Cyclosporin A induces an atypical heat shock response

Comparative RNA-Sequencing Analysis Reveals High Complexity and Heterogeneity of Transcriptomic and Immune Profiles in Hepatocellular Carcinoma Tumors of Viral (HBV, HCV) and Non-Viral Etiology

Background and Objectives: Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is the leading cause of cancer-related mortality. It arises and progresses against fibrotic or cirrhotic backgrounds mainly due to infection with hepatitis viruses B (HBV) or C (HCV) or non-viral causes that lead to chronic inflammation and genomic changes. A better understanding of molecular and immune mechanisms in HCC subtypes is needed. Materials and Methods: To identify transcriptional changes in primary HCC tumors with or without hepatitis viral etiology, we analyzed the transcriptomes of 24 patients by next-generation sequencing. Results: We identified common and unique differentially expressed genes for each etiological tumor group and analyzed the expression of SLC, ATP binding cassette, cytochrome 450, cancer testis, and heat shock protein genes. Metascape functional enrichment analysis showed mainly upregulated cell-cycle pathways in HBV and HCV and upregulated cell response to stress in non-viral infection. GeneWalk analysis identified regulator, hub, and moonlighting genes and highlighted CCNB1, ACTN2, BRCA1, IGF1, CDK1, AURKA, AURKB, and TOP2A in the HCV group and HSF1, HSPA1A, HSP90AA1, HSPB1, HSPA5, PTK2, and AURKB in the group without viral infection as hub genes. Immune infiltrate analysis showed that T cell, cytotoxic, and natural killer cell markers were significantly more highly expressed in HCV than in non-viral tumors. Genes associated with monocyte activation had the highest expression levels in HBV, while high expression of genes involved in primary adaptive immune response and complement receptor activity characterized tumors without viral infection. Conclusions: Our comprehensive study underlines the high degree of complexity of immune profiles in the analyzed groups, which adds to the heterogeneous HCC genomic landscape. The biomarkers identified in each HCC group might serve as therapeutic targets.

Gene networking in colistin-induced nephrotoxicity reveals an adverse outcome pathway triggered by proteotoxic stress

Colistin has been widely used for the treatment of infections of multidrug-resistant Gram-negative bacteria, despite the fact that it induces serious kidney injury as a side effect. To investigate the mechanism underlying its nephrotoxicity, colistin methanesulfonate sodium (CMS; 25 or 50 mg/kg) was administered via intraperitoneal injection to Sprague-Dawley rats daily over 7 days. Serum biochemistry and histopathology indicated that nephrotoxicity occurred in the rats administered with CMS. Whole-genome microarrays indicated 894 differentially expressed genes in the group treated with CMS (analysis of variance, false discovery rate <0.05, fold-change ≥1.3). Gene pathway and networking analyses revealed that genes associated with proteotoxic stress, including ribosome synthesis, protein translation, and protein folding, were significantly associated with the nephrotoxicity induced by CMS. It was found that colistin inhibited the expression of the target genes heat shock factor 1 and nuclear factor erythroid-2-related factor-2, which are associated with proteostasis, and that nephrotoxicity of CMS may be initiated by proteotoxic stress due to heat shock response inhibition, leading to oxidative stress, endoplasmic reticulum stress, cell cycle arrest and apoptosis, eventually leading to cell death. A putative adverse outcome pathway was constructed based on the integrated gene networking data, which may clarify the mode of action of colistin-induced nephrotoxicity.

Tubular Cytoplasmic Expression of Zinc Finger Protein SNAI1 in Renal Transplant Biopsies: A Sign of Diseased Epithelial Phenotype?

The aim of the present study was to analyze in vivo the role of zinc finger protein SNAI1 (SNAI1) on renal fibrosis. Unilateral ureteral obstruction injury was induced in Snai1 knockout mice. Snai1 gene deletion was, however, only partial and could therefore not be correlated to reduced fibrosis. Expression of SNAI1 protein and epithelial-mesenchymal transformation markers was then assessed in human chronic allograft nephropathy biopsy specimens. Significant up-regulation of SNAI1 protein was detected within cytoplasm of proximal tubules localized, for some of them, near foci of fibrosis and tubular atrophy. No concomitant epithelial-mesenchymal transformation could, however, be demonstrated analyzing the expression of the fibroblast markers vimentin, α-smooth muscle actin, and S100A4. SNAI1 cytoplasmic up-regulation was particularly evident in biopsy specimens obtained from calcineurin inhibitor-treated patients, which might be because of, as suggested by in vitro experiments, a decrease of the proteasome chimotrypsin activity. Deeper analysis on chronic allograft nephropathy biopsy specimens suggested that SNAI1 cytoplasmic up-regulation was preceded by a transient increase of phosphorylated heat shock protein 27, p38 mitogen-activated protein kinase, and glycogen synthase kinase 3β. Concomitant down-regulation of the polyubuquitinylated conjugates was detected in SNAI1⁺ tubules. Altogether, these results might suggest that calcineurin inhibitor-induced tubular SNAI1 protein cytoplasmic accumulation, possibly because of impaired SNAI1 proteasomal degradation and nuclear translocation, might be a sign of a diseased profibrotic epithelial phenotype.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

The effect of Cyclosporine A on cardiomyocytes differentiation

Cyclosporine A (CsA) is a powerful immunosuppressive drug which significantly improved the success of organ transplantation; however, the major limiting factors for the drug's clinical use are its long and short term adverse effects. The present study was conducted to examine, in a dose-dependent manner, in a model of cardiogenesis, the effect of CsA on cardiomyocytes differentiation.

Role of heat shock response and Hsp27 in mutant SOD1-dependent cell death

The fatal neurodegenerative disorder amyotrophic lateral sclerosis (ALS) is characterized by selective loss of motor neurons and mutations in the copper-zinc superoxide dismutase (SOD1) enzyme underlie one form of familial ALS. The pathogenic mechanism of these mutations is elusive but is thought to involve oxidative stress and protein aggregation. These two phenomena are known to induce heat shock proteins (Hsps) which protect stressed cells through their chaperoning and anti-apoptotic activity. In order to investigate the role of Hsp27 in mutant SOD1-dependent cell death, we used mutant and wild type SOD1 overexpressing N2a mouse neuroblastoma cells. Mutant SOD1-dependent cell death could be induced by heat shock, and by treating the cells with cyclosporine A or lactacystin. Transfection with an Hsp27 expression construct did not protect the N2a cells against mutant SOD1-dependent cell death. However, pre-conditioning N2a cells with a mild heat shock was accompanied by a significant upregulation of Hsp27 in the mutant SOD1 cells, and protected these cells against subsequent cell death induced by a more severe heat shock. Selective inhibition of the Hsp27 upregulation, through the use of Hsp27 siRNA, did not attenuate the protective effect of this treatment. These results show that activation of the heat shock response protects cells against mutant SOD1-dependent cell death, but that Hsp27 is not an essential component of the stress response leading to protection.

Pharmacological modulation of the heat shock response

Life presents a continuous series of stresses. Increasing the adaptation capacity of the organism is a long-term survival factor of various organisms and has become an attractive field of intensive therapeutic research. Induction of the heat shock response promotes survival after a wide variety of environmental stresses. Preclinical studies have proven that physiological and pharmacological chaperone inducers and co-inducers are an efficient therapeutic approach in different acute and chronic diseases. In this chapter, we summarize current knowledge of the current state of chaperone modulation and give a comprehensive list of the main drug candidates.

Amelioration of cyclosporine nephrotoxicity by irbesartan, A selective AT1 receptor antagonist

Cyclosporine A (CsA), a fungal undecapeptide, is the most common immunosuppressive drug used in organ transplantation and autoimmune diseases. However, nephrotoxicity is the major adverse effect of CsA use. The molecular mechanisms of CsA nephrotoxicity are not well characterized, but more recent studies suggest an involvement of angiotensin II (ANG II) and reactive oxygen species in the development of cyclosporine nephrotoxicity. Induction of heat shock proteins (HSPs) is one of the best-described cellular responses to heat stress, hypoxia, and exposure to oxidants. HSPs have beneficial roles in protein processing and protection against cell injury. There is emerging evidence that ANG II induces oxidative stress in vitro and in vivo. This study was thus designed to investigate the role of Angiotensin II type I (AT1) receptor antagonist, irbesartan, on CsA-induced nephrotoxicity. Five groups of rats were employed in this study: group 1 served as control, group 2 rats were treated with CsA (20 mg kg(-1), subcutaneously for 21 days), and groups 3, 4, and 5 received CsA along with irbesartan (10, 25, and 50 mg kg(-1), perorally 24 hr before and 21 days concurrently), respectively. Renal function was assessed by measuring serum creatinine, blood urea nitrogen, creatinine, and urea clearance. The renal oxidative stress was measured by renal malondialdehyde levels, reduced glutathione levels, and enzymatic activity of catalase, glutathione reductase, and superoxide dismutase. Renal morphological alterations were assessed by histopathological examination. CsA administration for 21 days resulted in a marked renal oxidative stress and significantly deranged the renal functions as well as renal morphology. All these factors were significantly improved by irbesartan (50 mg kg(-1)) treatment. HSP72, HSP47, and HSP25 were clearly induced and expressed in CsA-treated animals. The induction and expression of HSP25 was markedly protected by treatment with irbesartan, whereas the induction and expression of HSP47 and HSP72 remained unaltered with the irbesartan treatment. These results clearly demonstrate the pivotal role of ANG II-induced oxidative stress and therapeutic potential of AT, receptor antagonist in ameliorating CsA-induced nephrotoxicity.

Phenotypic characterization of mouse embryonic fibroblasts lacking heat shock factor 2

In murine cells, the heat shock response is regulated by a transcription factor, HSF1, which triggers the transcription of heat shock genes. HSF2 has been shown to be involved in meiosis and mouse brain development. We characterized the effects of the absence of HSF2 in mouse embryonic fibroblasts (MEFs). The temperature threshold of the heat shock response appeared lowered in Hsf2(-/-) MEFS as monitored by the synthesis of heat shock protein HSP70. In contrast to unstressed wild type MEFS, HSP70 and HSF1 are localized in the nucleus of unstressed Hsf2(-/-) MEFS, a characteristic of stressed cells. HSF1 is not activated for DNA-binding at unstressed temperature in Hsf2(-/-) MEFS. Therefore, the absence of HSF2 induces some but not all of the characteristics of the stress response. In addition, Hsf2(-/-) MEFS exhibited proliferation defects, altered morphology, remodeling of the fibronectin network.

Cyclosporine A regulate oxidative stress-induced apoptosis in cardiomyocytes: mechanisms via ROS generation, iNOS and Hsp70

1. Previous study suggested that cyclosporine A (CsA) could partially reduce ischaemia/reperfusion-induced injury in isolated heart, but the mechanism was still unclear. In this study, the possible mechanisms of cyclosporine A in regulating oxidative stress-induced cardiomyocyte apoptosis were examined. 2. Morphological (cell shrinkage, apoptotic body formation, and DNA fragmentation) and biochemical (annexin-V staining for exposed phosphatidylserine residues) evidences showed that both hydrogen peroxide (H(2)O(2)) and hypoxia/reoxygenation could induce apoptotic change in the embryonal rat heart myoblast-derived cells (H9c2). These effects were inhibited by pre-treatment with CsA at concentration of 0.01-1.0 micro M for 24 h, but were increased with 10.0 micro M CsA. 3. While examining the mechanisms of CsA in protecting cardiomyocyte apoptosis, we found that the collapse of mitochondria membrane potential (DeltaPsim) induced by oxidative stress was partially reversed by CsA (0.01-1.0 micro M). 4. Compared to the control, CSA at the concentration of 0.1 and 10.0 micro M significantly increased the level of intracellular reactive oxygen species (ROS) to 117.2+/-12.4% and 234.4+/-9.3%, respectively. Co-incubating with the antioxidant, ascorbic acid (10.0 micro M), could partially reduce the protective effect of CsA (0.01-1.0 micro M) and the toxic effect of 10.0 micro M CsA. 5. Pre-treatment with CsA at concentration of 0.01-1.0 micro M for 24 h produced up-regulation of heat shock protein 70 (Hsp 70), inducible nitric oxide synthase (iNOS) and also induced NO production, indicating that these factors might be associated with the cell protective effects of CsA. 6. These results suggest that CsA could protect the oxidative stress-induced cardiomyocyte apoptosis not only by preventing the loss of DeltaPsim in mitochondria, but also through ROS generation, Hsp70, and iNOS up-regulation.

Small heat shock proteins expression in rat kidneys treated with cyclosporine A alone and combined with melatonin

Small heat shock proteins (sHSPs) are cytoskeletal chaperones constitutively expressed in the normal kidney but enhanced with beneficial roles during adverse stimuli. Cyclosporine A is an immunosuppressive drug with major adverse side effect such as severe nephrotoxicity. Among possible mechanisms of cyclosporine A-induced renal damage, oxidative stress and cytoskeletal damage have been suggested. Melatonin has been successfully used as antioxidant against many renal diseases. This in vivo study was performed to shed light on the protective effect of melatonin against cyclosporine A-induced renal alterations. We treated rats with cyclosporine A alone, or combined with melatonin, and with melatonin alone (as controls) for 40 days and analysed the renal abundance and distribution of two sHSPs, HSP25 and alpha B-crystallin. These data were correlated with the histopathological effects of the treatments. Cyclosporine A induced insoluble isoforms that moved to soluble fractions after melatonin coadministration as in controls. After cyclosporine A treatment, an intense signal for sHSPs was found within the glomeruli, nucleus and cytoplasm of cortical tubules, collecting ducts and vascular wall. After melatonin supply, the staining was faint, limited to the cytoplasm of cortical tubules, similar to controls. Both fibrosis and tubular alterations significantly decreased after melatonin coadministration. In conclusion, HSP25 and alpha B-crystallin are overexpressed in the rat kidney treated with cyclosporine A but are similar to controls after combined melatonin. This could be a consequence of the cytoprotective effect of melatonin in this nephrotoxic model so that a beneficial sHSPs response is unnecessary.

Stress-specific activation and repression of heat shock factors 1 and 2

Vertebrate cells express a family of heat shock transcription factors (HSF1 to HSF4) that coordinate the inducible regulation of heat shock genes in response to diverse signals. HSF1 is potent and activated rapidly though transiently by heat shock, whereas HSF2 is a less active transcriptional regulator but can retain its DNA binding properties for extended periods. Consequently, the differential activation of HSF1 and HSF2 by various stresses may be critical for cells to survive repeated and diverse stress challenges and to provide a mechanism for more precise regulation of heat shock gene expression. Here we show, using a novel DNA binding and detection assay, that HSF1 and HSF2 are coactivated to different levels in response to a range of conditions that cause cell stress. Above a low basal activity of both HSFs, heat shock preferentially activates HSF1, whereas the amino acid analogue azetidine or the proteasome inhibitor MG132 coactivates both HSFs to different levels and hemin preferentially induces HSF2. Unexpectedly, we also found that heat shock has dramatic adverse effects on HSF2 that lead to its reversible inactivation coincident with relocalization from the nucleus. The reversible inactivation of HSF2 is specific to heat shock and does not occur with other stressors or in cells expressing high levels of heat shock proteins. These results reveal that HSF2 activity is negatively regulated by heat and suggest a role for heat shock proteins in the positive regulation of HSF2.

Distribution of heat shock proteins in kidneys of rats after immunosuppressive treatment with cyclosporine A

Cyclosporine A (CsA), a fungal undecapeptide, is the most common immunosuppressive drug used in organ transplantation and auto-immune diseases. However, it has severe side effects mainly on renal structures and functions. Therefore, nephrotoxicity is the major limiting side effect. Heat shock proteins (HSPs) are molecular chaperones, that are induced or expressed at high levels in mammalian cells due to a variety of adverse effects. HSPs have beneficial roles in protein processing and protection against cell injury. In the present study, we examined immunohistochemically levels of expression and localization patterns of various HSPs in rat kidneys after administration of a therapeutic CsA dose during 30 days. After CsA treatment, both constitutive HSP 25 and alpha B-crystallin immunoreactivity became stronger in glomeruli, proximal tubules and collecting ducts. Nuclear translocation of these proteins was detected in renal tubules. HSP 47 was detected in the interstitial space between tubules, vascular smooth muscle and medullary rays. Finally, HSP 72 was induced in the cytoplasm of epithelial cells of proximal and distal tubules, and in the cytoplasm of epithelial cells of Henle limbs and collecting ducts. These data demonstrate that CsA clearly induces increased immunoreactivity of HSPs in defined structures of rat kidneys. These findings suggest that these proteins are functionally involved in the defence against renal cellular damage caused by prolonged drug treatment in rat.