ants and Inflammation

Skin reactions to the sting of the imported fire ant have characteristic clinicopathological features.. One case of experimental envenomation was prospectively followed during 48 hours, with biopsies. In addition, 6 cases from our laboratory were retrospectively evaluated histopathologically for the following features: spongiosis, exocytosis (and type of cells), pustule formation, erosion/ulceration, epidermal necrosis, scale/crust, papillary dermal edema, inflammatory dermal infiltrate (cell type, density, depth, distribution, shape), red blood cell extravasation, vasculopathy and vasculitis.. The typical lesion follows a very distinctive clinical and histopathologic evolution over 48 hours, with the formation of a subepidermal pustule overlying a wedge-shaped area of dermal collagen basophilic degeneration with scattered neutrophils. In the 6 cases retrieved from our files, the main features were a superficial and deep dermal, perivascular, periadnexal and interstitial infiltrate consisting of neutrophils, with basophilic degeneration of the collagen. A subepidermal pustule was noted in half of the cases.. In biopsies taken in a clinical setting, even in the absence of the characteristic subepidermal pustule, the diagnosis of imported fire ant sting can be suspected if there is a superficial and deep perivascular, periadnexal and interstitial infiltrate composed of neutrophils, with some basophilic denaturation of collagen.

Topics: Adult; Aged; Aged, 80 and over; Animals; Ant Venoms; Ants; Arthropods; Biopsy; Bites and Stings; Collagen; Dermis; Edema; Epidermis; Exanthema; Female; Humans; Inflammation; Male; Middle Aged; Neutrophils; Retrospective Studies; Skin Diseases; Violence

Dinoponera quadriceps (Hymenoptera, Formicidae, Ponerinae) is a primitive and endemic ant of Northeastern Brazil, that uses its sting and associated venom gland to capture preys and for defense. Venom of Dinoponera is of potential clinical importance, since it causes intense local pain, accompanied by erythema and edema, when injected by the sting. With other hymenopteran venoms, inflammatory effects are also reported. The aim of this study was to evaluate the inflammatory activity of D. quadriceps venom (DqV) in mice. Acrylamide electrophoresis of DqV revealed five main protein bands varying between 15 and 100 kDa, confirming the proteinous nature of DqV. DqV subplantar injection elicited edema at 5 μg/kg (3 fold), 50 μg/kg (4 fold) or 500 μg/kg (7 fold) from zero to 360 min compared to saline. DqV (50 μg/kg) increased vascular permeability (4 fold) in the first hour after induction. The paw tissue histology showed moderate inflammatory focus caused by DqV (50 μg/kg) in the first hour of paw edema, but severe tissue changes (edema, inflammatory infiltrate and focal areas of hemorrhage) in the third hour. Intraperitoneal injection of DqV (50 μg/kg) stimulated neutrophil (7 fold) and mononuclear (1.4 fold) migration vs saline. DqV edematogenic effect was inhibited by dexamethasone (92%), thalidomide (82%), cyproheptadine (62%), AA861 (58%), celecoxib (34%) or l-NAME (34%), but the neutrophil migration was only by dexamethasone (57%). DqV-elicited neutrophil migration at 50 μg/kg was potentiated 1.7 fold by the animals pre-treatment with 3% thioglycolate. DqV injection increased the levels of interleukin-1 beta (IL-1β) in peritoneal cavities. DqV (50, 100 and 200 μg/mL) increased phospholipase activity (A425nm) from 10 min to 40 min. Raw 267 macrophages incubated with DqV (from 3.12 to 50 mg/mL) showed no significant decrease in cell viability or LDH measurements and at 35 μg/mL induced increase in IL-1β (from 3 to 6 h). This study demonstrated, in mice, the inflammatory effect of D. quadriceps venom, characterized by edema, increase in vascular permeability and neutrophil migration, implying the participation of resident macrophages and IL-1β, among other inflammatory mediators.

Topics: Animals; Ant Venoms; Ants; Cell Movement; Cell Survival; Cells, Cultured; Inflammation; Interleukin-1beta; Leukocytes; Macrophages; Mice; Peritonitis; Toxicity Tests

Invertebrates, and especially insects, constitute valuable and convenient models for the study of the evolutionary roots of immune-related behaviors. With stable conditions in the nest, high population densities, and frequent interactions, social insects such as ants provide an excellent system for examining the spread of pathogens. The evolutionary success of these species raises questions about the behavioral responses of social insects to an infected nestmate. In this experiment, we tested the behavioral changes of the red wood ant Formica polyctena toward an immune-stimulated nestmate. We used bacterial endotoxin (lipopolysaccharides, LPS) to active the innate immune system of individual worker ants without biasing our observation with possible cues or host-manipulation from a living pathogen. We show that LPS-induced immune activation in ants triggers behavioral changes in nestmates. Contrary to what would be expected, we did not find removal strategies (e.g. agonistic behaviors) or avoidance of the pathogenic source, but rather a balance between a limitation of pathogen dissemination (i.e. decreased trophallaxis and locomotion of the LPS-treated ant), and what could constitute the behavioral basis for a "social vaccination" (i.e. increased grooming). This supports the importance of social interactions in resistance to disease in social insects, and perhaps social animals in general.

Topics: Animals; Ants; Behavior, Animal; Immunity, Innate; Inflammation; Lipopolysaccharides; Nesting Behavior; Social Behavior