Does calcium channel blockade have a role in prevention of expression of sepsis in renal transplant recipients?

Disseminated intravascular coagulation phenotype is regulated by the TRPM7 channel during sepsis

BACKGROUND

Sepsis is an uncontrolled inflammatory response against a systemic infection that results in elevated mortality, mainly induced by bacterial products known as endotoxins, producing endotoxemia. Disseminated intravascular coagulation (DIC) is frequently observed in septic patients and is associated with organ failure and death. Sepsis activates endothelial cells (ECs), promoting a prothrombotic phenotype contributing to DIC. Ion channel-mediated calcium permeability participates in coagulation. The transient reception potential melastatin 7 (TRPM7) non-selective divalent cation channel that also contains an α-kinase domain, which is permeable to divalent cations including Ca²⁺, regulates endotoxin-stimulated calcium permeability in ECs and is associated with increased mortality in septic patients. However, whether endothelial TRPM7 mediates endotoxemia-induced coagulation is not known. Therefore, our aim was to examine if TRPM7 mediates coagulation during endotoxemia.

RESULTS

The results showed that TRPM7 regulated endotoxin-induced platelet and neutrophil adhesion to ECs, dependent on the TRPM7 ion channel activity and by the α-kinase function. Endotoxic animals showed that TRPM7 mediated neutrophil rolling on blood vessels and intravascular coagulation. TRPM7 mediated the increased expression of the adhesion proteins, von Willebrand factor (vWF), intercellular adhesion molecule 1 (ICAM-1), and P-selectin, which were also mediated by the TRPM7 α-kinase function. Notably, endotoxin-induced expression of vWF, ICAM-1 and P-selectin were required for endotoxin-induced platelet and neutrophil adhesion to ECs. Endotoxemic rats showed increased endothelial TRPM7 expression associated with a procoagulant phenotype, liver and kidney dysfunction, increased death events and an increased relative risk of death. Interestingly, circulating ECs (CECs) from septic shock patients (SSPs) showed increased TRPM7 expression associated with increased DIC scores and decreased survival times. Additionally, SSPs with a high expression of TRPM7 in CECs showed increased mortality and relative risk of death. Notably, CECs from SSPs showed significant results from the AUROC analyses for predicting mortality in SSPs that were better than the Acute Physiology and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scores.

CONCLUSIONS

Our study demonstrates that sepsis-induced DIC is mediated by TRPM7 in ECs. TRPM7 ion channel activity and α-kinase function are required by DIC-mediated sepsis-induced organ dysfunction and its expression are associated with increased mortality during sepsis. TRPM7 appears as a new prognostic biomarker to predict mortality associated to DIC in SSPs, and as a novel target for drug development against DIC during infectious inflammatory diseases.

Alterations of complex IV in the tissues of a septic mouse model

OBJECTIVES

To characterize the mitochondrial respiratory chain complex IV(complex IV) activity and protein expression during polymicrobial sepsis.

MATERIAL AND METHODS

Polymicrobial peritonitis, a clinically relevant mouse model of sepsis, was generated by cecum ligation and puncture (CLP) in Sprague- Dawley rats. The rats were randomly divided into 3 groups as follows: the sepsis without resuscitation (S), sepsis and fluid resuscitated (R) group, and a control (C) group. Twelve hours after the sepsis model was established, tissue specimens were obtained from the myocardium, liver and skeletal muscle. Mitochondrial respiratory chain complex IV activity of all tissue specimens was detected by spectrophotometry. Western blot was used to measure the liver mitochondrial respiratory chain complex IV protein content. The ultrastructure changes of mitochondria were detected by transmission electron microscopy.

RESULTS

In myocardial cells, complex IV activity decreased significantly in the S and R groups as compared to the C group. There were no differences in complex IV activity between groups in skeletal muscle cells while in liver cells, complex IV activity and content was significantly decreased for the S group but no differences were observed between the C and R groups. Increased matrix volume and reduced density with generalized disruption of the normal cristae pattern was most extensive in the liver, followed by cardiac muscle cells with that in skeletal muscle cells been relatively mild in the S group. Mitochondrial fusion/fission and mitochondrial autophagy was also observed in the S group by transmission electron microscopy. Mitochondrial ultrastructure was preserved in the R-group and was similar to that seen in the C-group.

CONCLUSIONS

Changes in complex IV activity and mitochondrial ultrastructure, a manifestation of the mitochondrial dysfunction varied depending on cell type. These changes are partly reversed by fluid therapy. Therapies aimed at mitochondrial resuscitation should be explored.

Infection and Malignancy Outweigh Cardiovascular Mortality in Kidney Transplant Recipients: Post Hoc Analysis of the FAVORIT Trial

OBJECTIVE

Now that long-term survival after successful renal transplantation is no longer limited by excessive cardiovascular risk, the primary care physician should consider that infection and malignancy are leading noncardiovascular causes of death even in the recipient with diabetes.

METHODS

We accessed the National Institutes of Health-sponsored Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) study population (4010 renal transplant recipients with elevated homocysteine levels) studied to determine whether folate and B12 supplementation would reduce cardiovascular end points. This trial had a null result. Patients were classified as being nondiabetic or having type 1 or type 2 diabetes.

RESULTS

We report an excess (cardiovascular and noncardiovascular) 6-year mortality risk associated with the presence of diabetes mellitus. Two thirds of fatal events in our renal transplant recipients were centrally adjudicated as noncardiovascular. The incidence of noncardiovascular death was 70% higher in the diabetic patient cohort than in the nondiabetic cohort.

CONCLUSIONS

These results demonstrate that infection (but not malignancy) risks are far higher in diabetic than nondiabetic immunosuppressed individuals (although noncardiovascular death rate in nondiabetic individuals also exceeded cardiovascular deaths) and may play a larger role in the excess mortality populations than previously thought. Given that follow-up in this study was 4 to 10 years after allograft surgery, there was a lesser degree of acute rejection requiring high-dose immunosuppression than in the initial postallograft years. This unique perspective allows transplant recipients to return to primary physicians when taking low doses of immunosuppressive agents and provides focus for follow-up care.

Calcium channel blockade and survival in recipients of successful renal transplant: an analysis of the FAVORIT trial results

INTRODUCTION

Single-center and observational studies have suggested that calcium channel blocking agents may decrease the expression of sepsis in individual populations. In the renal transplant population, a role for calcium channel blockers in allograft protection and in prevention of sepsis has been postulated. We hypothesized that any important survival benefit or risk related to chronic use of calcium channel blocking agents should be discernable through an analysis of a large database of stable recipients of renal allografts who had enrolled in a large international trial.

METHODS

A retrospective analysis of 4,110 renal transplant recipients who enrolled in the international Folic Acid for Vascular Outcome Reduction in Transplantation trial between 2002 and 2007 and were followed until 2010 was undertaken comparing cohorts (FAVORIT) of patients either taking (n=1,436) or not taking (n=2,674) calcium channel blocking medications. The endpoint was all-cause mortality (cardiovascular, noncardiovascular mortality, or unknown). Results were adjusted for country, age, race, sex, smoker, systolic blood pressure, diabetes mellitus, low-density lipoprotein, and chronic kidney disease status.

RESULTS

There were no statistically significant differences in incidence rates of cardiovascular, noncardiovascular, and all-cause mortality between patients taking or not taking calcium channel blocking medications.

CONCLUSION

Although physiologic reasoning and small series results suggest a benefit for calcium channel blocking agents for allograft protection and sepsis prevention in immunosuppressed patients, we find no clear survival benefit in a large international renal transplant trial.