The Role of Dysbiosis in Critically Ill Patients With COVID-19 and Acute Respiratory Distress Syndrome.

In late December 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) quickly spread worldwide, and the syndrome it causes, coronavirus disease 2019 (COVID-19), has reached pandemic proportions. Around 30% of patients with COVID-19 experience severe respiratory distress and are admitted to the intensive care unit for comprehensive critical care. Patients with COVID-19 often present an enhanced immune response with a hyperinflammatory state characterized by a "cytokine storm," which may reflect changes in the microbiota composition. Moreover, the evolution to acute respiratory distress syndrome (ARDS) may increase the severity of COVID-19 and related dysbiosis. During critical illness, the multitude of therapies administered, including antibiotics, sedatives, analgesics, body position, invasive mechanical ventilation, and nutritional support, may enhance the inflammatory response and alter the balance of patients' microbiota. This status of dysbiosis may lead to hyper vulnerability in patients and an inappropriate response to critical circumstances. In this context, the aim of our narrative review is to provide an overview of possible interaction between patients' microbiota dysbiosis and clinical status of severe COVID-19 with ARDS, taking into consideration the characteristic hyperinflammatory state of this condition, respiratory distress, and provide an overview on possible nutritional strategies for critically ill patients with COVID-19-ARDS.

Clinical efficacy of eucaloric ketogenic nutrition in the COVID-19 cytokine storm: A retrospective analysis of mortality and intensive care unit admission.

OBJECTIVES: Our primary objective was to explore the effect of a eucaloric ketogenic diet (EKD) on mortality, admission to the intensive care unit, and need for non-invasive ventilation in hospitalized patients with COronaVIrus Disease 19 (COVID-19), in comparison to a eucaloric standard diet. Secondary objectives were verification of the safety and feasibility of the diet and its effects on inflammatory parameters, particularly interleukin-6. METHODS: The study is a retrospective analysis of 34 patients fed with an EKD in comparison to 68 patients fed with a eucaloric standard diet, selected and matched using propensity scores 1:2 to avoid the confounding effect of interfering variables. Our hypothesis was that an EKD would reduce mortality, admission to the intensive care unit, and need for non-invasive ventilation in patients with COVID-19. RESULTS: The preliminary multivariate analysis showed a statistically significant difference in survival (P = 0.046) and need for the intensive care unit (P = 0.049) for the EKD compared with a eucaloric standard diet. Even considering the EKD start day as a time-dependent variable, the results maintain a positive trend for application of the diet, and it is not possible to reject the null hypothesis (P < 0.05). Interleukin-6 concentrations between t0 and t7 (7 d after the beginning of the diet) in the ketogenic nutrition group show a trend that is almost significant (P = 0.062). The EKD was safe and no adverse events were observed. CONCLUSIONS: These results show a possible therapeutic role of an EKD in the clinical management of COVID-19. Currently, a prospective controlled randomized trial is running to confirm these preliminary data.

Induction of ketosis as a potential therapeutic option to limit hyperglycemia and prevent cytokine storm in COVID-19.

The severe form of coronavirus disease 19 (COVID-19) is characterized by cytokine storm syndrome (CSS) and disseminated intravascular coagulation (DIC). Diabetes, obesity, and hypertension have, as minor common denominators, chronic low-grade inflammation and high plasma myeloperoxidase levels, which could be linked to pulmonary phagocytic hyperactivation and CSS. The hyperactivation of M1 macrophages with a proinflammatory phenotype, which is linked to aerobic glycolysis, leads to the recruitment of monocytes, neutrophils, and platelets from circulating blood and plays a crucial role in thrombo-inflammation (as recently demonstrated in COVID-19) through the formation of neutrophil extracellular traps and monocyte-platelet aggregates, which could be responsible for DIC. The modulation of glucose availability for activated M1 macrophages by means of a eucaloric ketogenic diet (EKD) could represent a possible metabolic tool for reducing adenosine triphosphate production from aerobic glycolysis in the M1 macrophage phenotype during the exudative phase. This approach could reduce the overproduction of cytokines and, consequently, the accumulation of neutrophils, monocytes, and platelets from the blood. Second, an EKD could be advantageous for the metabolism of anti-inflammatory M2 macrophages because these cells predominantly express oxidative phosphorylation enzymes and are best fed by the oxidation of fatty acids in the mitochondria. An EKD could guarantee the availability of free fatty acids, which are an optimal fuel supply for these cells. Third, an EKD, which could reduce high lactate formation by macrophages due to glycolysis, could favor the production of interferon type I, which are inhibited by excessive lactate production. From a practical point of view, the hypothesis, in addition to being proven in clinical studies, must obviously take into account the contraindications of an EKD, particularly type 1 or 2 diabetes treated with drugs that can cause hypoglycemia, to avoid the risk for side effects of the diet.