Humoral and cellular response after BNT162b2 vaccine booster in hemodialysis patients and kidney transplant recipients.

BACKGROUND: Vulnerable populations, such as hemodialysis (HD) patients and kidney transplant (RTx) recipients, have priority for anti-COVID-19 vaccination, because of their impaired immune status. Here, we investigated the immune response after vaccination with BNT162b2 (two doses plus booster) in HD and RTx patients. METHODS: A prospective, observational study was started in two homogeneous groups of 55 HD and 51 RTx patients previously matched from a cohort of 336 patients. Anti-RBD IgG levels, assayed after the second dose with BNT162b2 mRNA, were used to stratify subjects into quintiles. After the second dose and after booster, anti-RBD and IGRA test were evaluated in RTx and HD, belonging to the first and fifth quintiles. RESULTS: After the second dose of vaccine, the median circulating levels of anti-RBD IgG were significantly higher in HD (1456 AU/mL) compared to RTx (27.30 AU/mL). IGRA test showed significantly higher values in the HD (382 mIU/mL) compared with the RTx (73 mIU/mL). After the booster, humoral response increased significantly in both HD (p = 0.0002) and RTx groups (p = 0.009), whereas the T-cellular immunity remained essentially stable in most patients. In RTx patients with a low humoral response after the second dose, the third dose did not significantly strengthen either humoral or cellular immunity. CONCLUSIONS: For HD and RTx, there is great variability in the humoral response to anti-COVID-19 vaccination, with a stronger response in the HD group. The booster dose was ineffective at reinforcing the humoral and cellular immune response in most RTx patients hyporesponsive to the second dose.

Long-term intravenous epoetin-alpha / darbepoetin-alpha ratio in iron-replete hemodialysis patients.

BACKGROUND: Equivalence of intravenous (i.v.) and subcutaneous (s.c.) dosage requirements is a notable characteristic of darbepoetin-alpha (DPO), as opposed to other epoetins (EPOs). Currently in Europe, the EPOs/DPO conversion factor (200 IU EPOs = 1 microg DPO) does not take into account the route of drugs administration. To better define this ratio we have conducted a prospective, long-term trial in a group of hemodialysis patients. SUBJECTS AND METHODS: At the start, we evaluated 40 iron-replete hemodialysis patients, but the final study was performed in the remaining 25 patients. During the first 6 months, patients were on i.v. epoetin-alpha (EPOalpha) maintenance therapy (phase 1: T-6 to T0). After conversion to i.v. DPO (initial 200:1 ratio) the observation was prolonged for a period of 12 months (phase 2: T0 to T12). DPO was administered at extended dose intervals and the EPOalpha/DPO rate was adjusted every month to maintain hemoglobin (Hgb) stability. Iron status and factors inhibiting erythropoiesis were continually checked to exclude unstable patients. RESULTS: Phase 1: EPOalpha weekly mean dose showed no significant variation. Phase 2: EPOalpha/DPO conversion factor progressively rose from 200 to 256.7 +/- 86.9 IU/microg at T7 (p<0.005) and 336.8 +/- 104.3 IU/microg at T12 (p<0.0005). DPO weekly mean dosage decreased from 40.0 +/- 12.0 microg/week at T0 to 31.6 +/- 3.7 microg/week at T7 (p<0.005) and 24.6 +/- 7.0 microg/week at T12 (p<0.0005). Mean weekly/patient acquisition cost of EPOalpha was euro 70.6 +/- 21.3 (T-6 to T0); after switching, the cost of DPO was euro 72.4 +/- 22.7 (T0) and fell to euro 53.1 +/- 11.2 during T6 to T12. CONCLUSIONS: The progressive increase of EPOalpha/DPO ratio demonstrated that i.v. DPO requires lower doses compared with i.v. EPOalpha. When drugs are administered i.v., the starting EPOalpha/DPO conversion factor should be increased over the 200:1 ratio, similar to recommendations outlined in the United States and Japan. DPO dose reduction translated to notable cost-savings.

Testosterone promotes apoptotic damage in human renal tubular cells.

BACKGROUND: Apoptosis is a mode of cell death that participates in the kidney physiologic remodeling processes and is thought to contribute to cell loss and kidney structural damage in chronic renal diseases. Gender is one factor which contributes to accelerated nephron loss, with progression more rapid in men than in women in diabetic and nondiabetic chronic renal diseases. Mechanisms by which androgens may cause higher rate of progression of chronic renal diseases in men are poorly explored. METHODS: In this study, to investigate the role of androgens on apoptotic damage and its associated mechanisms, we examined the effects of testosterone (T) (0.1 nmol/L to 1 micromol/L) on apoptosis, and apoptosis-related proteins in a proximal human tubule cell line (HK-2 cells). Additional experiments were performed in primary cultures of proximal tubular epithelial cells (PTECs). Cells were grown to subconfluence in normal growth medium, and apoptotic damage was induced by serum deprivation for 24 to 48 hours. Cycloheximide, flutamide (a T-receptor antagonist), 17-beta estradiol, or caspase inhibitors were added to cultures that were successively processed for terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end-labeling (TUNEL) analysis, annexin V/propidium iodide staining, immunofluorescence, or immunoblots to identify effects and apoptotic pathways that could be modulating cell survival. RESULTS: Both morphologic analysis by annexin V/propidium iodide staining and TUNEL showed that physiologic T levels (1 to 10 nmol/L) induced a significant increase in apoptosis both in HK-2 cells and PTECs. In both types of cell lines pretreatment with the androgen receptor antagonist flutamide prevented the T-induced apoptosis. T-induced apoptosis was enhanced by treatment with cycloheximide and prevented by 17beta-estradiol. Fas, Fas ligand (FasL), and Fas-associating death domain containing protein (FADD) were clearly up-regulated within 48 hours of T treatment in HK-2 cells. Also, T significantly increased the expression of Bax protein (P < 0.01 vs. control) (an effect which was blocked by flutamide), and decreased the expression of Bcl-2. Western blot analysis showed that caspase-3 was activated. Moreover, cleavage into an 85-kD poly(ADP-ribose) polymerase-1 (PARP-1) terminal breakdown product was detectable. The changes in cellular morphology induced by T at 48 hours were no longer observed after the addition of caspase-8, caspase-9, and caspase-3 inhibitors to the culture medium. CONCLUSION: These results indicate that T increases the permissiveness of proximal tubule kidney cells to apoptotic effects by triggering an apoptotic pathway involving caspase activation, Fas up-regulation, and FasL expression, thus potentially interacting with mechanisms of cell loss which have been already shown to be activated in chronic renal diseases. This is consistent with a role for T in promoting renal injury in men.

Oxidative stress mediates apoptotic changes induced by hyperglycemia in human tubular kidney cells.

Reactive oxygen species (ROS) are important mediators for several biologic responses, including apoptosis. The present study evaluated the time course of changes in intracellular ROS production and apoptosis-related proteins, as well as apoptotic changes in human tubular proximal cells (HK-2 cells) exposed to hyperglycemia. Apoptosis (annexin V binding), ROS formation (fluorescence probe dichlorofluorescin diacetate and FACScan flow cytometry), and X chromosome-linked protein (XIAP; Western blot) were studied in HK-2 cells grown in a medium containing normal (NG) or high glucose (HG) concentrations (5.5 or 30 mM, respectively) for 18 to 48 h. HG promoted an increase (65% at 18 h and 73% at 24 h; P < 0.05 versus NG) in intracellular ROS generation. At 18 h, the NF-kB binding activity (evaluated by electrophoretic mobility-shift assay) was suppressed by HG. At the same time, the expression of NF-kB-induced antiapoptotic XIAP was reduced in HG-treated cells. Apoptotic changes were observed at 48 h (34 +/- 7% in HG versus 10 +/- 3% in NG; P < 0.001). Changes in ROS production at 24 h predicted changes in the apoptotic index at 48 h (r = 0.96, P < 0.0001). These results suggest that hyperglycemia induces apoptotic changes in human tubular cells via an increase in oxidative stress and that a downregulation of antiapoptotic protein XIAP is a component of this response.