Long-term shedding of viable SARS-CoV-2 in kidney transplant recipients with COVID-19

The exact duration of viable SARS-CoV-2 shedding in kidney transplant recipients (KTRs) remains unclear. Here, we retrospectively investigated this issue using cell cultures of SARS-CoV-2 RT-PCR-positive nasopharyngeal samples (n = 40) obtained from 16 KTRs with symptomatic COVID-19 up to 39 days from symptom onset. A length of viable SARS-CoV-2 shedding >3 weeks from the onset of symptoms was identified in four KTRs (25%). These results suggest that a significant proportion of KTRs can shed viable SARS-CoV-2 for at least 3 weeks, which may favor the emergence of new variants. Based on these data, we recommend prolonging the isolation of KTRs with COVID-19 until negative SARS-CoV-2 RT-PCR testing.     

Is COVID-19 infection more severe in kidney transplant recipients?

There are no studies which have compared the risk of severe COVID-19 and related mortality between transplant recipients and nontransplant patients. We enrolled two groups of patients hospitalized for COVID-19, that is, kidney transplant recipients (KTR) from the French Registry of Solid Organ Transplant (n = 306) and a single-center cohort of nontransplant patients (n = 795). An analysis was performed among subgroups matched for age and risk factors for severe COVID-19 or mortality. Severe COVID-19 was defined as admission (or transfer) to an intensive care unit, need for mechanical ventilation, or death. Transplant recipients were younger and had more comorbidities compared to nontransplant patients. They presented with higher creatinine levels and developed more episodes of acute kidney injury. After matching, the 30-day cumulative incidence of severe COVID-19 did not differ between KTR and nontransplant patients; however, 30-day COVID-19-related mortality was significantly higher in KTR (17.9% vs 11.4%, respectively, p = .038). Age >60 years, cardiovascular disease, dyspnea, fever, lymphopenia, and C-reactive protein (CRP) were associated with severe COVID-19 in univariate analysis, whereas transplant status and serum creatinine levels were not. Age >60 years, hypertension, cardiovascular disease, diabetes, CRP >60 mg/L, lymphopenia, kidney transplant status (HR = 1.55), and creatinine level >115 µmol/L (HR = 2.32) were associated with COVID-19-related mortality in univariate analysis. In multivariable analysis, cardiovascular disease, dyspnea, and fever were associated with severe disease, whereas age >60 years, cardiovascular disease, dyspnea, fever, and creatinine level>115 µmol/L retained their independent associations with mortality. KTR had a higher COVID-19-related mortality compared to nontransplant hospitalized patients.     

Humoral response to SARS-CoV-2 is well preserved and symptom dependent in kidney transplant recipients

Data on the immune response to SARS-CoV-2 in kidney transplant recipients are scarce. Thus, we conducted a single-center observational study to assess the anti-SARS-CoV-2 IgG seroprevalence in outpatient kidney transplant recipients (KTR; n = 1037) and healthcare workers (HCW; n = 512) during the second wave of the COVID-19 pandemic in fall 2020 and evaluated the clinical variables affecting antibody levels. Antibodies against S1 and S2 subunit of SARS-CoV-2 were evaluated using immunochemiluminescent assay (cut off 9.5 AU/ml, sensitivity of 91.2% and specificity of 90.2%). Anti-SARS-CoV-2 IgG seroprevalence was lower in KTR than in HCW (7% vs. 11.9%, p = .001). Kidney transplant recipients with SARS-CoV-2 infection were younger (p = .001) and received CNI-based immunosuppression more frequently (p = .029) than seronegative KTR. Anti-SARS-CoV-2 IgG positive symptomatic KTR had a higher BMI (p = .04) than asymptomatic KTR. Interestingly, anti-SARS-CoV-2 IgG levels were higher in KTR than in HCW (median 31 AU/ml, IQR 17–84 vs. median 15 AU/ml, IQR 11–39, p < .001). The presence of moderate to severe symptoms in KTR was found to be the only independent factor affecting IgG levels (Beta coefficient = 41.99, 95% CI 9.92–74.06, p = .011) in the multivariable model. In conclusion, KTR exhibit a well-preserved symptom-dependent humoral response to SARS-CoV-2 infection.     

COVID-19 in pediatric kidney transplantation: The Improving Renal Outcomes Collaborative

There are limited data on the impact of COVID-19 in children with a kidney transplant (KT). We conducted a prospective cohort study through the Improving Renal Outcomes Collaborative (IROC) to collect clinical outcome data about COVID-19 in pediatric KT patients. Twenty-two IROC centers that care for 2732 patients submitted testing and outcomes data for 281 patients tested for SARS-CoV-2 by PCR. Testing indications included symptoms and/or potential exposures to COVID-19 (N = 134, 47.7%) and/or testing per hospital policy (N = 154, 54.8%). Overall, 24 (8.5%) patients tested positive, of which 15 (63%) were symptomatic. Of the COVID-19-positive patients, 16 were managed as outpatients, six received non-ICU inpatient care and two were admitted to the ICU. There were no episodes of respiratory failure, allograft loss, or death associated with COVID-19. To estimate incidence, subanalysis was performed for 13 centers that care for 1686 patients that submitted all negative and positive COVID-19 results. Of the 229 tested patients at these 13 centers, 10 (5 asymptomatic) patients tested positive, yielding an overall incidence of 0.6% and an incidence among tested patients of 4.4%. Pediatric KT patients in the United States had a low estimated incidence of COVID-19 disease and excellent short-term outcomes.     

Subclinical inflammation phenotypes and long‐term outcomes after pediatric kidney transplantation

The implementation of surveillance biopsies in pediatric kidney transplantation remains controversial. Surveillance biopsies detect subclinical injury prior to clinical dysfunction, which could allow for early interventions that prolong allograft survival. We conducted a single‐center retrospective cohort study of 120 consecutive pediatric kidney recipients, of whom 103 had surveillance biopsies ≤6 months posttransplant. We tested the hypothesis that subclinical inflammation (borderline or T cell–mediated rejection without clinical dysfunction) is associated with a 5‐year composite endpoint of acute rejection and allograft failure. Overall, 36% of subjects had subclinical inflammation, which was associated with increased hazard for the composite endpoint (adjusted hazard ratio 2.89 [1.27, 6.57]; P < .01). Subjects with treated vs untreated subclinical borderline rejection had a lower incidence of the composite endpoint (41% vs 67%; P < .001). Subclinical vascular injury (subclinical inflammation with Banff arteritis score > 0) had a 78% incidence of the composite endpoint vs 11% in subjects with no major surveillance abnormalities (P < .001). In summary, we showed that subclinical inflammation phenotypes were prevalent in pediatric kidney recipients without clinical dysfunction and were associated with increased acute rejection and allograft failure. Once prospectively validated, our data would support implementation of surveillance biopsies as standard of care in pediatric kidney transplantation.     

Using computer‐assisted morphometrics of 5‐year biopsies to identify biomarkers of late renal allograft loss

The current Banff scoring system was not developed to predict graft loss and may not be ideal for use in clinical trials aimed at improving allograft survival. We hypothesized that scoring histologic features of digitized renal allograft biopsies using a continuous, more objective, computer‐assisted morphometric (CAM) system might be more predictive of graft loss. We performed a nested case‐control study in kidney transplant recipients with a surveillance biopsy obtained 5 years after transplantation. Patients that developed death‐censored graft loss (n = 67) were 2:1 matched on age, gender, and follow‐up time to controls with surviving grafts (n = 134). The risk of graft loss was compared between CAM‐based models vs a model based on Banff scores. Both Banff and CAM identified chronic lesions associated with graft loss (chronic glomerulopathy, arteriolar hyalinosis, and mesangial expansion). However, the CAM‐based models predicted graft loss better than the Banff‐based model, both overall (c‐statistic 0.754 vs 0.705, P < .001), and in biopsies without chronic glomerulopathy (c‐statistic 0.738 vs 0.661, P < .001) where it identified more features predictive of graft loss (% luminal stenosis and % mesangial expansion). Using 5‐year renal allograft surveillance biopsies, CAM‐based models predict graft loss better than Banff models and might be developed into biomarkers for future clinical trials.     

Positive flow cytometry crossmatch with discrepant antibody testing results following COVID-19 vaccination

The impact of COVID-19 vaccination on the alloimmunity of transplant candidates is unknown. We report a case of positive B cell flow cytometry crossmatch in a patient waiting for second kidney transplantation, 37 days after receiving the COVID-19 vaccine. The preliminary crossmatch, using sample collected before COVID-19 vaccination, was negative. The antibodies to mismatched donor HLA-DR7 were detected only with multi-antigen beads but not with single-antigen beads, excluding possible prozone effects in solid-phase antibody assays. The crossmatches were positive with HLA-DR7–positive surrogates (n = 2) while negative with HLA-DR7–negative surrogates (n = 3), which confirms the HLA-DR7 alloreactivity. The antigen configurations on B lymphocytes are similar to that on the multi-antigen beads while distinct from the single-antigen beads. HLA-DR7 was the repeating mismatched antigen with the failing first kidney allograft. The newly emerged antibody to HLA-DR7 probably is the consequence of bystander activation of memory response by the COVID-19 vaccination. This case highlights the importance of verifying allo-sensitization history and utilizing multiple assays, including cell-based crossmatch and solid-phase assays with multi-antigens. COVID-19 immunization may deserve special attention when assessing the immunological risk before and after organ transplantation.     

Outcomes of kidney retransplantation after graft loss as a result of BK virus nephropathy in the era of newer immunosuppressant agents

We conducted this study using the updated 2005‐2016 Organ Procurement and Transplantation Network database to assess clinical outcomes of retransplant after allograft loss as a result of BK virus–associated nephropathy (BKVAN). Three hundred forty‐one patients had first graft failure as a result of BKVAN, whereas 13 260 had first graft failure as a result of other causes. At median follow‐up time of 4.70 years after the second kidney transplant, death‐censored graft survival at 5 years for the second renal allograft was 90.6% for the BK group and 83.9% for the non‐BK group. In adjusted analysis, there was no difference in death‐censored graft survival (P = .11), acute rejection (P = .49), and patient survival (P = .13) between the 2 groups. When we further compared death‐censored graft survival among the specific causes for first graft failure, the BK group had better graft survival than patients who had prior allograft failure as a result of acute rejection (P < .001) or disease recurrence (P = .003), but survival was similar to those with chronic allograft nephropathy (P = .06) and other causes (P = .05). The better allograft survival in the BK group over acute rejection and disease recurrence remained after adjusting for potential confounders. History of allograft loss as a result of BKVAN should not be a contraindication to retransplant among candidates who are otherwise acceptable.     

Early technical pancreas failure in Simultaneous Pancreas–Kidney Recipients does not impact renal allograft outcomes

Early pancreas loss in simultaneous pancreas–kidney (SPK) transplants has been associated with longer perioperative recovery and reduced kidney allograft function. We assessed the impact of early pancreas allograft failure on transplant outcomes in a contemporary cohort of SPK patients (n = 218). Early pancreas allograft loss occurred in 12.8% (n = 28) of recipients. Delayed graft function (DGF) was more common (21.4% vs. 7.4%, p = 0.03) in the early pancreas loss group, but there were no differences in hospital length of stay (median 6.5 vs. 7.0, p = 0.22), surgical wound complications (p = 0.12), or rejection episodes occurring in the first year (p = 0.87). Despite differences in DGF, both groups had excellent renal function at 1 year post‐transplant (eGFR 64.1 ± 20.8 vs. 65.8 ± 22.9, p = 0.75). There were no differences in patient (HR 0.58, 95% CI 0.18–1.87, p = 0.26) or kidney allograft survival (HR 0.84, 95% CI 0.23–3.06, p = 0.77). One‐ and 2‐year protocol kidney biopsies were comparable between the groups and showed minimal chronic changes; the early pancreas loss group showed more cv changes at 2 years (p = 0.04). Current data demonstrate good outcomes and excellent kidney allograft function following early pancreas loss.     

Short‐term adverse effects of early subclinical allograft inflammation in kidney transplant recipients with a rapid steroid withdrawal protocol

The impact of subclinical inflammation (SCI) noted on early kidney allograft biopsies remains unclear. This study evaluated the outcome of SCI noted on 3‐month biopsy. A total of 273/363 (75%) kidney transplant recipients with a functioning kidney underwent allograft biopsies 3‐months posttransplant. Among those with stable allograft function at 3 months, 200 biopsies that did not meet the Banff criteria for acute rejection were identified. These were Group I: No Inflammation (NI, n = 71) and Group II: Subclinical Inflammation (SCI, n = 129). We evaluated differences in kidney function at 24‐months and allograft histology score at 12‐month biopsy. SCI patients had a higher serum creatinine (1.6 ± 0.7 vs 1.38 ± 0.45; P = .02) at 24‐months posttransplant, and at last follow‐up at a mean of 42.5 months (1.69 ± 0.9 vs 1.46 ± 0.5 mg/dL; P = .027). The allograft chronicity score (ci + ct + cg + cv) at 12‐months posttransplant was higher in the SCI group (2.4 ± 1.35 vs 1.9 ± 1.2; P = .02). The incidence of subsequent rejections within the first year in SCI and NI groups was 24% vs 10%, respectively (P = .015). De novo donor‐specific antibody within 12 months was more prevalent in the SCI group (12/129 vs 1/71, P = .03). SCI is likely not a benign finding and may have long‐term implications for kidney allograft function.     

Predictors of severe COVID-19 in kidney transplant recipients in the different epidemic waves: Analysis of the Spanish Registry

SARS-CoV-2 infection has produced high mortality in kidney transplant (KT) recipients, especially in the elderly. Until December 2020, 1011 KT with COVID-19 have been prospectively included in the Spanish Registry and followed until recovery or death. In multivariable analysis, age, pneumonia, and KT performed ≤6 months before COVID-19 were predictors of death, whereas gastrointestinal symptoms were protective. Survival analysis showed significant increasing mortality risk in four subgroups according to recipient age and time after KT (age <65 years and posttransplant time >6 months, age <65 and time ≤6, age ≥65 and time >6 and age ≥65 and time ≤6): mortality rates were, respectively, 11.3%, 24.5%, 35.4%, and 54.5% (p < .001). Patients were significantly younger, presented less pneumonia, and received less frequently specific anti-COVID-19 treatment in the second wave (July–December) than in the first one (March–June). Overall mortality was lower in the second wave (15.1 vs. 27.4%, p < .001) but similar in critical patients (66.7% vs. 58.1%, p = .29). The interaction between age and time post-KT should be considered when selecting recipients for transplantation in the COVID-19 pandemic. Advanced age and a recent KT should foster strict protective measures, including vaccination.     

Changes in humoral immune response after SARS-CoV-2 infection in liver transplant recipients compared to immunocompetent patients

The protective capacity and duration of humoral immunity after SARS-CoV-2 infection are not yet understood in solid organ transplant recipients. A prospective multicenter study was performed to evaluate the persistence of anti-nucleocapsid IgG antibodies in liver transplant recipients 6 months after coronavirus disease 2019 (COVID-19) resolution. A total of 71 liver transplant recipients were matched with 71 immunocompetent controls by a propensity score including variables with a well-known prognostic impact in COVID-19. Paired case–control serological data were also available in 62 liver transplant patients and 62 controls at month 3 after COVID-19. Liver transplant recipients showed a lower incidence of anti-nucleocapsid IgG antibodies at 3 months (77.4% vs. 100%, p < .001) and at 6 months (63.4% vs. 90.1%, p < .001). Lower levels of antibodies were also observed in liver transplant patients at 3 (p = .001) and 6 months (p < .001) after COVID-19. In transplant patients, female gender (OR = 13.49, 95% CI: 2.17–83.8), a longer interval since transplantation (OR = 1.19, 95% CI: 1.03–1.36), and therapy with renin–angiotensin–aldosterone system inhibitors (OR = 7.11, 95% CI: 1.47–34.50) were independently associated with persistence of antibodies beyond 6 months after COVID-19. Therefore, as compared with immunocompetent patients, liver transplant recipients show a lower prevalence of anti-SARS-CoV-2 antibodies and more pronounced antibody levels decline.     

T cell–mediated response to SARS-CoV-2 in liver transplant recipients with prior COVID-19

Whether immunosuppression impairs severe acute respiratory syndrome coronavirus 2-specific T cell–mediated immunity (SARS-CoV-2-CMI) after liver transplantation (LT) remains unknown. We included 31 LT recipients in whom SARS-CoV-2-CMI was assessed by intracellular cytokine staining (ICS) and interferon (IFN)-γ FluoroSpot assay after a median of 103 days from COVID-19 diagnosis. Serum SARS-CoV-2 IgG antibodies were measured by ELISA. A control group of nontransplant immunocompetent patients were matched (1:1 ratio) by age and time from diagnosis. Post-transplant SARS-CoV-2-CMI was detected by ICS in 90.3% (28/31) of recipients, with higher proportions for IFN-γ-producing CD4⁺ than CD8⁺ responses (93.5% versus 83.9%). Positive spike-specific and nucleoprotein-specific responses were found by FluoroSpot in 86.7% (26/30) of recipients each, whereas membrane protein-specific response was present in 83.3% (25/30). An inverse correlation was observed between the number of spike-specific IFN-γ-producing SFUs and time from diagnosis (Spearman's rho: −0.418; p value = .024). Two recipients (6.5%) failed to mount either T cell–mediated or IgG responses. There were no significant differences between LT recipients and nontransplant patients in the magnitude of responses by FluoroSpot to any of the antigens. Most LT recipients mount detectable—but declining over time—SARS-CoV-2-CMI after a median of 3 months from COVID-19, with no meaningful differences with immunocompetent patients.     

Post-mortem molecular investigations of SARS-CoV-2 in an unexpected death of a recent kidney transplant recipient

Solid organ transplant recipients are vulnerable to severe infection during induction therapy. We report a case of a 67-year-old male who died unexpectedly 10 days after receiving a kidney transplant on February 10, 2020. There was no clear cause of death, but COVID-19 was considered retrospectively, as the death occurred shortly after the first confirmed case of COVID-19 in Canada. We confirmed the presence of SARS-CoV-2 components in the renal allograft and native lung tissue using immunohistochemistry for SARS-CoV-2 spike protein and RNA scope in situ hybridization for SARS-CoV-2 RNA. Results were reaffirmed with the Food and Drug Administration Emergency Use Authorization approved Bio-Rad SARS-CoV-2 digital droplet PCR for the kidney specimen. Our case highlights the importance of patient autopsies in an unfolding global pandemic and demonstrates the utility of molecular assays to diagnose SARS-CoV-2 post-mortem. SARS-CoV-2 infection during induction therapy may portend a fatal clinical outcome. We also suggest COVID-19 may be transmittable via renal transplant.     

Single nucleotide variant counts computed from RNA sequencing and cellular traffic into human kidney allografts

Advances in bioinformatics allow identification of single nucleotide polymorphisms (variants) from RNA sequence data. In an allograft biopsy, 2 genomes contribute to the RNA pool, 1 from the donor organ and the other from the infiltrating recipient's cells. We hypothesize that imbalances in genetic variants of RNA sequence data of kidney allograft biopsies provide an objective measure of cellular infiltration of the allograft. We performed mRNA sequencing of 40 kidney allograft biopsies, selected to represent a comprehensive range of diagnostic categories. We analyzed the sequencing reads of these biopsies and of 462 lymphoblastoid cell lines from the 1000 Genomes Project, for RNA variants. The ratio of heterozygous to nonreference genome homozygous variants (Het/Hom ratio) on all autosomes was determined for each sample, and the estimation of stromal and immune cells in malignant tumors using expression data (ESTIMATE) score was computed as a complementary estimate of the degree of cellular infiltration into biopsies. The Het/Hom ratios (P = .02) and the ESTIMATE scores (P < .001) were associated with the biopsy diagnosis. Both measures correlated significantly (r = .67, P < .0001), even though the Het/Hom ratio is based on mRNA sequence variation, while the ESTIMATE score uses mRNA expression. Het/Hom ratio and the ESTIMATE score may offer unbiased and quantitative parameters for characterizing cellular traffic into human kidney allografts.     

COVID-19 severity in kidney transplant recipients is similar to nontransplant patients with similar comorbidities

Higher rates of severe COVID-19 have been reported in kidney transplant recipients (KTRs) compared to nontransplant patients. We aimed to determine if poorer outcomes were specifically related to chronic immunosuppression or underlying comorbidities. We used a 1:1 propensity score-matching method to compare survival and severe disease-free survival (defined as death and/or need for intensive care unit [ICU]) incidence in hospitalized KTRs and nontransplant control patients between February 26 and May 22, 2020. Patients were matched for risk factors of severe COVID-19: age, sex, body mass index, diabetes mellitus, preexisting cardiopathy, chronic lung disease, and basal renal function. We included 100 KTRs (median age [interquartile range (IQR)]) 64.7 years (55.3–73.1) in three French transplant centers. After a median follow-up of 13 days (7–30), transfer to ICU was required for 34 patients (34%) and death occurred in 26 patients (26%). Overall, 43 patients (43%) developed a severe disease during a median follow-up of 8.5 days (2–14). Propensity score matching to a large French cohort of 2017 patients hospitalized in 24 centers, revealed that survival was similar between KTRs and matched nontransplant patients with respective 30-day survival of 62.9% and 71% (p = .38) and severe disease-free 30-day survival of 50.6% and 47.5% (p = .91). These findings suggest that severity of COVID-19 in KTRs is related to their associated comorbidities and not to chronic immunosuppression.     

Predictor factor for worse outcomes in kidney transplant recipients infected with coronavirus disease 2019: A systematic review and meta-analysis

IntroductionThe pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a massive impact on the health sector, especially in patients with pre-existing comorbidities. This study aims to define the predictor factors for worse outcomes in kidney transplant patients infected with SARS-CoV-2 and affected by coronavirus disease 2019 (COVID-19). We have analyzed in these patients their prior medical history, their clinical symptoms, and their laboratory results.MethodWe assessed outcomes of kidney transplant patients with confirmed COVID-19 until July 2021 from PubMed, Medline, Science Direct, Cochrane databases, EMBASE, Scopus, and EBSCO. We performed meta-analyses of nine published studies to estimate predictor factors. The analysis was analyzed by the Newcastle-Ottawa Scale (NOS) and then using the Review Manager 5.4 software.ResultOur analysis demonstrated that the most significant risk factors for the worse COVID-19 outcomes for kidney transplant patients included: age of 60 and older [MD 9.31(95% CI, 6.31–12.30), p < 0.0001, I2 = 76%], diabetic nephropathy [OR 2.13 (95% CI, 1.49–3.04), p < 0.0001, I2 = 76%], dyspnea [OR 4.53, (95% CI, 2.22–9.22), p < 0.0001, I2 = 76%], acute kidney injury (AKI) [OR 4.53 (95% CI, 1.10–5.21), p = 0.03, I2 = 58%], and some laboratory markers. Many patients had two or multiple risk factors in combination.ConclusionAge and several comorbidities were the most significant factors for COVID-19 outcomes for kidney transplant recipients.