Microcirculation abnormalities provoked by Loxosceles spiders' envenomation

Area of Science:

• Toxicology
• Immunology
• Microcirculation Research

Background:

• Loxoscelism, caused by Loxosceles spider venom, presents with local (dermonecrosis) and systemic (hemolysis, coagulation, renal failure) effects.
• Microcirculatory network alterations are implicated in inflammatory disease pathogenesis.
• Understanding venom's impact on microcirculation is crucial for Loxoscelism treatment.

Purpose of the Study:

• To investigate the effects of male and female Loxosceles intermedia and Loxosceles laeta venoms on the microcirculatory network.
• To examine the systemic production of inflammatory mediators in a murine model of Loxoscelism.
• To correlate microcirculatory changes with inflammatory mediator levels.

Main Methods:

• Murine model of Loxoscelism induced by systemic envenomation.
• Observation of microcirculatory network alterations, including leukocyte rolling and adhesion.
• Measurement of serum levels of inflammatory mediators, such as TNF-α and NO.

Main Results:

• Systemic envenomation caused increased leukocyte rolling in the microcirculation.
• Female Loxosceles spider venoms induced more intense leukocyte rolling compared to male venoms.
• Increased rolling correlated with higher serum levels of TNF-α and NO, with female venoms showing greater induction.

Conclusions:

• Female Loxosceles venoms have a more pronounced effect on microcirculation and inflammatory mediator production in mice.
• Increased leukocyte rolling without enhanced adhesion/extravasation may explain the absence of cutaneous Loxoscelism in mice.
• Targeting neutrophil adhesion and extravasation could be a therapeutic strategy to prevent cutaneous pathology in envenomed patients.