Long COVID: The latest manifestations, mechanisms, and potential therapeutic interventions

Abstract:

COVID-19 caused by SARS-CoV-2 infection affects humans not only during the acute phase of the infection, but also several weeks to 2 years after the recovery. SARS-CoV-2 infects a variety of cells in the human body, including lung cells, intestinal cells, vascular endothelial cells, olfactory epithelial cells, etc. The damages caused by the infections of these cells and enduring immune response are the basis of long COVID. Notably, the changes in gene expression caused by viral infection can also indirectly contribute to long COVID.

We summarized the occurrences of both common and uncommon long COVID, including damages to lung and respiratory system, olfactory and taste deficiency, damages to myocardial, renal, muscle, and enduring inflammation. Moreover, we provided potential treatments for long COVID symptoms manifested in different organs and systems, which were based on the pathogenesis and the associations between symptoms in different organs.

Importantly, we compared the differences in symptoms and frequency of long COVID caused by breakthrough infection after vaccination and infection with different variants of concern, in order to provide a comprehensive understanding of the characteristics of long COVID and propose improvement for tackling COVID-19.

Source: He ST, Wu K, Cheng Z, He M, Hu R, Fan N, Shen L, Li Q, Fan H, Tong Y. Long COVID: The latest manifestations, mechanisms, and potential therapeutic interventions. MedComm (2020). 2022 Dec 8;3(4):e196. doi: 10.1002/mco2.196. PMID: 36514781; PMCID: PMC9732402. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9732402/ (Full text)

Stellate Ganglion Block for Long COVID Symptom Management: A Case Report

Abstract:

Stellate ganglion block (SGB) is gaining increasing acceptance as a treatment modality for various medical conditions. It works by blocking neuronal transmissions which in turn alleviates sympathetically-driven disease processes. Many of the prolonged sequelae of long COVID are thought to be mediated by dysregulation of the autonomic nervous system, and SGB is being investigated as a potential option for symptomatic management of long COVID. This case report demonstrates the efficacy of SGB in a previously healthy patient for the management of long COVID symptoms including fatigue, post-exertional malaise, shortness of breath, and gastrointestinal symptoms.

Source: Khan M H, Kirkpatrick K P, Deng Y, et al. (December 07, 2022) Stellate Ganglion Block for Long COVID Symptom Management: A Case Report. Cureus 14(12): e32295. doi:10.7759/cureus.32295 https://www.cureus.com/articles/127985-stellate-ganglion-block-for-long-covid-symptom-management-a-case-report (Full text)

Pharmacological Mechanism of NRICM101 for COVID-19 Treatments by Combined Network Pharmacology and Pharmacodynamics

Abstract:

Symptom treatments for Coronavirus disease 2019 (COVID-19) infection and Long COVID are one of the most critical issues of the pandemic era. In light of the lack of standardized medications for treating COVID-19 symptoms, traditional Chinese medicine (TCM) has emerged as a potentially viable strategy based on numerous studies and clinical manifestations. Taiwan Chingguan Yihau (NRICM101), a TCM designed based on a medicinal formula with a long history of almost 500 years, has demonstrated its antiviral properties through clinical studies, yet the pharmacogenomic knowledge for this formula remains unclear. The molecular mechanism of NRICM101 was systematically analyzed by using exploratory bioinformatics and pharmacodynamics (PD) approaches.

Results showed that there were 434 common interactions found between NRICM101 and COVID-19 related genes/proteins. For the network pharmacology of the NRICM101, the 434 common interacting genes/proteins had the highest associations with the interleukin (IL)-17 signaling pathway in the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Moreover, the tumor necrosis factor (TNF) was found to have the highest association with the 30 most frequently curated NRICM101 chemicals.

Disease analyses also revealed that the most relevant diseases with COVID-19 infections were pathology, followed by cancer, digestive system disease, and cardiovascular disease. The 30 most frequently curated human genes and 2 microRNAs identified in this study could also be used as molecular biomarkers or therapeutic options for COVID-19 treatments.

In addition, dose-response profiles of NRICM101 doses and IL-6 or TNF-α expressions in cell cultures of murine alveolar macrophages were constructed to provide pharmacodynamic (PD) information of NRICM101. The prevalent use of NRICM101 for standardized treatments to attenuate common residual syndromes or chronic sequelae of COVID-19 were also revealed for post-pandemic future.

Source: Singh S, Yang YF. Pharmacological Mechanism of NRICM101 for COVID-19 Treatments by Combined Network Pharmacology and Pharmacodynamics. Int J Mol Sci. 2022 Dec 6;23(23):15385. doi: 10.3390/ijms232315385. PMID: 36499711; PMCID: PMC9740625. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9740625/ (Full text)

Effects of l-Arginine Plus Vitamin C Supplementation on Physical Performance, Endothelial Function, and Persistent Fatigue in Adults with Long COVID: A Single-Blind Randomized Controlled Trial

Abstract:

Long COVID, a condition characterized by symptom and/or sign persistence following an acute COVID-19 episode, is associated with reduced physical performance and endothelial dysfunction. Supplementation of l-arginine may improve endothelial and muscle function by stimulating nitric oxide synthesis.

A single-blind randomized, placebo-controlled trial was conducted in adults aged between 20 and 60 years with persistent fatigue attending a post-acute COVID-19 outpatient clinic. Participants were randomized 1:1 to receive twice-daily orally either a combination of 1.66 g l-arginine plus 500 mg liposomal vitamin C or a placebo for 28 days. The primary outcome was the distance walked on the 6 min walk test. Secondary outcomes were handgrip strength, flow-mediated dilation, and fatigue persistence.

Fifty participants were randomized to receive either l-arginine plus vitamin C or a placebo. Forty-six participants (median (interquartile range) age 51 (14), 30 [65%] women), 23 per group, received the intervention to which they were allocated and completed the study. At 28 days, l-arginine plus vitamin C increased the 6 min walk distance (+30 (40.5) m; placebo: +0 (75) m, p = 0.001) and induced a greater improvement in handgrip strength (+3.4 (7.5) kg) compared with the placebo (+1 (6.6) kg, p = 0.03).

The flow-mediated dilation was greater in the active group than in the placebo (14.3% (7.3) vs. 9.4% (5.8), p = 0.03). At 28 days, fatigue was reported by two participants in the active group (8.7%) and 21 in the placebo group (80.1%; p < 0.0001). l-arginine plus vitamin C supplementation improved walking performance, muscle strength, endothelial function, and fatigue in adults with long COVID. This supplement may, therefore, be considered to restore physical performance and relieve persistent symptoms in this patient population.

Source: Tosato M, Calvani R, Picca A, Ciciarello F, Galluzzo V, Coelho-Júnior HJ, Di Giorgio A, Di Mario C, Gervasoni J, Gremese E, Leone PM, Nesci A, Paglionico AM, Santoliquido A, Santoro L, Santucci L, Tolusso B, Urbani A, Marini F, Marzetti E, Landi F; Gemelli against COVID-19 Post-Acute Care Team. Effects of l-Arginine Plus Vitamin C Supplementation on Physical Performance, Endothelial Function, and Persistent Fatigue in Adults with Long COVID: A Single-Blind Randomized Controlled Trial. Nutrients. 2022 Nov 23;14(23):4984. doi: 10.3390/nu14234984. PMID: 36501014; PMCID: PMC9738241. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9738241/ (Full text)

Pathophysiological mechanisms of thrombosis in acute and long COVID-19

Abstract:

COVID-19 patients have a high incidence of thrombosis, and thromboembolic complications are associated with severe COVID-19 and high mortality. COVID-19 disease is associated with a hyper-inflammatory response (cytokine storm) mediated by the immune system. However, the role of the inflammatory response in thrombosis remains incompletely understood.

In this review, we investigate the crosstalk between inflammation and thrombosis in the context of COVID-19, focusing on the contributions of inflammation to the pathogenesis of thrombosis, and propose combined use of anti-inflammatory and anticoagulant therapeutics. Under inflammatory conditions, the interactions between neutrophils and platelets, platelet activation, monocyte tissue factor expression, microparticle release, and phosphatidylserine (PS) externalization as well as complement activation are collectively involved in immune-thrombosis. Inflammation results in the activation and apoptosis of blood cells, leading to microparticle release and PS externalization on blood cells and microparticles, which significantly enhances the catalytic efficiency of the tenase and prothrombinase complexes, and promotes thrombin-mediated fibrin generation and local blood clot formation.

Given the risk of thrombosis in the COVID-19, the importance of antithrombotic therapies has been generally recognized, but certain deficiencies and treatment gaps in remain. Antiplatelet drugs are not in combination with anticoagulant treatments, thus fail to dampen platelet procoagulant activity. Current treatments also do not propose an optimal time for anticoagulation. The efficacy of anticoagulant treatments depends on the time of therapy initiation. The best time for antithrombotic therapy is as early as possible after diagnosis, ideally in the early stage of the disease.

We also elaborate on the possible mechanisms of long COVID thromboembolic complications, including persistent inflammation, endothelial injury and dysfunction, and coagulation abnormalities. The above-mentioned contents provide therapeutic strategies for COVID-19 patients and further improve patient outcomes.

Source: Jing H, Wu X, Xiang M, Liu L, Novakovic VA, Shi J. Pathophysiological mechanisms of thrombosis in acute and long COVID-19. Front Immunol. 2022 Nov 16;13:992384. doi: 10.3389/fimmu.2022.992384. PMID: 36466841; PMCID: PMC9709252. https://www.frontiersin.org/articles/10.3389/fimmu.2022.992384/full (Full text)

Long COVID: mechanisms, risk factors and recovery

Abstract:

New findings: What is the topic of this review? The emerging condition of long COVID, its epidemiology, pathophysiological impacts on patients of different backgrounds, physiological mechanisms emerging as explanations of the condition, and treatment strategies being trialled. The review leads from a Physiological Society online conference on this topic. What advances does it highlight? Progress in understanding the pathophysiology and cellular mechanisms underlying Long COVID and potential therapeutic and management strategies.

Abstract: Long COVID, the prolonged illness and fatigue suffered by a small proportion of those infected with SARS-CoV-2, is placing an increasing burden on individuals and society. A Physiological Society virtual meeting in February 2022 brought clinicians and researchers together to discuss the current understanding of long COVID mechanisms, risk factors and recovery.

This review highlights the themes arising from that meeting. It considers the nature of long COVID, exploring its links with other post-viral illnesses such as myalgic encephalomyelitis/chronic fatigue syndrome, and highlights how long COVID research can help us better support those suffering from all post-viral syndromes. Long COVID research started particularly swiftly in populations routinely monitoring their physical performance – namely the military and elite athletes.

The review highlights how the high degree of diagnosis, intervention and monitoring of success in these active populations can suggest management strategies for the wider population. We then consider how a key component of performance monitoring in active populations, cardiopulmonary exercise training, has revealed long COVID-related changes in physiology – including alterations in peripheral muscle function, ventilatory inefficiency and autonomic dysfunction. The nature and impact of dysautonomia are further discussed in relation to postural orthostatic tachycardia syndrome, fatigue and treatment strategies that aim to combat sympathetic overactivation by stimulating the vagus nerve.

We then interrogate the mechanisms that underlie long COVID symptoms, with a focus on impaired oxygen delivery due to micro-clotting and disruption of cellular energy metabolism, before considering treatment strategies that indirectly or directly tackle these mechanisms. These include remote inspiratory muscle training and integrated care pathways that combine rehabilitation and drug interventions with research into long COVID healthcare access across different populations.

Overall, this review showcases how physiological research reveals the changes that occur in long COVID and how different therapeutic strategies are being developed and tested to combat this condition.

Source: Astin R, Banerjee A, Baker MR, Dani M, Ford E, Hull JH, Lim PB, McNarry M, Morten K, O’Sullivan O, Pretorius E, Raman B, Soteropoulos DS, Taquet M, Hall CN. Long COVID: mechanisms, risk factors and recovery. Exp Physiol. 2022 Nov 22. doi: 10.1113/EP090802. Epub ahead of print. PMID: 36412084. https://physoc.onlinelibrary.wiley.com/doi/10.1113/EP090802 (Full text)

Post COVID and Apheresis – Where are we Standing?

Abstract:

A continual increase in cases of Long/Post COVID constitutes a medical and socioeconomic challenge to health systems around the globe. While the true extent of this problem cannot yet be fully evaluated, recent data suggest that up to 20% of people with confirmed SARS-CoV-2 suffer from clinically relevant symptoms of Long/Post COVID several weeks to months after the acute phase. The clinical presentation is highly variable with the main symptoms being chronic fatigue, dyspnea, and cognitive symptoms. Extracorporeal apheresis has been suggested to alleviate symptoms of Post/COVID. Thus, numerous patients are currently treated with apheresis.

However, at present there is no data from randomized controlled trials available to confirm the efficacy. Therefore, physicians rely on the experience of practitioners and centers performing this treatment. Here, we summarize clinical experience on extracorporeal apheresis in patients with Post/COVID from centers across Germany.

Source: Steenblock C, Walther R, Tselmin S, Jarzebska N, Voit-Bak K, Toepfner N, Siepmann T, Passauer J, Hugo C, Wintermann G, Julius U, Barbir M, Khan TZ, Puhan MA, Straube R, Hohenstein B, Bornstein SR, Rodionov RN. Post COVID and Apheresis – Where are we Standing? Horm Metab Res. 2022 Nov;54(11):715-720. doi: 10.1055/a-1945-9694. Epub 2022 Sep 16. PMID: 36113501. https://www.thieme-connect.de/products/ejournals/html/10.1055/a-1945-9694 (Full text)

Clinical trials on the pharmacological treatment of long COVID: A systematic review

Abstract:

The postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC), also known as post-acute coronavirus disease 19 (COVID-19) or the long COVID syndrome (long COVID) is an emerging public health concern. A substantial proportion of individuals may remain symptomatic months after initial recovery. An updated review of published and ongoing trials focusing on managing long COVID will help identify gaps and address the unmet needs of patients suffering from this potentially debilitating syndrome.

A comprehensive literature search was conducted on the international databases and clinical trial registries from inception to 31 July 2022. This review included 6 published trials and 54 trial registration records. There is significant heterogeneity in the characterization of long COVID and ascertainment of primary outcomes. Most of the trials are focused on individual symptoms of long COVID or isolated organ dysfunction, classified according to cardiovascular, respiratory and functional capacity, neurological and psychological, fatigue, and olfactory dysfunction.

Most of the interventions are related to the mechanisms causing the individual symptoms. Although the six published trials showed significant improvement in the symptoms or organ dysfunction studied, these initial studies lack internal and external validity limiting the generalizability. This review provides an update of the pharmacological agents that could be used to treat long COVID. Further standardization of the diagnostic criteria, inclusion of participants with concomitant chronic cardiometabolic diseases and standardization of outcomes will be essential in future clinical trials.

Source: Chee YJ, Fan BE, Young BE, Dalan R, Lye DC. Clinical trials on the pharmacological treatment of long COVID: A systematic review. J Med Virol. 2022 Nov 8:e28289. doi: 10.1002/jmv.28289. Epub ahead of print. PMID: 36349400. https://pubmed.ncbi.nlm.nih.gov/36349400/

Transcutaneous Vagus Nerve Stimulation in the Treatment of Long Covid-Chronic Fatigue Syndrome

Abstract:

Many patients do not recover following Covid infection. The resulting illness is called Long Covid. Because there is no agreed upon treatment for this ailment, we decided to do an open label pilot study using non-invasive, transcutaneous stimulation of the auricular branch of the vagus nerve. Inclusion criteria required the patient to fulfill criteria for having chronic fatigue syndrome. Fourteen patients provided evaluable data. Eight of these fulfilled our requirements for treatment success. Since our criterion for a successful study was that at least a third of patients had to show a positive response to treatment, this was a successful pilot that warrants a follow up study that is appropriately sham controlled.

Source: Benjamin H NatelsonMichelle BlateTiffany Soto. Transcutaneous Vagus Nerve Stimulation in the Treatment of Long Covid-Chronic Fatigue Syndrome.

Co-Ultramicronized Palmitoylethanolamide/Luteolin normalizes GABAB-ergic activity and cortical plasticity in long COVID-19 syndrome

Abstract:

Objective: Transcranial magnetic stimulation (TMS) studies showed that patients with cognitive dysfunction and fatigue after COVID-19 exhibit impaired cortical GABAB-ergic activity, as revealed by reduced long-interval intracortical inhibition (LICI).

Aim of this study was to test the effects of co-ultramicronized palmitoylethanolamide/luteolin (PEA-LUT), an endocannabinoid-like mediator able to enhance GABA-ergic transmission and to reduce neuroinflammation, on LICI.

Methods: Thirty-nine patients (26 females, mean age 49.9 ± 11.4 years, mean time from infection 296.7 ± 112.3 days) suffering from persistent cognitive difficulties and fatigue after mild COVID-19 were randomly assigned to receive either PEA-LUT 700mg + 70mg or PLACEBO, administered orally bid for eight weeks. The day before (PRE) and at the end of the treatment (POST), they underwent TMS protocols to assess LICI. We further evaluate short-latency afferent inhibition (SAI) and long-term potentiation (LTP)-like cortical plasticity.

Results: Patients treated with PEA-LUT but not with PLACEBO showed a significant increase of LICI and LTP-like cortical plasticity. SAI remained unaffected.

Conclusions: Eight weeks of treatment with PEA-LUT restore GABAB activity and cortical plasticity in long Covid patients.

Significance: This study confirms altered physiology of the motor cortex in long Covid and indicates PEA-LUT as a candidate for the treatment of this post-viral condition.

Source: Viviana Versace, Paola Ortelli, Sabrina Dezi, Davide Ferrazzoli, Alessia Alibardi, Ilenia Bonini, Michael Engl, Roberto Maestri, Martina Assogna, Valentina Ajello, Elke Pucks-Faes, Leopold Saltuari, Luca Sebastianelli, Markus Kofler, Giacomo Koch. Co-Ultramicronized Palmitoylethanolamide/Luteolin normalizes GABAB-ergic activity and cortical plasticity in long COVID-19 syndrome. Clinical Neurophysiology, 2022, ISSN 1388-2457, https://doi.org/10.1016/j.clinph.2022.10.017. https://www.sciencedirect.com/science/article/pii/S1388245722009385 (Full text)