Background: The main targets of the host’s immune system inTrichinella spiralisinfection are the adult worms (AW), at the gut level, and the migrant or newborn larvae (NBL), at systemic and pulmonary levels. Most of the studies carried out in the gut mucosa have been performed on the Payer’s patches and/or the mesenteric lymph nodes but not on the lamina propria, therefore, knowledge on the gut immune response againstT. spiralisremains incomplete.Methods: This study aimed at characterizing the early mucosal immune response againstT. spiralis, particularly, the events taking place between 1 and 13 dpi. For this purpose, Wistar rats were orally infected with muscle larvae ofT. spiralisand the humoral and cellular parameters of the gut immunity were analysed, including the evaluation of the ADCC mechanism exerted by lamina propria cells.Results: A marked inflammation and structural alteration of the mucosa was found. The changes involved an increase in goblet cells, eosinophils and mast cells, and B and T lymphocytes, initially displaying a Th1 profile, characterised by the secretion of IFN-γ and IL-12, followed by a polarization towards a Th2 profile, with a marked increase in IgE, IgG1, IL-4, IL-5 and IL-13 levels, which occurred once the infection was established. In addition, the helminthotoxic activity of lamina propria cells demonstrated the role of the intestine as a place of migrant larvae destruction, indicating that not all the NBLs released in the gut will be able to reach the muscles.Conclusions: The characterization of the immune response triggered in the gut mucosa duringT. spiralisinfection showed that not only an effector mechanism is directed toward the AW but also towards the NBL as a cytotoxic activity was observed against NBL exerted by lamina propria cells.

Helminths are a major health concern as over one billion people are infected worldwide and, despite the multiple efforts made, there is still no effective human vaccine against them. The most important drugs used nowadays to control helminth infections belong to the benzimidazoles, imidazothiazoles (levamisole) and macrocyclic lactones (avermectins and milbemycins) families. However, in the last 20 years, many publications have revealed increasing anthelmintic resistance in livestock which is both an economical and a potential health problem, even though very few have reported similar findings in human populations. To deal with this worrying limitation of anthelmintic drugs, alternative treatments based on plant extracts or probiotics have been developed. Probiotics are defined by the Food and Agriculture Organization as live microorganisms, which, when consumed in adequate amounts, confer a health benefit to the host. It has been proven that probiotic microbes have the ability to exert an immunomodulatory effect both at the mucosa and the systemic level. The immune response against gastrointestinal helminths is characterized as a type 2 response, with high IgE levels, increased numbers and/or activity of Th2 cells, type 2 innate lymphoid cells, eosinophils, basophils, mast cells, and alternatively activated macrophages. The oral administration of probiotics may contribute to controlling gastrointestinal helminth infections since it has been demonstrated that these microorganisms stimulate dendritic cells to elicit a type 2 or regulatory immune response, among other effects on the host immune system. Here we review the current knowledge about the use of probiotic bacteria as anthelmintic therapy or as a complement to traditional anthelmintic treatments. Considering all research papers reviewed, we may conclude that the effect generated by probiotics on helminth infection depends not only on the parasite species, their stage and localization but also on the administration scheme.

Trichinella spiralis muscle larvae-derived extracellular vesicles (TsEV) are key mediators of host–parasite interaction, yet the impact of isolation protocols on their properties and function remains unclear. This study compared four TsEV isolation protocols differing in culture duration (20 h vs. 4 days) and medium composition (with or without fetal bovine serum, FBS). Dynamic light scattering revealed that FBS supplementation yielded small particles (average ~150 nm), whereas FBS-free protocols produced larger, more heterogeneous populations, particularly with extended culture. Proteomic analysis identified a constitutive protein core across all conditions, alongside protocol-specific proteins, with exportin-1 consistently more abundant under FBS-free conditions irrespective of culture duration. Functional assays in RAW 264.7 macrophages showed that TsEV induced both nitric oxide (NO) and arginase activity, but the magnitude and kinetics of these responses varied markedly depending on the protocol. Among the conditions tested, Protocol 3 (4 days without FBS) induced the highest NO levels, whereas Protocol 4 (4 days with FBS) showed the strongest potentiation of lipopolysaccharide (LPS)-induced arginase. These divergent profiles likely reflect differences in EVs’ size and cargo arising from distinct culture conditions, although the relative contribution of duration and medium composition could not be fully dissected. Our findings demonstrate that culture parameters profoundly influence TsEVs’ properties and immunomodulatory capacity, underscoring the need for standardized isolation protocols.