COVID-19 caused by SARS-CoV-2 infection is a highly contagious disease affecting both the higher and lower portions of the respiratory tract. This disease reached over 265 million people and has been responsible for over 5.25 million deaths worldwide. Skeletal muscle quality and total mass seem to be predictive of COVID-19 outcome. This systematic review aimed at providing a critical analysis of the studies published so far reporting on skeletal muscle mass in patients with COVID-19, with the intent of examining the eventual association between muscle status and disease severity. A meta-analysis was performed to evaluate whether skeletal muscle quantity, quality and function were related to disease severity. Systematic reviews and meta-analyses were conducted according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions and reported according to the guidelines of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guide. From a total of 1,056 references found, 480 were selected after removing duplicates. Finally, only 7 met the specified inclusion criteria. The results of this meta-analysis showed that skeletal muscle quality, rather than quantity, was associated with COVID-19 severity, as confirmed by lower skeletal muscle density and lower handgrip strength in patients with severe disease. Muscle function assessment can thus be a valuable tool with prognostic value in COVID-19.

Cachexia is a syndrome that affects the entire organism and presents a variable plethora of symptoms in patients, always associated with continuous and involuntary degradation of skeletal muscle mass and function loss. In cancer, this syndrome occurs in 50% of all patients, while prevalence increases to 80% as the disease worsens, reducing quality of life, treatment tolerance, therapeutic response, and survival. Both chronic systemic inflammation and immunosuppression, paradoxically, correspond to important features in cachexia patients. Systemic inflammation in cachexia is fueled by the interaction between tumor and peripheral tissues with significant involvement of infiltrating immune cells, both in the peripheral tissues and in the tumor itself. Autophagy, as a process of regulating cellular metabolism and homeostasis, can interfere with the metabolic profile in the tumor microenvironment. Under a scenario of balanced autophagy in the tumor microenvironment, the infiltrating immune cells control cytokine production and secretion. On the other hand, when autophagy is unbalanced or dysfunctional within the tumor microenvironment, there is an impairment in the regulation of immune cell’s inflammatory phenotype. The inflammatory phenotype upregulates metabolic consumption and cytokine production, not only in the tumor microenvironment but also in other tissues and organs of the host. We propose that cachexia-related chronic inflammation can be, at least, partly associated with the failure of autophagic processes in tumor cells. Autophagy endangers tumor cell viability by producing immunogenic tumor antigens, thus eliciting the immune response necessary to counteract tumor progression, while preventing the establishment of inflammation, a hallmark of cachexia. Comprehensive understanding of this complex functional dichotomy may enhance cancer treatment response and prevent/mitigate cancer cachexia. This review summarizes the recent available literature regarding the role of autophagy within the tumor microenvironment and the consequences eliciting the development of cancer cachexia.

Gonçalves RC. Translational study of the metabolic regulation of the microenvironment tumor through physical training in modulating the antitumor immune response in cancer patients [thesis]. São Paulo: "Faculdade de Medicina, Universidade de São Paulo"; 2022. Millions of people are diagnosed with cancer every year, of which more than half do not survive. The second and third most common types are colon and stomach. In the last decade, research efforts regarding the role of the immune system in the eradication of malignant cells have been significantly reinforced by major discoveries such as T cells, which recognize, regulate and eradicate cancer cells, representing an important advance in the treatment of cancer. cancer. Dendritic cells are constantly monitoring the environment and when activated by the encounter of microorganisms or other patterns of tissue damage, they have a stimulating role to a T cell response, extremely necessary for the induction of the atitumoral immune response. Observational studies indicate that practice of post-diagnostic cancer exercise is associated with risk reductions of recurrence and specific mortality (as well as general mortality) in patients with non-metastatic, prostate and colorectal breast cancer. Physical exercise is able to reduce systemic

Fernandes, minha orientadora, que acreditou muito nesse trabalho, me acolheu e me ensinou a não desistir diante das dificuldades neste percurso, sempre com muita paciência. Ao professor Dr. Francisco Raphael Martins Laurindo, que com todo o seu