Relevance of complement immunity with brain fog in patients with long COVID

Interrelationships Between Plasma Levels of Brain Natriuretic Peptide and Prolonged Symptoms Due to Long COVID

Objectives: Evidence for the usefulness of biomarkers that aid in diagnosis, assessment of severity, and prediction of prognosis in patients with long COVID is limited. The aim of this study was to clarify the characteristics of brain natriuretic peptide (BNP) in long COVID. Methods: We conducted a retrospective observational study of patients who visited the COVID-19 aftercare outpatient clinic at Okayama University Hospital from February 2021 to April 2024. Results: A total of 428 patients were enrolled in this study, and the patients were divided into a group with normal BNP (n = 314, ≤18.4 pg/mL) and a group with increased BNP (n = 114, >18.4 pg/mL). The long COVID group with increased BNP had a higher proportion of females (44.3% vs. 73.7%, p < 0.01) and an older median age (38 vs. 51 years, p < 0.01). Fatigue and brain fog were commonly manifested in both groups, while dyspnea was a more frequent complaint in the group with increased BNP. Various symptoms including fatigue, palpitations, and taste and/or olfactory disorders were associated with elevated BNP (23 to 24 pg/mL). Memory impairment was also linked to higher BNP (OR: 2.36, p = 0.05). In long COVID patients, plasma BNP elevation appears to be more pronounced in females and is often related to cardiogenic factors, in which inflammatory responses are also involved. Conclusions: Plasma BNP measurement may be useful for evaluating the severity of long COVID, especially in female patients and those with respiratory symptoms and/or memory impairment.

Phase-dependent trends in the prevalence of myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) related to long COVID: A criteria-based retrospective study in Japan

BACKGROUND

The characteristics of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) related to COVID-19 have remained uncertain. To elucidate the clinical trend of ME/CFS induced by long COVID, we examined data for patients who visited our outpatient clinic established in a university hospital during the period from Feb 2021 to July 2023.

METHODS

Long COVID patients were classified into two groups, an ME/CFS group and a non-ME/CFS group, based on three diagnostic criteria.

RESULTS

The prevalence of ME/CFS in the long COVID patients was 8.4% (62 of 739 cases; female: 51.6%) and factors related to ME/CFS were severe illness, smoking and alcohol drinking habits, and fewer vaccinations. The frequency of ME/CFS decreased from 23.9% in the Preceding period to 13.7% in the Delta-dominant period and to 3.3% in the Omicron-dominant period. Fatigue and headache were commonly frequent complaints in the ME/CFS group, and the frequency of poor concentration in the ME/CFS group was higher in the Omicron period. Serum ferritin levels were significantly higher in female patients in the ME/CFS group infected in the Preceding period. In the ME/CFS group, the proportion of patients complaining of brain fog significantly increased from 22.2% in the Preceding period to 47.9% in the Delta period and to 81.3% in the Omicron period. The percentage of patients who had received vaccination was lower in the ME/CFS group than the non-ME/CFS group over the study period, whereas there were no differences in the vaccination rate between the groups in each period.

CONCLUSION

The proportion of long COVID patients who developed ME/CFS strictly diagnosed by three criteria was lower among patients infected in the Omicron phase than among patients infected in the other phases, while the proportion of patients with brain fog inversely increased. Attention should be paid to the variant-dependent trends of ME/CFS triggered by long COVID (300 words).

Type 2 Diabetes Mellitus Aggravates Complement Dysregulation and Affects Cortisol Response in Patients with Post-COVID-19

Purpose

COVID-19 viral infection results in dysregulation of the complement system and a decrease in cortisol and adrenocorticotropin hormone (ACTH) levels. This study aimed to explore the complement system, as well as cortisol and ACTH responses in patients with post-COVID-19 conditions (PCC) and type 2 diabetes mellitus (T2DM).

Patients and Methods

This study recruited 31 patients with PCC and T2DM (PCC-T2DM), 19 patients with PCC (PCC), 10 patients with T2DM (T2DM), and 10 healthy participants (control). Cortisol and ACTH in the PCC and PCC-T2DM groups were assessed using the insulin tolerance test. In the fasting state, serum samples were collected for proteomic analyses. Spearman correlation analysis was performed between proteins and cortisol, as well as between proteins and ACTH.

Results

Cortisol and ACTH levels were consistently decreased in the PCC and PCC-T2DM groups. Proteomic analyses revealed that most of the differentially abundant proteins (DAPs) in the PCC vs control and PCC-T2DM vs T2DM were involved in the coagulation and complement cascade, and the essential complement C3 was significantly upregulated in the PCC and PCC-T2DM groups when compared to their controls. Additionally, complement-related DAPs in the PCC vs control and PCC-T2DM vs T2DM were significantly correlated with cortisol and ACTH levels. In comparing PCC-T2DM samples with PCC samples, we found that upregulated DAPs were linked to the complement system and other immune system, and most DAPs were negatively correlated with cortisol and ACTH.

Conclusion

Our study revealed that T2DM exacerbated dysregulation of the complement system in patients with PCC, and significant correlations were present between complement protein levels and those of cortisol and ACTH. These results provide novel insights into the dysregulation of complement and endocrine hormones in patients with PCC and T2DM.

Occult endocrine disorders newly diagnosed in patients with post-COVID-19 symptoms

Determination of long COVID requires ruling out alternative diagnoses, but there has been no report on the features of alternative diagnoses. This study was a single-center retrospective study of outpatients who visited our clinic between February 2021 and June 2023 that was carried out to determine the characteristics of alternative diagnoses in patients with post-COVID-19 symptoms. In a total of 731 patients, 50 patients (6.8%) were newly diagnosed with 52 diseases requiring medical intervention, and 16 (32%) of those 50 patients (2.2% of the total) were considered to have priority for treatment of the newly diagnosed disorders over long COVID treatment. The proportion of patients with a new diagnosis increased with advance of age, with 15.7% of the patients aged 60 years or older having a new diagnosis. Endocrine and metabolic diseases and hematological and respiratory diseases were the most common, being detected in eight patients (16%) each. Although 35 of the 52 diseases (67%) were related to their symptoms, endocrine and metabolic diseases were the least associated with specific symptoms. Other disorders that require attention were found especially in elderly patients with symptomatic long COVID. Thus, appropriate assessment and differentiation from alternative diagnoses are necessary for managing long COVID.