The HSP72 stress response of monocytes from patients on haemodialysis is impaired

Development of a new prognostic index PNPI for prognosis prediction of CKD patients with pneumonia at hospital admission

Background

The aim of this study was to investigate the relationship between pneumonia and chronic kidney disease (CKD), to elucidate potential risk factors, and to develop a new predictive model for the poor prognosis of pneumonia in CKD patients.

Method

We conducted a retrospective observational study of CKD patients admitted to Tongji Hospital between June 2012 and June 2022. Demographic information, comorbidities or laboratory tests were collected. Applying univariate and multivariate logistic regression analyses, independent risk factors associated with a poor prognosis (i.e., respiratory failure, shock, combined other organ failure, and/or death during hospitalization) for pneumonia in CKD patients were discovered, with nomogram model subsequently developed. Predictive model was compared with other commonly used pneumonia severity scores.

Result

Of 3,193 CKD patients with pneumonia, 1,013 (31.7%) met the primary endpoint during hospitalization. Risk factors predicting poor prognosis of pneumonia in CKD patients were selected on the result of multivariate logistic regression models, including chronic cardiac disease; CKD stage; elevated neutrophil to lymphocyte ratio (NLR) and D-dimer; decreased platelets, PTA, and chloride iron; and significant symptom presence and GGO presentation on CT. The nomogram model outperformed other pneumonia severity indices with AUC of 0.82 (95% CI: 0.80, 0.84) in training set and 0.83 (95% CI: 0.80, 0.86) in testing set. In addition, calibration curve and decision curve analysis (DCA) proved its efficiency and adaptability.

Conclusion

We designed a clinical prediction model PNPI (pneumonia in nephropathy patients prognostic index) to assess the risk of poor prognosis in CKD patients with pneumonia, which may be generalized after more external validation.

Heat Shock Proteins: Connectors between Heart and Kidney

Over the development of eukaryotic cells, intrinsic mechanisms have been developed in order to provide the ability to defend against aggressive agents. In this sense, a group of proteins plays a crucial role in controlling the production of several proteins, guaranteeing cell survival. The heat shock proteins (HSPs), are a family of proteins that have been linked to different cellular functions, being activated under conditions of cellular stress, not only imposed by thermal variation but also toxins, radiation, infectious agents, hypoxia, etc. Regarding pathological situations as seen in cardiorenal syndrome (CRS), HSPs have been shown to be important mediators involved in the control of gene transcription and intracellular signaling, in addition to be an important connector with the immune system. CRS is classified as acute or chronic and according to the first organ to suffer the injury, which can be the heart (CRS type 1 and type 2), kidneys (CRS type 3 and 4) or both (CRS type 5). In all types of CRS, the immune system, redox balance, mitochondrial dysfunction, and tissue remodeling have been the subject of numerous studies in the literature in order to elucidate mechanisms and propose new therapeutic strategies. In this sense, HSPs have been targeted by researchers as important connectors between kidney and heart. Thus, the present review has a focus to present the state of the art regarding the role of HSPs in the pathophysiology of cardiac and renal alterations, as well their role in the kidney–heart axis.

The role of heat shock proteins in kidney disease

Heat Shock Proteins (HSP) belong to the family of intracellular proteins that are constitutively expressed and are upregulated by various stressors including heat, oxidative and chemical stress. HSP helps in reparative processes, including the refolding of damaged proteins and the removal of irreparably damaged proteins that would initiate cellular death or apoptosis. A growing body of evidence has expanded the role of HSP and defined their role in diseases such as neurodegenerative disorders, cancer, ischemic heart disease and kidney diseases. The protective role of HSP in ischemic renal injury has been described and HSP impairment has been noted in other forms of kidney injuries including post-transplant situation. Further research into the role of HSP in prevention of kidney injury is crucial if translation from the laboratory to patient bedside has to occur. This article aims to be a review of heat shock protein, and its relevance to kidney diseases.

Keratin 18 and heat-shock protein in chronic kidney disease

Chronic kidney disease (CKD) is an affliction associated with increased systemic stress and cell death. We will review the role of keratin 18 (K-18) and caspase-cleaved CK-18 (ccK-18) as markers for increased apoptosis and necrosis during renal failure progression. The importance of preventative expression of heat-shock proteins (HSPs) in response to cell stress will also be discussed. The frequent development of CKD leads to serious complications. The potential of use of K-18 and HSP as early biomarkers of renal failure will be reviewed. Also, the role of these proteins with respect to dialysis regimes and in acute ischemic kidney injury following renal transplantation will be discussed.

Induction of intracellular heat-shock protein 72 prevents the development of vascular smooth muscle cell calcification

AIMS

Vascular calcification (VC) is a significant contributor to cardiovascular mortality in patients with chronic kidney disease (CKD) and coronary artery disease (CAD). Osteo/chondrocytic transformation and simultaneous dedifferentiation of smooth muscle cells (SMCs) are important in the pathogenesis of VC. Heat-shock protein 72 (HSP72) is a cardioprotective inducible heat-shock protein that functions as a molecular chaperone. However, its role in the development of accelerated vascular dysfunction and calcification is largely unexplored.

METHODS AND RESULTS

We describe for the first time marked reduction in HSP72 expression in arteries from patients with CKD and CAD, compared with healthy controls, in vivo. Induction of HSP72 by heat-shock treatment (HST) significantly prevented the development of calcification of human aortic smooth muscle cells (HA-SMCs), in vitro. These anti-calcific effects were abolished following treatment with both quercetin, an HST inhibitor, and HSP72 siRNA knockdown. Induction of HSP72 suppressed Cbfa-1-dependent osteo/chondrocytic transformation and stabilized SMC contractile phenotype through the myocardin-serum response factor (SRF) pathway. Co-immunoprecipitation studies demonstrated physical association between SRF and HSP72. Furthermore, organ culture of arteries from CKD and CAD patients showed that these arteries retained their ability to induce HSP72 following HST, despite initially reduced expression.

CONCLUSION

Our study shows for the first time that intracellular HSP72 may function as a central regulator of molecular pathways involved in the development of VC. We suggest treatment strategies that up-regulate HSP72 as a new approach to inhibit VC.

Circulating endothelial progenitor cells in kidney transplant patients

BACKGROUND

Kidney transplantation (RTx) leads to amelioration of endothelial function in patients with advanced renal failure. Endothelial progenitor cells (EPCs) may play a key role in this repair process. The aim of this study was to determine the impact of RTx and immunosuppressive therapy on the number of circulating EPCs.

METHODS

We analyzed 52 RTx patients (58±13 years; 33 males, mean ± SD) and 16 age- and gender-matched subjects with normal kidney function (57±17; 10 males). RTx patients received a calcineurin inhibitor (CNI)-based (65%) or a CNI-free therapy (35%) and steroids. EPC number was determined by double positive staining for CD133/VEGFR2 and CD34/VEGFR2 by flow cytometry. Stromal cell-derived factor 1 alpha (SDF-1) levels were assessed by ELISA. Experimentally, to dissociate the impact of RTx from the impact of immunosuppressants, we used the 5/6 nephrectomy model. The animals were treated with a CNI-based or a CNI-free therapy, and EPCs (Sca+cKit+) and CD26+ cells were determined by flow cytometry.

RESULTS

Compared to controls, circulating number of CD34+/VEGFR2+ and CD133+/VEGFR2+ EPCs increased in RTx patients. There were no correlations between EPC levels and statin, erythropoietin or use of renin angiotensin system blockers in our study. Indeed, multivariate analysis showed that SDF-1--a cytokine responsible for EPC mobilization--is independently associated with the EPC number. 5/6 rats presented decreased EPC counts in comparison to control animals. Immunosuppressive therapy was able to restore normal EPC values in 5/6 rats. These effects on EPC number were associated with reduced number of CD26+ cells, which might be related to consequent accumulation of SDF-1.

CONCLUSIONS

We conclude that kidney transplantation and its associated use of immunosuppressive drugs increases the number of circulating EPCs via the manipulation of the CD26/SDF-1 axis. Increased EPC count may be associated to endothelial repair and function in these patients.

Heat shock proteins in chronic kidney disease

Heat shock proteins (HSP) form a heterogenous, evolutionarily conserved group of molecules with high sequence homology. They mainly act as intracellular chaperones, protecting the protein structure and folding under stress conditions. The extracellular HSP, released in the course of damage or necrosis, play a pivotal role in the innate and adaptive immune responses. They also take part in many pathological processes. The aim of this review is to update the recent developments in the field of HSP in chronic kidney disease (CKD), in regard to three different aspects. The first is the assessment of the role of HSP, either positive or deleterious, in the pathogenesis of CKD and the possibilities to influence its progression. The second is the impact of dialysis, being a potentially modifiable stressor, on HSP and the attempt to assess the value of these proteins as the biocompatibility markers. The last area is that of kidney transplantation and the potential role of HSP in the induction of the immune tolerance in kidney recipients.

Potential of noninvasive serial assessment of acute renal allograft rejection by 18F-FDG PET to monitor treatment efficiency

We propose (18)F-FDG PET as a method to monitor acute rejection of allogeneic renal transplants in a rat model.

METHODS

Allogeneically transplanted (aTX) rats (binephrectomized Lewis-brown Norway to Lewis) served as the renal transplant model. aTX rats treated with cyclosporine A (CSA) served as a therapy monitoring group. Healthy control rats, rats with acute CSA nephrotoxicity, rats with acute tubular necrosis, syngeneically transplanted (sTX) rats, and aTX rats treated with CSA since postoperative day 0 served as controls. After surgery, renal glucose metabolism was assessed in vivo serially up to postoperative day 7 by performing small-animal PET 3 h after intravenous injection of 30 MBq of (18)F-FDG. Mean radioactivity (cps/mm(3) of tissue) was measured and the percentage injected dose calculated. Results were confirmed by histologic, functional, and autoradiographic analysis.

RESULTS

Renal (18)F-FDG uptake was significantly elevated at postoperative day 4 in aTX rats, when compared with control, sTX, acute tubular necrosis, or CSA-treated rats (P < 0.05). In vivo (18)F-FDG uptake correlated with the results of autoradiography and with inflammatory infiltrates observed on histologic examination. Notably, (18)F-FDG PET assessed the response to therapy 48 h earlier than the time at which serum creatinine decreased and when histologic examination still showed signs of allograft rejection. In aTX rats, the CSA-susceptible graft infiltrate was dominated by activated cytotoxic T cells and monocytes/macrophages.

CONCLUSION

(18)F-FDG PET is an option to noninvasively assess early response to therapy in rat renal allograft rejection.