Dissertação
Estimulação elétrica da via anti-inflamatória colinérgica protege da doença do enxerto-versus-hospedeiro (GVHD)
Fecha
2021-05-28Autor
Layara Roberta Ferreira Duarte
Institución
Resumen
Graft-versus-host disease (GVHD) is a systemic inflammatory syndrome that occurs
after allogeneic hematopoietic stem cell transplantation. This disease affects GVHD target
organs, including liver, intestine and spleen. The cholinergic anti-inflammatory pathway
(CAIP), a neurological mechanism capable of controlling peripheral inflammation through the
vagus nerve, has been shown to be important in immune system modulation and reducing
inflammation in several models of inflammatory diseases such as colitis, sepsis and rheumatoid
arthritis. However, there are no studies exploring this neuroimmune regulation in GVHD.
Therefore, the aim of this study was to evaluate the role of the cholinergic anti-inflammatory
pathway in modulation of the GVHD inflammatory response. Acute GVHD was induced by
transplant of allogeneic bone marrow cells and splenocytes from Balb/c mice to C57BL/6J in
GVHD and GVHD+VNS groups. Mice that received bone marrow cells and splenocytes from
syngeneic animals (C57BL/6J) did not develop any disease and were considered the control
group. To analyze the CAIP stimulation, GVHD+VNS mice were subjected to vagus nerve
electrical stimulation (VNS) 6 hours before the transplant. The liver and intestine were
processed for histopathological analysis and the stimulated animals showed reduced intestinal
and hepatic injury, while the animals in the GVHD group had severe intestinal injuries leading
the loss of the organ architecture and a proeminent inflammatory infiltrate in the liver. ELISA
assays for the main inflammatory cytokines and chemokines were also performed and the
GVHD+VNS group presented an increase in intestinal levels of IL-10, TNF-α and CCL2 and a
decrease in hepatic levels of CCL2, CCL5 and TNF-α. We also observed a reduction in splenic
atrophy in GVHD+VNS mice. N-acetil-β-D-glicosaminidase (NAG), myeloperoxidase (MPO)
and peripheral blood smear assays were performed to quantify the total and differential
leukocytes in the intestine, liver, spleen and blood. The mice that received electrical stimulation
showed a reduction in the infiltrate of neutrophils in the spleen and macrophages in the liver.
Moreover, there was a reduction in lymphopenia and neutrophilia related to GVHD in the
GVHD+VNS group. Cardiac function was also analyzed by echocardiogram and in the
GVHD+VNS group, we observed a prevention of cardiac damage related to graft-versus-host
disease. Finally, recipient mice were clinically evaluated with a standard scoring system and
monitored for mortality. Electrical stimulation resulted in effective protection from GVHD,
reducing clinical signs and lethality of the disease. Altogether, our results demonstrated that the
activation of the cholinergic anti-inflammatory pathway contributes to regulation of
inflammatory response and severity related to GVHD. Thus, VNS has a potential therapeutic
application in graft-versus-host disease treatment.