Banca de QUALIFICAÇÃO: LUDMILA DE JESUS PEREIRA DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUDMILA DE JESUS PEREIRA DA SILVA
DATE: 02/10/2025
TIME: 09:30
LOCAL: Sala 5 do CICS
TITLE:

The immunomodulatory role of Stomoxys calcitrans (L.) saliva

 

KEY WORDS:

vector insects, Immune system, Macrophages, Leishmania infantum, Herpetomonas muscarum.

PAGES: 53
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUMMARY:

Stomoxys calcitrans (L.), commonly known as the stable fly, is a hematophagous insect of the order Diptera. Its bite causes intense pain in hosts, which are mainly cattle and horses. When present in large numbers, it leads to significant blood loss and stress, resulting in weight loss and a reduction in meat and milk production, with a major economic impact on agricultural activities. During blood feeding, the insect can mechanically transmit various pathogens to the host, causing further losses. The saliva of hematophagous insects contains several pharmacologically active molecules that facilitate feeding and can also influence pathogen infection through immunomodulatory effects on their hosts. This immunomodulatory potential can affect different cells of the immune system, including macrophages—cells of the innate immune system that have the potential to secrete large amounts of cytokines and pro-inflammatory mediators. The genus Herpetomonas is a monophyletic group, present on almost all continents, associated with a wide variety of insect species, and has potential for use in the biological control of its hosts. Recently, the species Herpetomonas muscarum was isolated from S. calcitrans for the first time by our group. Leishmaniases comprise a group of diseases that may present with four distinct clinical manifestations, depending on the species of the parasite (cutaneous, diffuse cutaneous, mucocutaneous, and visceral). Visceral leishmaniasis, also known as kala-azar, among other regional names, is a systemic and chronic disease. In Brazil, it is caused by the species Leishmania infantum and transmitted by phlebotomine sandflies. Visceral leishmaniasis (VL) is a zoonotic disease known to affect several animal species, such as marsupials, rodents, edentates, and canids, with dogs being the main reservoir and source of human infection in urban areas. Given the above, the main objective of this study is to analyze the immunomodulatory effect of the salivary gland extract of S. calcitrans on macrophages, as well as to evaluate its cytotoxicity on promastigote forms of L. infantum and opimastigote forms of H. muscarum, and to assess the cytotoxicity of the salivary gland extract on macrophages—the host cell of L. infantum—through a colorimetric assay. We also aim to elucidate the possible mechanisms of action of the salivary gland extract through the production of nitric oxide and reactive oxygen species, cytokine production, and evaluation of parasite load in macrophages infected with L. infantum in the presence and absence of fly saliva. Additionally, we will evaluate the growth curve of the protozoa after treatment and the mitochondrial membrane potential of the protozoa following treatment with the salivary gland extract (SGE) of S. calcitrans. Preliminary results showed that the salivary gland extract of S. calcitrans does not have cytotoxic potential for macrophages. The saliva showed no significant effect on binding or phagocytosis in macrophages infected with L. infantum. However, an increase in NO was observed in macrophages previously treated with saliva, whether stimulated or not with IFN and LPS. When evaluating the direct effect of the extract on L. infantum promastigotes and H. muscarum opimastigotes, proliferation of H. muscarum was observed along with a lower survival rate of L. infantum compared to untreated controls. The saliva of S. calcitrans plays an important role in the parasitic control of L. infantum and in the establishment of H. muscarum in the fly.

COMMITTEE MEMBERS:
Interna - 1335855 - DANIELLE DE OLIVEIRA NASCIMENTO
Interna - 1792175 - PATRICIA FAMPA NEGREIROS LIMA
Externo ao Programa - 1674073 - BRUNO GUIMARAES MARINHO - UFRRJExterno ao Programa - ***.389.836-** - MATHEUS DIAS CORDEIRO - UFRRJ