Multi-omics identify LRRC15 as a COVID-19 severity predictor and persistent pro-thrombotic signals in convalescence

Patients with end-stage kidney disease (ESKD) are at high risk of severe COVID-19. Here, we performed longitudinal blood sampling of ESKD haemodialysis patients with COVID-19, collecting samples pre-infection, serially during infection, and after clinical recovery. Using plasma proteomics, and RNA-sequencing and flow cytometry of immune cells, we identified transcriptomic and proteomic signatures of COVID-19 severity, and found distinct temporal molecular profiles in patients with severe disease. Supervised learning revealed that the plasma proteome was a superior indicator of clinical severity than the PBMC transcriptome. We showed that both the levels and trajectory of plasma LRRC15, a proposed co-receptor for SARS-CoV-2, are the strongest predictors of clinical outcome. Strikingly, we observed that two months after the acute infection, patients still display dysregulated gene expression related to vascular, platelet and coagulation pathways, including PF4 (platelet factor 4), which may explain the prolonged thrombotic risk following COVID-19.

Immune responses following 3rd and 4th doses of heterologous and homologous COVID-19 vaccines in kidney transplant recipients

BackgroundSolid organ transplant recipients have attenuated immune responses to SARS-CoV-2 vaccines. In this study, we report on immune responses to 3rd- (V3) and 4th- (V4) doses of heterologous and homologous vaccines in a kidney transplant population. Methods724 kidney transplant recipients were prospectively screened for serological responses following 3 primary doses of a SARS-CoV2 vaccine. 322 patients were sampled post-V4 for anti-spike (anti-S), with 69 undergoing assessment of SARS-CoV-2 T-cell responses. All vaccine doses were received post-transplant, only mRNA vaccines were used for V3 and V4 dosing. All participants had serological testing performed post-V2 and at least once prior to their 1st dose of vaccine. Results586/724 (80.9%) patients were infection-naive post-V3; 141/2586 (24.1%) remained seronegative at 31 (21-51) days post-V3. Timing of vaccination in relation to transplantation, OR: 0.28 (0.15-0.54), p=0.0001; immunosuppression burden, OR: 0.22 (0.13-0.37), p<0.0001, and a diagnosis of diabetes, OR: 0.49 (0.32-0.75), p=0.001, remained independent risk factors for non-seroconversion. Seropositive patients post-V3 had greater anti-S if primed with BNT162b2 compared with ChAdOx1, p=0.001. Post-V4, 45/239 (18.8%) infection-naive patients remained seronegative. De novo seroconversion post-V4 occurred in 15/60 (25.0%) patients who were seronegative post-V3. There was no difference in anti-S post-V4 by vaccine combination, p=0.50. Anti-S post-V4 were sequentially greater in those seroconverting post V2- compared with V3-, and V3- compared with V4-, at 1561 (567-5211), 379 (101-851) and 19 (9.7-48) BAU/ml respectively. T-cell responses were poor, with only 11/54 (20.4%) infection-naive patients having detectable T-cell responses post-V4, with no difference seen by vaccine type. ConclusionA significant proportion of transplant recipients remain seronegative following 3- and 4- doses of SARS-CoV-2 vaccines, with poor T-cell responses, and are likely to have inadequate protection against infection.

Comparative immunogenicity of heterologous versus homologous 3rd SARS-CoV-2 vaccine doses in kidney transplant recipients

BackgroundSolid organ transplant recipients have attenuated immune responses to SARS-CoV-2 vaccines. Emerging evidence suggests at least equivalent immunogenicity of heterologous compared with homologous vaccine regimens in the general population. In this study, we report on immune responses to 3rd dose BNT162b2 vaccines in transplant recipients either primed with ChAdOx1 or BNT162b2. Methods700 kidney transplant recipients were prospectively screened for serological responses (median time of 33 (21-52) days) following 3 primary doses of a SARS-CoV2 vaccine. All vaccine doses were received post-transplant, and all 3rd doses were BNT162b2. All participants had serological testing performed post-2nd vaccination at a median time of 34 (IQR 26-46) days following the 2nd inoculation, and at least once prior to their 1st dose of vaccine. Results366/700 (52.3%) participants were primed with BNT162b2, whilst 334/700 (47.7) had received ChAdOx1. Overall, 139/700 (19.9%) participants had evidence of prior infection. Of 561 infection naive participants, 263 (46.9%) had no detectable anti-S following 2-doses of vaccine (V2). 134 (23.9%) participants remained seronegative post 3rd vaccine (V3); 54/291 (18.6%) and 79/270 (29.3%) of participants receiving BNT162b2 and ChAdOx1 respectively, p=0.0029. Median anti-S concentrations were significantly higher post-V3 in patients who had received BNT162b2 compared with ChAdOx1, at 612 (27-234) versus 122 (7.1-1111) BAU/ml respectively, p<0.0001. Cellular responses were investigated in 30 infection naive participants at a median time of 35 (24-46) days post-V3. Eighteen of 30 (60.0%) participants had undetectable T-cell responses. There were neither qualitative or quantitative differences in T-cell responses between those patients who received BNT162b2 or ChAdOx1 as their first 2-doses, with 10/16 (62.5%) and 8/14 (57.1%) respectively having undetectable T-cell responses, p=0.77. ConclusionA significant proportion of transplant recipients remain seronegative following 3 doses of SARS-CoV-2 vaccines, with anti-S concentrations lower in patients receiving heterologous versus homologous vaccinations.

Comparison of humoral and cellular responses in kidney transplant recipients receiving BNT162b2 and ChAdOx1 SARS-CoV-2 vaccines

BackgroundAttenuated immune responses to mRNA SARS-CoV-2 vaccines have been reported in solid organ transplant recipients. Most studies have assessed serological responses alone, and there is limited immunological data on vector-based vaccines in this population. This study compares the immunogenicity of BNT162b2 with ChAdOx1 in a cohort of kidney transplant patients, assessing both serological and cellular responses. Methods920 patients were screened for spike protein antibodies (anti-S) following 2 doses of either BNT162b2 (n=490) or ChAdOx1 (n=430). 106 patients underwent assessment with T-cell ELISpot assays. 65 health care workers were used as a control group. ResultsAnti-S was detected in 569 (61.8%) patients. Seroconversion rates in infection-naive patients who received BNT162b2 were higher compared with ChAdOx1, at 269/410 (65.6%) and 156/358 (43.6%) respectively, p<0.0001. Anti-S concentrations were higher following BNT162b, 58(7.1-722) BAU/ml, compared with ChAdOx1, 7.1(7.1-39) BAU/ml, p<0.0001. Calcineurin inhibitor monotherapy, vaccination occurring >1st year post-transplant and receiving BNT162b2 was associated with seroconversion. Only 28/106 (26.4%) of patients had detectable T-cell responses. There was no difference in detection between infection-naive patients who received BNT162b2, 7/40 (17.5%), versus ChAdOx1, 2/39 (5.1%), p=0.15. There was also no difference in patients with prior infection who received BNT162b2, 8/11 (72.7%), compared with ChAdOx1, 11/16 (68.8%), p=0.83. ConclusionsEnhanced humoral responses were seen with BNT162b2 compared with ChAdOx1 in kidney transplant patients. T-cell responses to both vaccines were markedly attenuated. Clinical efficacy data is still required but immunogenicity data suggests weakened responses to both vaccines in transplant patients, with ChAdOx1 less immunogenic compared with BNT162b2.

Longitudinal proteomic profiling of high-risk patients with COVID-19 reveals markers of severity and predictors of fatal disease

End-stage kidney disease (ESKD) patients are at high risk of severe COVID-19. We measured 436 circulating proteins in serial blood samples from hospitalised and non-hospitalised ESKD patients with COVID-19 (n=256 samples from 55 patients). Comparison to 51 non-infected patients revealed 221 differentially expressed proteins, with consistent results in a separate subcohort of 46 COVID-19 patients. 203 proteins were associated with clinical severity, including IL6, markers of monocyte recruitment (e.g. CCL2, CCL7), neutrophil activation (e.g. proteinase-3) and epithelial injury (e.g. KRT19). Machine learning identified predictors of severity including IL18BP, CTSD, GDF15, and KRT19. Survival analysis with joint models revealed 69 predictors of death. Longitudinal modelling with linear mixed models uncovered 32 proteins displaying different temporal profiles in severe versus non-severe disease, including integrins and adhesion molecules. These data implicate epithelial damage, innate immune activation, and leucocyte-endothelial interactions in the pathology of severe COVID-19 and provide a resource for identifying drug targets.