Increased extracellular Ca 2+ concentrations ([Ca 2+ ] ex) trigger activation of the NLRP3 inflammasome in monocytes through calcium-sensing receptor (CaSR). To prevent extraosseous calcification in vivo, the serum protein fetuin-A stabilizes calcium and phosphate into 70-100 nm-sized colloidal calciprotein particles (CPPs). Here we show that monocytes engulf CPPs via macropinocytosis, and this process is strictly dependent on CaSR signaling triggered by increases in [Ca 2+ ] ex. Enhanced macropinocytosis of CPPs results in increased lysosomal activity, NLRP3 inflammasome activation, and IL-1β release. Monocytes in the context of rheumatoid arthritis (RA) exhibit increased CPP uptake and IL-1β release in response to CaSR signaling. CaSR expression in these monocytes and local [Ca 2+ ] in afflicted joints are increased, probably contributing to this enhanced response. We propose that CaSR-mediated NLRP3 inflammasome activation contributes to inflammatory arthritis and systemic inflammation not only in RA, but possibly also in other inflammatory conditions. Inhibition of CaSRmediated CPP uptake might be a therapeutic approach to treating RA.

Patients with rheumatoid arthritis (RA) are at an increased risk of acquiring infections due to two reasons: the disease itself and the immunosuppressive therapy. Vaccinations against preventable diseases are therefore of utmost importance for these group of patients. To estimate vaccination frequencies among patients with rheumatoid arthritis, we studied patients in a survey and calculated vaccination rates based on their vaccination documents. Patients have been recruited from our outpatient clinic during one of their routine visits. For the statistical analysis, they have been divided by age (≥60 vs <60 years) and medication (DMARD, Biologics, TNF inhibitors) for further subgroup analysis. Among the studied patients (n = 331), we found rather low vaccination rates, in particular for the strongly recommended vaccines against Pneumococcus and Influenza (33 and 53%, respectively). Furthermore, protection rates for important basic vaccinations, e.g. against Pertussis, were found to be very low with 12% only. Beside these findings, we saw age-dependent differences for a variety of vaccines: while Pneumococcus and Influenza vaccines were more often given to patients ≥60 years, MMR, Pertussis, Diphtheria and Hepatitis were significantly more often applied to younger patients. Vaccination rates have to be improved among RA patients, in particular for vaccines protecting from respiratory tract infections such as Pneumococcus.

Objectives Successful vaccination is key to overcoming the COVID-19 pandemic. Immunosuppressive medication is known to potentially compromise vaccination responses, and expansion of our knowledge on vaccination efficacy in patients with autoimmune inflammatory rheumatic diseases (AIIRD) is therefore of utmost importance. Methods We conducted a single-centre observational study and evaluated the efficacy of approved COVID-19 vaccines in 303 adult AIIRD patients. Serum levels of IgG antibodies against the S1 subunit of SARS-CoV-2 spike proteins (anti-S IgG) were measured at least two weeks after vaccination. In a subgroup of patients without humoral response, T cell responses were determined using an interferon-γ gamma release assay. Results Overall seropositivity rate was 78.5% and was significantly lower in patients under immunosuppressive therapy (75.7 vs. 93.2%, p = 0.009). No difference regarding the vaccination type was observed. Glucocorticoids, mycophenolate-mofetil, TNF inhibitors, tocilizumab, abatacept and rituximab were all associated with non-response after proper vaccination. The risk was highest under RTX therapy (OR 0.004, 95%CI0.001-0.023, p &lt; 0.0001). A strong negative correlation was observed between time since vaccination with an mRNA vaccine and anti-S antibody levels (r=-0.6149, p &lt; 0.0001). In patients without humoral response, a T cell response was found in 50%. Conclusions COVID-19 vaccination in patients with AIIRD is effective using any approved vaccine. Humoral response might be impaired depending on the individual immunosuppressive medication. The risk of non-response is highest under rituximab therapy. Anti-S IgG antibody levels wane over time after mRNA vaccination. Importantly, 50% of humoral non-responders showed a T cellular response, suggesting T cell-mediated protection to a certain extent.

Vaccination rates have to be improved among SLE patients, in particular for vaccines protecting from respiratory tract infections such as pneumococcus and influenza.

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