O efeito imunomodulador de derivados do ácido ursólico nos modelos murinos de edema de pata e encefalomielite autoimune experimental

Abstract

Inflammation is a natural protective response of the body triggered by specific cells in the body in response to infections or cellular damage, to ensure the removal of harmful stimuli. However, a long-term inflammatory response has a detrimental effect and plays a critical role in the development of several chronic inflammatory diseases. It is believed that interventions in the inflammatory process are a potential therapeutic target to reduce the risk of diseases, which are often disabling, such as Multiple Sclerosis. The use of experimental murine models of inflammatory diseases is important for evaluating the immunomodulatory potential of new substances with therapeutic potential. Within this context, the induction of edema in mouse paws by carrageenan, for example, is an experimental model widely used to test the anti-inflammatory activity of new substances, where acute inflammation is associated with increased levels of pro-inflammatory cytokines. inflammatory. In the evaluation of a chronic inflammatory process of an autoimmune nature, experimental autoimmune encephalomyelitis (EAE) stands out, an animal model used to study Multiple Sclerosis, a chronic inflammatory disease of autoimmune origin, characterized by inflammation, demyelination, loss axonal and gliosis. It is also known that 3β-hydroxy-urs-12-en-28-oic acid called ursolic acid (AU), a triterpenoid compound widely found in nature, has anti-inflammatory activity. Therefore, the present work aimed to evaluate the immunomodulatory effect of UA and its derivatives methyl 3β-hydroxy-urs-12-en-28-oate (AUD1) and 3β-acetoxy-urs-12-en-28 -methyl oate (AUD2) in murine models of carrageenan-induced paw edema and experimental autoimmune encephalomyelitis (EAE). In the carrageenan-induced paw edema model, the reduction of paw edema and IL-6 levels in paw macerates and lymph nodes of female BALB/c mice that received treatments with AU, AUD1 or AUD2 (200mg/kg i.p.) ink minutes before model induction. In the EAE model, the use of AU and its derivatives AUD1 and AUD2 in the evolution of the disease induced in female C57BL/6 mice through the application of MOG35–55 was investigated. On the 15th day after MOG induction, mice were treated with AU, AUD1 or AUD2 (50 mg/kg i.p.) for six days. Parameters were evaluated in the spinal cord, lymph nodes and brain on the 21st day after induction and clinical signs were monitored until the 21st day after induction. The results showed a significant reduction in paw edema, accompanied by a reduction in the levels of the proinflammatory cytokine IL-6 in the supernatant of paw macerates and lymph nodes, in the groups treated with AU, AUD1 and AUD2. In the context of the acute inflammation model, both AUD1 and AUD2 demonstrated comparable efficacy to dexamethasone, an antiinflammatory widely used in clinical practice.Treatments with AUD1 and AUD2 attenuated the clinical signs of EAE, in a similar way, with a reduction in the number of cells CD11c+MHC-II+, CD11c+CD80+, CD11c+CD86+, CD4+, CD8+, CD4+IL-17+ and CD4+IFNγ+ in the brain and reduction of pro-inflammatory cytokines IL-1β and TNF-α in the bone marrow. However, in the periphery, while AUD2 inhibited the number of CD11c+MHC-II+, CD11c+CD80+, CD11c+CD86+, CD4+, CD8+, CD4+IL-17+ and CD4+IFNγ+ cells, AUD1 promoted an increase in number of regulatory CD4+FOXP3+IL10+ cells and a reduction in the number of CD4+, CD8+, CD4+IL-17+ cells. In conclusion, in the EAE model, the regulation of immune cells in the periphery and the reduction in the number of pro-inflammatory cells in the CNS with treatments with AUD1 and AUD2 correlated with better histological aspects in the CNS that culminated in efficacy on the clinical parameters presented. in EAE, suggesting a therapeutic potential in the treatment of MS.