Evaluation of the Impact of Adaptive Progressive Supervised Resistance Training on Strength and Quality of Life in Patients with Breast Cancer During Chemotherapy: The VALESCO Study.

INTRODUCTION: Breast Cancer Patients (BCP) experience considerable side effects during and after treatment. Several studies have shown positive effects of exercise on therapy-related side-effects such as loss of muscle strength, loss of bone mineral density, lymphedema and several elements of quality of life (QoL). Resistance exercise has proven effective and beneficial for BCP; however optimal individual training parameters remain to be determined. METHODS: The aim of our study was to implement an adaptive, progressive, supervised resistance protocol for breast cancer patients during chemotherapy, improving muscle strength, physical condition, and overall QoL while reducing therapy-induced side-effects. 40 patients receiving adjuvant chemotherapy were included six to twelve weeks post-OP. 20 patients underwent high intensity resistance-training twice a week for twelve weeks, and the control group received usual care. RESULTS: Strength parameters improved significantly in the intervention group and in different scales of QoL. We documented a cyclic performance level underlining the importance of adaptive training and training control in further trials.

Beyond muscles: Investigating immunoregulatory myokines in acute resistance exercise - A systematic review and meta-analysis.

Myokines, released from the muscle, enable communication between the working muscles and other tissues. Their release during physical exercise is assumed to depend on immune-hormonal-metabolic interactions concerning mode (endurance or resistance exercise), duration, and intensity. This meta-analysis aims to examine the acute changes of circulating myokines inducing immunoregulatory effects caused by a bout of resistance exercise and to consider potential moderators of the results. Based on this selection strategy, a systematic literature search was conducted for resistance exercise intervention studies measuring interleukin (IL-) 6, IL-10, IL-1ra, tumor necrosis factor (TNF-) α, IL-15, IL-7, transforming growth factor (TGF-) ß1, and fractalkines (FKN) before and immediately after resistance exercise in healthy individuals. Random-effects meta-analysis was performed for each myokine. We identified a moderate positive effect of resistance exercise for IL-6 and IL-1ra. Regarding IL-15 and TNF-α, small to moderate effects were found. For IL-10, no significant effect was observed. Due to no data, meta-analyses for IL-7, TGF-ß1, and FKN could not be performed. No moderators (training status, type of exercise, risk of bias, age, sex, time of day, exercise volume, exercise intensity, exercise dose) of the results were detected for all tested myokines. Taken together, this systematic review and meta-analysis showed immediate positive effects of an acute resistance exercise session on IL-6, IL-1ra, TNF-α, and IL-15 levels.

Efficacy and safety of everolimus plus exemestane in patients with hormone receptor-positive, HER-2-negative advanced breast cancer: Results from the open-label, multicentre, non-interventional BRAWO study.

BRAWO, a real-world study, assessed the efficacy, quality of life (QoL) and safety of EVE + EXE in postmenopausal women with HR+/HER2- advanced breast cancer (ABC) in routine clinical practice. Postmenopausal women with HR+/HER2-ABC with recurrence or progression after a NSAI were included. Primary Observation parameters included the evaluation of the effectiveness of EVE + EXE. A multivariate-analysis using Cox proportional hazard model was built to identify predictors of progression. Overall, 2100 patients were enrolled (August 2012-December 2017); 2074 were evaluable for efficacy and safety analyses. Majority of patients (60.6%) received EVE + EXE as first (28.7%) or second-line (31.9%) therapy. Visceral metastases were present in 54.1% patients. Median progression-free survival (mPFS) reported as 6.6 months (95%CI: 6.3-7.0). Multivariate-analysis in a subset of patients (n = 1837) found higher body mass index (BMI) and non-visceral metastases to be independent predictors of favorable PFS. Patients with a BMI of 20 to <25 had a mPFS of 6.0 (95%CI: 5.4-6.4) and those with a BMI ≥30 had mPFS of 8.5 (95%CI: 6.9-9.9). 41.2% patients achieved stable disease and 7.3% partial response. No major changes were observed QoL; 86.4% patients received stomatitis prophylaxis and 41.4% experienced EVE related AEs of stomatitis, mainly low grade. AEs occurred in 91.2% of patients, of which stomatitis (42.6%) and fatigue (19.8%) were most frequent. The BRAWO study provides real-world evidence of efficacy and safety of EVE + EXE in patients with HR+, HER2- ABC. A high BMI and the absence of visceral metastases were independent predictors of PFS in this cohort of patients.

COVID-19 in Female and Male Athletes: Symptoms, Clinical Findings, Outcome, and Prolonged Exercise Intolerance-A Prospective, Observational, Multicenter Cohort Study (CoSmo-S).

BACKGROUND: An infection with SARS-CoV-2 can lead to a variety of symptoms and complications, which can impair athletic activity. OBJECTIVE: We aimed to assess the clinical symptom patterns, diagnostic findings, and the extent of impairment in sport practice in a large cohort of athletes infected with SARS-CoV-2, both initially after infection and at follow-up. Additionally, we investigated whether baseline factors that may contribute to reduced exercise tolerance at follow-up can be identified. METHODS: In this prospective, observational, multicenter study, we recruited German COVID elite-athletes (cEAs, n = 444) and COVID non-elite athletes (cNEAs, n = 481) who tested positive for SARS-CoV-2 by PCR (polymerase chain reaction test). Athletes from the federal squad with no evidence of SARS-CoV-2 infection served as healthy controls (EAcon, n = 501). Questionnaires were used to assess load and duration of infectious symptoms, other complaints, exercise tolerance, and duration of training interruption at baseline and at follow-up 6 months after baseline. Diagnostic tests conducted at baseline included resting and exercise electrocardiogram (ECG), echocardiography, spirometry, and blood analyses. RESULTS: Most acute and infection-related symptoms and other complaints were more prevalent in cNEA than in cEAs. Compared to cEAs, EAcon had a low symptom load. In cNEAs, female athletes had a higher prevalence of complaints such as palpitations, dizziness, chest pain, myalgia, sleeping disturbances, mood swings, and concentration problems compared to male athletes (p < 0.05). Until follow-up, leading symptoms were drop in performance, concentration problems, and dyspnea on exertion. Female athletes had significantly higher prevalence for symptoms until follow-up compared to male. Pathological findings in ECG, echocardiography, and spirometry, attributed to SARS-CoV-2 infection, were rare in infected athletes. Most athletes reported a training interruption between 2 and 4 weeks (cNEAs: 52.9%, cEAs: 52.4%), while more cNEAs (27.1%) compared to cEAs (5.1%) had a training interruption lasting more than 4 weeks (p < 0.001). At follow-up, 13.8% of cNEAs and 9.9% of cEAs (p = 0.24) reported their current exercise tolerance to be under 70% compared to pre-infection state. A persistent loss of exercise tolerance at follow-up was associated with persistent complaints at baseline, female sex, a longer break in training, and age > 38 years. Periodical dichotomization of the data set showed a higher prevalence of infectious symptoms such as cough, sore throat, and coryza in the second phase of the pandemic, while a number of neuropsychiatric symptoms as well as dyspnea on exertion were less frequent in this period. CONCLUSIONS: Compared to recreational athletes, elite athletes seem to be at lower risk of being or remaining symptomatic after SARS-CoV-2 infection. It remains to be determined whether persistent complaints after SARS-CoV-2 infection without evidence of accompanying organ damage may have a negative impact on further health and career in athletes. Identifying risk factors for an extended recovery period such as female sex and ongoing neuropsychological symptoms could help to identify athletes, who may require a more cautious approach to rebuilding their training regimen. TRIAL REGISTRATION NUMBER: DRKS00023717; 06.15.2021-retrospectively registered.

Resistance training does not increase myocellular garbage dumps: A pilot study on lipofuscin in skeletal muscle fibers of resistance trained young men.

Lipofuscin (LF) is an intracellular aggregate associated with proteostatic impairments, especially prevalent in nondividing skeletal muscle fibers. Reactive oxygen species (ROS) drive LF-formation. Resistance training (RT) improves muscle performance but also increases ROS production, potentially promoting LF-formation. Thus, we aimed to investigate if RT of a mesocycle duration increases LF-formation in type-I and II muscle fibers and whether RT increases the antioxidant capacity (AOC) in terms of SOD1 and SOD2 content. An intervention group (IG) performed 14 eccentrically accented RT-sessions within 7 weeks. Vastus lateralis muscle biopsies were collected before and after the intervention from IG as well as from a control group (CG) which refrained from RT for the same duration. LF was predominantly found near nuclei, followed by membrane-near and a minor amount in the fiber core, with corresponding spot sizes. Overall, LF-content was higher in type-I than type-II fibers (p < 0.05). There was no increase in LF-content in type-I or IIA fibers, neither for the IG following RT nor for the CG. The same is valid for SOD1/2. We conclude that, in healthy subjects, RT can be safely performed, without adverse effects on increased LF-formation.

Comparison of the cytokine responses to acute strength exercise between oral contraceptive users and naturally cycling women.

PURPOSE: Cytokines are released as part of an inflammatory reaction in response to strength exercise to initiate muscle repair and morphological adaptations. Whether hormonal fluctuations induced by the menstrual cycle or oral contraceptives affect inflammatory responses to strength exercise remains unknown. Therefore, we aimed to compare the response of cytokines after acute strength exercise in naturally menstruating women and oral contraceptive users. METHODS: Naturally menstruating women (MC, n = 13, 24 ± 4 years, weekly strength training: 4.3 ± 1.7 h) and women using a monophasic combined pill (> 9 months) (OC, n = 8, 22 ± 3 years, weekly strength training: 4.5 ± 1.9 h) were recruited. A one-repetition-maximum (1RM) test and strength exercise in the squat (4 × 10 repetitions, 70%1RM) was performed in the early follicular phase or pill free interval. Concentrations of oestradiol, IL-1ß, IL-1ra, IL-6, IL-8, and IL-10 were assessed before (pre), directly after (post) and 24 h after (post24) strength exercise. RESULTS: IL-1ra increased from pre to post (+ 51.1 ± 59.4%, p = 0.189) and statistically decreased from post to post24 (- 20.5 ± 13.5%, p = 0.011) only in OC. Additionally, IL-1ß statistically decreased from post to post24 (- 39.6 ± 23.0%, p = 0.044) only in OC. There was an interaction effect for IL-1ß (p = 0.038) and concentrations were statistically decreased at post24 in OC compared to MC (p = 0.05). IL-8 increased across both groups from post to post24 (+ 66.6 ± 96.3%, p = 0.004). CONCLUSION: We showed a differential regulation of IL-1ß and IL-1ra between OC users in the pill-free interval and naturally cycling women 24 h after strength exercise, while there was no effect on other cytokines. Whether this is associated with previously shown compromised morphological adaptations remains to be investigated.

Moderate Intensity Exercise Reduces Side Effects of Cancer Therapy and Maintains Cardiorespiratory Fitness in Male Breast Cancer Patients: Findings from the BRECA Male Crossover Study.

Introduction: There is growing evidence that aerobic exercise mitigates cancer therapy-related side effects and improves cardiorespiratory fitness (CRF). However, to the best of our knowledge, no exercise study has been conducted in male breast cancer (MBC) patients. The aim of this study was to investigate the feasibility and efficacy of different exercise intensities on CRF and self-reported questionnaire items in MBC patients. Methods: Twenty-two MBC patients (60 ± 9 years) participated in this randomized crossover study. After completion of medical treatment, MBC patients were randomly assigned to either moderate (40-50% of heart rate [HR] max. and self-perceived exertion: 11) or vigorous (70-80% of HR max. and self-perceived exertion: 15) exercise intensity during the first 3 months of the study. After a 1-month washout period, participants switched group assignments. Primary endpoints were CRF and questionnaire items. Results: We observed a dropout rate of 36% over 7 months, with the number of participants decreasing from 22 to 14. The results showed significant improvements in "Physical Function" (p = 0.037) and "Social Function" (p = 0.016) after moderate training. A non-significant improvement was also observed in "Breast Symptoms" (p = 0.095), but there was no change in "Fatigue" (p = 0.306). There were no differences observed in cardiovascular fitness (V̇O2 peak) between the treatment groups. Conclusion: This study emphasizes the effectiveness of exercise intervention for an exceedingly rare cancer, highlighting the vital role of moderate intensity aerobic exercise in mitigating treatment side effects. Despite minimal peak V̇O2 differences, both exercise protocols adequately sustain CRF. Future studies are imperative to design optimized, sex-specific rehabilitation strategies tailored to the unique requirements of MBC patients, advancing our understanding of this under explored realm.

Changes in Hematological and Hemorheological Parameters Following Mild COVID-19: A 4-Month Follow-Up Study.

BACKGROUND: Coronavirus Disease 2019 (COVID-19) was described to affect red blood cells (RBC) in both severe and mild disease courses. The aim of this study was to investigate whether hematological and hemorheological changes that were previously described for COVID-19 patients after the acute infection state are still prominent after another 4 months to assess potential long-term effects. METHODS: Hematological and RBC rheological parameters, including deformability and aggregation, were measured 41 days after infection in COVID-19 patients and non-COVID control (T0) and 4 months later in COVID-19 patients (T1). RESULTS: The data confirm alterations in hematological parameters, mainly related to cell volume and hemoglobin concentration, but also reduced deformability and increased aggregation at T0 compared to control. While RBC deformability seems to have recovered, hemoglobin-related parameters and RBC aggregation were still impaired at T1. The changes were thus more pronounced in male COVID-19 patients. CONCLUSION: COVID-19-related changes of the RBC partly consist of several months and might be related to persistent symptoms reported by many COVID-19 patients.

Global Alliance for the Promotion of Physical Activity: the Hamburg Declaration.

Non-communicable diseases (NCDs), including coronary heart disease, stroke, hypertension, type 2 diabetes, dementia, depression and cancers, are on the rise worldwide and are often associated with a lack of physical activity (PA). Globally, the levels of PA among individuals are below WHO recommendations. A lack of PA can increase morbidity and mortality, worsen the quality of life and increase the economic burden on individuals and society. In response to this trend, numerous organisations came together under one umbrella in Hamburg, Germany, in April 2021 and signed the 'Hamburg Declaration'. This represented an international commitment to take all necessary actions to increase PA and improve the health of individuals to entire communities. Individuals and organisations are working together as the 'Global Alliance for the Promotion of Physical Activity' to drive long-term individual and population-wide behaviour change by collaborating with all stakeholders in the community: active hospitals, physical activity specialists, community services and healthcare providers, all achieving sustainable health goals for their patients/clients. The 'Hamburg Declaration' calls on national and international policymakers to take concrete action to promote daily PA and exercise at a population level and in healthcare settings.

Safety and feasibility of exercise interventions in patients with hematological cancer undergoing chemotherapy: a systematic review.

OBJECTIVE: Exercise during and after cancer treatment has established quality of life and health benefits. However, particularly for patients with hematological cancer clear recommendations regarding the safety and feasibility of exercise are under-investigated. The aim of our systematic review was to summarize the literature regarding the feasibility and safety of exercise interventions in patients diagnosed with hematological cancer undergoing chemotherapy. METHOD: A systematic literature review was conducted using PubMed, SPORTDiscus, MEDLINE, Science Direct, and Web of Science electronic databases. Eligible studies were scientific publications reporting the feasibility and/or safety of an exercise intervention program carried out in inpatient patients diagnosed with hematological cancer undergoing chemotherapy. RESULT: Out of 12 studies (six RCTs) included in this review, six investigations reported results with regard to safety and 10 with regard to feasibility. While all studies claim that their exercise interventions were safe and/or feasible, it is noteworthy that this claim often remains unsupported as detailed information on how the feasibility of the intervention was asserted is missing. CONCLUSION: Exercise appears to be safe and feasible in hematological cancer patients. However, due to a striking lack of information on how the feasibility of the intervention was asserted, contextualizing the results and deducing recommendations for further studies remains challenging. Further research should therefore incorporate information on the execution of the exercise intervention in more detail.

Polarity signaling balances epithelial contractility and mechanical resistance.

Epithelia maintain a functional barrier during tissue turnover while facing varying mechanical stress. This maintenance requires both dynamic cell rearrangements driven by actomyosin-linked intercellular adherens junctions and ability to adapt to and resist extrinsic mechanical forces enabled by keratin filament-linked desmosomes. How these two systems crosstalk to coordinate cellular movement and mechanical resilience is not known. Here we show that in stratifying epithelia the polarity protein aPKCλ controls the reorganization from stress fibers to cortical actomyosin during differentiation and upward movement of cells. Without aPKC, stress fibers are retained resulting in increased contractile prestress. This aberrant stress is counterbalanced by reorganization and bundling of keratins, thereby increasing mechanical resilience. Inhibiting contractility in aPKCλ-/- cells restores normal cortical keratin networks but also normalizes resilience. Consistently, increasing contractile stress is sufficient to induce keratin bundling and enhance resilience, mimicking aPKC loss. In conclusion, our data indicate that keratins sense the contractile stress state of stratified epithelia and balance increased contractility by mounting a protective response to maintain tissue integrity.

ELSAH (electronic smart patch system for wireless monitoring of molecular biomarkers for healthcare and wellbeing): definition of possible use cases.

The ELSAH (electronic smart patch system for wireless monitoring of molecular biomarkers for healthcare and wellbeing) project has received funding from EU's Horizon 2020 research and innovation program (grant agreement no. 825549). Its aim is to develop a wearable smart patch-based microneedle sensor system that can simultaneously measure several biomarkers in users' dermal interstitial fluid. This system could have several use cases based on continuous glucose and lactate monitoring: early detection of (pre-) diabetes mellitus, increasing physical performance through optimal carbohydrate intake, achieving a healthier lifestyle through behavioral changes based on the interpretation of glucose data, performance diagnostics (lactate threshold test), control of optimal training intensities corresponding with certain lactate levels, or warning of diseases/health threats, such as the metabolic syndrome or sepsis associated with increased lactate levels. The ELSAH patch system has a high potential of increasing health and wellbeing in users.

The oxygen dissociation curve of blood in COVID-19-An update.

An impressive effect of the infection with SARS-Co-19 is the impairment of oxygen uptake due to lung injury. The reduced oxygen diffusion may potentially be counteracted by an increase in oxygen affinity of hemoglobin. However, hypoxia and anemia associated with COVID-19 usually decrease oxygen affinity due to a rise in [2,3-bisphosphoglycerate]. As such, COVID-19 related changes in the oxygen dissociation curve may be critical for oxygen uptake and supply, but are hard to predict. A Pubmed search lists 14 publications on oxygen affinity in COVID-19. While some investigations show no changes, three large studies found an increased affinity that was related to a good prognosis. Exact causes remain unknown. The cause of the associated anemia in COVID-19 is under discussion. Erythrocytes with structural alterations of membrane and cytoskeleton have been observed, and virus binding to Band 3 and also to ACE2 receptors in erythroblasts has been proposed. COVID-19 presentation is moderate in many subjects suffering from sickle cell disease. A possible explanation is that COVID-19 counteracts the unfavorable large right shift of the oxygen dissociation curve in these patients. Under discussion for therapy are mainly affinity-increasing drugs.

Dental Pulp Inflammation Initiates the Occurrence of Mast Cells Expressing the α1 and ß1 Subunits of Soluble Guanylyl Cyclase.

The binding of nitric oxide (NO) to heme in the ß1 subunit of soluble guanylyl cyclase (sGC) activates both the heterodimeric α1ß1 and α2ß1 isoforms of the enzyme, leading to the increased production of cGMP from GTP. In cultured human mast cells, exogenous NO is able to inhibit mast cell degranulation via NO-cGMP signaling. However, under inflammatory oxidative or nitrosative stress, sGC becomes insensitive to NO. The occurrence of mast cells in healthy and inflamed human tissues and the in vivo expression of the α1 and ß1 subunits of sGC in human mast cells during inflammation remain largely unresolved and were investigated here. Using peroxidase and double immunohistochemical incubations, no mast cells were found in healthy dental pulp, whereas the inflammation of dental pulp initiated the occurrence of several mast cells expressing the α1 and ß1 subunits of sGC. Since inflammation-induced oxidative and nitrosative stress oxidizes Fe2+ to Fe3+ in the ß1 subunit of sGC, leading to the desensitization of sGC to NO, we hypothesize that the NO- and heme-independent pharmacological activation of sGC in mast cells may be considered as a regulatory strategy for mast cell functions in inflamed human dental pulp.

Cellular Integrative Immune Markers in Elite Athletes.

The integrative immune markers neutrophil-lymphocyte-ratio (NLR), platelet-lymphocyte-ratio (PLR) and systemic immune inflammation index (SII) are established markers in clinical patient care. Adoption of these markers in elite athletics might prove beneficial for monitoring training and health. Blood samples of 195 healthy national Olympic squad athletes were collected before a graded bicycle-ergometric exercise test until complete exhaustion. Measurements included white blood cells, lymphocytes and platelets, allowing for the calculation of the integrative immune markers. Correlations between athlete characteristics (sex, age, sporting discipline, training experience, training volume) and integrative immune marker-values were assessed. In a subgroup analysis a second blood sample was collected from 25 athletes at 1 minute after exercise test to assess its effect on the immune marker levels.An inverse correlation between peak power output and SII-level (Pearson correlation coefficient=-.270, p<.001) and NLR-level (Pearson correlation coefficient=-.249, p<.001) was found. Athletes with higher aerobic fitness had significantly lower values of SII and PLR compared to athletes with lower aerobic fitness. An elevated SII (p=.003) and a reduced PLR (p=.001) was documented as acute response to the exercise test. The integrative immune markers might be a promising tool for monitoring training and health in elite athletes.

SARS-CoV-2 Altered Hemorheological and Hematological Parameters during One-Month Observation Period in Critically Ill COVID-19 Patients.

Hematological and hemorheological parameters are known to be altered in COVID-19; however, the value of combined monitoring in order to deduce disease severity is only scarcely examined. A total of 44 acute SARS-CoV-2-infected patients (aCOV) and 44 age-matched healthy controls (Con) were included. Blood of aCOV was sampled at admission (T0), and at day 2 (T2), day 5 (T5), day 10 (T10), and day 30 (T30) while blood of Con was only sampled once. Inter- and intra-group differences were calculated for hematological and hemorheological parameters. Except for mean cellular volume and mean cellular hemoglobin, all blood cell parameters were significantly different between aCOV and Con. During the acute disease state (T0-T5), hematological and hemorheological parameters were highly altered in aCOV; in particular, anemic conditions and increased immune cell response/inflammation, oxidative/nitrosative stress, decreased deformability, as well as increased aggregation, were observed. During treatment and convalescence until T30, almost all abnormal values of aCOV improved towards Con values. During the acute state of the COVID-19 disease, the hematological, as well as the hemorheological system, show fast and potentially pathological changes that might contribute to the progression of the disease, but changes appear to be largely reversible after four weeks. Measuring RBC deformability and aggregation, as well as oxidative stress induction, may be helpful in monitoring critically ill COVID-19 patients.

Structure, evolution and expression of zebrafish cartilage oligomeric matrix protein (COMP, TSP5). CRISPR-Cas mutants show a dominant phenotype in myosepta.

COMP (Cartilage Oligomeric Matrix Protein), also named thrombospondin-5, is a member of the thrombospondin family of extracellular matrix proteins. It is of clinical relevance, as in humans mutations in COMP lead to chondrodysplasias. The gene encoding zebrafish Comp is located on chromosome 11 in synteny with its mammalian orthologs. Zebrafish Comp has a domain structure identical to that of tetrapod COMP and shares 74% sequence similarity with murine COMP. Zebrafish comp is expressed from 5 hours post fertilization (hpf) on, while the protein is first detectable in somites of 11 hpf embryos. During development and in adults comp is strongly expressed in myosepta, craniofacial tendon and ligaments, around ribs and vertebra, but not in its name-giving tissue cartilage. As in mammals, zebrafish Comp forms pentamers. It is easily extracted from 5 days post fertilization (dpf) whole zebrafish. The lack of Comp expression in zebrafish cartilage implies that its cartilage function evolved recently in tetrapods. The expression in tendon and myosepta may indicate a more fundamental function, as in evolutionary distant Drosophila muscle-specific adhesion to tendon cells requires thrombospondin. A sequence encoding a calcium binding motif within the first TSP type-3 repeat of zebrafish Comp was targeted by CRISPR-Cas. The heterozygous and homozygous mutant Comp zebrafish displayed a patchy irregular Comp staining in 3 dpf myosepta, indicating a dominant phenotype. Electron microscopy revealed that the endoplasmic reticulum of myosepta fibroblasts is not affected in homozygous fish. The disorganized extracellular matrix may indicate that this mutation rather interferes with extracellular matrix assembly, similar to what is seen in a subgroup of chondrodysplasia patients. The early expression and easy detection of mutant Comp in zebrafish points to the potential of using the zebrafish model for large scale screening of small molecules that can improve secretion or function of disease-associated COMP mutants.

A scoping review of regulatory T cell dynamics in convalescent COVID-19 patients - indications for their potential involvement in the development of Long COVID?

Background: Recovery from coronavirus disease 2019 (COVID-19) can be impaired by the persistence of symptoms or new-onset health complications, commonly referred to as Long COVID. In a subset of patients, Long COVID is associated with immune system perturbations of unknown etiology, which could be related to compromised immunoregulatory mechanisms. Objective: The objective of this scoping review was to summarize the existing literature regarding the frequency and functionality of Tregs in convalescent COVID-19 patients and to explore indications for their potential involvement in the development of Long COVID. Design: A systematic search of studies investigating Tregs during COVID-19 convalescence was conducted on MEDLINE (via Pubmed) and Web of Science. Results: The literature search yielded 17 relevant studies, of which three included a distinct cohort of patients with Long COVID. The reviewed studies suggest that the Treg population of COVID-19 patients can reconstitute quantitatively and functionally during recovery. However, the comparison between recovered and seronegative controls revealed that an infection-induced dysregulation of the Treg compartment can be sustained for at least several months. The small number of studies investigating Tregs in Long COVID allowed no firm conclusions to be drawn about their involvement in the syndrome's etiology. Yet, even almost one year post-infection Long COVID patients exhibit significantly altered proportions of Tregs within the CD4+ T cell population. Conclusions: Persistent alterations in cell frequency in Long COVID patients indicate that Treg dysregulation might be linked to immune system-associated sequelae. Future studies should aim to address the association of Treg adaptations with different symptom clusters and blood parameters beyond the sole quantification of cell frequencies while adhering to consensualized phenotyping strategies.