A fatal course of COVID-19 during the Omicron surge: can you estimate your patients' SARS-CoV-2 immune status?

We present a case of an ultimately fatal course of COVID-19 (coronavirus disease-19) in an 81-year-old female patient during the Omicron surge. The patient did not represent the typical patient at risk for severe COVID-19 with significant causes of immunodeficiency. However, she had been skeptical about the vaccination for severe acute respiratory syndrome virus-2 (SARS-CoV-2) and had refused it. Moreover, there had been no previous COVID-19 episodes. Our case report illustrates that with regard to SARS-CoV-2, immunologically naive patients are still at risk for severe and/or even fatal courses of COVID-19. We call to implement both, recommendations for SARS-CoV-2 vaccinations as well as for antiviral treatment.

Spontaneous Ca2+ transients in mouse microglia.

Microglia are the resident immune cells in the central nervous system and many of their physiological functions are known to be linked to intracellular calcium (Ca2+) signaling. Here we show that isolated and purified mouse microglia-either freshly or cultured-display spontaneous and transient Ca2+ elevations lasting for around ten to twenty seconds and occurring at frequencies of around five to ten events per hour and cell. The events were absent after depletion of internal Ca2+ stores, by phospholipase C (PLC) inhibition or blockade of inositol-1,4,5-trisphosphate receptors (IP3Rs), but not by removal of extracellular Ca2+, indicating that Ca2+ is released from endoplasmic reticulum intracellular stores. We furthermore provide evidence that autocrine ATP release and subsequent activation of purinergic P2Y receptors is not the trigger for these events. Spontaneous Ca2+ transients did also occur after stimulation with Lipopolysaccharide (LPS) and in glioma-associated microglia, but their kinetics differed from control conditions. We hypothesize that spontaneous Ca2+ transients reflect aspects of cellular homeostasis that are linked to regular and patho-physiological functions of microglia.