Avaliação da expressão gênica diferencial e da histopatologia de diferentes órgãos de camundongos em resposta ao envenenamento por Micrurus corallinus

Abstract

Snakes of the Elapidae family possess highly toxic venoms due to the presence of lethal neurotoxins. These venoms are rich, particularly, in two neurotoxic families of proteins: α-neurotoxins and phospholipases A2 (PLA2s). In the American continent, the Elapidae family is represented by the coral snakes group, which includes three genera (Micrurus, Leptomicrurus and Micruroides). Micrurus genus is the most specious among them and M. frontalis and M.corallinus are the most important species in Brazil in terms of public health. Their venoms are employed for the antivenoms production used in micruric envenoming. In the present work, we used RNA-Seq to gain deeper knowledge on the effects of M. corallinus venom, local and systemically, in a mice model injected with sublethal doses of the venom. Tissue samples from the brain, kidney, liver, spleen, heart, diaphragm and both gastrocnemius muscles were collected for total RNA isolation, at 8 and 24 hours after venom injection. Then, cDNA libraries were prepared and the sequencing was run in an Illumina HiSeq1500 instrument. The data obtained from the sequencing were processed by suitable bioinformatic programs. Those genes that changed their expression for a two-fold change cutoff (FDR ≤ 0.05) were submitted to enrichment analyses so as to investigate the affected pathways and networks. On the other hand, histopathological analyses were carried in order to help in the results interpretation. In terms of differential gene expression, the results showed a strong response in the right gastrocnemius, local of venom inoculation. The enrichment analyses identified a myriad of genes involved in pathways and networks related to cell adhesion, chemotaxis and inflammation processes, mainly at 8 hours. These findings were consistent with the histopathological observations, which showed an important leukocyte infiltrate and edema. At 24 hours, in addition to the identification of several pathways and networks involved in inflammatory processes, others related to cell cycle were also noticed, indicating the activation of satellite cells, responsible for the restoration of muscle tissue homeostasis. The systemic effects were more discrete and the liver was the organ exhibiting the greatest alterations among the other tissues and organs studied. Enrichment analyses of liver samples pointed out, at both times, the IL-6 signaling pathway as the most relevant one. In this pathway, normally activated in the presence of inflammatory processes, several up-regulated transcripts coding for acute phase proteins were identified. In addition, toxicity enrichment analyses revealed that a set of genes involved in the xenobiotics metabolism was down-regulated. The other samples studied did not show relevant results in the context of the experimental conditions. High-throughput technologies have been poorly exploited in the “toxicovenomic” field so far. Here, through the combination of a modern technology, RNA-seq, a powerful tool for the study of transcriptomes, bioinformatics programs and a traditional approach, such as histology, it was possible to obtain a comprehensive view of the molecular mechanisms underlying the pathological effects in response to venom of M. corallinus. Keywords: Envenoming, Micrurus corallinus,