Imbalance of Peripheral Temperature, Sympathovagal, and Cytokine Profile in Long COVID

Abstract

A persistent state of inflammation has been reported during the COVID-19 pandemic. This study aimed to assess short-term heart rate variability (HRV), peripheral body temperature, and serum cytokine levels in patients with long COVID. We evaluated 202 patients with long COVID symptoms categorized them according to the duration of their COVID symptoms (≤120 days, n = 81; >120 days, n = 121), in addition to 95 healthy individuals selected as controls. All HRV variables differed significantly between the control group and patients with long COVID in the ≤120 days group (p < 0.05), and participants in the long COVID ≤120 days group had higher temperatures than those in the long COVID >120 days group in all regions analysed (p < 0.05). Cytokine analysis showed higher levels of interleukin 17 (IL-17) and interleukin 2 (IL-2), and lower levels of interleukin 4 (IL-4) (p < 0.05). Our results suggest a reduction in parasympathetic activation during long COVID and an increase in body temperature due to possible endothelial damage caused by the maintenance of elevated levels of inflammatory mediators. Furthermore, high serum levels of IL-17 and IL-2 and low levels of IL-4 appear to constitute a long-term profile of COVID-19 cytokines, and these markers are potential targets for long COVID-treatment and prevention strategies.

Analysis of heart rate variability in post-COVID-19 population

“…Previous studies have shown the signi cance of HRV parameter reduction 39,40 and increased in ammatory parameters [41][42][43] in long-COVID individuals compared to the healthy population. Consistent with the results of this study regarding changes in the lower SDNN, TP, and VLF in the study subjects, the difference in results was not signi cant.…”

Risk Factors for Long COVID in Older Adults

“…Another study among 318 recovered COVID-19 patients discovered that 67.8% of them reported long COVID symptoms, and those reporting long COVID symptoms had elevated levels of plasma IL-1β, IL-6, and TNF [95]. Similarly, a study in Brazil found that long COVID patients had elevated levels of IL-17 and IL-2, reduced levels of IL-4, and decreased parasympathetic nervous system activation, along with increased body temperature [96]. The authors suggested that the variations in serum IL-17, IL-4, and IL-2 seemed to represent characteristic cytokine features of long COVID, which could potentially serve as therapeutic and preventive targets.…”