Immunosuppressive Agents and Metabolic Factors of Cardiovascular Risk in Renal Transplant Recipients

Outcomes of Infrapopliteal Bypass for Chronic Limb-Threatening Ischemia are Worse in Renal Transplant Patients than in Hemodialysis-Dependent Patients

BACKGROUND

Comparisons of distal bypass outcomes between hemodialysis-dependent (HD) and renal transplant (RT) patients have been reported, but the influences of immunosuppressive therapy on the outcomes remain unclear because of the limited number of RT patients who underwent distal bypass or cohort heterogenicity. We compared outcomes of distal bypass for chronic limb-threatening ischemia (CLTI) with homogenous ischemic limb pathology.

METHODS

Between January 2014 and December 2019, we performed 334 infrapopliteal bypass procedures using vein grafts for 275 consecutive CLTI patients with tissue loss. Among them, there were 130 HD patients (47.3%) (163 limbs) and 11 RT patients (4%) (15 limbs), and 30-day mortality, 5-year primary and secondary patency (PP and SP), limb salvage (LS), amputation-free survival rates, and wound healing (WH) status were compared between the HD and RT patient groups.

RESULTS

Nine HD patients died within 30 days after surgery (7%), whereas no deaths were observed among the RT patients. Five-year PP and SP rates in the RT group 39% and 41%, which were significantly worse compared to 64% and 82% in the HD group (P < 0.01). Unsuccessful rate of revision surgery including hemodynamically failed grafts after revision reached over 80% in the RT group, which was technically unfeasible pathology for graft salvage (vs. 3% in the HD group), and WH, and LS rates were significantly worse in the RT group.

CONCLUSIONS

In comparison with HD patients, RT patients showed a lower LS rate for CLTI. The lower LS rate was associated with a lower SP rate, which was caused by disease progression of distal arteries in the foot.

Cardiovascular effects of immunosuppression agents

Immunosuppressive medications are widely used to treat patients with neoplasms, autoimmune conditions and solid organ transplants. Key drug classes, namely calcineurin inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and purine synthesis inhibitors, have direct effects on the structure and function of the heart and vascular system. In the heart, immunosuppressive agents modulate cardiac hypertrophy, mitochondrial function, and arrhythmia risk, while in vasculature, they influence vessel remodeling, circulating lipids, and blood pressure. The aim of this review is to present the preclinical and clinical literature examining the cardiovascular effects of immunosuppressive agents, with a specific focus on cyclosporine, tacrolimus, sirolimus, everolimus, mycophenolate, and azathioprine.

Evaluation of the Relationship Between Homocysteine, Parathormone, Vitamin D3, and Bone Mineral Densitometry in Recipients of Kidney Transplant

PURPOSE

In this study, we evaluated the relationship between serum homocysteine level and proteinuria, parathyroid hormone, vitamin D, and bone mineral density in kidney transplant recipients (KTR).

MATERIALS AND METHODS

A total of 117 stable KTR older than 18 years was followed in our outpatient clinic. Demographic data were recorded. Simultaneously biochemical parameters, including glucose, blood urea nitrogenous, creatinine, calcium, phosphorus, sodium, potassium, albumin, parathormone, vitamin D₃, homocysteine, vitamin B₁₂, folate, and 24-hour urine protein, and bone mineral density of the femoral neck and spine by dual-energy x-ray absorptiometry (DEXA) were measured.

RESULTS

DEXA measurements were normal, osteoporotic, and osteopenic (12.3%, 36.3%, and 51.3%, respectively). There was a relationship between the serum homocysteine and usage of rapamycin (P = .05), statins (P = .057), and beta blockers (P = .01), DEXA measurements were not related with serum homocysteine levels and immunosuppressive drugs used. Serum homocysteine levels correlated negatively with blood urea nitrogen (P = .002), creatinine (P = .001), vitamin B₁₂ (P < .001), and a positively daily proteinuria (rho = 0.203, P = .031). There was a negative relationship between proteinuria and serum level of vitamin D.

CONCLUSIONS

The bone mineral density decreased in more than 87% of our KTR. We did not find any relationship between DEXA measurements and levels of homocysteine, vitamin D, parathormone, and immunosuppressive drugs. It should be noted that some drugs used may affect serum homocysteine levels. Interestingly, there was a relationship between proteinuria and serum levels of homocysteine and vitamin D. Therefore, serum levels of homocysteine and vitamin D should be evaluated for preventing renal damage in KTR.

Impaired mitochondrial calcium uptake caused by tacrolimus underlies beta-cell failure

BACKGROUND

One of the most common side effects of the immunosuppressive drug tacrolimus (FK506) is the increased risk of new-onset diabetes mellitus. However, the molecular mechanisms underlying this association have not been fully clarified.

METHODS

We studied the effects of the therapeutic dose of tacrolimus on mitochondrial fitness in beta-cells.

RESULTS

We demonstrate that tacrolimus impairs glucose-stimulated insulin secretion (GSIS) in beta-cells through a previously unidentified mechanism. Indeed, tacrolimus causes a decrease in mitochondrial Ca²⁺ uptake, accompanied by altered mitochondrial respiration and reduced ATP production, eventually leading to impaired GSIS.

CONCLUSION

Our observations individuate a new fundamental mechanism responsible for the augmented incidence of diabetes following tacrolimus treatment. Indeed, this drug alters Ca²⁺ fluxes in mitochondria, thereby compromising metabolism-secretion coupling in beta-cells.

Lipid profile changes during the first year after kidney transplantation: risk factors and influence of the immunosuppressive drug regimen

AIM

This study analyzed the incidence, time course, and risk factors associated with dyslipidemia during the first year after kidney transplantation among patients receiving various immunosuppressive regimens.

METHODS

The analysis included 474 kidney transplant recipients receiving cyclosporine (CSA) combined with sirolimus (SRL; n=137) or mycophenolate (MMF, n=58) or everolimus (EVR, n=47); or SRL combined with MMF (n=32); or tacrolimus (TAC) combined with SRL (n=86) or MMF (n=114). All patients received prednisone. We evaluated the influence of demographic features, clinical outcomes, and statin use on lipid profiles during the first year after transplantation. total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (hdl-C), low-density lipoprotein cholesterol (ldl-C), non-HDL-C, TC:HDL-C, LDL-C:HDL-C, TG:HDL-C.

RESULTS

Lipid profiles were within the recommended ranges in 28% of patients pretransplantation and in 10% at 1 year; 27% of them received statins. At 1 year, LDL-C<100 mg/dL was observed in 31.8% of patients but more than 35% of these patients still showed other lipid fractions or ratios outside recommended target concentrations. Among all patients with LDL-C>100 mg/dL, almost 70% to 80% had other lipid fractions or ratios within target ranges. A logistic regression analysis showed age, gender, time on dialysis, diabetes, type of calcineurin inhibitor (CSA vs TAC), adjunctive therapy (SRL/EVR vs MMF) and prednisone dose to be associated with dyslipidemia.

CONCLUSION

Dyslipidemia is frequent at 1 year after transplantation. The lack of agreement among changes observed in lipid fractions and ratios suggests that more studies are necessary to guide therapy besides targeting LDL-C concentrations as recommended by current guidelines.