Urea, the toxic end-product of protein catabolism, is elevated in end-stage renal disease (ESRD), although it is unclear whether or how it contributes to disease. Urea can promote the carbamylation of proteins on multiple lysine side chains, including human albumin, which has a predominant carbamylation site on lysine 549. The proportion of serum albumin carbamylated on Lys-549 (%C-Alb) correlated with time-averaged blood urea concentrations and was twice as high in ESRD patients than in non-uremic subjects (0.90% vs. 0.42%, P<0.0001). Baseline %C-Alb was higher in ESRD subjects who died within 1-year than in those who survived longer than 1 year (1.01% vs. 0.77%, P<0.001) and was associated with an increased risk of death within 1 year (HR of 3.76, 95% CI: 2.20–6.43, P<0.0001). These findings were validated in an independent cohort of diabetic ESRD subjects (HR 3.73, 95% CI: 2.00–6.96, P<0.001). Decreased concentrations of serum amino acids correlated with higher %C-Alb in ESRD patients, and mice with diet-induced amino acid deficiencies exhibited greater susceptibility to albumin carbamylation than did chow-fed mice. In vitro studies showed that amino acids such as cysteine, histidine, arginine, lysine, as well as other nucleophiles such as taurine, inhibited cyanate-induced C-Alb formation at physiologic pH and temperature. Together, these results suggest that chronically elevated urea promotes carbamylation of proteins in ESRD, and that serum amino acid concentrations may modulate this protein modification. In summary, we have identified serum %C-Alb as a risk factor for mortality in patients with ESRD and propose that this risk factor may be modifiable with supplemental amino acid therapy.

Objectives The immunogenicity and safety of the Pfizer-BioNTech BNT162b2 mRNA vaccine in people living with HIV-1 (PLWH) are unknown. We thus aimed to assess the immunogenicity and safety of this vaccine in PLWH. Methods In this prospective open study, we enrolled 143 PLWH, aged ≥18 years, who attended our clinic and 261 immunocompetent health care workers (HCWs). SARS-CoV-2 receptor binding domain (RBD) IgG and neutralizing antibodies were measured. Adverse events, viral load and CD4 cell counts were monitored. Results At a median of 18 days (IQR 14-21) after the second dose, anti-RBD IgG was positive in 139/141 (98%) PLWH. Among HCWs, 258/261 (98.9%) developed anti-RBD IgG at a median of 26 (IQR 24-27) days after the second dose. Following the second dose, immune sera neutralized SARS-CoV-2 pseudo-virus in 97% and 98% of PLWH and HCW, respectively. Adverse events were reported in 60% of PLWH, mainly pain at the injection site, fatigue, and headache. AIDS-related adverse events were not reported. HIV viral load increased in 3/143 (2%) patients from < 40 copies/mL to ≤ 100 copies/mL. CD4+ T cell count decreased from a geometric mean of 700 (95% CI 648–757) cells per μL to 633.8 (95% CI 588–683) cells per μL (P<0.01). Conclusions BNT162b2 mRNA vaccine appears immunogenic and safe in PLWH who are on ART with unsuppressed CD4 count and suppressed viral load.