Heat shock proteins in the kidney

Dihydromyricetin protects against cisplatin-induced renal injury and mitochondria-mediated apoptosis via the EGFR/HSP27/STAT3 signaling pathway

BACKGROUND

Cisplatin (CP) has been used as an effective chemotherapy drug for different types of cancers. Despite its therapeutic benefits, the clinical utility of CP is often hindered by adverse effects, notably acute kidney injury (AKI), which restricts its widespread application. Dihydromyricetin (DHM) is a flavonoid acquired from Ampelopsis grossedentata, exhibiting a range of pharmacological activities. The major objective of this research was to examine the possible molecular mechanism involved in CP-induced AKI and the protective function of DHM.

METHODS

In this study, the protective function of DHM against CP-induced AKI was assessed in both mice and HK-2 cells. Kidney dysfunction parameters and renal morphology were evaluated to ascertain the extent of protection. Additionally, proteomics techniques were employed to investigate the protective effect of DHM and elucidate the underlying molecular mechanisms involved in mitigating CP-induced AKI. In addition, protein levels of epidermal growth factor receptor (EGFR), p-EGFR, heat shock protein 27 (HSP27), p-HSP27, STAT3, and p-STAT3 in renal tissues were investigated. Furthermore, an EGFR-blocking agent (gefitinib) or si-RNA of HSP27 was used to study the effects of inhibiting EGFR or HSP27 on CP-induced renal injury.

RESULTS

DHM decreased blood urea nitrogen (BUN) and creatinine in serum, alleviated renal morphological injury and downregulated the expression of CP-induced kidney injury molecule-1 and neutrophil gelatinase-related lipocalin. Proteomic data revealed HSP27 as a potential therapeutic target for AKI. DHM treatment resulted in the downregulation of EGFR, HSP27, and STAT3 phosphorylation, ultimately mitigating CP-induced AKI. In addition, the inhibition of EGFR or HSP27 reduced mitochondria-mediated apoptosis and CP-induced cell damage in HK-2 cells.

CONCLUSIONS

DHM effectively inhibited CP-induced oxidative stress, inflammation, and mitochondria-mediated apoptosis through the EGFR/HSP27/STAT3 pathway.

Distinct Urinary Proteome Changes Across Estimated Glomerular Filtration Rate Stages in a Cohort of Black South Africans

Kidney function parameters including estimated glomerular filtration rate (eGFR) and urine albumin excretion are commonly used to diagnose chronic kidney disease (CKD). However, these parameters are relatively insensitive, limiting their utility for screening and early detection of kidney disease. Studies have suggested that urinary proteomic profiles differ by eGFR stage, offering potential insights into kidney disease pathogenesis alongside opportunities to increase the sensitivity of current testing strategies. In this study, we characterized and compared the urinary proteome across different eGFR stages in a Black African cohort from rural Mpumalanga Province, South Africa. We stratified 81 urine samples by eGFR stage (mL/min/1.73 m2): Stage G1 (eGFR ≥ 90; n = 36), Stage G2 (eGFR 60-89; n = 35), and Stage G3-G5 (eGFR < 60; n = 10). Urine proteomic analysis was performed using an Evosep One liquid chromatography system coupled to a Sciex 5600 TripleTOF in data-independent acquisition mode. Nonparametric multivariate analysis and receiver operating characteristic (ROC) curves were used to assess the performance of differentially abundant proteins (DAPs). Pathway analysis was performed on DAPs. Creatinine-based eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. In this study, thirty-eight urinary proteins were differentially abundant for eGFR Stages 3-5 when compared to Stages G1 (AUC = 0.95; CI: 0.86-1) and G2 (AUC = 0.84; CI: 0.64-0.98). Notably, only six urinary proteins (Cystatin M (CST6), glutathione hydrolase 6 (GGT6), sushi domain containing 2 (SUSD2), insulin-like growth factor binding protein 6 (IGFBP6), heat shock protein 90 beta family member 1 (HSP90B1), and mannosidase alpha class 1A member 1 (MAN1A1)) were differentially abundant when comparing Stage G1 and Stage G2 with a modest AUC = 0.81 (CI: 0.67-0.92). Pathway analysis indicated that DAPs were associated with haemostasis and fibrin clot formation. In a rural cohort from South Africa, the urinary proteome differed by eGFR stage, and we identified six differentially abundant proteins which, in combination, could help to differentiate earlier eGFR stages with higher predictive accuracy than the currently available tests.

Sex differences in the association of long-term exposure to heat stress on kidney function in a large Taiwanese population study

The incidence and prevalence of dialysis in Taiwan are high compared to other regions. Consequently, mitigating chronic kidney disease (CKD) and the worsening of kidney function have emerged as critical healthcare priorities in Taiwan. Heat stress is known to be a significant risk factor for CKD and kidney function impairment. However, differences in the impact of heat stress between males and females remains unexplored. We conducted this retrospective cross-sectional analysis using data from the Taiwan Biobank (TWB), incorporating records of the wet bulb globe temperature (WBGT) during midday (11 AM-2 PM) and working hours (8 AM-5 PM) periods based on the participants' residential address. Average 1-, 3-, and 5-year WBGT values prior to the survey year were calculated and analyzed using a geospatial artificial intelligence-based ensemble mixed spatial model, covering the period from 2010 to 2020. A total of 114,483 participants from the TWB were included in this study, of whom 35.9% were male and 1053 had impaired kidney function (defined as estimated glomerular filtration rate < 60 ml/min/1.73 m2). Multivariable analysis revealed that in the male participants, during the midday period, the 1-, 3-, and 5-year average WBGT values per 1 ℃ increase were significantly positively associated with eGFR < 60 ml/min/1.73 m2 (odds ratio [OR], 1.096, 95% confidence interval [CI] = 1.002-1.199, p = 0.044 for 1 year; OR, 1.093, 95% CI = 1.000-1.196, p = 0.005 for 3 years; OR, 1.094, 95% CI = 1.002-1.195, p = 0.045 for 5 years). However, significant associations were not found for the working hours period. In the female participants, during the midday period, the 1-, 3-, and 5-year average WBGT values per 1 ℃ increase were significantly negatively associated with eGFR < 60 ml/min/1.73 m2 (OR, 0.872, 95% CI = 0.778-0.976, p = 0.018 for 1 year; OR, 0.874, 95% CI = 0.780-0.978, p = 0.019 for 3 years; OR, 0.875, 95% CI = 0.784-0.977, p = 0.018 for 5 years). In addition, during the working hours period, the 1-, 3-, and 5-year average WBGT values per 1 ℃ increase were also significantly negatively associated with eGFR < 60 ml/min/1.73 m2 (OR, 0.856, 95% CI = 0.774-0.946, p = 0.002 for 1 year; OR, 0.856, 95% CI = 0.774-0.948, p = 0.003 for 3 years; OR, 0.853, 95% CI = 0.772-0.943, p = 0.002 for 5 years). In conclusion, our results revealed that increased WBGT was associated with impaired kidney function in males, whereas increased WBGT was associated with a protective effect against impaired kidney function in females. Further studies are needed to elucidate the exact mechanisms underlying these sex-specific differences.

Hsp27 over expression protect against cadmium induced nephrotoxicity in Drosophila melanogaster

Cadmium (Cd) exposure to the animals including humans is reported as nephrotoxic compounds i.e., disturbing redox status (increase oxidative stress), mitochondrial dysfunction, renal cell death and altered transporters in the renal system. Hsp27 (a small heat shock protein) has been shown as one of the modulators in the renal dysfunction and increased against the Cd induced toxicity. However, no studies are reported on the genetic modulation of stress protein against the Cd-induced nephrotoxicity. The current study aimed to examine the protective role of hsp27 overexpression against the Cd-induced nephrotoxicity using Drosophila melanogaster as an animal model. D. melanogaster renal system includes nephrocytes and Malpighian tubules (MTs) that show the functional similarity with mammalian kidney nephron. Overexpression of the hsp27 was found to reduce the Cd induced oxidative stress, rescue cell death in MTs of Cd exposed D. melanogaster larvae. The rescued GSH level, NADPH level and glucose 6 phosphate dehydrogenase (G6PD) activity were also observed in the MTs of the Cd exposed organism. Function (efflux activity and fluid secretion rate) of the MTs was restored in Cd exposed hsp27 overexpressed larvae. Further, results were confirmed by restored brush border microvilli density and reduced uric acid level. Tissue specific knockdown of hsp27 developed Cd like phenotypes in MTs and the phenotypes enhanced in Cd exposed condition. The present study clearly shows the role of hsp27 overexpression in restoration of the MTs function and protection against the Cd induced renal toxicity.

Heat Shock Proteins in Tooth Development and Injury Repair

Heat shock proteins (HSPs) are a class of molecular chaperones with expression increased in response to heat or other stresses. HSPs regulate cell homeostasis by modulating the folding and maturation of intracellular proteins. Tooth development is a complex process that involves many cell activities. During tooth preparation or trauma, teeth can be damaged. The damaged teeth start their repair process by remineralizing and regenerating tissue. During tooth development and injury repair, different HSPs have different expression patterns and play a special role in odontoblast differentiation and ameloblast secretion by mediating signaling pathways or participating in protein transport. This review explores the expression patterns and potential mechanisms of HSPs, particularly HSP25, HSP60 and HSP70, in tooth development and injury repair.

Genome-wide identification and low-salinity stress analysis of the Hsp70 gene family in swimming crab (Portunus trituberculatus)

No genome-wide identification and expression analysis have been performed on the heat shock protein 70 (Hsp70) gene family, which is essential to key cellular processes and responses to environmental change, in decapods. In the present study, we identified nine members of the Hsp70 gene family within the genome of swimming crab (Portunus trituberculatus) and provided insights into their response to long-term low-salinity stress. Results demonstrated that gene structure and motifs are conserved among members of this gene family in P. trituberculatus. Under low-salinity stress, the expression of this gene family in the gill of P. trituberculatus showed that hsc70l.2 was significantly upregulated, hyou1 was significantly downregulated. The hsc70l.4 was not expressed. Furthermore, selection test on duplicated genes showed a negative selection on hsc70l.1, hsc70l.2, hsc70l.3, and hsc70l.4, suggesting functional redundancy. This may be the first study that systematically identified and analyzed the Hsp70 gene family in decapods. These results can provide fundamental data for the biological research of P. trituberculatus and enhance understanding of the biological function of Hsp70 in crustaceans adapting to salinity changes.

Renal expression of Hsp27, 60, and 70 in cases of fatal hypothermia

Macromorphological findings can be missing in cases of fatal hypothermia when the agonal period is very short because of a large difference between environmental and core body temperatures. Expression of heat shock proteins (Hsps) increases under endogenous and exogenous cellular stresses such as thermal stress. These stress proteins can be revealed by immunohistochemical staining. Forty-five cases of death due to hypothermia and a control group of 100 deaths without any antemortem thermal stress were examined for Hsp27, 60, and 70 expression in renal tissue because renal tissue is sensitive to cellular stress. The results revealed no significant difference between Hsp27, 60, and 70 expression in both groups (28.8% positive staining in the study group and 19.0% positive staining in the control group), which is contradictory to a previous study on expression of Hsp70 in renal tissue in cases of fatal hypothermia. Hence, it is currently unclear whether immunohistochemical staining of Hsps supports a morphological diagnosis of fatal hypothermia.

The small heat shock protein HSPB5 attenuates the severity of lupus nephritis in lupus-prone mice

Lupus nephritis (LN) is a common and serious complication of systemic lupus erythematosus. The current treatments for LN are accompanied with severe immunotoxicity and have limits of effectiveness. Since our in vitro experiments demonstrated that a small heat shock protein (HSP), alpha-B crystallin (HSPB5; CRYAB), selectively modulates myeloid cells towards anti-inflammatory and tolerogenic phenotypes, the aim of this study was to investigate whether HSPB5 can attenuate the severity of LN. MRL/lpr mice were treated intravenously with HSPB5 at 2.5 or 10 μg/dose twice per week after disease onset, from 11 to 21 weeks of age. Disease progression was monitored by weekly measurements of proteinuria, and sera, spleens, and kidneys were collected for assessment at the terminal time point. Treatment with 10 μg HSPB5 substantially reduced endocapillary proliferation and tubular atrophy, which significantly reduced proteinuria and blood urea nitrogen (BUN). Compared to vehicle, 10 μg HSPB5 treatment substantially decreased activation/proliferation of splenocytes, increased IL-10+ macrophages, T and B regulatory cells (Treg, Breg), increased serum IL-10, and lowered expression of IL-6 in kidneys, which correlated with improved kidney function and pathology. This study demonstrated the utility of exogenous human HSPB5 to attenuate severe nephropathy in MRL/lpr mice and provides evidence in favour of a novel therapeutic approach for lupus nephritis.

Identification, classification and functional characterization of HSP70s in rainbow trout (Oncorhynchus mykiss) through multi-omics approaches

Heat shock protein 70s (HSP70s) are known to play vital biological processes in rainbow trout. However, information on the numerous roles and classification of many different HSP70s is insufficient. The purpose of this study was to investigate the characteristics of all HSP70s in rainbow trout using multi-dimensional genomic and transcriptomic analyses for inspecting HSP70 homologs, phylogenetic characteristics, DNA motifs, and transcription factor binding sites (TFBSs). Also, the transcriptomic results in conditions of acute thermal stress and Ichthyophthirius multifiliis infection were used to characterize the expression of all HSP70 homologs, and the isoforms of the most sensitive HSP70 were predicted in silico. A total of 23 HSP70s were identified, and they were divided into seven evolutionary groups (groups 1-7). Groups 1 and 2 had relatively longer phylogenetic distances compared to the other groups, which can speculate origin of groups 1 and 2 HSP70s would be different compared to others. With transcriptomic profiling, most HSPs belonging to group 3 showed highly sensitive responses to I. multifiliis infection, not thermal stress, but the group 6 HSP70s had the opposite expression tendencies. Likewise, the composition of the TFBS in each HSP70 was consistent with its group classification. Since TFBSs are widely known to influence transcriptomic expression, they could be one of the major reasons for the different patterns of expression within the HSP70 groups. Moreover, this study demonstrated several isoforms of HSP70a, by far the most sensitive HSP70s, under several stress environments such as hypoxia, thermal, and overcrowding stress. This is an important fundamental study to expand the understanding of HSP70s in rainbow trout as well as for selecting the most sensitive biomarkers for types of stress.

ERK and p38 MAPK inhibition controls NF-E2 degradation and profibrotic signaling in renal proximal tubule cells

AIMS

Transforming growth factor-β (TGF-β) mediates fibrotic manifestations of diabetic nephropathy. We demonstrated proteasomal degradation of anti-fibrotic protein, nuclear factor-erythroid derived 2 (NF-E2), in TGF-β treated human renal proximal tubule (HK-11) cells and in diabetic mouse kidneys. The current study examined the role of mitogen-activated protein kinase (MAPK) pathways in mediating NF-E2 proteasomal degradation and stimulating profibrotic signaling in HK-11 cells.

MAIN METHODS

HK-11 cells were pretreated with vehicle or appropriate proteasome and MAPK inhibitors, MG132 (0.5 μM), SB203580 (1 μM), PD98059 (25 μM) and SP600125 (10 μM), respectively, followed by treatment with/without TGF-β (10 ng/ml, 24 h). Cell lysates and kidney homogenates from FVB and OVE26 mice treated with/without MG132 were immunoblotted with appropriate antibodies. pUse vector and pUse-NF-E2 cDNA were transfected in HK-11 cells and effects of TGF-β on JNK MAPK phosphorylation (pJNK) was examined.

KEY FINDINGS

We demonstrated activation of p38, ERK, and JNK MAPK pathways in TGF-β treated HK-11 cells. Dual p38 and ERK MAPK blockade prevented TGF-β-induced pSer82Hsp27, fibronectin and connective tissue growth factor (CTGF) expression while preserving NF-E2 expression. Blockade of JNK MAPK inhibited TGF-β-induced CTGF expression without preserving NF-E2 expression. MG132 treatment prevented TGF-β-induced pJNK in HK-11 cells and in type 1 diabetic OVE26 mouse kidneys, demonstrating that TGF-β- and diabetes-induced pJNK occurs downstream of proteasome activation. A direct role for NF-E2 in modulating pJNK activation was demonstrated by NF-E2 over-expression.

SIGNIFICANCE

ERK and p38 MAPK promotes NF-E2 proteasomal degradation while proteasome activation promotes pJNK and profibrotic signaling in renal proximal tubule cells.

Posttranslational modification and beyond: interplay between histone deacetylase 6 and heat-shock protein 90

Posttranslational modification (PTM) and regulation of protein stability are crucial to various biological processes. Histone deacetylase 6 (HDAC6), a unique histone deacetylase with two functional catalytic domains (DD1 and DD2) and a ZnF-UBP domain (ubiquitin binding domain, BUZ), regulates a number of biological processes, including gene expression, cell motility, immune response, and the degradation of misfolded proteins. In addition to the deacetylation of histones, other nonhistone proteins have been identified as substrates for HDAC6. Hsp90, a molecular chaperone that is a critical modulator of cell signaling, is one of the lysine deacetylase substrates of HDAC6. Intriguingly, as one of the best-characterized regulators of Hsp90 acetylation, HDAC6 is the client protein of Hsp90. In addition to regulating Hsp90 at the post-translational modification level, HDAC6 also regulates Hsp90 at the gene transcription level. HDAC6 mainly regulates the Hsp90-HSF1 complex through the ZnF-UBP domain, thereby promoting the HSF1 entry into the nucleus and activating gene transcription. The mutual interaction between HDAC6 and Hsp90 plays an important role in the regulation of protein stability, cell migration, apoptosis and other functions. Plenty of of studies have indicated that blocking HDAC6/Hsp90 has a vital regulatory role in multifarious diseases, mainly in cancers. Therefore, developing inhibitors or drugs against HDAC6/Hsp90 becomes a promising development direction. Herein, we review the current knowledge on molecular regulatory mechanisms based on the interaction of HDAC6 and Hsp90 and inhibition of HDAC6 and/or Hsp90 in oncogenesis and progression, antiviral and immune-related diseases and other vital biological processes.

Genome-wide identification of Hsp70/110 genes in rainbow trout and their regulated expression in response to heat stress

Heat shock proteins (Hsps) play an important role in many biological processes. However, as a typical cold water fish, the systematic identification of Hsp70/110 gene family of rainbow trout (Oncorhynchus mykiss) has not been reported, and the role of Hsp70/110 gene in the evolution of rainbow trout has not been described systematically. In this study, bioinformatics methods were used to analyze the Hsp70/110 gene family of rainbow trout. A total of 16 hsp70/110 genes were identified and classified into ten subgroups. The 16 Hsp70/110 genes were all distributed on chromosomes 2, 4, 8 and 13. The molecular weight is ranged from 78.93 to 91.39 kD. Gene structure and motif composition are relatively conserved in each subgroup. According to RNA-seq analysis of rainbow trout liver and head kidney, a total of four out of 16 genes were significantly upregulated in liver under heat stress, and a total of seven out of 16 genes were significantly upregulated in head kidney. RT-qPCR was carried out on these gene, and the result were consistent with those of RNA-seq. The significantly regulated expressions of Hsp70/110 genes under heat stress indicats that Hsp70/110 genes are involved in heat stress response in rainbow trout. This systematic analysis provided valuable information about the diverse roles of Hsp70/110 in the evolution of teleost, which will contribute to the functional characterization of Hsp70/110 genes in further research.

Hsp90 Relieves Heat Stress-Induced Damage in Mouse Kidneys: Involvement of Antiapoptotic PKM2-AKT and Autophagic HIF-1α Signaling

Heat stress can particularly affect the kidney because of its high rate of adenosine triphosphate consumption. Competition between apoptosis and autophagy-mediated survival always exists in damaged tissue. And Hsp90 can enhance cellular protection to resist heat stress. However, the relationship between Hsp90 and the above competition and its underlying mechanism in the kidney are unclear. The present study found that heat stress induced obvious histopathological and oxidative injury, which was connected with cellular apoptosis and autophagy in the kidney and was associated with the levels of Hsp90 expression or function. The data showed that during heat stress, Hsp90 activated the PKM2-Akt signaling pathway to exert antiapoptotic effects and induce Hsp70 expression regulated by HSF-1, stimulated autophagy-mediated survival through the HIF-1α-BNIP3/BNIP3L pathway, and finally protected the kidney from heat-stress injury. Moreover, the nuclear translocation of PKM2, (p-) Akt, HSF-1, and HIF-1α was enhanced by heat stress, but only intranuclear p-Akt and HSF-1 were specifically influenced by Hsp90, contributing to regulate the cellular ability of resisting heat-stress damage. Our study provided new insights regarding the molecular mechanism of Hsp90 in the kidney in response to heat-stress injury, possibly contributing to finding new targets for the pharmacological regulation of human or animal acute kidney injury from heat stress in future research.

Di (2-ethyl hexyl) phthalate (DEHP)-induced kidney injury in quail (Coturnix japonica) via inhibiting HSF1/HSF3-dependent heat shock response

Di (2-ethyl hexyl) phthalate (DEHP) as a plasticizer can leach away from the plastic and hence entrances into the animal food chain which caused serious hazard in organs of animals, but there are few studies on DEHP kidney toxicity. The heat-shock response (HSR) consisting of the HSPs and HSFs plays an important role in various toxicity stress conditions. To investigate the influence on kidney toxicity and the modulation of HSR during DEHP exposure, female quail were fed the diet with 0, 250, 500 and 750 mg/kg DEHP by gavage administration for 45 days. The shrinkages of glomeruli and dilation of kidney tubule epithelia cells were observed in the kidney of DEHP-exposed quail. DEHP treatment could significantly decrease the expressions of HSP25, HSP27, HSP47, HSP60, while the expressions of HSP10, HSP40, HSP70, HSP90, HSP110 were upregulated in the kidney. In addition, the expression levels of HSF1 and HSF3 were significantly increased under DEHP. This is the first study to demonstrate quail exposure to DEHP is in fact detrimental to bird kidney. Besides, DEHP could attack HSR by affecting the synthesis of HSFs to mediate the transcription of the HSPs resulting in kidney damage.

Taurine Supplementation Alleviates Puromycin Aminonucleoside Damage by Modulating Endoplasmic Reticulum Stress and Mitochondrial-Related Apoptosis in Rat Kidney

Taurine (TAU) is a sulfur-containing beta amino acid that is not involved in protein composition and anabolism, conditionally essential in mammals provided through diet. Growing evidence supports a protective role of TAU supply in osmoregulation, calcium flux, and reduction of inflammation and oxidant damage in renal diseases like diabetes. Endoplasmic reticulum (ER) stress, due to abnormal proteostasis, is a contributor to nephrotic syndrome and related renal damage. Here, we investigated the effect of dietary TAU (1.5% in drinking water for 15 days) in an established rat model that mimics human minimal change nephrosis, consisting of a single puromycin aminonucleoside (PAN) injection (intraperitoneally 15 mg/100 g body weight), with sacrifice after eight days. TAU limited proteinuria and podocytes foot processes effacement, and balanced slit diaphragm nephrin and glomerular claudin 1 expressions. In cortical proximal tubules, TAU improved lysosomal density, ER perimeter, restored proper ER-mitochondria tethering and mitochondrial cristae, and decreased inflammation. Remarkably, TAU downregulated glomerular ER stress markers (GRP78, GRP94), pro-apoptotic C/EBP homologous protein, activated caspase 3, tubular caspase1, and mitochondrial chaperone GRP75, but maintained anti-apoptotic HSP25. In conclusion, TAU, by targeting upstream ER stress separate from mitochondria dysfunctions at crucial renal sites, might be a promising dietary supplement in the treatment of the drug-resistant nephrotic syndrome.

Unravelling Pathophysiology of Crystalline Nephropathy in Ceftriaxone-Associated Acute Kidney Injury: A Cellular Proteomic Approach

BACKGROUND

Previous studies showed that ceftriaxone can cause acute kidney injury (AKI) in the pediatric population. This study proposed a cellular model of crystalline nephropathy in ceftriaxone-associated AKI and explored the related pathophysiology by using a proteomic approach.

METHODS

Ceftriaxone was crystallized with calcium in artificial urine. Madin-Darby Canine Kidney (MDCK) cells, a model of distal renal tubular cell, were cultured in the absence (untreated control) or presence of ceftriaxone crystals for 48-h (n = 5 each). MDCK cells were harvested and subsequently analyzed by proteomic analysis. Protein bioinformatics (i.e., STRING and Reactome) was used to predict functional alterations, and subsequently validated by Western blotting and cellular studies. p < 0.05 was considered statistically significant.

RESULTS

Phase-contrast microscopy showed increased intracellular vesiculation and cell enlargement as a result of ceftriaxone crystal exposure. Proteome analysis revealed a total of 20 altered proteins (14 increased, 5 decreased and 1 absent) in ceftriaxone crystal-treated MDCK cells as compared to untreated cells (p < 0.05). Protein bioinformatics and validation studies supported heat stress response mediated by heat shock protein 70 (Hsp70) and downregulation of annexin A1 as the proposed pathophysiology of crystalline nephropathy in ceftriaxone-associated AKI, in which impaired proliferation and wound healing of crystal-induced distal tubular cells were outcomes.

CONCLUSIONS

This study, for the first time, used the in vitro model of crystalline nephropathy to investigate the underlying pathophysiology of ceftriaxone-associated AKI, which should be investigated in vivo for potential clinical benefits in the future.

New Pharmacologic Agents That Target Inflammation and Fibrosis in Nonalcoholic Steatohepatitis-Related Kidney Disease

Epidemiologic data show an association between the prevalence and severity of nonalcoholic fatty liver disease and the incidence and stage of chronic kidney disease (CKD); furthermore, nonalcoholic steatohepatitis (NASH)-related cirrhosis has a higher risk of renal failure, a greater necessity for simultaneous liver-kidney transplantation, and a poorer renal outcome than cirrhosis of other etiologies even after simultaneous liver-kidney transplantation. These data suggest that NASH and CKD share common proinflammatory and profibrotic mechanisms of progression, which are targeted incompletely by current treatments. We reviewed therapeutic approaches to late preclinical/early clinical stage of development in NASH and/or CKD, focusing on anti-inflammatory and antifibrotic treatments, which could slow the progression of both disease conditions. Renin inhibitors and angiotensin-converting enzyme-2 activators are new renin-angiotensin axis modulators that showed incremental advantages over angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers in preclinical models. Novel, potent, and selective agonists of peroxisome proliferator-activated receptors and of farnesoid X receptor, designed to overcome limitations of older compounds, showed promising results in clinical trials. Epigenetics, heat stress response, and common effectors of redox regulation also were subjected to intensive research, and the gut was targeted by several approaches, including synbiotics, antilipopolysaccharide antibodies, Toll-like receptor-4 antagonists, incretin mimetics, and fibroblast growth factor 19 analogs. Promising anti-inflammatory therapies include inhibitors of NOD-like receptor family, pyrin domain containing 3 inflammasome, of nuclear factor-κB, and of vascular adhesion protein-1, chemokine antagonists, and solithromycin, and approaches targeting common profibrogenic pathways operating in the liver and the kidney include galectin-3 antagonists, and inhibitors of rho-associated protein kinase and of epidermal growth factor activation. The evidence, merits, and limitations of each approach for the treatment of NASH and CKD are discussed.

HSP72 is an early biomarker to detect cisplatin and acetaminophen nephrotoxicity

OBJECTIVE

To evaluate whether the urinary HSP72 levels (uHSP72) are a useful biomarker for early diagnosis of acute kidney injury (AKI) induced by two widely used drugs: cisplatin and acetaminophen.

MATERIALS AND METHODS

To analyze the time-course of nephrotoxic injury and uHSP72 levels, male Wistar rats were administered a single high dose of cisplatin (7 mg/kg) or acetaminophen (750 mg/kg) and were assessed at 6, 12, 24, 48, 72, 96 and 120 h.

RESULTS

AKI induced by cisplatin was characterized by tubular injury that started at 6 h and was enhanced after 48 h. Plasma creatinine was increased only after 72 h. In contrast, uHSP72 levels were augmented after 6 h and were enhanced after 48 h of cisplatin administration, which was consistent with the tubular injury. In acetaminophen-induced AKI, the tubular lesions were less severe and predominantly characterized by tubular cell detachment. Interestingly, uHSP72 levels were increased after 6 h of acetaminophen injection and remained elevated at the following time points, reflecting the tubular injury, even in the absence of major functional changes.

CONCLUSIONS

In two models of renal injury induced by nephrotoxic drugs, we showed that uHSP72 could be used as an early biomarker to detect subtle to severe tubular injury.

Expression times for hsp27 and hsp70 as an indicator of thermal stress during death due to fire

The expression of heat shock proteins (hsps) increases in cases of hyperthermal cellular stress in order to protect cellular structures. Hsps can be visualized with immunohistochemical staining. We examined 48 cases of death from fire and excessive heat and a control group of 100 deaths without any perimortem thermal stress, measuring both the hsp27 and hsp70 expressions in myocardial, pulmonary, and renal tissues. The results revealed a correlation between hsp expression and survival time. Hsps are expressed rapidly within seconds or minutes after exposure to heat stress. In particular, hsp27 is expressed fast in high levels, whereas hsp70 expression is higher in the pulmonary and renal tissue of long-term survivors. In the myocardial tissue, hsp27 expression dominated in both short- and long-term survival. The expression pattern is strongly dependent on the organ structure and the survival time, which should be considered in future postmortem studies on hsps.