The effect of immunosuppressive therapies on the endothelial host response in critically ill COVID-19 patients

While several effective therapies for critically ill patients with COVID-19 have been identified in large, well-conducted trials, the mechanisms underlying these therapies have not been investigated in depth. Our aim is to investigate the association between various immunosuppressive therapies (corticosteroids, tocilizumab and anakinra) and the change in endothelial host response over time in critically ill COVID-19 patients. We conducted a pre-specified multicenter post-hoc analysis in a Dutch cohort of COVID-19 patients admitted to the ICU between March 2020 and September 2021 due to hypoxemic respiratory failure. A panel of 18 immune response biomarkers in the complement, coagulation and endothelial function domains were measured using ELISA or Luminex. Biomarkers were measured on day 0-1, day 2-4 and day 6-8 after start of COVID-19 treatment. Patients were categorized into four treatment groups: no immunomodulatory treatment, corticosteroids, anakinra plus corticosteroids, or tocilizumab plus corticosteroids. The association between treatment group and the change in concentrations of biomarkers was estimated with linear mixed-effects models, using no immunomodulatory treatment as reference group. 109 patients with a median age of 62 years [IQR 54-70] of whom 72% (n = 78) was male, were included in this analysis. Both anakinra plus corticosteroids (n = 22) and tocilizumab plus corticosteroids (n = 38) were associated with an increase in angiopoietin-1 compared to no immune modulator (n = 23) (beta of 0.033 [0.002-0.064] and 0.041 [0.013-0.070] per day, respectively). These treatments, as well as corticosteroids alone (n = 26), were further associated with a decrease in the ratio of angiopoietin-2/angiopoietin-1 (beta of 0.071 [0.034-0.107], 0.060 [0.030-0.091] and 0.043 [0.001-0.085] per day, respectively). Anakinra plus corticosteroids and tocilizumab plus corticosteroids were associated with a decrease in concentrations of complement complex 5b-9 compared to no immunomodulatory treatment (0.038 [0.006-0.071] and 0.023 [0.000-0.047], respectively). Currently established treatments for critically ill COVID-19 patients are associated with a change in biomarkers of the angiopoietin and complement pathways, possibly indicating a role for stability of the endothelium. These results increase the understanding of the mechanisms of interventions and are possibly useful for stratification of patients with other inflammatory conditions which may potentially benefit from these treatments.

25-Hydroxyvitamin D concentrations do not affect the humoral or cellular immune response following SARS-CoV-2 mRNA vaccinations

BACKGROUND

To improve effectiveness of vaccination against SARS-CoV-2, it is important to identify factors that influence the immune response induced by vaccination. Evidence for the role of vitamin D in immune response against SARS-CoV-2 is contradictory. It is therefore of interest whether 25-hydroxyvitamin D (25[OH]D) concentrations affect the humoral and/or cellular response following SARS-CoV-2 vaccination.

METHODS

In this prospective cohort study, blood samples were collected from 98 SARS-CoV-2 naive health care workers (HCW) receiving the first two doses of either BNT162b2 or mRNA-1273 in 2021. Wild-type spike (S) protein binding and neutralizing antibodies were determined approximately three weeks after the first dose and four to five weeks after the second dose. Antigen specific T-cells and functionality (proliferative response and interferon gamma [IFN-γ] release) were determined in 18 participants four weeks after the second dose of BNT162b2. We studied the association between 25(OH)D concentrations, which were determined prior to vaccination, and humoral and cellular immune responses following vaccination.

RESULTS

We found no association between 25(OH)D concentrations (median 55.9 nmol/L [IQR 40.5-69.8]) and binding or neutralizing antibody titers after complete vaccination (fold change of antibody titers per 10 nmol/L 25(OH)D increase: 0.98 [95% CI 0.93-1.04] and 1.03 [95% CI: 0.96-1.11], respectively), adjusted for age, sex and type of mRNA vaccine. Subsequently, continuous 25(OH)D concentrations were divided into commonly used clinical categories (<25 nmol/L [n = 6, 6%], 25-49 nmol/L [n = 33, 34%], 50-75 nmol/L [n = 37, 38%] and ≥75 nmol/L [n = 22, 22%]), but no association with the humoral immune response following vaccination was found. Also, 25(OH)D concentrations were not associated with the SARS-CoV-2 specific T cell response.

CONCLUSION

No association was found between 25(OH)D concentrations and the humoral or cellular immune response following mRNA vaccination against SARS-CoV-2. Based on our findings there is no rationale to advise vitamin D optimization preceding SARS-CoV-2 vaccination in HCW with moderate vitamin D status.

Non-conventional immunomodulation in the management of sepsis

Sepsis remains a critical global health issue, demanding novel therapeutic strategies. Traditional immunomodulation treatments such as corticosteroids, specific modifiers of cytokines, complement or coagulation, growth factors or immunoglobulins, have so far fallen short. Meanwhile the number of studies investigating non-conventional immunomodulatory strategies is expanding. This review provides an overview of adjunctive treatments with herbal-based medicine, immunonutrition, vasopressors, sedative treatments and targeted temperature management, used to modulate the immune response in patients with sepsis. Herbal-based medicine, notably within traditional Chinese medicine, shows promise. Xuebijing injection and Shenfu injection exhibit anti-inflammatory and immune-modulatory effects, and the potential to lower 28-day mortality in sepsis. Selenium supplementation has been reported to reduce the occurrence of ventilator-associated pneumonia among sepsis patients, but study results are conflicting. Likewise, the immune-suppressive effects of omega-3 fatty acids have been associated with improved clinical outcomes in sepsis. The immunomodulating properties of supportive treatments also gain interest. Vasopressors like norepinephrine exhibit dual dosage-dependent roles, potentially promoting both pro- and anti-inflammatory effects. Dexmedetomidine, a sedative, demonstrates anti-inflammatory properties, reducing sepsis mortality rates in some studies. Temperature management, particularly maintaining higher body temperature, has also been associated with improved outcomes in small scale human trials. In conclusion, emerging non-conventional immunomodulatory approaches, including herbal medicine, immunonutrition, and targeted supportive therapies, hold potential for sepsis treatment, but their possible implementation into everyday clinical practice necessitates further research and stringent clinical validation in different settings.