The immune response against Trichinella spiralis at the intestinal level depends on the CD4⁺ T cells, which can both suppress or promote the inflammatory response through the synthesis of diverse cytokines. During the intestinal phase, the immune response is mixed (Th1/Th2) with the initial predominance of the Th1 response and the subsequent domination of Th2 response, which favor the development of intestinal pathology. In this context, the glucocorticoids (GC) are the pharmacotherapy for the intestinal inflammatory response in trichinellosis. However, its therapeutic use is limited, since studies have shown that treatment with GC suppresses the host immune system, favoring T. spiralis infection. In the search for novel pharmacological strategies that inhibit the Th1 immune response (proinflammatory) and assist the host against T. spiralis infection, recent studies showed that resiniferatoxin (RTX) had anti-inflammatory activity, which decreased the serum levels of IL-12, INF-γ, IL-1β, TNF-α, NO, and PGE₂, as well the number of eosinophils in the blood, associated with decreased intestinal pathology and muscle parasite burden. These researches demonstrate that RTX is capable to inhibit the production of Th1 cytokines, contributing to the defense against T. spiralis infection, which places it as a new potential drug modulator of the immune response.
Cytokines ; Drug Therapy ; Eosinophils ; Glucocorticoids ; Immune System ; Inflammation* ; Interleukin-12 ; Parasites ; Pathology ; T-Lymphocytes ; Therapeutic Uses* ; Trichinella spiralis ; Trichinellosis*

Members of the genus Trichinella are small nematodes that can infect a wide range of animal hosts. However, their infectivity varies depending on the parasite and host species combination. In this study, we examined the susceptibility of 4 species of laboratory rodents, i.e., mice, rats, hamsters, and gerbils to Trichinella papuae, an emerging non-encapsulated Trichinella species. Trichinella spiralis and Trichinella pseudospiralis were also included in this study for comparison. Fifteen animals of each rodent species were infected orally with 100 muscle larvae of each Trichinella species. Intestinal worm burden was determined at day 6 and 10 post-inoculation (PI). The numbers of muscle larvae were examined at day 45 PI. The reproductive capacity index (RCI) of the 3 Trichinella species in different rodent hosts was determined. By day 6 PI, 33.2-69.6% of the inoculated larvae of the 3 Trichinella species became adult worms in the small intestines of the host animals. However, in rats, more than 96% of adult worms of all 3 Trichinella species were expelled from the gut by day 10 PI. In gerbils, only 4.8-18.1% of adult worms were expelled by day 10 PI. In accordance with the intestinal worm burden and the persistence of adults, the RCI was the highest in gerbils with values of 241.5+/-41.0 for T. papuae, 432.6+/-48 for T. pseudospiralis, and 528.6+/-20.6 for T. spiralis. Hamsters ranked second and mice ranked third in susceptibility in terms of the RCI, Rats yielded the lowest parasite RCI for all 3 Trichinella species. Gerbils may be an alternative laboratory animal for isolation and maintenance of Trichinella spp.
Animals ; *Animals, Laboratory ; Cricetinae ; *Disease Susceptibility ; Gerbillinae ; Intestines/parasitology ; Male ; Mice ; Muscles/parasitology ; Parasite Load ; Rats ; Rodent Diseases/*parasitology/pathology ; Trichinella/*growth & development ; Trichinellosis/parasitology/pathology/*veterinary

Reptiles, unlike mammals, have been considered to be unsuitable hosts of Trichinella spp., though larvae have been detected in their muscles and human outbreaks related to their consumption have, in fact, occurred. Herein we report 2 Korean cases of trichinosis, possibly transmitted via consumption of reptile meat. Both patients suffered from myalgia, headache, and facial edema. Laboratory examinations revealed leukocytosis with eosinophilia (54% and 39%, respectively) and elevated creatinine phosphokinase. ELISA was performed under the suspicion of trichinosis, showing positivity at the 29th and 60th day post-infection. Since they had consumed raw soft-shelled turtle meat, turtle was strongly suggested to be an infection source of trichinosis in Korea next to the wild boar and badger.
Adult ; Animals ; Enzyme-Linked Immunosorbent Assay ; Foodborne Diseases/*diagnosis/parasitology/*pathology ; Humans ; Korea ; Male ; Meat ; Serologic Tests ; Trichinella/*isolation & purification ; Trichinellosis/*diagnosis/parasitology/*pathology ; Turtles

OBJECTIVE: To explore forensic pathology features of the fatal trichinosis cases and to summarize the population distribution characteristics of trichinosis in Yunnan. METHODS: Nine recent fatal trichinosis cases were collected from the Forensic Science Identification Center of Kunming Forensic Hospital. Pathological and epidemiological characteristics of trichinosis were analyzed. RESULTS: The nine cases were all died in heart failure due to myocarditis. Among them, 1 case was complicated by encephalitis and 3 cases were complicated by pneumonia. The population mainly involved Bai and Dai nationalities. The geographic distribution was concentrated in Dali, Dehong, Lincang, Xishuangbanna, etc. The cases commonly appeared in winter and spring. CONCLUSION The cause of trichinosis is closely due to the habit of eating raw pork. It can be diagnosis through the pathological changes of the muscle system in the death cases.
Adult ; Animals ; Cause of Death ; China/epidemiology* ; Female ; Food Contamination ; Forensic Pathology ; Heart Failure/etiology* ; Humans ; Male ; Meat/parasitology* ; Middle Aged ; Muscle, Skeletal/pathology* ; Myocarditis/pathology* ; Myocardium/pathology* ; Swine ; Trichinellosis/pathology* ; Young Adult

In intestinal helminth infections, Th2 immune respones are generally associated with mucin secretion for worm expulsion from the host intestine. In particular, IL-4 and IL-13 are the important cytokines related with intestinal mucus production via STAT6 signalling in nematode infections. However, this perspective has never been studied in Gymnophalloides seoi infection. The present study aimed to observe the STAT6 signalling and cytokine responses in C57BL/6 mice, a mouse strain resistant to infection with this trematode. The results showed that worm expulsion occurred actively during days 1-2 post-infection (PI), when goblet cells began to proliferate in the small intestine. The STAT6 gene expression in the mouse spleen became remarkable from day 2 PI. Moreover, G. seoi infection induced a significant increase of IL-13 from day 4 PI in the spleen of infected mice. Our results suggested that goblet cell hyperplasia and worm expulsion in G. seoi-infected mice should be induced by STAT6 signalling, in which IL-13 may be involved as a dominant triggering cytokine.
Animals ; Crassostrea ; Female ; Goblet Cells/*pathology ; Hyperplasia/pathology ; Interleukin-13/*metabolism ; Interleukin-4/*metabolism ; Intestine, Small/immunology ; Metacercariae ; Mice ; Mice, Inbred C57BL ; STAT6 Transcription Factor/*metabolism ; Signal Transduction ; Specific Pathogen-Free Organisms ; Spleen/immunology ; Trematoda/*immunology ; Trichinellosis/*immunology/parasitology

The 5th outbreak of trichinosis occurred in a mountainous area of North Vietnam in 2012, involving 24 patients among 27 people who consumed raw pork together. Six of these patients visited several hospitals in Hanoi for treatment. Similar clinical symptoms appeared in these patients within 5-8 days after eating infected raw pork, which consisted of fever, muscle pain, difficult moving, edema, difficult swallowing, and difficult breathing. ELISA revealed all (6/6) positive reactions against Trichinella spiralis antigen and all cases showed positive biopsy results for Trichinella sp. larvae in the muscle. The larvae detected in the patients were identified as T. spiralis (Vietnamese strain) by the molecular analysis of the mitochondrial cytochrome c oxidase subunit III (cox3) gene.
Adult ; Animals ; Antigens, Helminth/analysis/immunology ; *Disease Outbreaks ; Electron Transport Complex IV/genetics ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Larva ; Male ; Meat/*parasitology ; Mitochondria/genetics ; Muscles/parasitology/pathology ; Swine ; Trichinella spiralis/genetics/immunology/*isolation & purification ; Trichinellosis/*epidemiology/parasitology/pathology ; Vietnam/epidemiology

In order to know the effect of pre-existing Trichinella spiralis infection on experimentally induced intestinal inflammation and immune responses, we induced colitis in T. spiralis-infected mice and observed the severity of colitis and the levels of Th1, Th2, and regulatory cytokines and recruitment of CD4+CD25+Foxp3+ T (regulatory T; Treg) cells. Female C57BL/6 mice were infected with 250 muscle larvae; after 4 weeks, induction of experimental colitis was performed using 3% dextran sulfate sodium (DSS). During the induction period, we observed severity of colitis, including weight loss and status of stool, and evaluated the disease activity index (DAI). A significantly low DAI and degree of weight loss were observed in infected mice, compared with uninfected mice. In addition, colon length in infected mice was not contracted, compared with uninfected mice. We also observed a significant increase in production of pro-inflammatory cytokines, IL-6 and IFN-gamma, in spleen lymphocytes treated with DSS; however, such an increase was not observed in infected mice treated with DSS. Of particular interest, production of regulatory cytokines, IL-10 and transforming growth factor (TGF)-beta, in spleen lymphocytes showed a significant increase in mice infected with T. spiralis. A similar result was observed in mesenteric lymph nodes (MLN). Subsets of the population of Treg cells in MLN and spleen showed significant increases in mice infected with T. spiralis. In conclusion, T. spiralis infection can inhibit the DSS-induced colitis in mice by enhancing the regulatory cytokine and Treg cells recruitment.
Animals ; Colitis/chemically induced/*immunology/pathology ; Cytokines/genetics/*immunology/metabolism ; Dextran Sulfate/adverse effects ; Disease Models, Animal ; Female ; Forkhead Transcription Factors/immunology/metabolism ; *Gene Expression Regulation ; Larva ; Mice ; Mice, Inbred C57BL ; Spleen/immunology ; T-Lymphocytes, Regulatory/*immunology ; Trichinella spiralis/*immunology ; Trichinellosis/*immunology/parasitology