Refueling the post COVID-19 brain: potential role of ketogenic medium chain triglyceride supplementation: an hypothesis

Analyzing the causal relationship between gut microbiotas, blood metabolites, and COVID-19 susceptibility: A Mendelian randomization study

Gut microbiota and blood metabolites play crucial roles in the progression and outcomes of COVID-19, but the causal relationships and mechanisms remain unclear. Our aim is to use two-sample Mendelian randomization (MR) to explore the causal relationships between gut microbiota, COVID-19 susceptibility, and potential mediating blood metabolites. We utilized summary statistics from the largest genome-wide association studies (GWAS) to date on gut microbiota (n = 18,340), blood metabolites (n = 115,078), and COVID-19 susceptibility (cases n = 60,176 and controls n = 1310,725 from the COVID-19 Host Genetics Initiative meta-analysis). We conducted bidirectional MR analyses to explore the causal relationships between gut microbiota and COVID-19 susceptibility and performed two-step MR to identify potential mediating blood metabolites. Five analytical methods were used to assess two-sample causal relationships, with inverse variance weighted (IVW) being the primary method. Sensitivity analyses were also conducted to ensure the robustness of the main MR results. Using the IVW method, we found causal relationships between 3 types of gut microbiota and 34 blood metabolites with COVID-19 susceptibility. In the two-step MR, the non-oxidative branch of the Pentose phosphate pathway was shown to reduce Sebacate (C10-DC) levels, and the species Parabacteroides goldsteinii was negatively correlated with Acetoacetate levels. Sebacate (C10-DC) levels were negatively associated with COVID-19 susceptibility, while Acetoacetate levels were positively associated with COVID-19 susceptibility. Furthermore, these causal relationships remained significant after correcting for false discovery rates (all q-values < 0.05). Heterogeneity and pleiotropy tests showed no statistical significance (P > .05). Mediation analysis indicated that the abundance of the non-oxidative branch of the Pentose phosphate pathway and COVID-19 susceptibility was mediated by Sebacate (C10-DC) levels (mediation proportion of 15.8%), and the abundance of P goldsteinii and COVID-19 susceptibility was mediated by Acetoacetate levels (mediation proportion of 31.7%). The current MR study provides evidence supporting the causal relationships between several specific gut microbiotas and COVID-19 susceptibility, as well as potential mediating blood metabolites. Our findings warrant further validation through larger epidemiological studies.

The Impact of a Very-Low-Calorie Ketogenic Diet on Monocyte Subsets of Patients with Obesity: A Pilot Study

Background/Objectives: Obesity is closely linked to chronic low-grade inflammation and the development of cardio-metabolic comorbidities. Monocyte subsets, which are crucial in immune responses, have been reported to be altered in individuals with obesity, potentially exacerbating inflammation. Although very-low-calorie ketogenic diets (VLCKDs) are recognized for their efficacy in promoting weight loss and improving metabolic health, their impact on circulating monocyte subsets remains poorly understood. The objective of our study is to investigate the impact of VLCKDs on monocyte subset distribution in people with obesity. Methods: Thirty-six participants were divided into four groups-healthy controls, individuals with obesity and no dietary intervention, and individuals with obesity following either a low-calorie diet (LCD) or VLCKD for 28 days. Blood samples were analyzed to assess the distribution of classical monocytes (CMs), intermediate monocytes (IMs), and non-classical monocytes (NCMs) using flow cytometry. Results: Individuals with obesity exhibited significant increases in IMs and NCMs, alongside a decrease in CMs compared to healthy controls. The VLCKD led to a notable shift in monocyte distribution, with increased CMs and reduced IMs and NCMs, restoring levels closer to those observed in healthy individuals. In contrast, the LCD group showed no significant changes in monocyte subsets. Conclusions: VLCKDs may exert anti-inflammatory effects by modulating monocyte subset distribution, offering potential therapeutic benefits in mitigating obesity-related inflammation. These preliminary findings suggest that VLCKDs could be an effective strategy for improving immune function in individuals with obesity.

Neurovascular coupling impairment as a mechanism for cognitive deficits in COVID-19

Components that comprise our brain parenchymal and cerebrovascular structures provide a homeostatic environment for proper neuronal function to ensure normal cognition. Cerebral insults (e.g. ischaemia, microbleeds and infection) alter cellular structures and physiologic processes within the neurovascular unit and contribute to cognitive dysfunction. COVID-19 has posed significant complications during acute and convalescent stages in multiple organ systems, including the brain. Cognitive impairment is a prevalent complication in COVID-19 patients, irrespective of severity of acute SARS-CoV-2 infection. Moreover, overwhelming evidence from in vitro, preclinical and clinical studies has reported SARS-CoV-2-induced pathologies in components of the neurovascular unit that are associated with cognitive impairment. Neurovascular unit disruption alters the neurovascular coupling response, a critical mechanism that regulates cerebromicrovascular blood flow to meet the energetic demands of locally active neurons. Normal cognitive processing is achieved through the neurovascular coupling response and involves the coordinated action of brain parenchymal cells (i.e. neurons and glia) and cerebrovascular cell types (i.e. endothelia, smooth muscle cells and pericytes). However, current work on COVID-19-induced cognitive impairment has yet to investigate disruption of neurovascular coupling as a causal factor. Hence, in this review, we aim to describe SARS-CoV-2's effects on the neurovascular unit and how they can impact neurovascular coupling and contribute to cognitive decline in acute and convalescent stages of the disease. Additionally, we explore potential therapeutic interventions to mitigate COVID-19-induced cognitive impairment. Given the great impact of cognitive impairment associated with COVID-19 on both individuals and public health, the necessity for a coordinated effort from fundamental scientific research to clinical application becomes imperative. This integrated endeavour is crucial for mitigating the cognitive deficits induced by COVID-19 and its subsequent burden in this especially vulnerable population.

MCT-Induced Ketosis and Fiber in Rheumatoid Arthritis (MIKARA)-Study Protocol and Primary Endpoint Results of the Double-Blind Randomized Controlled Intervention Study Indicating Effects on Disease Activity in RA Patients

Fatty acids, such as medium-chain fatty acids (MCFAs) and short-chain fatty acids (SCFAs), both important components of a normal diet, have been reported to play a role in bone-related diseases such as rheumatoid arthritis (RA). However, the role of medium-chain triglycerides (MCTs) has not been investigated in RA to date. The aim of this study was to investigate the effect of supplementation of regular diet with MCT with and without fiber on disease activity as measured with the SDAI (Simplified Disease Activity Index) in RA patients. A total of 61 RA patients on stable drug treatment were randomly assigned to a twice-daily control regimen or to a twice-daily regimen of a formulation containing medium-chain triglycerides (MCTs) 30 g/day for 8 weeks followed by a second twice-daily regimen of combining MCT (30 g/day) plus fiber (30 g/day) for an additional 8 weeks. The control group received a formulation containing long-chain triglycerides (LCTs) instead of MCTs. The preliminary results showed a significant reduction in SDAI from baseline to week 16 in the test group and a significant increase in β-hydroxybutyrate (BHB) levels, while no improvement in SDAI was observed in the control group.