Flow cytometry profiling of cellular immune response in COVID-19 infected, recovered and vaccinated individuals.

INTRODUCTION: SARS-CoV-2 has infected over 753 million individuals and caused more than 6.8 million deaths globally to date. COVID-19 disease severity has been associated with SARS-CoV-2 induced hyper inflammation and the immune correlation with its pathogenesis remains unclear. Acute viral infection is characterised by vigorous coordinated innate and adaptive activation, including an early cellular response that correlates well with the amplitude of virus specific humoral response. OBJECTIVE: The present study covers a wide spectrum of cellular immune response against COVID-19, irrespective of infection and vaccination. METHODS: We analysed immune status of (a) COVID-19 hospitalised patients including deceased and recovered patients, and compared with home isolated and non-infected healthy individuals, and (b) infected home isolated individuals with vaccinated individuals, using flow cytometry. We performed flow cytometry analysis of PBMCs to determine non-specific cell-mediated immune response. RESULTS: The immune response revealed extensive induction and activation of multiple immune lineages, including T and B cells, Th17 regulatory subsets and M1, M2 macrophages in deceased and hospitalised recovered patients, vaccinated and healthy individuals. Compromised immune cell expression was observed in deceased patients even in later stages, while expression was restored in hospitalised recovered patients and home isolated individuals. CONCLUSION: The findings associated with recovery and convalescence define a new signature of cellular immune response that persists in individuals with SARS-CoV-2 infection and vaccination. The findings will help in providing a better understanding of COVID-19 disease and will aid in developing better therapeutic strategies for treatment.

Impact of high altitude on composition and functional profiling of oral microbiome in Indian male population.

The oral cavity of human contains bacteria that are critical for maintaining the homeostasis of the body. External stressors such as high altitude (HA) and low oxygen affect the human gut, skin and oral microbiome. However, compared to the human gut and skin microbiome, studies demonstrating the impact of altitude on human oral microbiota are currently scarce. Alterations in the oral microbiome have been reported to be associated with various periodontal diseases. In light of the increased occurrence of HA oral health related problems, the effect of HA on the oral salivary microbiome was investigated. We conducted a pilot study in 16 male subjects at two different heights i.e., H1 (210 m) and H2 (4420 m). Total of 31 saliva samples,16 at H1 and 15 at H2 were analyzed by utilizing the 16S rRNA high-throughput sequencing, to explore the relationship between the HA environment and salivary microbiota. The preliminary results suggesting that, the most abundant microbiome at the phylum level are: Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Interestingly, 11 genera were identified at the both heights with different relative abundances. In addition, the salivary microbiome was more diverse at H1 compared to H2 as demonstrated by decreased alpha diversity. Further, predicted functional results indicate that microbial metabolic profiles significantly decreased at H2 as compared to H1, including two major metabolic pathways involving carbohydrates, and amino acids. Our findings show that HA induces shifts in the composition and structure of human oral microbiota which can affect host health homeostasis.

"Mitochondrial pathogenic mutations and metabolic alterations associated with COVID-19 disease severity".

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) caused global pandemic and drastically affected the humankind. Mitochondrial mutations have been found to be associated with several respiratory diseases. Missense mutation and pathogenic mitochondrial variants might unveil the potential involvement of the mitochondrial genome in coronavirus disease 2019 (COVID-19) pathogenesis. The present study aims to elucidate the role of mitochondrial DNA (mtDNA) mutations, mitochondrial haplogroup, and energy metabolism in disease severity. The study was performed on 58 subjects comprising COVID-19-positive (n = 42) and negative (n = 16) individuals. COVID-19-positive subjects were further categorized into severe deceased (SD), severe recovered (SR), moderate (Mo), and mild (Mi) patients, while COVID-19-negative subjects were healthy control (HC) for the study. High throughput next-generation sequencing was done to investigate mtDNA mutations and haplogroups. The computational approach was applied to study the effect of mtDNA mutations on protein secondary structure. Real time polymerase chain reaction was used for mtDNA copy number determination and mitochondrial function parameters were also analyzed. We found 15 mtDNA mutations in MT-ND5, MT-ND4, MT-ND2, and MT-COI genes uniquely associated with COVID-19 severity affecting the secondary structure of proteins in COVID-19-positive subjects. Haplogroup analysis suggests that mtDNA haplogroups M3d1a and W3a1b might be potentially associated with COVID-19 pathophysiology. The mitochondrial function parameters were significantly altered in severe patients (SD and SR; p < 0.05). No significant relationship was found between mtDNA mutations and oxidative stress markers (p > 0.05). The study highlights the importance of mitochondrial reprogramming in COVID-19 patients and may provide a feasible approach toward finding a path for therapeutic interventions to COVID-19 disease.

Evaluation of altered miRNA expression pattern to predict COVID-19 severity.

Outbreak of COVID-19 pandemic in December 2019 affected millions of people globally. After substantial research, several biomarkers for COVID-19 have been validated however no specific and reliable biomarker for the prognosis of patients with COVID-19 infection exists. Present study was designed to identify specific biomarkers to predict COVID-19 severity and tool for formulating treatment. A small cohort of subjects (n = 43) were enrolled and categorized in four study groups; Dead (n = 16), Severe (n = 10) and Moderate (n = 7) patients and healthy controls (n = 10). Small RNA sequencing was done on Illumina platform after isolation of microRNA from peripheral blood. Differential expression (DE) of miRNA (patients groups compared to control) revealed 118 down-regulated and 103 up-regulated known miRNAs with fold change (FC) expression ≥2 folds and p ≤ 0.05. DE miRNAs were then subjected to functional enrichment and network analysis. Bioinformatic analysis resulted in 31 miRNAs (24 Down-regulated; 7 up-regulated) significantly associated with COVID-19 having AUC>0.8 obtained from ROC curve. Seventeen out of 31 DE miRNAs have been linked to COVID-19 in previous studies. Three miRNAs, hsa-miR-147b-5p and hsa-miR-107 (down-regulated) and hsa-miR-1299 (up-regulated) showed significant unique DE in Dead patients. Another set of 4 miRNAs, hsa-miR-224-5p (down-regulated) and hsa-miR-4659b-3p, hsa-miR-495-3p and hsa-miR-335-3p were differentially up-regulated uniquely in Severe patients. Members of three miRNA families, hsa-miR-20, hsa-miR-32 and hsa-miR-548 were significantly down-regulated in all patients group in comparison to healthy controls. Thus a distinct miRNA expression profile was observed in Dead, Severe and Moderate COVID-19 patients. Present study suggests a panel of miRNAs which identified in COVID-19 patients and could be utilized as potential diagnostic biomarkers for predicting COVID-19 severity.

Unique mutations in mitochondrial DNA and associated pathways involved in high altitude pulmonary edema susceptibility in Indian lowlanders.

High altitude pulmonary edema (HAPE) is a life threatening non-cardiogenic pulmonary edema that occurs in an otherwise healthy individuals travelling to altitude above 2500 m. Earlier studies have reported association of mutations in nuclear (nDNA) and mitochondrial DNA (mtDNA) with HAPE susceptibility. However, the molecular mechanisms involved in the pathobiology of HAPE have not been fully understood. The present study investigates the genetic predisposition to HAPE by analyzing the mtDNA mutations in HAPE susceptibles (n = 23) and acclimatized controls (n = 23) using next generation sequencing. Structural analysis of mutations was done using SWISS Model server and stability was determined using ΔΔG values. Meta-analysis of GSE52209 dataset was done to identify differentially expressed genes (DEGs) in HAPE susceptibles and acclimatized controls. Fourteen non-synonymous, conserved and pathogenic mutations were predicted using SIFT and PolyPhen scoring in protein coding genes, whereas six mutations in mt-tRNA genes showed association with HAPE (p ≤ 0.05). The structural analysis of these mutations revealed conformational changes in critical regions in Complexes I-V which are involved in subunit assembly and proton pumping activity. The protein-protein interaction network analysis of DEGs showed that HIF1α, EGLN2, EGLN3, PDK1, TFAM, PPARGC1α and NRF1 genes form highly interconnected cluster. Further, pathway enrichment analysis using DAVID revealed that "HIF-1 signaling", "oxidative phosphorylation" and "Metabolic pathways" had strong association with HAPE. Based on the findings it appears that the identified mtDNA mutations may be a potential risk factor in development of HAPE with the associated pathways providing mechanistic insight into the understanding of pathobiology of HAPE and sites for development of therapeutic targets.Communicated by Ramaswamy H. Sarma.

Gene variants in pro-coagulant and anti-coagulant genes could be prognostic genetic markers of COVID-19 susceptibility.

Background: Present study aimed to identify DNA polymorphisms (variants) which can modulate the risk of COVID-19 infection progression to severe condition. TaqMan based SNP genotyping assay was performed for 11 single nucleotide polymorphisms (SNPs) in pro-coagulant and anti-coagulant genes. Methodology: A total of 33 COVID-19 patients, including dead, severe and moderately infected individuals were compared to 35 healthy controls. Both alleles in the SNP were labelled with two different fluorescent dyes (FAM and VIC) during assay formulation. DNA of study subjects were mixed with SNP assay and TaqMan master mix on 96 well PCR plate according to manufacturer's protocol and RT-PCR was performed. Allelic discrimination assay gave clear results for presence of specific allele in each sample. Three SNPs were located in the pro-coagulant genes, another three involved in blood clot dissolution while rest five were in the genes encoding natural anti-coagulants. COVID-19 infected patients were further sub-divided into three groups, deceased (n = 16), severe (n = 10) and moderately infected (n = 7). Results: SNP genotyping showed significant differences between COVID-19 patients and controls in two SNPs, rs6133 in Selectin-P (SELP) and rs5361 in Selectin-E (SELE) gene. Also, rs2020921 and rs8176592, in clot dissolution genes, tissue Plasminogen activator (tPA) and tissue factor pathway inhibitor (TFPI) respectively showed significant genotypic and allelic difference in patients of COVID-19 compared to healthy controls. Further three SNPs rs2227589, rs757583846, and rs121918476 in natural anti-coagulant genes anti-thrombin III (ATIII), protein C (PROC), and protein S (PROS) respectively showed statistically significant difference between the study groups. Conclusion: Our findings indicate that gene variants, those involved in coagulation and anti-coagulation may play a major role in determining individual susceptibility to COVID-19.

Development of robust, indigenous ELISA for detection of IgG antibodies against CoV-2 N and S proteins: mass screening.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has adversely affected humankind and caused millions of deaths globally since January 2020. Robust and quick serological tests such as antibody detection assays for SARS-CoV-2 provide relevant information and aid in the process of vaccine development and diagnostics, as well as in sero-epidemiological monitoring of antibody response to the virus. The receptor-binding domain (RBD) of spike and nucleocapsid protein are specific targets for detecting SARS-CoV-2 antibodies. Here, we present the development of a stable spike (S) and nucleocapsid (N) protein-based ELISA antibody detection test "CoroSuchak," with 99% sensitivity, 98% specificity, cost-effective, and detection in a minimum time for serodiagnosis and mass screening of the population for antibodies against SARS-CoV-2. Blood samples were analyzed from 374 SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) positive, 772 negative and asymptomatic, and 874 random groups of subjects. We found that the antibody titer was significantly higher (p < 0.0001) in infected and vaccinated group compared to the only vaccinated and only infected group. Using enzyme-linked immunosorbent assay (ELISA), we detected SARS-CoV-2 immunoglobulin G (IgG) antibodies in 118/123 (96%) infected individuals, 570/653 (87%) non-infected but vaccinated individuals, 231/237 (97%) individuals who were both infected and vaccinated, and 499/874 (57%) from randomly selected individuals from the first and second waves of the pandemic. Similarly in the third wave, 14/14 (100%) infected and 16/20 (80%) RT-PCR-negative but symptomatic subjects were detected. Thus, the highly sensitive and specific in-house developed ELISA antibody detection kit "CoroSuchak" is extremely useful to determine the seroprevalence of SARS-CoV-2 antibodies in the coronavirus-exposed population. KEY POINTS: •Indigenous kit using a combination of spike and nucleocapsid proteins and peptide sequences. •High sensitivity and specificity to detect variants. •Highly sensitive for mass screening.

Severe heat stress modulated nuclear factor erythroid 2-related factor 2 and macrophage migration inhibitory factor pathway in rat liver.

Heat stress impairs physiology and overall functionality of the body at tissue and organ level in animals. Liver being a vital organ performs more than hundreds regulatory functions of the body. Present study investigates the modulation of molecular pathways that are responsible for liver damage triggered by heat stress. Male Sprague dawley rats were exposed to heat stress (45 °C) in heat simulation chamber till core temperature reaches 40 °C and 42 °C in 25 and 42 min respectively. For in-depth evaluation of liver functions during severe heat stress, hepatic transcriptome and proteome were analysed by microarray and two dimensional gel electrophoresis respectively. Results revealed major alterations in redox status, inflammation, mitochondrial dysfunction and proteostasis related pathways. Data of molecular pathway analysis demonstrate that nuclear factor erythroid 2-related factor 2 (NRF-2) mediated oxidative stress response and macrophage migration inhibitory factor (MIF) regulated inflammatory pathways were upregulated in severe heat stressed liver. Expression levels of downstream molecules of above pathways such as heat shock protein 90AB 1, peroxiredoxin 5, Jun N-terminal kinases 1/2, heme-oxygenase 1, apolipoprotein 1 and interleukin 10 were examined and result suggested the upregulation of these genes modulates the NRF-2 and MIF regulated pathways in heat stressed liver. Irregularity in molecular signalling networks lead to mitochondrial dysfunction indicated by upregulation of ATP synthase ß and peroxiredoxin 1 along with decreased levels of glucose-6-phosphate dehydrogenase and enhanced activity of cytochrome c in liver mitochondria. Thus, current study demonstrated heat induced alterations in key liver functions were regulated by NRF-2 and MIF pathways.

Dysfunctional State of T Cells or Exhaustion During Chronic Viral Infections and COVID-19: A Review.

Coronavirus disease 2019 (COVID-19) continuously affecting the lives of millions of people. The virus is spread through the respiratory route to an uninfected person, causing mild-to-moderate respiratory disease-like symptoms that sometimes progress to severe form and can be fatal. When the host is infected with the virus, both innate and adaptive immunity comes into play. The effector T cells act as the master player of adaptive immune response in eradicating the virus from the system. But during cancer and chronic viral infections, the fate of an effector T cell is altered, and the T cell may enters a state of exhaustion, which is marked by loss of effector function, depleted proliferative capacity and cytotoxic effect accomplished by an increased expression of numerous inhibitory receptors such as programmed cell death protein 1 (PD-1), lymphocyte-activation protein 3 (LAG-3), and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) on their surface. Various other transcriptional and epigenetic changes take place inside the T cell when it enters into an exhausted state. Latest studies point toward the induction of an abnormal immune response such as lymphopenia, cytokine storm, and T cell exhaustion during SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection. This review sheds light on the dysfunctional state of T cells during chronic viral infection and COVID-19. Understanding the cause and the effect of T cell exhaustion observed during COVID-19 may help resolve new therapeutic potentials for treating chronic infections and other diseases.

Implications of COVID-19 on Thrombotic Profile of Severely Affected Patients.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) is a novel viral disease that spread as a global pandemic in 2020 by infecting millions of people across the world. Its clinical prognosis is dependent on various coagulatory parameters since thrombotic events are frequently associated with infection severity. METHODS: A total of 383 COVID-19 patients enrolled in Rajiv Gandhi Super Specialty Hospital, Delhi, India, were included in the present retrospective study. Patients were divided into three categories, severe (n = 141), moderate (n = 138), and mild (n = 104) based on infection severity. Various thrombotic parameters and anticoagulant levels were measured in 70 patients and further analyzed. RESULTS: Coagulopathy is seen in COVID-19 patients (n = 70) with a significant increase in fibrinogen, D-dimer levels, and prothrombin time in patients with severe and moderate disease compared to patients with a mild infection. Approximately, 70% of patients with severe and moderate disease demonstrated fibrinogen levels higher than the standard reference range. 60.41% of patients with severe disease showed significantly higher D-dimer levels. Thrombotic parameters were notably elevated in the nonsurvivors group compared to COVID-19 survivors. Nearly, 91% of patients with severe infection had anticoagulant protein S levels below the reference range. CONCLUSION: COVID-19 infection severely impacts the blood coagulation cascade, which might lead to the manifestation of severe symptoms and increased mortality in patients.

Nanocurcumin formulation: a possible therapeutic agent for post COVID inflammatory syndrome.

Over the last twenty months, the attention of the world has been focusing on managing the unprecedented and devastating wave of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV 2) and mitigating its impacts. Recent findings indicated that high levels of pro-inflammatory cytokines are leading cause of poor prognosis in severely ill COVID-19 patients. Presently, the multiple variants and highly contagious nature of virus makes challenge humongous. The shortage and vaccine hesitancy also prompted to develop antiviral therapeutic agents to manage this pandemic. Nanocurcumin has potential antiviral activities and also beneficial in post COVID inflammatory complications. We have developed nanocurcumin based formulation using pyrroloquinoline quinone (PQQ) which protects cardio-pulmonary function and mitochondrial homeostasis in hypobaric hypoxia induced right ventricular hypertrophy in animal model and human ventricular cardiomyocytes. Nanocurcumin based formulation (NCF) with improved bioavailability, has proven several holistic therapeutic effects including myocardial protection, and prevents edema formation, anti-inflammatory and antioxidant properties, maintaining metabolic and mitochondrial homeostasis under hypoxic condition. The post COVID-inflammatory syndrome also reported to cause impaired heart function, lung injuries and increased C-reactive protein level in severely ill patients. Thus, we speculate that NCF could be a new treatment option to manage post COVID-19 inflammatory syndrome.

Probiotics maintain the gut microbiome homeostasis during Indian Antarctic expedition by ship.

Ship voyage to Antarctica is a stressful journey for expedition members. The response of human gut microbiota to ship voyage and a feasible approach to maintain gut health, is still unexplored. The present findings describe a 24-day long longitudinal study involving 19 members from 38th Indian Antarctic Expedition, to investigate the impact of ship voyage and effect of probiotic intervention on gut microbiota. Fecal samples collected on day 0 as baseline and at the end of ship voyage (day 24), were analyzed using whole genome shotgun sequencing. Probiotic intervention reduced the sea sickness by 10% compared to 44% in placebo group. The gut microbiome in placebo group members on day 0 and day 24, indicated significant alteration compared to a marginal change in the microbial composition in probiotic group. Functional analysis revealed significant alterations in carbohydrate and amino acid metabolism. Carbohydrate-active enzymes analysis represented functional genes involved in glycoside hydrolases, glycosyltransferases and carbohydrate binding modules, for maintaining gut microbiome homeostasis. Suggesting thereby the possible mechanism of probiotic in stabilizing and restoring gut microflora during stressful ship journey. The present study is first of its kind, providing a feasible approach for protecting gut health during Antarctic expedition involving ship voyage.

Potential association of COVID-19 and ABO blood group: An Indian study.

Coronavirus disease 2019 (COVID-19) transmits from person to person mainly through respiratory droplets and coughing. Infection severity ranges from asymptomatic and mild infection to those with moderate and severe symptoms which may lead to multiple organ failure and mortality. Infection severity largely depends on individual's immune response, age and co-morbidities. Present study categorized COVID-19 infected patients based on their infection severity and linked COVID-19 severity with age, gender and ABO blood group types. Clinical details of 383 COVID-19 patients were collected from Rajiv Gandhi Super Specialty hospital (RGSSH), India; divided into three groups; mild, moderate and severe patients, based on their symptoms. Present analysis revealed that age plays major role in infection severity, as the symptoms are more severe in patients above 45 years. Infection rate was higher in males compared to females. Most patients with A(+ve) and B(+ve) blood group were severely affected compared to those of blood group type O(+ve) and AB(+ve). O(+ve) blood group was least represented in severe patients. Present findings could be helpful in generating awareness amongst the population regarding susceptibility towards the COVID-19 infection. This supportive information would help clinicians and health workers to propose new strategies and tactical solution against COVID-19 infection.

Re-exposure to alarmin HMGB1 and cytokine IL-1 beta induces differential innate immune response generation in mouse brain.

Innate immune memory, a crucial mechanism of epigenetically mediated myeloid cell plasticity, alters subsequent immune responses majorly by two types of immunological imprinting, training, and tolerance. Recent pioneer studies provided proof-of-principle for generation of both types of innate immune memory in brain macrophage, microglial cells. This novel study was designed to investigate whether the pattern of immune response generation, induced by peripheral administration of recombinant alarmin HMGB1, alone and in combination with other recombinant cytokines, is affected by prior exposure. The experimental outcomes revealed that full length recombinant HMGB1 exposure for seven consecutive days exhibit inflammatory response as evidenced by enhanced expression of inflammatory biomarkers and neurodegeneration. In contrary, combined doses of HMGB1 and IL-1ß, for three and seven consecutive days, exhibited lower inflammatory state compared to its alone HMGB1 counterpart. The immune tolerance state was evident by microglial polarization towards non-reactive M2 state, lower astrocyte activation, epigenetic reprogramming, and decreased neurodegeneration. This is the first demonstration that HMGB1 and IL-1ß priming can differentially affect inflammation in the brain when a host is confronted with a second, third stimulus or so on. The findings were further validated by suppressing major regulators of epigenetic reprogramming, by intranasal delivery of specific siRNAs targeting those regulators. These results may provide new evidence for the involvement of recombinant endogenous cytokine induced generation of innate immune tolerance within microglial cells and indicated the possible potential role in mediating cognitive and behavioural alterations during inflammatory diseases.

Urine metabolite profiling of Indian Antarctic Expedition members: NMR spectroscopy-based metabolomic investigation.

The southernmost region of earth, Antarctica, has world's most challenging environments. Those who live for long time and work in Antarctic stations are subjected to environmental stresses such as cold weather, photoperiod variations leading to disrupted sleep cycles, constrained living spaces, dry air, non-availability of fresh food items, and high electromagnetic radiations, psychological factors, such as geographical and social isolation, etc. All these factors have a significant impact on the human body. The present study investigated the impact of Antarctica harsh environment on human physiology and its metabolic processes by evaluating urine metabolome, using 1H NMR spectroscopy and analyzing certain physiological and clinical parameters for correlation with physiological expression data and metabolite results. Two study groups - before Antarctic exposure (B) and after Antarctic exposure (E), consisting of 11 subjects, exposed to one-month summer expedition, were compared. 35 metabolites in urine samples were identified from the 700 MHz 1H NMR spectra from where integral intensity of 22 important metabolites was determined. Univariate analysis indicated significant decrease in the levels of citrate and creatinine in samples collected post-expedition. Multivariate analysis was also performed using 1H NMR spectroscopy, because independent metabolite abundances may complement each other in predicting the dependent variables. 10 metabolites were identified among the groups; the OPLS-DA and VIP score indicated variation in appearance of metabolites over different time periods with insignificant change in the intensities. Metabolite results illustrate the impact of environmental stress or altered life style including the diet with absence of fresh fruits and vegetables, on the pathophysiology of the human health. Metabolic adaptation to Antarctic environmental stressors may help to highlight the effect of short-term physiological status and provide important information during Antarctic expeditions to formulate management programmes.

Mitochondrial DNA mutations contribute to high altitude pulmonary edema via increased oxidative stress and metabolic reprogramming during hypobaric hypoxia.

High altitude pulmonary edema (HAPE) is experienced by non-acclimatized sea level individuals on exposure to high altitude hypoxic conditions. Available evidence suggests that genetic factors and perturbed mitochondrial redox status may play an important role in HAPE pathophysiology. However, the precise mechanism has not been fully understood. In the present study, sequencing of mitochondrial DNA (mtDNA) from HAPE subjects and acclimatized controls was performed to identify pathogenic mutations and to determine their role in HAPE. Hypobaric hypoxia induced oxidative stress and metabolic alterations were also assessed in HAPE subjects. mtDNA copy number, mitochondrial oxidative phosphorylation (mtOXPHOS) activity, mitochondrial biogenesis were measured to determine mitochondrial functions. The data revealed that the mutations in Complex I genes affects the secondary structure of protein in HAPE subjects. Further, increased oxidative stress during hypobaric hypoxia, reduced mitochondrial biogenesis and mtOXPHOS activity induced metabolic reprogramming appears to contribute to mitochondrial dysfunctions in HAPE individuals. Haplogroup analysis suggests that mtDNA haplogroup H2a2a1 has potential contribution in the pathobiology of HAPE in lowlanders. This study also suggests contribution of altered mitochondrial functions in HAPE susceptibility.

Heat precondition is a potential strategy to combat hepatic injury triggered by severe heat stress.

AIM: Environmental heat stress alters physiological and biochemical functions which leads to multiorgan dysfunction including severe hepatic injury in animals. We hypothesize that heat preconditioning can be potential intervention in combating heat illnesses. MAIN METHODS: Sprague Dawley rats were exposed to moderate heat stress, severe heat stress and heat preconditioning in heat simulation chamber. Mean arterial pressure, heart rate, skin and core temperature were monitored in pre and post heat exposed animals. After stress exposure, blood for hemodynamic and liver tissue for liver function tests, oxidative stress, inflammatory variables and structural studies were collected from rats. Hepatic mitochondria were isolated to study the key structural alterations and functional changes by transmission electron microscopy. KEY FINDINGS: The effect of heat precondition shows improvement in time to attain the core temperature, weight loss, blood pressure and heart rate in rats. Results exhibited decreased levels of liver function tests, elevated levels of free radicals and inflammatory cytokines in heat exposed liver as compared with heat preconditioned animals. Expression levels of mitochondrial heat shock protein 60, superoxide dismutase 1 and uncoupling protein 1 along with activity of electron transport chain complexes I-V were examined and found to be increased in heat preconditioned as compared to heat stressed animals. Morphological studies of liver parenchyma demonstrated reduction in structural deterioration of hepatic lobules and restoration of mitochondrial structural integrity in heat preconditioned rats. SIGNIFICANCE: Present study suggests that heat preconditioning intervention plays a crucial role in protection against heat induced hepatic injury in animals.