Management of BK viremia is associated with a lower risk of subsequent cytomegalovirus infection in kidney transplant recipients

Risk Factors for CMV and BK Infections in an Elderly Veteran Population Following Kidney Transplantation: Implications for Immunosuppression Induction and Management

Cytomegalovirus (CMV) and BK Polyomavirus (BKPyV) are the most common opportunistic pathogens following kidney transplantation. We evaluated 102 patients with a median age of 63 at Edward Hines VA Hospital from November 2020 to December 2022. Our primary interest was the incidence of CMV and BKPyV infections, as well as CMV and BKPyV coinfection. Secondary interests included time to infection, rejection, and graft and patient survival. There were no statistically significant differences in patient age, donor age, race, transplant type, incidence of delayed graft function, or induction in both cohorts (any infection (N = 46) vs. those without (N = 56)). There was a 36% (37/102) incidence of CMV, a 17.6% (18/102) of BKPyV and an 8.8% (9/102) incidence of coinfection. There was a decreased incidence of CMV infection in Basiliximab induction versus antithymocyte globulin (21% and 43%). CMV risk status had no effect on the incidence of CMV infection following transplant. African American recipients had a lower incidence of BKPyV infection (12% vs. 39%), yet a higher incidence was observed in those with high cPRA (50% vs. 14%). Most CMV and/or BKPyV infections occurred within the first six months post-transplant (54%). Immunosuppression management of the elderly should continually be evaluated to reduce opportunistic infections post-transplant.

Delayed Graft Function Among Kidney Transplant Recipients Is Associated With an Increased Risk of Urinary Tract Infection and BK Viremia

Background

Delayed graft function (DGF) among deceased donor kidney transplant recipients (DDKTRs) is a well-known risk factor for allograft rejection, decreased graft survival, and increased cost. Although DGF is associated with an increased risk of rejection, it is unclear whether it also increases the risk of infection.

Methods

We reviewed all adult DDKTRs at our center between 2010 and 2018. The primary outcomes of interest were BK viremia, cytomegalovirus viremia, pneumonia, and urinary tract infection (UTI) within the first year of transplant. Additional analysis was made with censoring follow-up at the time of allograft rejection.

Results

A total of 1512 DDKTRs were included, of whom 468 (31%) had DGF. As expected, several recipient, donor, and baseline immunological characteristics differed by DGF status. After adjustment, DGF was significantly associated with an increased risk of BK viremia (hazard ratio: 1.34; 95% confidence interval, 1.0-1.81; P = 0.049) and UTI (hazard ratio: 1.70; 95% confidence interval, 1.31-2.19; P < 0.001) but not cytomegalovirus viremia or pneumonia. Associations were similar in models censored at the time of rejection.

Conclusions

DGF is associated with an increased risk of early infectious complications, mainly UTI and BK viremia. Close monitoring and appropriate management are warranted for better outcomes in this unique population.

Risk factors and outcomes of BK viremia among deceased donor kidney transplant recipients based on donor characteristics

INTRODUCTION

BK polyomavirus (BKV) is a common infection among kidney transplant recipients (KTR). Risk factors and outcomes based on donor characteristics remain largely unknown.

METHODS

In this study, we aimed to analyze the impact of donor factors through a paired kidney analysis. We included 289 pairs of adult deceased donor transplants (578 KTRs total); each pair had received kidneys from the same donor. Recipient pairs were divided into three groups: "no BK group" if neither KTR developed BK viremia (n = 336), "discordant" if the only one did (n = 176), and "concordant" if both did (n = 66). Acute rejection (AR), graft failure, and BK nephropathy (BKN) were outcomes of interest.

RESULTS

Donors in the concordant group were younger, had lower kidney donor profile index (KDPI), and were less likely to be donor after circulatory death (DCD). In multivariate analyses, KTRs who had a donor with a higher body mass index (BMI) (hazard ratio (HR): 0.97; 95% confidence interval (CI): 0.95-0.99; p = .009) were less likely to develop BKV. Concordance was not associated with AR (HR: 0.83; 95% CI: 0.51-1.34; p = .45), graft failure (HR: 1.77; 95% CI: 0.42-7.50; p = .43), or BKN (HR: 1.02; 95% CI: 0.51-2.03; p = .96).

DISCUSSION

Our study suggests lower donor BMI is associated with BKV infection, and concordance or discordance between paired kidney recipients is not associated with poor outcomes.

BK Virus and Cytomegalovirus Coinfections in Kidney Transplantation and Their Impact on Allograft Loss

We aimed to ascertain the interaction and effects of combined reactivations of BK virus and cytomegalovirus on kidney graft function. All consecutive kidney transplant recipients (KTR) between 2003 and 2016 were included. Of 1976 patients who received a kidney transplant, 23 (1.2%) presented BKV-associated nephropathy (BKVAN). Factors independently associated with BKVAN were diabetes mellitus (odds ratios (OR) 3.895%, confidence intervals (CI) (1.4-10.5)), acute allograft rejection (OR 2.8 95%, CI (1.1-7.6)) and nephrostomy requirement (OR 4.195%, CI (1.3-13)). Cytomegalovirus infection was diagnosed in 19% of KTR patients. Recipients with BKVAN presented more frequently with cytomegalovirus (CMV) infection compared to patients without BKVAN (39% vs. 19%, p = 0.02). Acute allograft rejection (OR 2.95%, CI (1.4-2.4)) and nephrostomy requirement (OR 2.95%, CI (1.2-3)) were independently associated with CMV infection. Sixteen patients (69%) with BKVAN had graft dysfunction at one-year post-transplant and eight of them (35%) lost their graft. Patients presenting with BKVAN and graft loss presented more frequently a cytomegalovirus infection (OR 2.295%, CI (1.3-4.3)). In conclusion, we found a relation between CMV infection and graft loss in patients presenting BKVAN, suggesting that patients with CMV reactivation should be actively screened for BKV.

Impact of low-level pretransplant donor-specific antibodies on outcomes after kidney transplantation

Background

The effect of low‐level pretransplant donor‐specific antibody (DSA) on kidney transplant outcomes is not well described. The goal of this study was to compare outcomes among patients of varying immunologic risk, based on the level of pretransplant DSA.

Methods

We retrospectively reviewed all adult kidney transplant recipients who had undergone a transplant at our center between January 2013 and May 2017. Patients were grouped as negative DSA (mean fluorescence intensity, [MFI_SUM < 100]), low‐level DSA (MFI_SUM 100–1000), and positive DSA (MFI_SUM > 1000). Rejection, infection, graft, and patient survival were outcomes measured.

Results

Of 952 patients, 82.1% had negative DSA, 10.7% had low‐level DSA, and 7.1% had positive DSA. The positive DSA group had the highest rate of antibody‐mediated rejection (10.3%), followed by low‐level DSA (7.8%) and the negative DSA group (4.5%) (p = .034). The rate of BK viremia was highest in the positive DSA group (39.7%), followed by the low‐level group (30.4%) and the negative DSA group (25.6%), (p = .025). None of the other outcomes, including graft or patient survival, were different between the groups.

Conclusion

While low‐level DSA should not prevent proceeding with kidney transplantation, it should not be ignored. Future studies are needed to investigate the long‐term effects of varying levels of pre‐transplant DSA on outcomes.

Advantages of plasmatic CXCL-10 as a prognostic and diagnostic biomarker for the risk of rejection and subclinical rejection in kidney transplantation

This study evaluate the potential of plasmatic CXCL-10 (pCXCL-10) as a pre&post transplantation prognostic and diagnostic biomarker of T-cell-mediated rejection (TCMR), antibody-mediated rejection (ABMR) and subclinical rejection (SCR) risk in adult kidney recipients considering BKV and CMV infections as possible clinical confounder factors. Twenty-eight of 100 patients included experienced rejection (TCMR:14; ABMR:14); 8 SCR; 13 and 16 were diagnosed with BKV and CMV infection, respectively. Pre-transplantation pCXCL-10 was significantly increased in TCMR and ABMR and post-transplantation in TCMR, ABMR and SCR compared with nonrejectors. All CMV⁺ patients showed pCXCL-10 levels above the cutoff values established for rejection whereas the 80% of BKV⁺ patients showed pCXCL-10 concentration < 100 pg/mL. pCXCL-10 could improve pre-transplantation patient stratification and immunosuppressive treatment selection according to rejection risk; and after kidney transplantation could be a potential early prognostic biomarker for rejection. Clinical confounding factor in BKV⁺ and particularly in CMV⁺ patients must be discarded.

Risk factors for progression from low level BK dnaemia to unfavorable outcomes after BK management via immunosuppressive reduction

BACKGROUNDS

Effective management of BK viremia (BKPyV-DNAemia) in kidney transplant recipients (KTRs) involves regular monitoring and adjustment of immunosuppression. With this strategy, the majority of patients will clear BK or have ongoing, but non-significant, low-level BKPyV-DNAemia. However, despite adjustments, some will develop more severe sequelae of BK including BKPyV-DNAemia >5 log₁₀ copies/mL and BK nephropathy, and others may develop de novo DSA (dnDSA) or acute rejection (AR).

METHODS

This was a single-center study of KTRs transplanted at the University of Wisconsin-Madison between 01/01/2015 and 12/31/2017. In this study, we sought to elucidate characteristics associated with the progression of BKPyV-DNAemia to unfavorable outcomes after decreasing immunosuppressive medications for the management of BK viremia as described in consensus guidelines.

RESULTS

A total of 224 KTRs fulfilled our selection criteria; 118 (53%) resolved or had persistent low DNAemia, 64 (28%) had severe BK/nephropathy, and 42 (19%) developed dnDSA or AR. In multivariable analysis, female gender (HR: 2.05; 95% CI: 1.08-3.90; P = .02); previous rejection (HR: 2.90; 95% CI: 1.04-8.12; P = .04), and early infection (HR: 0.81; 95% CI: 0.72-0.90; P < .001) were associated with the development of severe BK/nephropathy. Conversely, non-depleting induction at transplant (HR: 2.06; 95% CI: 1.03-4.11; P = .03), HLA mismatches >3 (HR: 2.27; HR: 1.01-5.06; P = .04), and delayed graft function (HR: 4.14; 95% CI: 1.12-15.28; P = .03) were associated with development of dnDSA and/or rejection.

CONCLUSION

Our study suggests that almost half of KTRs with BKPyV-DNAemia managed by our immunosuppressant adjustment protocol progress unfavorably. Identification of these risk factors could assist the frontline clinician in creating an individualized immunosuppressive modification plan potentially mitigating negative outcomes.

Clinical features of BK-polyomavirus and cytomegalovirus co-infection after kidney transplantation

BK polyomavirus (BKPyV) and cytomegalovirus (CMV) are the main viral pathogens affecting the graft and recipient outcome after allogenic kidney transplantation. It has recently been found that infection with both viruses has a greater impact on kidney graft function than a single infection. We retrospectively analyzed a cohort of 723 recipients who received kidney transplantation between 2007 and 2015 after living and postmortal donation for differences in risk and outcome parameters regarding BKPyV (DNAemia) and CMV (CMV DNAemia) co-infection compared to sole viremias and to patients without viremia. Of all kidney allograft recipients in our cohort, 8.2% developed co-infection with BKPyV DNAemia and CMV DNAemia, 15.1% showed BKPyV viremia alone and 25.2% sole CMV DNAemia. Acute rejection was closely linked with co-infection (multivariable analysis, p = 0.001). Despite the fact that the estimated glomerular filtration rate of patients with co-infection was noticeably reduced compared to patients with BKV or CMV infection alone, transplant survival and patient survival were not significantly reduced. Co-infection with BKPyV and CMV in kidney transplanted patients is significantly associated with inferior allograft function. Since co-infection is strongly associated with acute rejection, co-infected individuals should be considered a risk collective.

Treatment of Chronic Active Antibody-mediated Rejection With Pulse Steroids, IVIG, With or Without Rituximab is Associated With Increased Risk of Pneumonia

Background.

The risk of infection associated with specific treatments of chronic active antibody-mediated rejection (cAMR) after kidney transplantation remains unknown.

Methods.

This was a single-center study of kidney transplant recipients treated with pulse steroids, intravenous immunoglobulin (IVIG) ± rituximab for biopsy-confirmed cAMR. The control group consisted of age- and race-matched patients who underwent donor-specific antibody-based protocol biopsies but had no rejection. We collected data on BK virus (BKV), cytomegalovirus (CMV), urinary tract infection (UTI), and pneumonia postbiopsy.

Results.

There were 49 patients in each group. In those with cAMR, 21 (43%) were treated with steroids, IVIG, and rituximab; the remaining received steroids and IVIG only. The risk of graft failure was greater in the cAMR group [22 (45%) vs. 3 (6%), P < 0.001]. Kaplan-Meier analyses demonstrated a significantly greater risk of pneumonia in the cAMR group (P = 0.02). This was confirmed by multivariable Cox regression analyses [Hazard ratio (HR) = 6.04, P = 0.027, 95% CI, 1.22-29.75]. None of the patients with pneumonia were affected by opportunistic pathogens. Additionally, the risk of CMV, UTI, and BKV was not increased. Rituximab was not independently associated with any of the infections studied.

Conclusions.

Treatment of cAMR, but not rituximab, was associated with a 6-fold increased risk of pneumonia. Additional studies are needed to determine the safety and efficacy of prolonged antimicrobial prophylaxis and monitoring strategies, including for hypogammaglobulinemia, to reduce the risk of pneumonia following the treatment of cAMR.