SARS-CoV-2-specific immune responses and clinical outcomes after COVID-19 vaccination in patients with immune-suppressive disease

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune responses and infection outcomes were evaluated in 2,686 patients with varying immune-suppressive disease states after administration of two Coronavirus Disease 2019 (COVID-19) vaccines. Overall, 255 of 2,204 (12%) patients failed to develop anti-spike antibodies, with an additional 600 of 2,204 (27%) patients generating low levels (<380 AU ml−1). Vaccine failure rates were highest in ANCA-associated vasculitis on rituximab (21/29, 72%), hemodialysis on immunosuppressive therapy (6/30, 20%) and solid organ transplant recipients (20/81, 25% and 141/458, 31%). SARS-CoV-2-specific T cell responses were detected in 513 of 580 (88%) patients, with lower T cell magnitude or proportion in hemodialysis, allogeneic hematopoietic stem cell transplantation and liver transplant recipients (versus healthy controls). Humoral responses against Omicron (BA.1) were reduced, although cross-reactive T cell responses were sustained in all participants for whom these data were available. BNT162b2 was associated with higher antibody but lower cellular responses compared to ChAdOx1 nCoV-19 vaccination. We report 474 SARS-CoV-2 infection episodes, including 48 individuals with hospitalization or death from COVID-19. Decreased magnitude of both the serological and the T cell response was associated with severe COVID-19. Overall, we identified clinical phenotypes that may benefit from targeted COVID-19 therapeutic strategies

Patch clamp studies of human sperm under physiological ionic conditions reveal three functionally and pharmacologically distinct cation channels

Whilst fertilizing capacity depends upon a K+ conductance (GK) that allows the spermatozoon membrane potential (Vm) to be held at a negative value, the characteristics of this conductance in human sperm are virtually unknown. We therefore studied the biophysical / pharmacological properties of the K+ conductance in spermatozoa from normal donors held under voltage / current clamp in the whole cell recording configuration. Our standard recording conditions were designed to maintain quasi-physiological, Na+, K+ and Cl+ gradients. Experiments that explored the effects of ionic substitution / ion channel blockers upon membrane current / potential showed that resting Vm was dependent upon a hyperpolarizing K+ current that flowed via channels that displayed only weak voltage dependence and limited (∼7 fold) K+ versus Na+ selectivity. This conductance was blocked by quinidine (0.3 mM), bupivacaine (3 mM) and clofilium (50 µM), NNC55-0396 (2 µM) and mibefradil (30 µM), but not by 4-aminopyridine (2 mM, 4-AP). Progesterone had no effect upon the hyperpolarizing K+ current. Repolarization after a test depolarization consistently evoked a transient inward “tail current” (ITail) that flowed via a second population of ion channels with poor (∼3 fold) K+ versus Na+ selectivity. The activity of these channels was increased by quinidine, 4-AP and progesterone. Vm in human sperm is therefore dependent upon a hyperpolarizing K+ current that flows via channels that most closely resemble those encoded by Slo3. Although 0.5 µM progesterone had no effect upon these channels, this hormone did activate the pharmacologically-distinct channels that mediate ITail. In conclusion, this study reveals three functionally and pharmacologically distinct cation channels, Ik, ITail, ICatSper

Patterns of [Ca2+](i) mobilization and cell response in human spermatozoa exposed to progesterone

AbstractHuman spermatozoa stimulated with progesterone (a product of the cumulus and thus encountered by sperm prior to fertilization in vivo) apparently mobilize Ca2+ and respond very differently according to the way in which the steroid is presented. A progesterone concentration ramp (0–3 μM) induces [Ca2+]i oscillations (repetitive store mobilization) which modify flagellar beating, whereas bolus application of micromolar progesterone causes a single large transient (causing acrosome reaction) which is apparently dependent upon Ca2+ influx. We have investigated Ca2+-mobilization and functional responses in human sperm exposed to 3 μM progesterone. The [Ca2+]i response to progesterone was abolished by 4 min incubation in 0 Ca2+ medium (2 mM EGTA) but in nominally Ca2+-free medium (no added Ca2+; 0 EGTA) a smaller, slow response occurred. Single cell imaging showed a similar effect of nominally Ca2+-free medium and ≈5% of cells generated a small transient even in the presence of EGTA. When cells were exposed to EGTA-containing saline (5 min) and then returned to nominally Ca2+-free medium before stimulation, the [Ca2+]i transient was greatly delayed (≈50 s) and rise time was doubled in comparison to cells not subjected to EGTA pre-treatment. We conclude that mobilization of stored Ca2+ contributes a ‘slow’ component to the progesterone-induced [Ca2+]i transient and that incubation in EGTA-buffered saline is able rapidly to deplete this store. Analysis of flagellar activity induced by 3 μM progesterone showed an effect (modified beating) associated with the [Ca2+]i transient, in >80% of cells bathed in nominally Ca2+-free medium. This was reduced greatly in cells subjected to 5 min EGTA pre-treatment. The store-mediated transient showed a pharmacological sensitivity similar to that of progesterone-induced [Ca2+]i oscillations (consistent with filling of the store by an SPCA) suggesting that the transient induced by micromolar progesterone is a ‘single shot’ activation of the same store that generates Ca2+ oscillations