The Association of 25-Hydroxyvitamin D Levels with Late Cytomegalovirus Infection in Kidney Transplant Recipients: the Wisconsin Allograft Recipient Database

Immune Modulatory Effects of Vitamin D on Herpesvirus Infections

In addition to its classical role in calcium and phosphate metabolism regulation, vitamin D also has an important impact on immunity modulation. Vitamin D regulates the immune response, shifting from a proinflammatory state to a more tolerogenic one by increasing the release of anti-inflammatory cytokines while downregulating proinflammatory cytokines. Thus, low levels of vitamin D have been associated with an increased risk of developing autoimmune diseases like multiple sclerosis and type 1 diabetes. Furthermore, this prohormone also enhances the release of well-known antimicrobial peptides, like cathelicidin LL-37 and β-defensins; therefore, it has been proposed that vitamin D serum levels might be related to the risk of well-known pathogen infections, including herpesviruses. These are a group of widely spread viral pathogens that can cause severe encephalitis or tumors like Kaposi's sarcoma and Burkitt lymphoma. However, there is no consensus on the minimum levels of vitamin D or the recommended daily dose, making it difficult to establish a possible association between these two factors. This narrative non-systematic review will analyze the mechanisms by which vitamin D regulates the immune system and recent studies about whether there is an association between vitamin D serum levels and herpesvirus infections.

Low 25-Hydroxyvitamin D Post-Kidney Transplant Is Associated with Increased Risk of BK Polyomavirus-Associated Nephropathy

BK viremia (BKPyV-DNAemia) and nephropathy (BKPyVAN) are significant causes of morbidity and mortality in kidney transplant recipients (KTRs). Vitamin D supports immune function, yet low 25-hydroxyvitamin D [25(OH)D] is common among KTRs. The association between serum 25(OH)D, measured 61 days to 2 years post-transplant, and subsequent incident BKPyV-DNAemia and BKPyVAN was examined in KTRs without previous BKPyV-DNAemia or BKPyVAN, respectively. Out of 3308 KTRs, 399 (12%) were vitamin D deficient [25(OH)D ≤ 20 ng/mL], and 916 (27.7%) were insufficient [25(OH)D 21-29 ng/mL]. A total of 184 KTRs developed BKPyV-DNAemia and 44 developed BKPyVAN. The incidence rate (/100 person-years) for BKPyV-DNAemia was 2.88 in the 25(OH)D sufficient group, 2.22 in the insufficient group, and 2.37 in the deficient group. The incidence rate (/100 person-years) for BKPyVAN was 0.30 in the 25(OH)D sufficient group, 0.75 in the insufficient group, and 1.28 in the deficient group. Vitamin D deficiency (adjusted hazard ratio [aHR] compared to 25(OH)D sufficiency: 3.92; 95% CI: 1.66-9.23) and insufficiency (aHR: 2.22; 95% CI: 1.11-4.45) remained significantly associated with the incidence of BKPyVAN after adjustment for baseline characteristics. Low serum 25(OH)D was associated with an increased risk of BKPyVAN but not BKPyV-DNAemia.

Seasonal variation of cytomegalovirus disease in kidney transplant recipients

PURPOSE

Studies conducted in the northern United States found cytomegalovirus (CMV) disease after liver transplantation follows a seasonal pattern, with increased incidence in fall and winter. This has not been evaluated in kidney transplant recipients. Improved understanding of CMV seasonality may help guide use of preventative therapies.

METHODS

We evaluated adult patients receiving a kidney transplant at our center in Wisconsin from January 1, 1995 to December 31, 2018. CMV event was defined as quantifiable viral replication with clinical signs or symptoms suspicious for CMV per current consensus recommendations. Seasons were divided as follows: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). The primary objective was to evaluate the annual distribution of CMV disease and determine whether this differed by season.

RESULTS

There were 6151 kidney transplants in the study period. A total of 913 patients had 1492 episodes of CMV. Median time from transplant to first detection was 5.51 months (interquartile range [IQR] 2.87-11.7). The observed overall incidence exceeded the expected incidence in winter (+.7%), spring (+5.5%), and fall (+3.4%) and was less than expected in summer (-9.5%) (p = .18). The incidence of CMV during summer, however, was 21% less than expected (p = .001) in recipients who were CMV positive (R+) at the time of transplantation. No such difference was observed in CMV negative recipients (R-; p = .58).

CONCLUSION

CMV after kidney transplant appears to be less common during the summer season in patients who were R+ at transplant but does not follow seasonal variation in R-. Reasons for this are unclear but are likely related to CMV-specific cell-mediated immunity. These findings may have clinical implications, particularly the use of non-pharmacologic strategies to improve response to antiviral therapy.

Association of serum vitamin D with active human cytomegalovirus infections in Chinese children with systemic lupus erythematosus, CHINA

Vitamin D (VD) plays an important role in infectious and autoimmune diseases. We investigated the association between serum VD levels and active human cytomegalovirus (HCMV) infections in pediatric systemic lupus erythematosus (SLE) patients. From January 2015 to June 2021, one hundred and twenty children diagnosed with SLE and 100 healthy children were enrolled. Using ELISA, serum 25(OH)D levels were detected. Serum anti-HCMV IgM antibodies were measured by a chemiluminescence immunoassay. Comparisons of 25(OH)D levels between SLE patients and healthy children were performed, as well as subgroups of SLE patients with or without active HCMV infections. Serum 25(OH)D levels of SLE patients were significantly lower than those of healthy children (35.3 ± 12.9 vs 49.3 ± 15.3, P < 0.001). VD deficiency ratio was higher in SLE patients (89.2%) than that in healthy children (52.0%). Serum 25(OH)D levels in the positive anti-HCMV IgM group were significantly lower than those of the negative anti-HCMV IgM group (30.6 ± 12.3 vs 38.2 ± 12.5, P < 0.001). The severe VD deficiency ratio was significantly higher in HCMV-IgM(+)-SLE patients (42.2%) than that in HCMV-IgM(-)-SLE patients (13.3%). This study suggested that serum VD level is associated with active HCMV infections in pediatric SLE patients.

Prevalence of vitamin D deficiency and impact on clinical outcomes after kidney transplantation: a systematic review and meta-analysis

CONTEXT

The prevalence of vitamin D deficiency (VDD) and its impact on clinical outcomes after kidney transplant (KT) remain poorly defined.

OBJECTIVES

We conducted a meta-analysis to evaluate the impact of early VDD on clinical outcomes after KT.

DATA SOURCES

Electronic databases (PubMed, Embase, Web of Science, and The Cochrane Library) were systematically searched for eligible publications up to April 30, 2020.

DATA EXTRACTION

Relative risk was presented as hazard ratios (HRs) or odds ratios (ORs) and 95%CIs for dichotomous outcomes. Mean difference (MD) and 95%CIs were presented for continuous outcomes.

RESULTS

A total of 28 studies (13 prospective and 15 retrospective) were included. VDD was common early after KT, with a prevalence of 52% (95%CI: 41%-64%) at transplant, 34% (95%CI: 17%-51%) at 3 months, and 23% (95%CI: 10%-35%) at 6 months. Early VDD was associated with higher mortality rate after KT (HR, 1.56; 95%CI: 1.32-1.84; P < 0.001). In addition, early VDD led to higher risk of bacterial infection (OR, 1.82; 95%CI: 1.40-2.36; P < 0.001), BK polyomavirus infection (OR, 2.11, 95%CI: 1.23-3.61; P = 0.006), and cytomegalovirus infection (OR, 1.69; 95%CI: 1.24-2.31; P = 0.001). Early VDD increased the risk of acute rejection as well (HR, 2.28; 95%CI: 1.57-3.30; P < 0.001). Recipients with early VDD had lower estimated glomerular filtration rates (mean difference: -5.06; 95%CI: -7.28 to 2.83 mL/min; P < 0.001). Sensitivity analyses showed good stability of the pooled results.

CONCLUSION

VDD was common early after KT and associated with higher risk of death and adverse outcomes.

The association between vitamin D and acute rejection in human kidney transplantation: A systematic review and meta-analysis study

BACKGROUND

Vitamin D (VitD) deficiency is associated with several diseases such as multiple sclerosis, rheumatoid arthritis, respiratory infection, and so forth. In the field of transplantation (kidney transplantation), some studies reported that patients with VitD deficiency are of increased chance of acute rejection, but other studies did not show such a chance. On the other hand, since VitD is a modulatory factor and can reduce the inflammatory response, understanding the exact role of it in transplantation may contribute to tolerance condition in these patients.

METHODS

The electronic databases, including PubMed, Scopus, Embase, ProQuest, Web of Science, and Google Scholar, were searched for eligible studies. In general, 14 studies with a total of 4770 patients were included in this meta-analysis. Regarding the methodological heterogeneity, we selected a random-effects combination model. Moreover, OR was chosen as an effect size for this study.

RESULTS

After the combination of 14 studies, we showed that patients in the VitD-deficient group had an 82% increased chance of acute rejection compared with patients in the VitD-sufficient group, and this effect was significant (OR 1.82; 95% confidence interval [CI] [1.29, 2.56]; I² = 52.3%). This result was significant, and, regarding the narrow CI, it can be a conclusive result. Study quality and gender variables were the main sources of inconsistent results in the primary studies. Moreover, using meta-regression, we showed that VitD deficiency (independent from the estimated glomerular filtration rate (eGFR) of patients) increased the chance of acute rejection.

CONCLUSION

The normal VitD status of patients a few days before and after transplantation can reduce the chance of acute rejection.

Vitamin D Deficiency or Supplementation and the Risk of Human Herpesvirus Infections or Reactivation: A Systematic Review and Meta-analysis

BACKGROUND

Vitamin D may protect against respiratory virus infections, but any association with herpesviruses is unclear.

METHODS

We undertook a systematic review of vitamin D deficiency or supplementation and the risk of 8 human herpesviruses. Six databases and 4 gray literature databases were searched for relevant cohort studies, case-control studies, and clinical trials.

RESULTS

Ten studies were included, all conducted among immunosuppressed patients. There was no evidence that vitamin D deficiency is associated with cytomegalovirus (CMV) disease (pooled risk ratio, 1.06; 95% CI, 0.66-1.7), herpes zoster after transplantation (1 study), or HHV-8 among HIV patients (1 study). Vitamin D supplementation may decrease herpes zoster among hemodialysis patients (1 study) or CMV disease after renal transplantation (1 study), but supplementation was not associated with reduced EBV viral load among multiple sclerosis patients (1 study).

CONCLUSIONS

Any association between vitamin D and herpesviruses remains inconclusive. Further studies in the general population are needed.

General Approach to the Clinical Care of Solid Organ Transplant Recipients with COVID-19 Infection: Management for Transplant Recipients

PURPOSE OF REVIEW

Insufficient knowledge about COVID-19 and the potential risks of COVID-19 are limiting organ transplantation in wait-listed candidates and deferring essential health care in solid organ transplant recipients. In this review, we expand the understanding and present an overview of the optimized management of COVID-19 in solid organ transplant recipients.

RECENT FINDINGS

Transplant recipients are at an increased risk of severe COVID-19. The unique characteristics of transplant recipients can make it more difficult to identify COVID-19. Based on the COVID-19 data to date and our experience, we present testing, management, and prevention methods for COVID-19. Comprehensive diagnostic tests should be performed to determine disease severity, phase of illness, and identify other comorbidities in transplant recipients diagnosed with COVID-19. Outpatients should receive education for preventative measures and optimal health care delivery minimizing potential infectious exposures. Multidisciplinary interventions should be provided to hospitalized transplant recipients for COVID-19 because of the complexity of caring for transplant recipients.

SUMMARY

Transplant recipients should strictly adhere to infection prevention measures. Understanding of the transplant specific pathophysiology and development of effective treatment strategies for COVID-19 should be prioritized.