Evaluating the Toxocara cati extract as a therapeutic agent for allergic airway inflammation.

BACKGROUND: The hygiene hypothesis suggests that early life exposure to helminth infections can reduce hypersensitivity in the immune system. OBJECTIVE: The present study aims to evaluate the effects of Toxocara cati (T. cati) somatic products on allergic airway inflammation. METHODS: Between 2018 and 2020, T. cati adult worms were collected from stray cats in Mashhad, Iran (31 out of 186 cats), and their somatic extract was collected. Thirty BALB/c mice were equally divided into three groups, including the OVA group (sensitized and challenged with ovalbumin), the somatic administered group (received somatic extract along with ovalbumin sensitization), and the PBS group (sensitized and challenged with phosphate buffer saline). Bronchoalveolar lavage (BAL) fluid was collected to assess the number of cells, and lung homogenates were prepared for cytokine analysis. Histopathological analysis of the lungs was performed, and inflammatory cells and mucus were detected. Cytokine levels (IL-4, IL-5, IL-10) were measured using enzyme-linked immunosorbent assay (ELISA), and ovalbumin-specific immunoglobulin E (IgE) levels were determined using a capture ELISA. RESULTS: The somatic group significantly decreased regarding the lung pathological changes, including peribronchiolitis, perivasculitis, and eosinophil influx, compared to the group treated with ovalbumin alone. These changes were accompanied by a decrease in proinflammatory cytokines IL-4 and IL-5 and an increase in the anti-inflammatory cytokine IL-10, indicating a shift toward a more balanced immune response. The number of inflammatory cells in the BAL fluid was also significantly reduced in the somatic group, indicating a decrease in inflammation. CONCLUSION: These preclinical findings suggest that in experimental models, T. cati somatic extract exhibits promising potential as a therapeutic agent for mitigating allergic airway inflammation. Its observed effects on immune response modulation and reduction of inflammatory cell infiltration warrant further investigation in clinical studies to assess its efficacy and safety in human patients.

Distribution of Toxocara cati larvae in experimentally infected BALB/c mice.

The experimental infection of mice with Toxocara cati provides one of the best models for pathological and immunological study of the visceral larva migrans syndrome. To broaden our knowledge of T. cati larval migration, BALB/c mice were inoculated with 500 embryonated eggs of T. cati for a period of two months. In the present study, T. cati eggs, obtained from faeces of naturally infected cats, were used for infection. After oral infection of 500 embryonated eggs of T. cati, mice were euthanised at 1, 2, 3, 7, 14, 21, 28, 35, and 70 days post-infection (dpi) in groups of three per day. Systemic cytokine patterns of Th2 cytokines were evaluated 1 and 2 months after the experimental challenge using sandwich ELISA. The mean number of larval recovery from all infected mice was 16.53 % during infection. The highest number of larvae was obtained from the liver at 1 and 2 dpi; from lungs at 2 dpi and from the brain at 28 dpi. In muscles, the highest recovery rates of T. cati were obtained at 28 dpi. Our data showed that experimental infection with T. cati induced Th2 responses during the infection. In addition, IL-4, IL-5, and IL-10 levels increased significantly in the sera of the infected mice compared to the control group. Larval persistence of T. cati in the muscle of BALB/c mice and its migration behaviour highlights the important role of mouse as a paratenic host in the parasite life cycle and the host-parasite relationships, especially in human toxocariasis.

Survey of Toxocara eggs on Dog Hair as a Potential Transmission Route in Human Toxocariasis in Northeastern Iran.

BACKGROUND: Toxocara canis is a gastrointestinal nematode of dogs and other canids with high zoonotic potential. Human infection occurs following ingestion of infective eggs that have been passed in the dogs' feces. Contact with contaminated soils, is one of the most important risk factors for human infection by T. canis eggs. However, in recent studies transmission of infective eggs, through human contact with contaminated dogs' hair have been proposed. The aim of the present study was to assess the prevalence of Toxocara eggs on the hair and feces of dogs which attended to Veterinary Clinic of Ferdowsi University of Mashhad, Iran. METHODS: A total 100 dogs which attended to the clinic were used in the present study. The hair samples were collected from the head, back and perineal region of dogs' body. Besides collecting hairs, fecal samples were also collected and analyzed for the presence of T. canis eggs. RESULTS: T. canis eggs were found in 11% of the hair samples and 10% of the feces samples. Additionally, it has been observed that the risk factors impact such as breed, season of sampling, sex, hair length, indoor-outdoor access and age, were not significant on the T. canis eggs presence in the faecal and hair samples. CONCLUSION: Human exposure to the hair of dogs, may be significant risk factor for infection and regular anthelmintic treatment, hygiene of animals and public education of the importance of dogs are recommended to prevent human toxocariasis.

Evaluation of the effect of Toxocara cati infection in the mouse model of allergic asthma: Exacerbation of allergic asthma symptoms and Th2 types of response.

Toxocariasis is considered a neglected disease despite the importance of Toxocara spp. infections for human health and is little recognized as a significant problem by public health institutions in developing countries. Epidemiological studies suggest that infection with Toxocara cati contributes to the development of allergic asthma.In the present study, we investigated the effect of T. cati infection on experimental allergic airway inflammation using murine model. BALB/c mice were infected by oral administration with 500 embryonated T. cati eggs followed by ovalbumin (OVA) sensitization and challenge to induce allergic airway inflammation. Infection with T. cati in combination with OVA treatment leads to exacerbation of pulmonary inflammation, eosinophilia, airway hyperresponsiveness, OVA specific IgE. Cytokines measurement in bronchoalveolar lavage indicated that the levels of IL-4 and IL-5 in BAL fluid significantly increased after T. cati infected, OVA treated or a combination of both. Increased level of IL-5 was measured in the lungs of T. cati-infected or OVA-treated mice compared with controls. Moreover, combining infection and OVA treatment significantly increase the level of these cytokines. A direct association between T. cati infection and asthma was found in murine model. Although a wide range of helminth species have been demonstrated to modulate allergic responses, most notably the intestinal nematode T. cati, increases airway hyperresponsiveness, lung histopathology, eosinophil recruitment, and Th2 cytokines in alum-sensitized models of airway allergy.

A survey on Toxocara cati eggs on the hair of stray cats: A potential risk factor for human toxocariasis in Northeastern Iran.

The objective of this study was to investigate the presence of Toxocara eggs on the hair of stray cats. The total number of stray cats trapped and included in the trial was 167 that were collected weekly from different residential areas of Mashhad, in northeastern Iran, from November 2016 to December 2017. Among the 167 cats, 18 (10.8%) of them were positive to T. cati eggs in their hair. In the positive cats, 7 (39%) were adult, 1 (6%) was juvenile and 10 (55%) were kittens. Overall, the mean number of eggs from positive cats was 3.9 ± 1.7 eggs per gram (epg) of hair per cat with an average of 3.1 ± 1.4 in adults, 4.9 in juveniles and 4.3 ± 1.6 in kittens. In total, 39.9% of the eggs recovered were non-viable 35.5% were viable, 22.2% were embryonating and 2.3% were embryonated which embryonated eggs were found only in juveniles. Based on our data, kittens were responsible for 61.7% of the total number of eggs. The age of the cat was found to be an important risk factor associated with parasitic infection.. This study showed that cat hair contaminated by T. cati eggs in different developmental stages represents of potential source for human toxocariasis.