Core temperature correlates with expression of selected stress and immunomodulatory genes in febrile patients with sepsis and noninfectious SIRS

Comparative fitness trade-offs associated with azole resistance in Candida auris clinical isolates

Multidrug-resistant yeast Candida auris is a serious threat to public health with documented survival in various hospital niches. The dynamics of this survival benefit and its trade off with drug resistance are still unknown for this pathogen. In this study we investigate the oxidative stress response (OSR) in fluconazole-resistant C. auris and compare its relative fitness with fluconazole-susceptible strains. A total of 351 C. auris clinical isolates (61 fluconazole-susceptible and 290 fluconazole-resistant) were screened for stress tolerance by spot assay and 95.08 % fluconazole-susceptible isolates were hyper-resistant to oxidative stress while majority (94.5 %) fluconazole-resistant isolates had lower oxidative tolerance. Expression of Hog1 and Cta1 gene transcript levels and cellular catalase levels were significantly higher in fluconazole-susceptible isolates and a corresponding higher intracellular reactive oxygen species level (iROS) was accumulated in the fluconazole-resistant isolates. Biofilm formation and cell viability under oxidative stress revealed higher biofilm formation and better viability in fluconazole-susceptible isolates. Fluconazole-resistant isolates had higher basal cell wall chitin. On comparison of virulence, the % cytotoxicity in A549 cell line was higher in fluconazole-susceptible isolates and the median survival of the infected larvae in G. mellonella infection model was higher in fluconazole-resistant (5; IQR:4.5-5 days) vs. fluconazole-susceptible C. auris (2; IQR:1.5-2.5 days). All organisms evolve with changes in their environmental conditions, to ensure an optimal balance between proliferation and survival. Development of tolerance to a certain kind of stress example antifungal exposure in yeast can leads to a compensatory decrease in tolerance for other stresses. This study provides useful insights into the comparative fitness and antifungal susceptibility trade off in C. auris. We report a negative association between H2O2 tolerance and fluconazole susceptibility. Using in-vitro cell cytotoxicity and in-vivo survival assays we also demonstrate the higher virulence potential of fluconazole-susceptible C. auris isolates corroborating the negative correlation between susceptibility and pathogen survival or virulence. These findings could also be translated to clinical practice by investigating the possibility of using molecules targeting stress response and fitness regulating pathways for management of this serious infection.

Exploring Small Heat Shock Proteins (sHSPs) for Targeting Drug Resistance in Candida albicans and other Pathogenic Fungi

Fungal infections have predominantly increased worldwide that leads to morbidity and mortality in severe cases. Invasive candidiasis and other pathogenic fungal infections are a major problem in immunocompromised individuals and post-operative patients. Increasing resistance to existing antifungal drugs calls for the identification of novel antifungal drug targets for chemotherapeutic interventions. This demand for identification and characterization of novel drug targets leads to the development of effective antifungal therapy against drug resistant fungi. Heat shock proteins (HSPs) are important for various biological processes like protein folding, posttranslational modifications, transcription, translation, and protein aggregation. HSPs are involved in maintaining homeostasis of the cell. A subgroup of HSPs is small heat shock proteins (sHSPs), which functions as cellular chaperones. They are having a significant role in the many cellular functions like development, cytoskeletal organization, apoptosis, membrane lipid polymorphism, differentiation, autophagy, in infection recognition and are major players in various stresses like osmotic stress, pH stress, etc. Studies have shown that fungal cells express increased levels of sHSPs upon antifungal drug induced stress responses. Here we review the important role of small heat shock proteins (sHSPs) in fungal diseases and their potential as antifungal targets.

Expression of Hsp60 and its cell location in Paracoccidioides brasiliensis

Paracoccidioides species cause paracoccidioidomycosis (PCM), a systemic mycosis highly prevalent in Brazil. Therapy of PCM has some issues that make studies for new therapeutic and vaccine targets relevant, such as the P. brasiliensis 60-kDa-heat-shock protein (PbHsp60), an immunogenic antigen that induces protection in experimental mice infection. Here, we investigated the relative expression of mRNA for PbHsp60 in P. brasiliensis in the different morphotypes of P. brasiliensis and in morphological transition phases. In addition, antibodies to rPbHsp60 were produced and used to analyze the location of PbHsp60 in yeast and hyphae by electron microscopy. The analyses showed a substantial increase in the relative amounts of HSP60 mRNA in yeast when compared to mycelium and an intermediate expression in transitional forms. Regarding the cell location, immunoelectron microscopy analysis revealed that PbHsp60 is within the cell wall. These observations suggest that this protein may be involved in the maintenance of the cell wall integrity and the interaction with the host for colonization, infection and pathogenesis.

Molecular Analysis of BRCA1 in Human Breast Cancer Cells Under Oxidative Stress

The precise manner in which physical changes to the breast cancer susceptibility protein (BRCA1) affect its role in DNA repair events remain unclear. Indeed, cancer cells harboring mutations in BRCA1 suffer from genomic instability and increased DNA lesions. Here, we used a combination of molecular imaging and biochemical tools to study the properties of the BRCA1 in human cancer cells. Our results reveal new information for the manner in which full-length BRCA1 engages its binding partner, the BRCA1-associated Ring Domain protein (BARD1) under oxidative stress conditions. We also show how physical differences between wild type and mutated BRCA1^5382insC impact the cell's response to oxidative damage. Overall, we demonstrate how clinically relevant changes to BRCA1 affect its structure-function relationship in hereditary breast cancer.

Hsp72 and Hsp90α mRNA transcription is characterised by large, sustained changes in core temperature during heat acclimation

Increased intracellular heat shock protein-72 (Hsp72) and heat shock protein-90α (Hsp90α) have been implicated as important components of acquired thermotolerance, providing cytoprotection during stress. This experiment determined the physiological responses characterising increases in Hsp72 and Hsp90α mRNA on the first and tenth day of 90-min heat acclimation (in 40.2 °C, 41.0 % relative humidity (RH)) or equivalent normothermic training (in 20 °C, 29 % RH). Pearson's product-moment correlation and stepwise multiple regression were performed to determine relationships between physiological [e.g. (Trec, sweat rate (SR) and heart rate (HR)] and training variables (exercise duration, exercise intensity, work done), and the leukocyte Hsp72 and Hsp90α mRNA responses via reverse transcription quantitative polymerase chain reaction (RT-QPCR) (n = 15). Significant (p < 0.05) correlations existed between increased Hsp72 and Hsp90α mRNA (r = 0.879). Increased core temperature was the most important criteria for gene transcription with ΔTrec (r = 0.714), SR (r = 0.709), Trecfinal45 (r = 0.682), area under the curve where Trec ≥ 38.5 °C (AUC38.5 °C; r = 0.678), peak Trec (r = 0.661), duration Trec ≥ 38.5 °C (r = 0.650) and ΔHR (r = 0.511) each demonstrating a significant (p < 0.05) correlation with the increase in Hsp72 mRNA. The Trec AUC38.5 °C (r = 0.729), ΔTrec (r = 0.691), peak Trec (r = 0.680), Trecfinal45 (r = 0.678), SR (r = 0.660), duration Trec ≥ 38.5 °C (r = 0.629), the rate of change in Trec (r = 0.600) and ΔHR (r = 0.531) were the strongest correlate with the increase in Hsp90α mRNA. Multiple regression improved the model for Hsp90α mRNA only, when Trec AUC38.5 °C and SR were combined. Training variables showed insignificant (p > 0.05) weak (r < 0.300) relationships with Hsp72 and Hsp90α mRNA. Hsp72 and Hsp90α mRNA correlates were comparable on the first and tenth day. When transcription of the related Hsp72 and Hsp90α mRNA is important, protocols should rapidly induce large, prolonged changes in core temperature.

Secreted tryptophanyl-tRNA synthetase as a primary defence system against infection

The N-terminal truncated form of a protein synthesis enzyme, tryptophanyl-tRNA synthetase (mini-WRS), is secreted as an angiostatic ligand. However, the secretion and function of the full-length WRS (FL-WRS) remain unknown. Here, we report that the FL-WRS, but not mini-WRS, is rapidly secreted upon pathogen infection to prime innate immunity. Blood levels of FL-WRS were increased in sepsis patients, but not in those with sterile inflammation. FL-WRS was secreted from monocytes and directly bound to macrophages via a toll-like receptor 4 (TLR4)-myeloid differentiation factor 2 (MD2) complex to induce phagocytosis and chemokine production. Administration of FL-WRS into Salmonella typhimurium-infected mice reduced the levels of bacteria and improved mouse survival, whereas its titration with the specific antibody aggravated the infection. The N-terminal 154-amino-acid eukaryote-specific peptide of WRS was sufficient to recapitulate FL-WRS activity and its interaction mode with TLR4-MD2 is now suggested. Based on these results, secretion of FL-WRS appears to work as a primary defence system against infection, acting before full activation of innate immunity.

Ergonomics and Beyond: Understanding How Chemical and Heat Exposures and Physical Exertions at Work Affect Functional Ability, Injury, and Long-Term Health

OBJECTIVE

To honor Tom Waters's work on emerging occupational health issues, we review the literature on physical along with chemical exposures and their impact on functional outcomes.

BACKGROUND

Many occupations present the opportunity for exposure to multiple hazardous exposures, including both physical and chemical factors. However, little is known about how these different factors affect functional ability and injury. The goal of this review is to examine the relationships between these exposures, impairment of the neuromuscular and musculoskeletal systems, functional outcomes, and health problems with a focus on acute injury.

METHOD

Literature was identified using online databases, including PubMed, Ovid Medline, and Google Scholar. References from included articles were searched for additional relevant articles.

RESULTS

This review documented the limited existing literature that discussed cognitive impairment and functional disorders via neurotoxicity for physical exposures (heat and repetitive loading) and chemical exposures (pesticides, volatile organic compounds [VOCs], and heavy metals).

CONCLUSION

This review supports that workers are exposed to physical and chemical exposures that are associated with negative health effects, including functional impairment and injury. Innovation in exposure assessment with respect to quantifying the joint exposure to these different exposures is especially needed for developing risk assessment models and, ultimately, preventive measures.

APPLICATION

Along with physical exposures, chemical exposures need to be considered, alone and in combination, in assessing functional ability and occupationally related injuries.

Sulfide exposure results in enhanced sqr transcription through upregulating the expression and activation of HSF1 in echiuran worm Urechis unicinctus

Sulfide is a natural, widely distributed, poisonous substance. Sulfide: quinone oxidoreductase (SQR) is responsible for the initial oxidation of sulfide in mitochondria. To study transcriptional regulation of sqr after sulfide exposure, a 2.6-kb sqr upstream sequence from echiuran worm Urechis unicinctus was cloned by genome walking. Bioinformatics analysis showed 3 heat shock elements (HSEs) in proximal promoter region of the sqr upstream sequence. Moreover, an Hsf1 cDNA in U. unicinctus (UuHsf1) was isolated with a full-length sequence of 2334 bp and its polyclonal antibody was prepared using U. unicinctus HSF1 (UuHSF1) expressed prokaryotically with whole sequence of its open reading frame (ORF). In vivo ChIP and in vitro EMSA assays revealed UuHSF1 could interact with the sqr proximal promoter region. Transient transfection and mutation assays indicated that UuHSF1 bound specifically to HSE (-155bp to -143bp) and enhanced the transcription of sqr. Furthermore, sulfide treatment experiments demonstrated that sulfide could increase the expression of HSF1 protein, and induce trimerization of the protein which binds to HSEs and then activate sqr transcription. Quantitative real-time PCR analysis revealed sqr mRNA level increased significantly after U. unicinctus was exposed to sulfide for 6h, which corresponded to content changes of both trimeric HSF1 and HSF1-HSE complex. We concluded that UuHSF1 is a transcription factor of sqr and sulfide could induce sqr transcription by upregulating the expression and activation of HSF1 in U. unicinctus exposed to sulfide.

Role of Heat-Shock Proteins in Cellular Function and in the Biology of Fungi

Stress (biotic or abiotic) is an unfavourable condition for an organism including fungus. To overcome stress, organism expresses heat-shock proteins (Hsps) or chaperons to perform biological function. Hsps are involved in various routine biological processes such as transcription, translation and posttranslational modifications, protein folding, and aggregation and disaggregation of proteins. Thus, it is important to understand holistic role of Hsps in response to stress and other biological conditions in fungi. Hsp104, Hsp70, and Hsp40 are found predominant in replication and Hsp90 is found in transcriptional and posttranscriptional process. Hsp90 and Hsp70 in combination or alone play a major role in morphogenesis and dimorphism. Heat stress in fungi expresses Hsp60, Hsp90, Hsp104, Hsp30, and Hsp10 proteins, whereas expression of Hsp12 protein was observed in response to cold stress. Hsp30, Hsp70, and Hsp90 proteins showed expression in response to pH stress. Osmotic stress is controlled by small heat-shock proteins and Hsp60. Expression of Hsp104 is observed under high pressure conditions. Out of these heat-shock proteins, Hsp90 has been predicted as a potential antifungal target due to its role in morphogenesis. Thus, current review focuses on role of Hsps in fungi during morphogenesis and various stress conditions (temperature, pH, and osmotic pressure) and in antifungal drug tolerance.

Host response biomarkers in the diagnosis of sepsis: a general overview

Critically ill patients who display a systemic inflammatory response syndrome (SIRS) are prone to develop nosocomial infections. The challenge remains to distinguish as early as possible among SIRS patients those who are developing sepsis. Following a sterile insult, damage-associated molecular patterns (DAMPs) released by damaged tissues and necrotic cells initiate an inflammatory response close to that observed during sepsis. During sepsis, pathogen-associated molecular patterns (PAMPs) trigger the release of host mediators involved in innate immunity and inflammation through identical receptors as DAMPs. In both clinical settings, a compensatory anti-inflammatory response syndrome (CARS) is concomitantly initiated. The exacerbated production of pro- or anti-inflammatory mediators allows their detection in biological fluids and particularly within the bloodstream. Some of these mediators can be used as biomarkers to decipher among the patients those who developed sepsis, and eventually they can be used as prognosis markers. In addition to plasma biomarkers, the analysis of some surface markers on circulating leukocytes or the study of mRNA and miRNA can be helpful. While there is no magic marker, a combination of few biomarkers might offer a high accuracy for diagnosis.

Heat shock protein 72 expressing stress in sepsis: unbridgeable gap between animal and human studies--a hypothetical "comparative" study

Heat shock protein 72 (Hsp72) exhibits a protective role during times of increased risk of pathogenic challenge and/or tissue damage. The aim of the study was to ascertain Hsp72 protective effect differences between animal and human studies in sepsis using a hypothetical “comparative study” model. Forty-one in vivo (56.1%), in vitro (17.1%), or combined (26.8%) animal and 14 in vivo (2) or in vitro (12) human Hsp72 studies (P < 0.0001) were enrolled in the analysis. Of the 14 human studies, 50% showed a protective Hsp72 effect compared to 95.8% protection shown in septic animal studies (P < 0.0001). Only human studies reported Hsp72-associated mortality (21.4%) or infection (7.1%) or reported results (14.3%) to be nonprotective (P < 0.001). In animal models, any Hsp72 induction method tried increased intracellular Hsp72 (100%), compared to 57.1% of human studies (P < 0.02), reduced proinflammatory cytokines (28/29), and enhanced survival (18/18). Animal studies show a clear Hsp72 protective effect in sepsis. Human studies are inconclusive, showing either protection or a possible relation to mortality and infections. This might be due to the fact that using evermore purified target cell populations in animal models, a lot of clinical information regarding the net response that occurs in sepsis is missing.

Association of HSPA1B SNP rs6457452 with Alopecia Areata in the Korean population

The heat shock 70 kDa protein 1B (HSPA1B), which has been well-studied among the famous heat shock proteins HSPA1A/B/L, is related to autoimmune diseases, including Alopecia Areata (AA). In this study, the association of a 5'-untranslated region (5'UTR) SNP rs6457452 and a promoter SNP rs2763979 (-1140C > T) of HSPA1B with AA was investigated in 236 controls and 228 AA patients. Statistical analyses using the multiple logistic models were done, according to the onset and the clinical features of AA, including the age of onset, family history, type of AA lesion, nail involvement and body hair involvement. The results showed that rs6457452 was associated with the onset of AA (p < 0.002). In the analysis of clinical features of AA, rs6457452 was weakly related to the age of onset (p ≤ 0.04) and that rs2763979 was only weakly related to the type of AA lesion (p = 0.041). In conclusion, we suggest that the 5'UTR SNP rs6457452 of HSPA1B may be associated with the onset of AA and the T allele of rs6457452 may confer the reduced susceptibility to AA in the Korean population.

Identification of fever and vaccine-associated gene interaction networks using ontology-based literature mining

Background

Fever is one of the most common adverse events of vaccines. The detailed mechanisms of fever and vaccine-associated gene interaction networks are not fully understood. In the present study, we employed a genome-wide, Centrality and Ontology-based Network Discovery using Literature data (CONDL) approach to analyse the genes and gene interaction networks associated with fever or vaccine-related fever responses.

Results

Over 170,000 fever-related articles from PubMed abstracts and titles were retrieved and analysed at the sentence level using natural language processing techniques to identify genes and vaccines (including 186 Vaccine Ontology terms) as well as their interactions. This resulted in a generic fever network consisting of 403 genes and 577 gene interactions. A vaccine-specific fever sub-network consisting of 29 genes and 28 gene interactions was extracted from articles that are related to both fever and vaccines. In addition, gene-vaccine interactions were identified. Vaccines (including 4 specific vaccine names) were found to directly interact with 26 genes. Gene set enrichment analysis was performed using the genes in the generated interaction networks. Moreover, the genes in these networks were prioritized using network centrality metrics. Making scientific discoveries and generating new hypotheses were possible by using network centrality and gene set enrichment analyses. For example, our study found that the genes in the generic fever network were more enriched in cell death and responses to wounding, and the vaccine sub-network had more gene enrichment in leukocyte activation and phosphorylation regulation. The most central genes in the vaccine-specific fever network are predicted to be highly relevant to vaccine-induced fever, whereas genes that are central only in the generic fever network are likely to be highly relevant to generic fever responses. Interestingly, no Toll-like receptors (TLRs) were found in the gene-vaccine interaction network. Since multiple TLRs were found in the generic fever network, it is reasonable to hypothesize that vaccine-TLR interactions may play an important role in inducing fever response, which deserves a further investigation.

Conclusions

This study demonstrated that ontology-based literature mining is a powerful method for analyzing gene interaction networks and generating new scientific hypotheses.

A combined proteomic and transcriptomic approach shows diverging molecular mechanisms in thoracic aortic aneurysm development in patients with tricuspid- and bicuspid aortic valve

Thoracic aortic aneurysm is a pathological local dilatation of the aorta, potentially leading to aortic rupture or dissection. The disease is a common complication of patients with bicuspid aortic valve, a congenital disorder present in 1-2% of the population. Using two dimensional fluorescence difference gel electrophoresis proteomics followed by mRNA expression, and alternative splicing analysis of the identified proteins, differences in dilated and nondilated aorta tissues between 44 patients with bicuspid and tricuspid valves was examined. The pattern of protein expression was successfully validated with LC-MS/MS. A multivariate analysis of protein expression data revealed diverging protein expression fingerprints in patients with tricuspid compared with the patients with bicuspid aortic valves. From 302 protein spots included in the analysis, 69 and 38 spots were differentially expressed between dilated and nondilated aorta specifically in patients with tricuspid and bicuspid aortic valve, respectively. 92 protein spots were differentially expressed between dilated and nondilated aorta in both phenotypes. Similarly, mRNA expression together with alternative splicing analysis of the identified proteins also showed diverging fingerprints in the two patient groups. Differential splicing was abundant but the expression levels of differentially spliced mRNA transcripts were low compared with the wild type transcript and there was no correlation between splicing and the number of spots. Therefore, the different spots are likely to represent post-translational modifications. The identification of differentially expressed proteins suggests that dilatation in patients with a tricuspid aortic valve involves inflammatory processes whereas aortic aneurysm in patients with BAV may be the consequence of impaired repair capacity. The results imply that aortic aneurysm formation in patients with bicuspid and tricuspid aortic valves involve different biological pathways leading to the same phenotype.

Glutamine-mediated dual regulation of heat shock transcription factor-1 activation and expression

BACKGROUND

Regulation of transcriptional activity of heat shock factor-1 (HSF1) is widely thought to be the main point of control for heat shock protein (Hsp) expression.

RESULTS

Glutamine increases Hsf1 gene transcription in a C/EBPβ-dependent manner and up-regulates HSF1 activity.

CONCLUSION

Glutamine is an activator for both HSF1 expression and transactivation.

SIGNIFICANCE

Glutamine-induced HSF1 expression provides a novel mechanistic frame for HSF1-Hsp axis regulation. Heat shock transcription factor-1 (HSF1) is the master regulator for cytoprotective heat shock protein (Hsp) expression. It is widely thought that HSF1 expression is non-inducible, and thus the key control point of Hsp expression is regulation of the transactivation activity of HSF1. How HSF1 expression is regulated remains unknown. Herein we demonstrate that glutamine (Gln), a preferred fuel substrate for the gut, enhanced Hsp expression both in rat colonic epithelium in vivo and in cultured non-transformed young adult mouse colonic epithelial cells. This was associated with up-regulation of the transactivation activity of HSF1 via increased HSF1 trimerization, nuclear localization, DNA binding, and relative abundance of activating phosphorylation at Ser-230 of HSF1. More intriguingly, Gln enhanced HSF1 protein and mRNA expression and Hsf1 gene promoter activity. Within the -281/-200 region of the Hsf1 promoter, deletion of the putative CCAAT enhancer-binding protein (C/EBP) binding site abolished the HSF1 response to Gln. C/EBPβ was further shown to bind to this 82-bp sequence both in vitro and in vivo. Gln availability strikingly altered the ratio of C/EBPβ inhibitory and active isoforms, i.e. liver-enriched inhibitory protein and liver-enriched activating protein. Liver-enriched inhibitory protein and liver-enriched activating protein were further shown to be an independent repressor and activator, respectively, for Hsf1 gene transcription, and the relative abundance of these two C/EBPβ isoforms was demonstrated to determine Hsf1 transcription. We show for the first time that Gln not only enhances the transactivation of HSF1 but also induces Hsf1 expression by activating its transcription in a C/EBPβ-dependent manner.

Glutamine randomized studies in early life: the unsolved riddle of experimental and clinical studies

Glutamine may have benefits during immaturity or critical illness in early life but its effects on outcome end hardpoints are controversial. Our aim was to review randomized studies on glutamine supplementation in pups, infants, and children examining whether glutamine affects outcome. Experimental work has proposed various mechanisms of glutamine action but none of the randomized studies in early life showed any effect on mortality and only a few showed some effect on inflammatory response, organ function, and a trend for infection control. Although apparently safe in animal models (pups), premature infants, and critically ill children, glutamine supplementation does not reduce mortality or late onset sepsis, and its routine use cannot be recommended in these sensitive populations. Large prospectively stratified trials are needed to better define the crucial interrelations of “glutamine-heat shock proteins-stress response” in critical illness and to identify the specific subgroups of premature neonates and critically ill infants or children who may have a greater need for glutamine and who may eventually benefit from its supplementation. The methodological problems noted in the reviewed randomized experimental and clinical trials should be seriously considered in any future well-designed large blinded randomized controlled trial involving glutamine supplementation in critical illness.

Gene expression of Hsp70, Hsp90 and Hsp110 families in normal palate and cleft palate during mouse embryogenesis

Most previous studies focused on a small number of heat shock proteins (Hsps) and their relationships with embryogenesis, and the actual roles of these Hsps in normal and abnormal embryonic development remain unclear. It was found in the present systemic study that except for Grp170, whose expression was not detectable at GD18, all 19 Hsps of Hsp70, Hsp90 and Hsp110 families were expressed in the normal development of embryonic palate tissue in mice, but their expression patterns varied with different Hsps, presenting as a correlation with the developmental phases. In the treatment group by all-trans retinoic acid (atRA), the messenger RNA (mRNA) abundance of HspA1A, HspA1L, HspA8, HspA9, HspA12A, HspA12B, HspA13, HspA14, Hsp90AA1, Hsp90AB1, Grp94, Trap1, Hsp105, Hsp110 and Grp170 was higher in the palates at GD11 (the beginning of palate development), the mRNA abundance of HspA1A, HspA12A and HspA12B was higher at GD18 (before birth) and an mRNA expression peak of HspA1L, HspA8, HspA9, Hsp90AA1, Grp94, Hsp110 and Grp170 was observed at GD17. The mRNA abundance of most genes in atRA-induced cleft palates of the treatment group was different from that of the control group. Grp78, HspA14 and Hsp105 were closely associated with the normal palate development and cleft palate in mouse embryo, possibly as palate development-related genes. Except Grp170, the other genes may be closely associated with the development of mouse palates through participating in the stress response process and/or the antiapoptosis process.

Pediatric Sepsis - Part V: Extracellular Heat Shock Proteins: Alarmins for the Host Immune System

Heat shock proteins (HSPs) are molecular chaperones that facilitate the proper folding and assembly of nascent polypeptides and assist in the refolding and stabilization of damaged polypeptides. Through these largely intracellular functions, the HSPs maintain homeostasis and assure cell survival. However, a growing body of literature suggests that HSPs have important effects in the extracellular environment as well. Extracellular HSPs are released from damaged or stressed cells and appear to act as local "danger signals" that activate stress response programs in surrounding cells. Importantly, extracellular HSPs have been shown to activate the host innate and adaptive immune response. With this in mind, extracellular HSPs are commonly included in a growing list of a family of proteins known as danger-associated molecular patterns (DAMPs) or alarmins, which trigger an immune response to tissue injury, such as may occur with trauma, ischemia-reperfusion injury, oxidative stress, etc. Extracellular HSPs, including Hsp72 (HSPA), Hsp27 (HSPB1), Hsp90 (HSPC), Hsp60 (HSPD), and Chaperonin/Hsp10 (HSPE) are especially attractrive candidates for DAMPs or alarmins which may be particularly relevant in the pathophysiology of the sepsis syndrome.

Molecular detection and characterisation of fungal heat shock protein 60

Heat shock proteins (Hsp) are highly conserved molecules, which are both constitutively expressed and up-regulated in response to various stress conditions. In particular, fungal Hsp60 can act as immunodominant antigens and facilitate powerful immunological properties. A possible cellular heat shock response was investigated in eight fungi (Aspergillus fumigatus, Aspergillus terreus, Penicillium chrysogenum, Cladosporium cladosporioides, Scedosporium apiospermum, Trichophyton mentagrophytes, Candida albicans and Saccharomyces cerevisiae). Fully automated RNA extraction was followed by quantitative real-time RT-PCR targeting fungus-specific Hsp60 mRNA and sequencing of the amplicon. Levels of temperature-dependent gene expression were evaluated and rates of similarity and identity were compared. While Hsp60 mRNA was constitutively expressed in all the samples tested, a temperature-dependent induction was not shown in C. cladosporioides. In the 80-amino acid fragment from the hypothetical protein, 66% of the amino acids were identical, 20% showed a conserved and 8% a semi-conserved substitution. Our findings should contribute to a better understanding of host-pathogen relationship and suggest that fungal Hsp60 under temperature-related stress conditions might act as an immunogenic trigger in orchestrating fungi-related diseases.

Body temperature effects on lung injury in ventilated preterm lambs

AIMS

Mechanical ventilation causes lung injury in premature infants. Hypothermia may protect against and hyperthermia may augment lung injury. We tested the effects of hypo- and hyperthermia on ventilation induced acute lung injury in preterm lambs.

METHODS

Twin sheep fetuses at 128 d GA (term 150 d) were surgically delivered and randomized to unventilated control (UVC), normothermia (38-39 degrees C) without lung injury (NTNI), or to 1 of 3 injurious ventilation groups: hypothermic (33-34 degrees C, LT), normothermic (38-39 degrees C, NT) or hyperthermic (40-41 degrees C, HT). NT, LT and HT groups had 15 min of injurious ventilation (PEEP 0 cmH(2)O, V(T) escalation to 15 mL/kg) following delivery and prior to surfactant. The animals were then gently ventilated (PEEP 5cmH(2)O, V(T) 7.5 mL/kg) for 2h 45 min. NTNI lambs received surfactant at birth prior to gentle ventilation. The lambs were then euthanized, and bronchoalveolar lavage (BAL) fluid and lung tissue were used to evaluate lung injury, inflammatory cell counts, inflammatory markers and cytokine mRNA.

RESULTS

Target temperatures were achieved by 15 min of age and maintained for 3h. All ventilated groups had increased BAL protein, lung inflammation and increased cytokine mRNA. HT animals developed acidosis, premature death, pneumothoraces, impaired lung function and increased inflammatory mRNA expression. LT animals remained clinically stable without pneumothoraces or death, had improved ventilatory efficiency and trended toward lower inflammatory mRNA expression than NT animals.

CONCLUSION

Hyperthermia exacerbated ventilator induced lung injury, while hypothermia may protect against lung injury in the preterm lamb.