heat stroke-induced damage.

Materials and Methods

A total of 32 Sprague-Dawley rats were randomly divided into 4 groups (n=8/group), including control, HS[core body temperature (Tc)], HS(Tc-1°C) and HS(Tc+1°C) group. Heat stroke model was established in rats of HS(Tc), HS(Tc-1°C) and HS(Tc+1°C) group. Rats in HS(Tc) group were cooled to baseline core body temperature after establishing heat stroke model, HS(Tc-1°C) group to baseline core body temperature minus 1°C and HS(Tc+1°C) group to baseline core body temperature plus 1°C. We compared the histopathological changes of lung, liver and renal tissue, as well as cell apoptosis and expression of critical proteins in phosphatidylinositol 3´-kinase (PI3K)/Akt signaling pathway.

Results

Heat stroke caused the histopathological damage and cell apoptosis of lung, liver and renal tissue, which could be alleviated by cooling intervention to a certain extent. Notably, HS(Tc+1°C) group demonstrated a better effect on alleviating cell apoptosis although the differences were not significant. Heat stroke lead to the elevated expression of p-Akt, which subsequently induced the elevated expression of Caspase-3 and Bax, as well as the decreased expression of Bcl-2. Cooling intervention could reverse this trend. Notably, the expression level of Bax in lung tissue of HS(Tc+1°C) group was significantly lower than that of HS(Tc) and HS(Tc-1°C) group.

Conclusion

The mechanisms of cooling intervention in alleviating heat stroke-induced damage were associated with the expression changes of p-Akt, Caspase-3, Bax and Bcl-2. The better effect of Tc+1°C might be associated with low expression of Bax.

A Comparative Evaluation of the Genotoxic Effects of Mobile Phone Radiation Using Buccal Micronucleus Assay

Statement of the Problem

Mobile usage has increased worldwide over the past two decades. There are conflicting reports about the carcinogenic effects of cell phone radiation on the oral mucosa. Micronucleus (MN) is considered a reliable marker for genotoxic damage.

Purpose

This study aimed to identify the impact of mobile phone radiation on the MN frequency in oral mucosal cells.

Materials and Method

In this descriptive-analytical study, 50 mobile phone users between the age group of 20-38 years were included. Samples were obtained from the right and left cheek mucosa of each subject (a total 100 cell samples). Every participant filled out a questionnaire about his or her cell phone usage habits. Additionally, personal information such as age, gender, and body mass index (BMI) were assessed. The Feulgen and Papanicolaou staining methods were used for staining of the cell samples. A total of 1000 cells in each sample were evaluated for MNs.

Results

The mean number of MN in exposed and non-exposed mucosa by Feulgen method was 0.71±1.13 and 0.57±1.36, respectively. Also in Papanicolaou staining, the mean number of MN in the exposed mucosa and non-exposed mucosa was 6.94±6.61 and 6.54±6.88, respectively, but these differences were not significant (p> 0.05). The frequency of MN in non-specific DNA staining was significantly (5- to 6-fold) higher than DNA-specific staining. We observed no statically significant differences between MN frequency according to age, gender, BMI, and other cell phone usage habits (p> 0.05).

Conclusion

This study showed that cell phone use does not cause genotoxic effects in the buccal mucosa in the oral cavity. Moreover, using non-specific DNA staining methods can increase the frequency of MN by more than 5- to 6-fold.

Inflammation, coagulation, and cellular injury in heat-induced shock

BACKGROUND

The number of heatstroke victims hit record numbers in 2022 as global warming continues. In heat-induced injuries, circulatory shock is the most severe and deadly complication. This review aims to examine the mechanisms and potential approaches to heat-induced shock and the life-threatening complications of heatstroke.

METHODS

A computer-based online search was performed using the PubMed database and Web of Science database for published articles concerning heatstroke, shock, inflammation, coagulopathy, endothelial cell, cell death, and heat shock proteins.

RESULTS

Dehydration and heat-induced cardiomyopathy were reported as the major causes of heat-induced shock, although other heat-induced injuries are also involved in the pathogenesis of circulatory shock. In addition to dehydration, the blood volume decreases considerably due to the increased vascular permeability as a consequence of endothelial damage. Systemic inflammation is induced by factors that include elevated cytokine and chemokine levels, dysregulated coagulation/fibrinolytic responses, and the release of damage-associated molecular patterns (DAMPs) from necrotic cell death that cause distributive shock. The cytoprotective heat shock proteins can also facilitate circulatory disturbance under excess heat stress.

CONCLUSIONS

Multiple mechanisms are involved in the pathogenesis of heat-induced shock. In addition to dehydration, heat stress-induced cardiomyopathy due to the thermal damage of mitochondria, upregulated inflammation via damage-associated molecular patterns released from oncotic cells, unbalanced coagulation/fibrinolysis, and endothelial damage are the major factors that are related to circulatory shock.

High-Intensity Focused Ultrasound Decreases Subcutaneous Fat Tissue Thickness by Increasing Apoptosis and Autophagy

High-intensity focused ultrasound (HIFU) leads to decreased subcutaneous adipose tissue (SAT) thickness via heat-induced adipocyte necrosis. Heat can induce adipocyte apoptosis and autophagy, and it is known that nuclear or mitochondrial p53 is involved in apoptosis and autophagy. However, whether HIFU leads to apoptosis or autophagy is unclear. We evaluated whether HIFU decreases SAT thickness via p53-related apoptosis or autophagy in high-fat diet (HFD)-fed animals. The expression of nuclear and mitochondrial p53 was increased by HIFU. HIFU also led to decreased expression of BCL2/BCL-xL (an antiapoptotic signal), increased expression of BAX/BAK (an apoptotic signal), increased levels of cleaved caspase 3/9, and increased numbers of apoptotic cells as evaluated by TUNEL assay. Furthermore, HIFU led to increased levels of ATG5, BECN1, and LC3II/LC3I, and decreased levels of p62, a marker of increased autophagy. The thickness of SAT was decreased by HIFU. In conclusion, HIFU led to nuclear and mitochondrial p53 expression, which led to apoptosis and autophagy, and eventually decreased SAT thickness in HFD-fed animals.

Effect of Heat Stress on Hippocampal Neurogenesis: Insights into the Cellular and Molecular Basis of Neuroinflammation-Induced Deficits

Heat stress is known to result in neuroinflammation, neuronal damage, and disabilities in learning and memory in animals and humans. It has previously been reported that cognitive impairment caused by neuroinflammation may at least in part be mediated by defective hippocampal neurogenesis, and defective neurogenesis has been linked to aberrantly activated microglial cells. Moreover, the release of cytokines within the brain has been shown to contribute to the disruption of cognitive functions in several conditions following neuroinflammation. In this review, we summarize evolving evidence for the current understanding of inflammation-induced deficits in hippocampal neurogenesis, and the resulting behavioral impairments after heat stress. Furthermore, we provide valuable insights into the molecular and cellular mechanisms underlying neuroinflammation-induced deficits in hippocampal neurogenesis, particularly relating to cognitive dysfunction following heat stress. Lastly, we aim to identify potential mechanisms through which neuroinflammation induces cognitive dysfunction, and elucidate how neuroinflammation contributes to defective hippocampal neurogenesis. This review may therefore help to better understand the relationship between hippocampal neurogenesis and heat stress.

COPA3 peptide supplementation alleviates the heat stress of chicken fibroblasts

Heat stress inhibits cellular proliferation and differentiation through the production of reactive oxygen species. Under stress conditions, antioxidant drugs promote stable cellular function by reducing the stress level. We sought to demonstrate 9-mer disulfide dimer peptide (COPA3) supplementation stabilizes fibroblast proliferation and differentiation even under heat stress conditions. In our study, fibroblasts were assigned to two different groups based on the temperature, like 38°C group presented as Control - and 43°C group presented as Heat Stress-. Each group was subdivided into two groups depending upon COPA3 treatment, like 38°C + COPA3 group symbolized Control+ and the 43°C + COPA3 group symbolized as Heat Stress+. Heat stress was observed to decrease the fibroblast viability and function and resulted in alterations in the fibroblast shape and cytoskeleton structure. In contrast, COPA3 stabilized the fibroblast viability, shape, and function. Moreover, heat stress and COPA3 were found to have opposite actions with respect to energy production, which facilitates the stabilization of cellular functions by increasing the heat tolerance capacity. The gene expression levels of antioxidant and heat shock proteins were higher after heat stress. Additionally, heat stress promotes the mitogen-activated protein kinase/ extracellular signal-regulated kinase-nuclear factor erythroid 2-related factor 2 (MAPK/ERK-Nrf2). COPA3 maintained the MAPK/ERK-Nrf2 gene expressions that promote stable fibroblast proliferation, and differentiation as well as suppress apoptosis. These findings suggest that COPA3 supplementation increases the heat tolerance capacity, viability, and functional activity of fibroblasts.

The pathogenesis and therapeutic strategies of heat stroke-induced liver injury

Heat stroke (HS) is a life-threatening systemic disease characterized by an elevated core body temperature of more than 40 ℃ and subsequent multiple organ dysfunction syndrome. With the growing frequency of global heatwaves, the incidence rate of HS has increased significantly, which has caused a huge burden on people's lives and health. Liver injury is a well-documented complication of HS and usually constitutes the direct cause of patient death. In recent years, a lot of research has been carried out on the pathogenesis and treatment strategies of HS-induced liver injury. In this review, we summarized the important pathogenesis of HS-induced liver injury that has been confirmed so far. In addition to the comprehensive effect of systemic factors such as heat cytotoxicity, coagulopathy, and systemic inflammatory response syndrome, excessive hepatocyte cell pyroptosis, dysfunction of Kupffer cells, abnormal expression of heat shock protein expression, and other factors are also involved in the pathogenesis of HS-induced liver injury. Furthermore, we have also established the current therapeutic strategies for HS-induced liver injury. Our study is of great significance in promoting the understanding of the pathogenesis and treatment of HS-induced liver injury.

Non-pharmacological interventions for vascular health and the role of the endothelium

The most common non-pharmacological intervention for both peripheral and cerebral vascular health is regular physical activity (e.g., exercise training), which improves function across a range of exercise intensities and modalities. Numerous non-exercising approaches have also been suggested to improved vascular function, including repeated ischemic preconditioning (IPC); heat therapy such as hot water bathing and sauna; and pneumatic compression. Chronic adaptive responses have been observed across a number of these approaches, yet the precise mechanisms that underlie these effects in humans are not fully understood. Acute increases in blood flow and circulating signalling factors that induce responses in endothelial function are likely to be key moderators driving these adaptations. While the impact on circulating factors and environmental mechanisms for adaptation may vary between approaches, in essence, they all centre around acutely elevating blood flow throughout the circulation and stimulating improved endothelium-dependent vascular function and ultimately vascular health. Here, we review our current understanding of the mechanisms driving endothelial adaptation to repeated exposure to elevated blood flow, and the interplay between this response and changes in circulating factors. In addition, we will consider the limitations in our current knowledge base and how these may be best addressed through the selection of more physiologically relevant experimental models and research. Ultimately, improving our understanding of the unique impact that non-pharmacological interventions have on the vasculature will allow us to develop superior strategies to tackle declining vascular function across the lifespan, prevent avoidable vascular-related disease, and alleviate dependency on drug-based interventions.

Protective Effect of Manganese on Apoptosis and Mitochondrial Function of Heat-Stressed Primary Chick Embryonic Myocardial Cells

Heat stress, as a kind of oxidative stress, induces cell apoptosis. Apoptosis is a form of programmed cell death, and mitochondria play an important role in apoptosis. Manganese (Mn) has an antioxidant capacity by enhancing the activity of manganese superoxide dismutase (MnSOD). To investigate the potential effect of Mn on heat stress-induced apoptosis and mitochondrial function, we examined crucial related factors in the context of heat stress using primary chick embryonic myocardial cells pretreated with Mn for 24 h. The results showed that Mn restored the heat stress-induced decrease in cell viability and reduced the activities of caspase-3 (P < 0.05). The repression of the Δψm and intracellular ATP content caused by heat stress was reversed dramatically in the Mn pretreatment group (P < 0.05). Additionally, Mn inhibited heat stress-induced mitochondrial fission, as shown by decreased mitochondrial fission-related protein dynamin-related protein 1 (Drp1) expression and increased mitochondrial fusion-related protein optic atrophy 1 (Opa1) and mitofusin 1 (Mfn1) (P < 0.05) in primary chick embryonic myocardial cells. It was concluded that Mn attenuates the mitochondrial-mediated apoptosis pathway and sustains mitochondrial structure and function under heat stress in primary chick embryonic myocardial cells.

Iron oxide@chlorophyll clustered nanoparticles eliminate bladder cancer by photodynamic immunotherapy-initiated ferroptosis and immunostimulation

The escape of bladder cancer from immunosurveillance causes monotherapy to exhibit poor efficacy; therefore, designing a multifunctional nanoparticle that boosts programmed cell death and immunoactivation has potential as a treatment strategy. Herein, we developed a facile one-pot coprecipitation reaction to fabricate cluster-structured nanoparticles (CNPs) assembled from Fe₃O₄ and iron chlorophyll (Chl/Fe) photosensitizers. This nanoassembled CNP, as a multifunctional theranostic agent, could perform red-NIR fluorescence and change the redox balance by the photoinduction of reactive oxygen species (ROS) and attenuate iron-mediated lipid peroxidation by the induction of a Fenton-like reaction. The intravesical instillation of Fe₃O₄@Chl/Fe CNPs modified with 4-carboxyphenylboronic acid (CPBA) may target the BC wall through glycoproteins in the BC cavity, allowing local killing of cancer cells by photodynamic therapy (PDT)-induced singlet oxygen and causing chemodynamic therapy (CDT)-mediated ferroptosis. An interesting possibility is reprogramming of the tumor microenvironment from immunosuppressive to immunostimulatory after PDT-CDT treatment, which was demonstrated by the reduction of PD-L1 (lower “off” signal to the effector immune cells), IDO-1, TGF-β, and M2-like macrophages and the induction of CD8⁺ T cells on BC sections. Moreover, the intravesical instillation of Fe₃O₄@Chl/Fe CNPs may enhance the large-area distribution on the BC wall, improving antitumor efficacy and increasing survival rates from 0 to 91.7%. Our theranostic CNPs not only demonstrated combined PDT-CDT-induced cytotoxicity, ROS production, and ferroptosis to facilitate treatment efficacy but also opened up new horizons for eliminating the immunosuppressive effect by simultaneous PDT-CDT.

Embryonic manipulations modulate differential expressions of heat shock protein, fatty acid metabolism, and antioxidant-related genes in the liver of heat-stressed broilers

In this study, the effects of in ovo feeding of γ-aminobutyric acid (GABA) and embryonic thermal manipulation (TM) on plasma biochemical parameters, organ weights, and hepatic gene expression in broilers exposed to cyclic heat stress (32 ± 1°C for 8 days) (HS) were investigated. A total of 175 chicks were assigned to five treatments: chicks hatched from control eggs (CON); chicks hatched from control eggs but exposed to HS (CON+HS); chicks hatched from eggs injected at 17.5 days of incubation with 0.6mL of 10% GABA and exposed to HS (G10+HS); chicks hatched from thermally manipulated eggs (39.6°C, 6h/d from embryonic days 10 to 18) and exposed to HS (TM+HS); chicks hatched from eggs that received both previous treatments during incubation and exposed to HS (G10+TM+HS). Results revealed that on day 36 post-hatch, hepatic NADPH oxidase 1 (P = 0.034) and 4 (P = 0.021) genes were downregulated in the TM+HS and G10+TM+HS compared to the CON+HS group. In addition, while acetyl-CoA carboxylase gene expression was reduced (P = 0.002) in the G10+TM group, gene expression of extracellular fatty acid-binding protein and peroxisome proliferator-activated receptor-γ was lower (P = 0.045) in the TM+HS group than in the CON+HS group. HS led to higher gene expression of heat shock protein 70 (HSP70) and 90 (HSP90) (P = 0.005, and P = 0.022). On the other hand, the TM+HS group exhibited lower expression of both HSP70 (P = 0.031) and HSP90 (P = 0.043) whereas the G10+TM+HS group had a reduced (P = 0.016) HSP90 expression compared to the CON+HS. MANOVA on different gene sets highlighted an overall lower (P = 0.034) oxidative stress and lower (P = 0.035) heat shock protein expression in the G10+TM+HS group compared to the CON+HS group. Taken together, the current results suggest that the combination of in ovo feeding of GABA with TM can modulate HSPs and antioxidant-related gene expression in heat-stressed broilers.

Engineered assistive materials for 3D bioprinting: support baths and sacrificial inks

Three-dimensional (3D) bioprinting is a promising technique for spatially patterning cells and materials into constructs that mimic native tissues and organs. However, a trade-off exists between printability and biological function, where weak materials are typically more suited for 3D cell culture but exhibit poor shape fidelity when printed in air. Recently, a new class of assistive materials has emerged to overcome this limitation and enable fabrication of more complex, biologically relevant geometries, even when using soft materials as bioinks. These materials include support baths, which bioinks are printed into, and sacrificial inks, which are printed themselves and then later removed. Support baths are commonly yield-stress materials that provide physical confinement during the printing process to improve resolution and shape fidelity. Sacrificial inks have primarily been used to create void spaces and pattern perfusable networks, but they can also be combined directly with the bioink to change its mechanical properties for improved printability or increased porosity. Here, we outline the advantages of using such assistive materials in 3D bioprinting, define their material property requirements, and offer case study examples of how these materials are used in practice. Finally, we discuss the remaining challenges and future opportunities in the development of assistive materials that will propel the bioprinting field forward toward creating full-scale, biomimetic tissues and organs.

Manganese Mitigates Heat Stress-Induced Apoptosis by Alleviating Endoplasmic Reticulum Stress and Activating the NRF2/SOD2 Pathway in Primary Chick Embryonic Myocardial Cells

Heat stress leads to oxidative stress and induces apoptosis in various cells. Endoplasmic reticulum (ER) stress is an important apoptosis pathway. Manganese (Mn) has been shown to enhance the activity of manganese superoxide dismutase (MnSOD). To explore the potential effect of Mn on ER stress and apoptosis induced by heat stress, we examined crucial factors associated with heat stress, ER stress, and apoptosis in cultured primary chick embryonic myocardial cells that had been pretreated with 20 μM Mn for 24 h and then subjected to 4 h of heat stress. The results showed that Mn decreased (P < 0.05) heat stress-induced reactive oxygen species (ROS) production and exerted antiapoptotic effects by increasing MnSOD enzymatic activity. The heat stress-induced accumulation of intracellular calcium was dramatically reduced (P < 0.05). Mn treatment significantly decreased (P < 0.05) the expression levels of the apoptosis-related gene Bax and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in primary chick embryonic myocardial cells. Additionally, Mn reduced oxidative stress by activating the nuclear factor E2-related factor 2 (NRF2)/SOD2 signaling pathway. Taken together, our findings indicate that Mn attenuates heat stress-induced apoptosis by inhibiting ROS generation, intracellular calcium accumulation, and the ER stress pathway and activating the NRF2/SOD2 signaling pathway to protect myocardial cells from oxidative stress during chick embryonic development.

Transcriptome analysis and potential mechanisms of bovine oocytes under seasonal heat stress

Heat stress is the major factor affecting cattle fertility but molecular mechanisms of deleterious impacts of elevated temperature on oocyte are still not well known. Therefore, the aim of this study is to gain a better understanding of the underlying molecular mechanism of how heat stress affects GV-stage and MII-stage oocytes and discover hub genes to heat resistance for cow oocytes. In this study, we used the bioinformatics approach to discover the differentially expressed genes between GV-stage and MII-stage oocytes, which were collected during spring and summer. When GV-stage oocytes were compared to MII-stage oocytes collected in July (Jul DEGs group) a total of 1068 genes were found as differentially expressed as a result of heat stress. Also, HSPA8, COPS5, POLR2L, PSMC6, and TPI1 were identified as the common top ranked genes for the Jul DEGs group. The highest connected hub gene for the Jul DEGs group was determined as HSPA8. Our results showed that different heat response mechanisms might be activated to protect oocytes from elevated temperatures in cattle. The identified genes and their associated pathways might play an important role in the response to heat stress that affects the oocytes in cattle.

Phototoxicity induced in living HeLa cells by focused femtosecond laser pulses: a data-driven approach

Nonlinear optical microscopy is a powerful label-free imaging technology, providing biochemical and structural information in living cells and tissues. A possible drawback is photodamage induced by high-power ultrashort laser pulses. Here we present an experimental study on thousands of HeLa cells, to characterize the damage induced by focused femtosecond near-infrared laser pulses as a function of laser power, scanning speed and exposure time, in both wide-field and point-scanning illumination configurations. Our data-driven approach offers an interpretation of the underlying damage mechanisms and provides a predictive model that estimates its probability and extension and a safety limit for the working conditions in nonlinear optical microscopy. In particular, we demonstrate that cells can withstand high temperatures for a short amount of time, while they die if exposed for longer times to mild temperatures. It is thus better to illuminate the samples with high irradiances: thanks to the nonlinear imaging mechanism, much stronger signals will be generated, enabling fast imaging and thus avoiding sample photodamage.

Pharmacological Activation Of Aldehyde Dehydrogenase 2 Protects Against Heatstroke-Induced Acute Lung Injury by Modulating Oxidative Stress and Endothelial Dysfunction

Heatstroke (HS) can cause acute lung injury (ALI). Heat stress induces inflammation and apoptosis via reactive oxygen species (ROS) and endogenous reactive aldehydes. Endothelial dysfunction also plays a crucial role in HS-induced ALI. Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that detoxifies aldehydes such as 4-hydroxy-2-nonenal (4-HNE) protein adducts. A single point mutation in ALDH2 at E487K (ALDH2*2) intrinsically lowers the activity of ALDH2. Alda-1, an ALDH2 activator, attenuates the formation of 4-HNE protein adducts and ROS in several disease models. We hypothesized that ALDH2 can protect against heat stress-induced vascular inflammation and the accumulation of ROS and toxic aldehydes. Homozygous ALDH2*2 knock-in (KI) mice on a C57BL/6J background and C57BL/6J mice were used for the animal experiments. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro experiment. The mice were directly subjected to whole-body heating (WBH, 42°C) for 1 h at 80% relative humidity. Alda-1 (16 mg/kg) was administered intraperitoneally prior to WBH. The severity of ALI was assessed by analyzing the protein levels and cell counts in the bronchoalveolar lavage fluid, the wet/dry ratio and histology. ALDH2*2 KI mice were susceptible to HS-induced ALI in vivo. Silencing ALDH2 induced 4-HNE and ROS accumulation in HUVECs subjected to heat stress. Alda-1 attenuated the heat stress-induced activation of inflammatory pathways, senescence and apoptosis in HUVECs. The lung homogenates of mice pretreated with Alda-1 exhibited significantly elevated ALDH2 activity and decreased ROS accumulation after WBH. Alda-1 significantly decreased the WBH-induced accumulation of 4-HNE and p65 and p38 activation. Here, we demonstrated the crucial roles of ALDH2 in protecting against heat stress-induced ROS production and vascular inflammation and preserving the viability of ECs. The activation of ALDH2 by Alda-1 attenuates WBH-induced ALI in vivo.

NF‑κB/IκBα signaling pathways are essential for resistance to heat stress‑induced ROS production in pulmonary microvascular endothelial cells

The results of a previous study demonstrated that heat stress (HS) triggered oxidative stress, which in turn induced the apoptosis of epithelial cells. These results uncovered a novel mechanism underlying the activation of NF-κB in primary human umbilical vein endothelial cells. The present study aimed to further investigate the role of NF-κB/IκBα signaling pathways in the inhibition of HS-induced reactive oxygen species (ROS) generation and cytotoxicity in endothelial cells. The results of the present study demonstrated that HS triggered a significant amount of NF-κB and IκBα nuclear translocation without IκBα degradation in a time-dependent manner. Mutant constructs of IκBα phosphorylation sites (Ser32, Ser36) were employed in rat pulmonary microvascular endothelial cells (PMVECs). Cell Counting Kit-8 assays demonstrated that both the small interfering (si)RNA-mediated knockdown of p65 and IκBα mutant constructs significantly decreased cell viability and aggravated ROS accumulation in HS-induced rat PMVECs compared with the control. Additionally, western blot analysis revealed that p65 siRNA attenuated the protein expression of IκBα. However, IκBα mutant constructs failed to attenuate NF-κB activation and nuclear translocation, indicating that IκBα-independent pathways contributed to NF-κB activity and nucleus translocation in a time-dependent manner following HS. Collectively, the results of the present study suggested that the NF-κB/IκBα pathway was essential for resistance to HS-induced ROS production and cytotoxicity in rat PMVECs, and that it could be a potential therapeutic target to reduce the mortality and morbidity of heat stroke.

Burn Injury: Mechanisms of Keratinocyte Cell Death

Cutaneous burn injury is associated with epidermal loss in the zone of coagulation zone and delayed tissue loss in the zone of stasis. Thus, thermal stress can trigger both necrosis and regulated cell death (RCD) or apoptosis. Experimental in vitro and in vivo work has clearly demonstrated apoptotic events of thermally injured keratinocytes that are accompanied by morphological and biochemical markers of regulated cell death. However, in vivo data for the different pathways of regulated cell death are sparse. In vitro experiments with heat-stressed human keratinocytes have demonstrated death receptor involvement (extrinsic apoptosis), calcium influx, and disruption of mitochondrial membrane potential (intrinsic apoptosis) in regulated cell death. In addition, caspase-independent pathways have been suggested in regulated cell death. Keratinocyte heat stress leads to reduced proliferation, possibly as a result of reduced keratinocyte adhesion (anoikis) or oncogene involvement. Understanding the underlying mechanisms of RCD and the skin’s responses to thermal stress may lead to improved strategies for treating cutaneous burn trauma.

Melatonin Attenuates Thrombin-induced Inflammation in BV2 Cells and Then Protects HT22 Cells from Apoptosis

Increasing evidence has revealed that the uncontrolled thrombin-induced inflammation following intracerebral hemorrhage (ICH) plays a key role in ICH. Oxidative stress and neuroinflammatory responses are interdependent and bidirectional events. Melatonin is now recognized as an antioxidant and a free radical scavenger due to its roles in various physiological and pathological processes. The aim of this study was to explore the molecular mechanisms underlying the effects of melatonin on thrombin-induced microglial inflammation and its indirect protection of HT22 cells from p53-associated apoptosis. Melatonin treatment attenuated the expression of IL-1β, IL-18, cleaved caspase-1, and NLRP3 and decreased the production of reactive oxygen species (ROS), revealing its inhibitory effects against ROS-NLRP3 inflammasome activation. In further experiments investigating the protection conferred by melatonin, incubating HT22 cells with conditioned medium (CM) from thrombin-stimulated microglia induced HT22 cell apoptosis, and this effect was reversed after treating CM with either melatonin or N-acetyl-L-cysteine (NAC). Additionally, the Bax/Bcl-2 ratio and the levels of cleaved caspase-3 and p53 were markedly lower in the cells cultured in thrombin + melatonin-CM than in the cells cultured in thrombin-CM. Furthermore, the levels of MMP, ROS, SOD, MDA, and GSH-PX in bystander HT22 cells suggested that melatonin decreased HT22 cell apoptosis instigated via the p53-associated apoptotic pathway. Therefore, these findings strongly indicate the anti-inflammatory properties of melatonin that may suppress ROS-NLRP3 inflammasome activation and protect HT22 cells against apoptosis by inhibiting the ROS-mediated p53-dependent mitochondrial apoptotic pathway.

In vitro evidence for glioblastoma cell death in temperatures found in the penumbra of laser-ablated tumors

The concept of thermal therapy toward the treatment of brain tumors has gained traction in recent years. Traditionally, thermal therapy has been subdivided into hyperthermia, with mild elevation of temperature in treated tissue above the physiologic baseline; and thermal ablation, where even higher temperatures are achieved. The recent surge in interest has been driven by the use of novel thermal ablation technologies, including laser interstitial thermal therapy (LITT), that are implemented in brain tumor treatment. Here, we review previous scientific literature on the biologic effects of thermal therapy on brain tumors, with an emphasis on glioblastoma (GBM), an aggressive brain malignancy. In addition, we present in vitro evidence from our laboratory that even moderate elevations in temperature achieved in the penumbra around laser-ablated coagulum may also produce GBM cell death. While much remains to be elucidated in terms of the biology of thermal therapy, we propose that it is a welcome addition to the neuro-oncology armamentarium, in particular with regard to GBM, which is generally resistant to current chemoradiotherapeutic regimens.

The Effect of Chemical Structure of OEG Ligand Shells with Quaternary Ammonium Moiety on the Colloidal Stabilization, Cellular Uptake and Photothermal Stability of Gold Nanorods

PURPOSE

Plasmonic photothermal cancer therapy by gold nanorods (GNRs) emerges as a promising tool for cancer treatment. The goal of this study was to design cationic oligoethylene glycol (OEG) compounds varying in hydrophobicity and molecular electrostatic potential as ligand shells of GNRs. Three series of ligands with different length of OEG chain (ethylene glycol units = 3, 4, 5) and variants of quaternary ammonium salts (QAS) as terminal functional group were synthesized and compared to a prototypical quaternary ammonium ligand with alkyl chain - (16-mercaptohexadecyl)trimethylammonium bromide (MTAB).

METHODS

Step-by-step research approach starting with the preparation of compounds characterized by NMR and HRMS spectra, GNRs ligand exchange evaluation through characterization of cytotoxicity and GNRs cellular uptake was used. A method quantifying the reshaping of GNRs was applied to determine the effect of ligand structure on the heat transport from GNRs under fs-laser irradiation.

RESULTS

Fourteen out of 18 synthesized OEG compounds successfully stabilized GNRs in the water. The colloidal stability of prepared GNRs in the cell culture medium decreased with the number of OEG units. In contrast, the cellular uptake of OEG+GNRs by HeLa cells increased with the length of OEG chain while the structure of the QAS group showed a minor role. Compared to MTAB, more hydrophilic OEG compounds exhibited nearly two order of magnitude lower cytotoxicity in free state and provided efficient cellular uptake of GNRs close to the level of MTAB. Regarding photothermal properties, OEG compounds evoked the photothermal reshaping of GNRs at lower peak fluence (14.8 mJ/cm2) of femtosecond laser irradiation than the alkanethiol MTAB.

CONCLUSION

OEG+GNRs appear to be optimal for clinical applications with systemic administration of NPs not-requiring irradiation at high laser intensity such as drug delivery and photothermal therapy inducing apoptosis.

Antioxidant cytochrome c-like activity of para-Mn(III)TMPyP

Manganese porphyrins are well-known protectors against the deleterious effects of pro-oxidant species such as superoxide ions and hydrogen peroxide. The present study investigated the antioxidant cytochrome c-like activities of Mn(III)TMPyP [meso-tetrakis (4-N-methyl pyridinium) porphyrin] against superoxide ion and hydrogen peroxide that remained unexplored for this porphyrin. The association of TMPyP with a model of the inner mitochondrial membrane, cardiolipin (CL)-containing liposomes, shifted +30 mV vs. NHE (normal hydrogen electrode) redox potential of the Mn^(II)/Mn^(III) redox couple. In CL-containing liposomes, Mn^(III)TMPyP was reduced by superoxide ions and recycled by Fe^(III)cytochrome c to the oxidized form. Similarly, isolated rat liver mitoplasts added to a sample of Mn^(II)TMPyP promoted immediate porphyrin reoxidation by electron transfer to the respiratory chain. These results show that Mn^(III)TMPyP can act as an additional pool of Fe^(III)cytochrome c capable of transferring electrons that escape from the IV complex back into the respiratory chain. Unlike Fe^(II)cytochrome c, Mn^(II)TMPyP was not efficient for hydrogen peroxide clearance. Therefore, by reducing cytochrome c, Mn^(II)TMPyP can indirectly contribute to hydrogen peroxide elimination.

Mouse liver is more resistant than skeletal muscle to heat-induced apoptosis

During passive heat stress, shifting of blood flow from the hepato-splanchnic to peripheral regions produces less favorable physiological conditions in the liver than in the skeletal muscle. We were wondering if the two organs differ in susceptibility to heat injury and thus examined the effects of heat shock exposure on apoptotic and heat stress-related markers in the gastrocnemius muscle and liver of mice. During heat exposure, mice had a peak core body temperature of 41.1 ± 0.7 °C. Heat-exposed mice showed higher levels of reactive oxygen species (ROS), cleaved caspases, fragmented DNA, and Drp1 protein expression in the gastrocnemius muscles than control mice. These changes were not observed in the livers of heat-exposed mice. Furthermore, the levels of glucocorticoid receptor, HSP70, and HSF1 proteins were significantly elevated in the gastrocnemius muscles of heat-exposed mice compared with that of control mice. The livers of heat-exposed mice also revealed increased expression of HSP70 but no changes in the other proteins. These results demonstrate that heat exposure induces significantly lower levels of the stress response and apoptosis in the liver than in the skeletal muscle of mice. The liver tissue resistance against heat stress is associated with low levels of heat-induced ROS production and mitochondrial fission protein expression.

Modulation of Heat-Shock Proteins Mediates Chicken Cell Survival against Thermal Stress

Heat stress is one of the most challenging environmental stresses affecting domestic animal production, particularly commercial poultry, subsequently causing severe yearly economic losses. Heat stress, a major source of oxidative stress, stimulates mitochondrial oxidative stress and cell dysfunction, leading to cell damage and apoptosis. Cell survival under stress conditions needs urgent response mechanisms and the consequent effective reinitiation of cell functions following stress mitigation. Exposure of cells to heat-stress conditions induces molecules that are ready for mediating cell death and survival signals, and for supporting the cell's tolerance and/or recovery from damage. Heat-shock proteins (HSPs) confer cell protection against heat stress via different mechanisms, including developing thermotolerance, modulating apoptotic and antiapoptotic signaling pathways, and regulating cellular redox conditions. These functions mainly depend on the capacity of HSPs to work as molecular chaperones and to inhibit the aggregation of non-native and misfolded proteins. This review sheds light on the key factors in heat-shock responses for protection against cell damage induced by heat stress in chicken.

Preventing necroptosis by scavenging ROS production alleviates heat stress-induced intestinal injury

Background: Worldwide heat stroke incidence has increased in recent years and is associated with high morbidity and mortality. Therefore, it is critical to identify mechanisms that mediate heat stroke. Previous studies suggested that damage to the small intestine may be a major factor in heat stroke-related morbidity and mortality. However, the mechanism underlying heat stroke related small intestine injury remains unclear.Methods: To explore how heat stroke promotes intestinal damage, we applied two well established models: mouse and IEC-6 cells heat stress (HS) to mimic heat stroke both in vivo and in vitro. The percentages of viability and cell death were assessed by WST-1 and LDH release assays. Induction of HS-induced cell death was analyzed by flow cytometry with Annexin V-FITC/PI staining. Flow cytometry was used to analyze HS-induced mitochondrial superoxide with MitoSOX staining. Malondialdehyde (MDA) levels and superoxide dismutase (SOD) levels were detected by ELISA. Flow cytometry was used to analyze HS-induced mitochondrial depolarization (low ΔΨm) with JC-1 staining. Histopathology changes in the ileum were detected by H&E staining.The ileum ultrastructure was observed by transmission electron microscopy (TEM). RIPK1, RIPK3, phosphorylated MLKL, and MLKL levels were detected by Western blot. RIPK1-RIPK3 complexes were measured by immunoprecipitation assay.Results: HS increased both necrotic cell rate and RIPK1, RIPK3, and phosphorylated MLKL expression levels in IEC-6 cells. These increased expression levels promoted higher RIPK1-RIPK3 complex formation, leading to necrosome formation both in vivo and in vitro. Moreover, HS caused dyshomeostasis, an oxidative stress response, and mitochondrial damage, along with small intestinal tissue injury and cell death. However, IEC-6 cells or mice pretreated with the RIPK1 activity chemical inhibitor Nec-1 or RIPK3 activity chemical inhibitor GSK'872 significantly reversed these phenomena and promoted balance in oxidative stress response homeostasis. More importantly, the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) pretreatment significantly inhibited HS-induced RIPK1/RIPK3-dependent necroptosis formation both in vivo and in vitro, suggesting that preventing necroptosis via scavenging ROS production might alleviate HS-induced small intestinal tissue injury and cell death.Conclusion: This study provides strong evidence that HS causes damage to both the small intestine and intestinal epithelial cells, scavenging ROS production can significantly alleviate such RIPK1/RIPK3-dependent necroptosis, mediating HS-induced intestinal damage both in vitro and in vivo. These findings provide a clear target for future mechanism-based therapeutic strategies for patients diagnosed with heat stroke.

Expression of Ascorbate Peroxidase Derived from Cyanidioschyzon merolae in Mammalian Cells

BACKGROUND/AIM

Ascorbate peroxidase (APX) derived from Cyanidioschyzon merolae, a primitive red alga living in high temperature and acidic environments, has greater anti-oxidative capacity than similar peroxidases occurring in other plants. In the present study, we examined whether expression of Cyanidioschyzon merolae-derived APX (cAPX) in mammalian cells increases cellular anti-oxidative capacity.

MATERIALS AND METHODS

The cAPX gene was introduced into the mouse fibroblast-like cell line C3H10T1/2. Production of reactive oxygen species (ROS) and/or cell viability was assessed after heat, H₂O₂ and acid stimulation.

RESULTS

Heat and H₂O₂ stimulation resulted in ROS production. cAPX-expressing cells were more tolerant to oxidative stress induced by heat, H₂O₂ and acid stimulations than control cells lacking cAPX.

CONCLUSION

Introduction of cAPX increases the anti-oxidative capacity in mammalian cells.

The soluble VEGF receptor sFlt-1 contributes to endothelial dysfunction in IgA nephropathy

Endothelial injury is a common manifestation in IgA nephropathy (IgAN). After the previous identification of the upregulated soluble fms-like tyrosine kinase-1 (sFlt-1) correlated with endothelial injury in IgAN, in the present study, we further explored the role of sFlt-1 in endothelial injury in IgAN. We enrolled 72 patients with IgAN and detected the sFlt-1 levels. The polymeric IgA1 (pIgA1) complexes were isolated from the pooled plasma samples of another 10 patients with IgAN. Apoptosis proteins were detected in cultured human umbilical vein endothelial cells (HUVECs) with the stimulation of recombinant sFlt-1 or the caspase-9 inhibitor Z-LEHD-FMK. We identified there were positive correlations between sFlt-1 and IgA-IgG complex as well as vWF levels in patients with IgAN. The sFlt-1 levels in HUVECs were significantly upregulated by pIgA1 complex derived from IgAN patients in a concentration-dependent manner. The proliferation ability of HUVECs was damaged when stimulated with sFlt-1 protein in a time- and dose- dependent manner. And the apoptosis rate was up-regulated significantly as the stimulation concentrations of sFlt-1 increased. We found sFlt-1 challenge could significantly increase the expression of vWF. In addition, sFlt-1 increased the levels of caspase-9, caspase-3, Bax and mitochondrial membrane potential; facilitated the release of cytochrome C from mitochondria to cytoplasma. In contrast, Z-LEHD-FMK attenuated high sFlt-1-induced HUVECs apoptosis. In conclusion, our study demonstrated that sFlt-1 expression was up-regulated by the challenge of pIgA1 complex derived from patients with IgAN. Furthermore, increased sFlt-1 facilitated human umbilical vein endothelial cells apoptosis via the mitochondrial-dependent pathway.

Heat stress induces RIP1/RIP3-dependent necroptosis through the MAPK, NF-κB, and c-Jun signaling pathways in pulmonary vascular endothelial cells

Necroptosis represents a newly defined form of regulated necrosis and participates in various human inflammatory diseases. It remains unclear whether necroptosis is presented in heatstroke-induced lung injury. We show that heat stress(HS) triggered an significant upregulation of receptor-interacting protein 1 (RIP1) and mixed lineage kinase domain-like protein (MLKL) expression in a time-dependent manner, without a significant change of receptor-interacting protein 3 (RIP3). Furthermore, co-immunoprecipitation assays showed that RIP1 binds to RIP3 to form the necrosome in heat stress-induced PMVECs. In vitro, necrostatin-1 (Nec-1) pre-treatment reduced heat stress-induced PMVECs necroptosis, which also inhibited HMGB1 translocation from the nucleus into the cytoplasm. Similarly, inhibition for ERK (PD98059), NF-κB (BAY11-7082) and c-Jun (c-Jun peptide), respectively, also suppressed the HMGB1 cytoplasm translocation. Furthermore, siRNA-mediated RIP1/RIP3 knockdown negatively regulated the release of HMGB1 in HS-induced necroptosis through the ERK, NF-κB, and c-Jun signaling pathways. Our study reveals that HS induces RIP1/RIP3-dependent necroptosis through the MAPK, NF-κB, and c-Jun signaling pathways in PMVECs.

Cold-hearted: A case for cold stress in cancer risk

A negative correlation exists between environmental temperature and cancer risk based on both epidemiological and statistical analyses. Previously, cold stress was reported to be an effective cause of tumorigenesis. Several studies have demonstrated that cold temperature serves as a potential risk factor in cancer development. Most recently, a link was demonstrated between the effects of extreme cold climate on cancer incidence, pinpointing its impact on tumour suppressor genes by causing mutation. The underlying mechanism behind cold stress and its association with tumorigenesis is not well understood. Hence, this review intends to shed light on the role of associated factors, genetic and/or non-genetic, which are modulated by cold temperature, and eventually influence tumorigenic potential. While scrutinizing the effect of cold exposure on the body, the expression of certain genes, e.g. uncoupled proteins and heat-shock proteins, were elevated. Biological chemicals such as norepinephrine, thyroxine, and cholesterol were also elevated. Brown adipose tissue, which plays an essential role in thermogenesis, displayed enhanced activity upon cold exposure. Adaptive measures are utilized by the body to tolerate the cold, and in doing so, invites both epigenetic and genetic changes. Unknowingly, these adaptive strategies give rise to a lethal outcome i.e., genesis of cancer. Concisely, this review attempts to draw a link between cold stress, genetic and epigenetic changes, and tumorigenesis and aspires to ascertain the mechanism behind cold temperature-mediated cancer risk.

Effects of triclosan on antioxidant- and apoptosis-related genes expression in the gill and ovary of zebrafish

Triclosan (TCS) is a broad-spectrum antibacterial and anti-fungal agent used in a broad variety of personal care products (PCPs) throughout the world. However, the molecular mechanism of TCS's effects on the gill and ovary of fish is not clear. In this study, the effects of TCS exposure on expression of antioxidant- and apoptosis-related genes were investigated in the gill and ovary of zebrafish (Danio rerio). Zebrafish were exposed to 0, 17, 34, or 68 µg/l TCS for 42 days. Antioxidant-related genes (SOD, GPx1a, CAT, sMT-B, and MT-2) in the gill were significantly downregulated in the 34 (except GPx1a) and 68 µg/l TCS groups, and these genes (except MT-2) in the ovary were significantly downregulated in the 68 µg/l TCS group. Apoptosis-related gene (Bax and p53) expression level in the gill were significantly downregulated in the 68 µg/l TCS group, while the ratios of BCL-2 to Bax and MDM2 gene were significantly upregulated. The Bax gene in the ovary was significantly upregulated in the 34 and 68 µg/l TCS groups, while the ratio of BCL-2 to Bax was significantly downregulated. Moreover, the p53 gene in the ovary in the 34 µg/l TCS group was significantly upregulated. In addition, the MDA contents in the gill in the 34 and 68 μg/l TCS treated groups and in the ovary in 68 μg/l group were significantly increased. The results showed that the higher dose of TCS might cause oxidative damage in the gills and ovaries and accelerate ROS-dependent ovary apoptosis in zebrafish.

Heat stress modulates differential response in skin fibroblast cells of native cattle (Bos indicus) and riverine buffaloes (Bubalus bubalis)

Heat stress in hot climates is a major cause that negatively affects dairy animals, leading to substantial economic loss. The present study was aimed to analyze the effect of heat stress on cellular and molecular levels in dermal fibroblast of cattle and buffaloes. Primary fibroblast culture was established using ear pinna tissue samples of cattle (Bos indicus) and riverine buffaloes (Bubalus Bubalis). The cells were exposed to thermal stress at 42°C for 1 h and subsequently allowed to recover and harvest at 37°C at different time points (0, 2, 4, 8, 16, and 24 h) along with control samples. Different cellular parameters viz., apoptosis, proliferation, mitochondrial membrane potential (ΔΨm), oxidative stress, along with expression pattern of heat responsive genes and miRNAs were determined. Cell viability and proliferation rate of heat-stressed fibroblasts decreased significantly (P < 0.05) albeit to a different extent in both species. The cell cytotoxicity, apoptosis, production of reactive oxygen species, and ΔΨm increased more significantly (P < 0.01) in heat stressed fibroblasts of buffalo than cattle. The pattern of heat shock proteins, inflammation/immune genes, and heat responsive miRNA showed differences in induction of their expression level in buffalo and native cattle fibroblasts. Conclusively, finding indicates that heat stress induces more profound impact on buffalo fibroblasts than native cattle fibroblasts. The differential response of cellular parameters, HSP genes, and miRNA expression could be due to better adaptive capacity of skin fibroblast of Bos indicus cattle in comparison with riverine buffaloes.

Triclosan stimulates human vascular endothelial cell injury via repression of the PI3K/Akt/mTOR axis

Triclosan (TCS) has potentially toxic effects on humans and animals. However, the possible roles and mechanisms of TCS in endothelial cells (ECs) are still unknown. Abnormal damage to ECs and vascular function is a critical process in various cardiovascular diseases, including coronary artery disease (CAD), atherosclerosis, stroke, and hypertension. Hence, we explored the potential toxicological roles of TCS in EC functions. Cell Counting Kit-8, apoptosis, transwell, wound healing, and tube-formation experiments were performed to evaluate the effects of TCS on human umbilical vein endothelial cell (HUVEC) function. Additionally, the levels of PI3K, Akt, and mTOR phosphorylation were measured by Western blot. The results indicated that TCS treatment suppressed HUVECs viability, migration and angiogenesis. TCS treatment increased the expression of inflammatory markers and ROS in cultured HUVECs. Moreover, TCS treatment inhibited PI3K/Akt/mTOR expression. All of these results reveal that TCS induces notable vascular injury and affects the viability, migration and angiogenic capacity of HUVECs, at least in part via the PI3K/Akt/mTOR signaling pathway.

Alpha-Lipoic Acid Protects Cardiomyocytes against Heat Stroke-Induced Apoptosis and Inflammatory Responses Associated with the Induction of Hsp70 and Activation of Autophagy

Heat stroke (HS) is a life-threatening illness and defined as when body temperature elevates above 40°C accompanied by the systemic inflammatory response syndrome that results in multiple organ dysfunctions. α-Lipoic acid (ALA) acts as a cofactor of mitochondrial enzymes and exerts anti-inflammatory and antioxidant properties in a variety of diseases. This study investigates the beneficial effects of ALA on myocardial injury and organ damage caused by experimental HS and further explores its underlying mechanism. Male Wistar rats were exposed to 42°C until their rectal core temperature reached 42.9°C and ALA was pretreared 40 or 80 mg/kg (i.v.) 1.5 h prior to heat exposure. Results showed that HS-induced lethality and hypothermia were significantly alleviated by ALA treatment that also improved plasma levels of CRE, LDH, and CPK and myocardial injury biomarkers myoglobin and troponin. In addition, ALA reduced cardiac superoxide anion formation and protein expression of cleaved caspase 3 caused by HS. Proinflammatory cytokine TNF-α and NF-κB pathways were significantly reduced by ALA treatment which may be associated with the upregulation of Hsp70. ALA significantly increased the Atg5-12 complex and LC3B II/LC3B I ratio, whereas the p62 and p-mTOR expression was attenuated in HS rats, indicating the activation of autophagy by ALA. In conclusion, ALA ameliorated the deleterious effects of HS by exerting antioxidative and anti-inflammatory capacities. Induction of Hsp70 and activation of autophagy contribute to the protective effects of ALA in HS-induced myocardial injury.