Nội dung

Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 7 (2020) Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2020.907.343 Effect of Resiniferatoxin as an Anti-Inflammatory Drug on Experimental Trichinellosis Doaa A.A. Balaha1*, Howaida I. H. Ismail1, Omnia M. K. Risk2 and Ghada A. M. Gamea1 1 Department of Medical Parasitology, Faculty of Medicine, Tanta University, Tanta, Egypt 2 Department of Pathology, Faculty of Medicine, Tanta University, Tanta, Egypt Tanta University, Tanta, Egypt *Corresponding author ABSTRACT Keywords Trichinella spiralis, Resiniferatoxin, Cortisone, Inflammation, IFNγ and iNOS Article Info Accepted: 22 June 2020 Available Online: 10 July 2020 Trichinellosis is a parasitic disease causing a harmful inflammatory response. Corticosteroids are used as anti-inflammatory drugs but cause immunesuppression. The present study evaluated the anti-inflammatory effect of resiniferatoxin (RTX), a TRPV1 receptor agonist as an adjuvant therapy with albendazoleon the early and late stages of experimental trichinellosis in comparison with cortisone. The effect of RTX was evaluated by determination of the total larval count in the skeletal muscles, degree of inflammation in intestine and muscles and and the determination of the serum level of interferon gamma (IFN-γ) and inducible nitric oxide synthase (iNOS) by ELISA. Our results showed that treatment with (albendazole and RTX) significantly decreased the total larval count and the inflammation in both the intestinal and the musclar phases in comparison with other groups. In addition, RTX decreased the serum levels of IFN-γ and iNOS. We concluded that RTX has valuable anti-inflammatory and immuno-modulatory effects against T. spiralis infection and is beneficial for the treatment of trichinellosis as compared to cortisone. Introduction Trichinellosis is a parasitic disease caused by T. spiralis which is the most common species of Trichinella infection all over the world. The infection is caused by ingestion of raw or undercooked meat containing the encysted larvae and has both enteral and parental phases (Sofronic-Milosavljevic et al., 2017). T. spiralis infection induces an intense inflammatory response in the small intestine. It destroys the epithelial cells it occupies. The inflammatory response caused by the invasion of muscles by the migrating larvae leads to damage of the muscle cells and loss of the myofibrils (Wu et al., 2012). 2906 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 Albendazole is a benzimidazole drug that has a worldwide usage against multiple helminthic infections including Trichinella. The T-cell immune response can be modulated by its stimulatory action on enzymes and mediators as glutathione transferase and iNOS during Trichinella infection (Shalaby et al., 2010). The anti-inflammatory treatment during trichinellosis includes steroids; but their side effects limit their usage as they mainly suppress the immune response increasing the parasite burden and its survival in the host tissue (Piekarska et al., 2010). The immune response against T. spiralis at the intestinal phase depends on the T-helper cells (Th). Stimulation of Th cells includes both Th1 and Th2 with initial predominance of the Th1 type and consequent response of Th2 in order to achieve protection and parasite expulsion (Ilic et al., 2012). This process is characterized by secretion of cytokines such as interleukin IL4, IL5, IL10 and IL13, as well as immunoglobulin E (Bruschi and Chiumiento, 2012).The activity of IL4 and IL13 causes release of tumour necrosis factor α (TNF- α) and INF-γ, by the activation of intestinal mucosal mast cells resulting in local inflammation (Akiho et al., 2011). Release of TNF-α leads to stimulation of iNOS, resulting in the production of nitric oxide (NO) which has an effect against both extracellular and intracellular parasites. The inflammatory response caused by TNF-α and NO enhances the development of enteropathy by T. spiralis (Wink et al., 2010). Therefore, there is a great need for a new drug that improves the host defense mechanism against trichinellosis. Resiniferatoxin (RTX) is derived from a cactus-like plant named Euphorbia resinifera. Most of the biological actions of RTX are mediated by the transient receptor potential vanilloid 1 (TRPV1) by intial desensitizing then blocking these receptors leading to its analgesic effect (Nilius and Szallasi, 2014). It also has a potent anti-inflammatory effect by reducing the expression of iNOS leading to decrease NO serum level (Chen et al., 2003). So there is a great need to evaluate the therapeutic effect of RTX on the inflammatory response against T. spiralis infection. The aim of the present study was to evaluate the antiinflammatory effect of RTXas an adjuvant therapy with albendazole on the early and late stages of experimental T. spiralis infection as a model of an intestinal and tissue parasite. Materials and Methods Parasite The strain of T. spiralis was obtained from infected albino mice in the Medical Parasitology Department Laboratory, Tanta University. This research was approved by the research ethical committee, Faculty of Medicine, Tanta University and its approval code is 32284/04/18. For this purpose 120 Swiss albino mice were classified into five main groups. Group (I) represented the negative control. Group II represented the positive control which was further subdivided into two subgroups: subgroup (IIa) was sacrificed on day 6 p.i. and subgroup (IIb) was sacrificed on day 35 p.i.. Group III represented the infected mice that were treated with albendazole only. This group was further subdivided into three subgroups as follows: subgroup (IIIa) starting treatment on day 3 p.i. (early treatment) and was sacrificed on day 6 p.i., subgroup (IIIb) starting treatment on day 3 p.i. (early treatment) and was sacrificed on day 35 p.i. and subgroup (IIIc) starting treatment on day 21 p.i. (late treatment) and was sacrificed on day 35 p.i. Group IV represented the infected mice that were treated with both (albendazole and RTX). Group V represented the infected mice that 2907 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 were treated with both (albendazole and dexamethasone (Dexa)). Both groups IV and V were subdivided as group III. from the thigh and kept in 10% formalin for histopathological examination. The rest of the skeletal muscles were used for TLC. Drugs Histopathological study Albendazole Histopathological examination of the small intestine and the muscle specimens A commercial preparation of the drug, alzental suspension (EIPICO) with a concentration of 20 mg/ml was used. The drug was given by intra-esophageal gavage to each mouse in a dose of 50 mg/kg body weight/day for 3 successive days starting on day 3 p.i for early treated subgroups and on day 21 p.i for late treated subgroups (Li et al., 2012). Resiniferatoxin (RTX) A raw material of the drug, resiniferatoxin powder (TOCRIS) weighing 1mg was used. The drug was administered intra-peritoneally in a dose of 20 μg/kg on days 3 and 5 p.i. for early treated subgroups and on days 21 and 23 p.i. for late treated subgroups (Ueda et al., 2008). Steroids A commercial preparation of the drug, dexamethasone sodium phosphate ampoule (Dexa) (AMRIYA) with a concentration of 8mg/2ml was used. The drug was administered intra-peritoneally in a dose of 1 mg/kg on days 3 and 5 p.i. for early treated subgroups and on days 21 and 23 p.i. for late treated subgroups (Sun et al., 2012). Intestinal specimens (1 cm from the small intestine) were taken from the mice sacrificed on day 6 p.i. (Nassef et al., 2010). Skeletal muscle specimens from the thighs were taken from the mice sacrificed on day 35 p.i. (Monib et al., 2010). Inflammatory scoring In order to score the degree of intestinal inflammatory infiltrate, the inflammatory reaction was assessed in the intestinal sections using semi-quantitative score of the inflammation. For muscle specimens, the intensity of the inflammatory reaction around the encapsulated larvae was evaluated by using the inflammatory score. This score was represented as mild < 2, moderate < 4 and severe > 4 (El-Kowrany et al., 2019). Immunological study Mice were subjected to the following Determination of the serum level of mouse interferon γ (IFN-γ) and mouse inducible nitric oxide synthase (iNOS) was done by enzyme-linked immune-sorbent assay technology (ELISA) on day 6 p.i. for the early treated subgroups (subgroups a) and on day 25p.i. for the late treated subgroups (subgroups c) and their controls. Parasitological study Statistical analysis Total larval count (TLC) in the skeletal muscles (Wranicz et al., 1998) Statistical presentation and analysis of the present study was conducted, using the mean, standard deviation (SD) and chi-square test by SPSS V.22. Significance was determined by a one way analysis of variance (ANOVA) (f On day 35 p.i., five mice from all groups were euthanized. Muscle samples were obtained 2908 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 test) for comparison between more than two means in quantitative data. A P value < 0.05 was considered statistically significant. A P value < 0.01 was considered statistically highly significant. Results and Discussion Parasitological study Total larval count (TLC) of T. spiralis in the muscles was performed on day 35 p.i. for all subgroups (b) The mean TLC in the infected non-treated mice (subgroup IIb) was 20000 ± 3807.89. In relation to the infected non-treated mice (subgroup IIb), there was a highly significant decrease in the mean TLC of the infected mice treated with albendazole (subgroup IIIb) reaching 500 ± 136.93(P = 0.001) with 97.5% reduction. Also, there was a highly significant decrease in the mean TLC in the infected mice treated with albendazole and RTX (subgroup IVb) to be 200 ± 48.99 (P = 0.001) with 99% reduction. In the infected mice treated with albendazole and Dexa (subgroup Vb), the mean TLC showed a highly significant decrease in relation to infected non-treated mice (subgroup IIb) reaching 1000 ± 158.11(P = 0.001) with 95% reduction. There was a highly significant difference between subgroup IIIb (treated with albendazole) and subgroup IVb (treated with albendazole and RTX) (P = 0.002). Also, there was a highly significant difference between subgroup IIIb and subgroup Vb (treated with albendazole and Dexa) (P = 0.001) and subgroup IVb and subgroup Vb (P = 0.001) (Fig.1a). TLC of T. spiralis was performed on day 35 p.i. for all subgroups (c) In relation to the infected non-treated mice (subgroup IIb), there was a highly significant decrease in the mean TLC of the infected mice treated with albendazole (subgroup IIIc) reaching 9000 ± 1457.74 (P = 0.001) with 55% reduction. Also, there was a highly significant decrease in the mean TLC of the infected mice treated with albendazole and RTX (subgroup IVc) reaching 7200 ± 972.11(P = 0.001) with 64% reduction. There was an insignificant difference between subgroup IIIc and subgroup IVc (P = 0.051). In the infected mice treated with albendazole and Dexa (subgroup Vc), there was a highly significant decrease in the mean TLC in relation to the infected non-treated mice (subgroup IIb) reaching 8000 ± 1369.31(P = 0.001) with 60% reduction. But there was an insignificant difference between both subgroup III c (treated with albendazole) and subgroup Vc (P = 0.296) and between subgroup IVc (treated with albendazole and RTX) and subgroup Vc (P = 0.318) (Fig.1b). Histopathological study with inflammatory scoring Small intestinal findings Small intestinal sections of T. spiralis infected non-treated mice (subgroup IIa) 6 days p.i. revealed edema and elongation of the villous core with severe inflammatory cellular infiltrate giving a mean inflammatory score of 5.40 ± 0.55. The infiltrate was in the form of lymphocytes, eosinophils and neutrophils (Fig.3a). In addition, there was goblet cell hyperplasia with high mitotic activity (Fig. 3b). Small intestinal section of T. spiralis infected mice treated with albendazole (subgroup IIIa) 6 days p.i. revealed moderately elongated villi, moderate edema and inflammatory cellular infiltrate with a mean inflammatory score of 3.20 ± 0.84 (P = 0.001) (Fig. 4a). However, in the infected mice treated with albendazole and RTX (subgroup IVa) there was mild inflammation 2909 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 and in some there was almost normal intestinal epithelium with a mean inflammatory score of 0.80 ± 0.45 (P = 0.001) (Fig. 4b).The infected mice treated with albendazole and Dexa (subgroup Va) revealed mild inflammatory cellular infiltrate with lymphoid hyperplasia, shortening of the villi and mild edema with a mean inflammatory score of 1.40 ± 0.55 (P = 0.001) (Fig. 4c). There was a highly significant difference between group III and IV (P= 0.001). However, there was insignificant difference between group IV and V (P = 0.094) (Fig.2a). Skeletal muscle findings Muscle sections of T. spiralis infected nontreated mice (subgroup IIb) 35 days p.i. revealed multiple encapsulated larvae surrounded by severe inflammatory cellular infiltrate giving a mean inflammatory score of 5.60 ± 0.55. The infiltrate was in the form of plasma cells, lymphocytes, macrophages and neutrophils (5b). There was loss of the myofibrils (Fig. 5a). Skeletal muscle findings in subgroups b (early treated) In the infected mice treated with albendazole (subgroup IIIb) 35 days p.i. revealed less number of the encapsulated larvae surrounded by moderate inflammatory cellular infiltrate around them with a mean inflammatory score of 2.80 ± 0.84 (P= 0.001) (Fig. 6a). In the contrary, those treated with albendazole and RTX (subgroup IVb) showed mild inflammatory cells and minimal amount of larvae, some showed absent larvae with normal striation with a mean inflammatory score of 0.80 ± 0.84 (P= 0.001) (Fig. 6b). However, in the infected mice treated with albendazole and Dexa (subgroup Vb), there were nurse cells with mild to moderate inflammatory cellular infiltrate giving a mean inflammatory score of 2.40 ± 0.89 (P= 0.001) (Fig. 6c). There was a highly significant difference between group III and IV (P= 0.005). However, there was insignificant difference between group IV and V (P = 0.019) (Fig.2b). Skeletal muscle findings in subgroups c (late treated) Muscle section of T. spiralis infected mice treated with albendazole (subgroup IIIc) 35 days p.i. revealed moderate to severe inflammatory cellular infiltrate, remnants of the larva and hyaline degeneration of some nurse cells with a mean inflammatory score of 4.20 ± 0.84 (P = 0.008) (Fig. 7a). Muscle section of T. spiralis infected mice treated with albendazole and RTX (subgroup IVc) revealed mild to moderate inflammatory infiltrate, remnants of the larva and hyaline degeneration of the nurse cells giving a mean inflammatory score of (1.60 ± 0.55) (P = 0.001) (Fig. 7b). Muscle section of T .spiralis infected mice treated with albendazole and Dexa (subgroup Vc) revealed encapsulated larvae with mild to moderate inflammatory cellular infiltrate and calcification giving a mean inflammatory score of 2.40 ± 0.89 (P = 0.001) (Fig. 7c). There was a highly significant difference between group III and IV (P= 0.001). However, there was insignificant difference between group IV and V (P = 0.100) (Fig.2c). Immunological study Determination of the serum level of IFN-γ by ELISA Serum levels of IFN-γ determined on day 6 p.i. in subgroups (a) The mean normal level of IFN γin the noninfected non-treated mice (group I) was 4.90 ± 1.21. The mean serum level in the infected non-treated group (subgroup IIa) was 2910 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 significantly increased reaching 23.00 ± 8.29 (P = 0.020). Compared to the infected nontreated group (subgroup IIa), there was an insignificant increase in the mean serum levels of the infected mice treated with albendazole (subgroup IIIa) reaching 27.30 ± 5.69 (P = 0.320). However, there was a significant decrease in the mean serum level in the infected mice treated with albendazole and RTX (subgroup IVa) reaching 9.57 ± 2.30 (P = 0.024). Also, there was an insignificant decrease in the mean serum levels of the infected mice treated with albendazole and Dexa (subgroup Va) as their mean levels were 14.10 ± 3.31 (P = 0.175) respectively. In addition, there was a significant decrease in the mean serum level in subgroup IVa and subgroup Va in relation to subgroup IIIa (P = 0.002) and (P = 0.009) respectively. There was an insignificant difference in the mean serum level between subgroup IVa (treated with albendazole and RTX) and subgroup Va (treated with albendazole and Dexa) (P = 0.181) (Fig. 8a). Serum levels of IFN-γ determined on day 25 p.i. in subgroups (c) The mean serum level in the infected nontreated group (subgroup IIb) was significantly increased as compared to the non-infected non-treated mice (group I) as their mean levels were 22.08 ± 9.35 and 4.90 ± 1.21 respectively (P = 0.034). In relation to subgroup IIb, there was an insignificant increase in the mean serum level in the infected mice treated with albendazole (subgroup IIIc) as their mean levels were 24.47 ± 7.83 (P = 0.634). However, there was a significant decrease in the mean serum level of the infected mice treated with albendazole and RTX (subgroup IVc) reaching 10.63 ± 4.10 (P = 0.038). In addition, in the infected mice treated with albendazole and Dexa (subgroup Vc), there was an insignificant decrease in the mean serum level reaching 12.90 ± 3.25 (P = 0.184). There was a significant decrease in the mean serum level of subgroup IVc and subgroup Vc in relation to subgroup IIIc (treated with albendazole) (P = 0.017) and (P = 0.021) respectively. However, there was an insignificant difference between subgroups IVc (treated with albendazole and RTX) and Vc (treated with albendazole and Dexa) (P = 0.495) (Fig. 8b). Determination of the serum levels of iNOS by ELISA Serum levels of iNOS determined on day 6 p.i. in subgroups (a) The mean normal serum level of iNOSin the non-infected non-treated mice (group I) was 135.67 ± 26.63. The mean serum level in the infected non-treated group (subgroup IIa) showed a highly significant increase reaching 488.33 ± 46.44 (P = 0.001). In relation to subgroup (IIa), there was a significant decrease in the mean serum level of the infected mice treated with albendazole and RTX (subgroup IVa) and those treated with albendazole and Dexa (subgroup Va) as their mean level reached 346.33 ± 57.13 (P = 0.029) and 382.67 ± 46.20 (P = 0.049) respectively. However, there was an insignificant increase in the mean serum level in the infected mice treated with albendazole (subgroup IIIa) as its mean level reached 500.67 ± 27.47 (P = 0.628). In addition, there was a significant decrease in the mean serum level in subgroup IVa and subgroup Va in relation to subgroup IIIa (P = 0.012 and 0.017). However, there was an insignificant difference in the mean serum level between subgroup IVa and subgroup Va (P = 0.440) (Fig. 9a). Serum levels of iNOS determined on day 25 p.i. in subgroups (c) The mean serum level in the infected nontreated group (subgroup IIb) was significantly 2911 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 increased reaching 372.33 ± 89.5 (P = 0.012). In relation to subgroup IIb, there was an insignificant increase in the mean serum level in the infected mice treated with albendazole (subgroup IIIc) as their mean level reached 437.0 ± 25.06 (P = 0.134). However, there was a significant decrease in the mean serum level in the infected mice treated with albendazole and RTX (subgroup IVc) reaching 266.0 ± 35.04 (P = 0.023). In addition, there was a significant decrease in the mean serum level in the infected mice treated with albendazole and Dexa (subgroup Vc) reaching 284.3 ± 35.02 (P = 0.049). There was a significant decrease in the mean serum level in subgroup IVc (treated with albendazole and RTX) in relation to subgroup IIIc (treated with albendazole) (p value = 0.002). There was an insignificant difference between subgroups IVc and Vc (treated with albendazole and Dexa) (P = 0.654) (Fig. 9b). Trichinellosis is a zoonotic parasitic disease caused byT. spiralis and has both intestinal and tissue phases.The immune response against T. spiralis at the intestinal phase depends on the T-helper cells (Th). Stimulation of Th cells includes both Th1 and Th2 with initial predominance of the Th1 type and subsequent domination of Th2 in order to achieve protection and parasite expulsion (Ilic et al., 2012). This process is characterized by secretion of cytokines such as interleukin IL4, IL5, IL10 and IL13, as well as immunoglobulin E (Bruschi and Chiumiento, 2012). The activity of IL4 and IL13 leads to release of TNF- α and INF-γ, by the activation of intestinal mucosal mast cells resulting in local inflammation (Akiho et al., 2011). Release of TNF-α leads to stimulation of iNOS, resulting in the production of nitric oxide (NO) which has an effect against both extracellular and intracellular parasites. The inflammatory response caused by TNF-α and NO enhances the development of enteropathy by T. spiralis (Wink et al., 2010). Albendazole is widely used in the treatment of trichinellosis with a high therapeutic index and low toxicity (Gottstein et al., 2009). In addition, steroids are used during trichinellosis in order to decrease the inflammatory response. However, their side effects limit their use and they mainly suppress the immune response. So, they increase the parasite burden and its survival in the host tissue (Gottstein et al., 2009). Resiniferatoxin (RTX) is derived from a cactus-like plant named Euphorbia resinifera. Most of the biological actions of RTX are mediated by the transient receptor potential vanilloid 1 (TRPV1) by intial desensitizing then blocking these receptors leading to its analgesic effect (Nilius and Szallasi, 2014). It also has a potent anti-inflammatory effect by reducing the expression of cyclooxygenase-2 (COX-2) and iNOS, therefore inhibiting the synthesis of both prostaglandin-E2 (PGE2) and NO (Chen et al., 2003). In the present study, the TLC of T. spiralis in the muscles was performed on day 35 p.i.. In early treated subgroup (IIIb), there was a highly significant decrease in the mean total larval count of the infected mice treated with albendazole as compared to the infected nontreated group(IIb) (P = 0.001) with 97.5% reduction while in late treated group (IIIc), the reduction rate was 55%. These results agreed with the study of Attia et al., (2015) who used albendazole in a dose of 50 mg/kg for three successive days starting on day 3 p.i.. There was a significant decrease in TLC detected in the mice which received albendazole during the intestinal phase with efficacy of 90.9% (p < 0.01). In the present study, there was a highly significant decrease in the mean TLC in the infected mice treated with albendazole and 2912 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 RTX (200±48.99) as compared with the infected control with 99% reduction. However, in the infected mice treated with albendazole and Dexa, the reduction was 95%. Moreover, there was a significant decrease in the larval count in mice treated with albendazole and RTX than those treated with albendazole only (P = 0.002). This may be explained on the basis of the possible effect of RTX on the fecundity of T. spiralis adults giving less larval count than was expected. Also, this could be attributed to the protective effect of RTX on the integrity of the intestinal wall. Moreover, this agree with Munoz-Carrillo et al., (2017-a) who showed that T. spiralisnewborn larvae (NBL) treated with RTX had decreased infectivity which further affected the development of the T. spiralis life cycle in mouse infection, as RTX decreased significantly both the implantation of T. spiralis- NBL and the parasite burden in the muscular phase. In the mice treated with (albendazole and Dexa), the TLC was larger than that in both albendazole treated subgroup and the subgroup treated with albendazole and RTX but with no statistically significant difference. It can be suggested that, this is a consequence of the immunosuppressive effect of cortisone which allowed large numbers of larvae to migrate and occupy the muscles of the host. The effect of cortisone alone as antiinflammatory drug was studied by Coker (2019) who declared that the TLC in the muscles of the cortisone-treated mice were almost twice those from the control group. These counts were not related only to the number of the adult worms but also due to the huge number of the larvae which were capable of establishing themselves in the muscles. These effects were due to the suppression of the cellular response in the intestine by cortisone. Similar results were obtained by Alvarado et al., (1996) who showed that in rats treated with betamethasone, there was an increase in the TLC as compared to the infected non-treated group. This was explained by Piekarska et al., (2010) who showed that Dexa increased the proportion of apoptotic and necrotic lymphocytes, as well as the number of larvae in the muscle tissue. The mechanism of immunosuppression by cortisone was explained by Ashwell et al., (2000) as it inhibits the expression of pro-inflammatory genes by transcription factors suppression; such as NF-κB and the activator protein which regulate the expression of genes encoding many inflammatory cytokines such as TNF-α, IL-1α, IL-1β, IL- 8, IFN-α and IFN-β. The effect of RTX alone on T. spiralis infected mice as compared to Dexa was studied by Munoz-Carrillo et al., (2016). They showed that in the infected group treated with Dexa on day 1 p.i., there was a non-significant increase in the parasite burden compared to the infected non-treated group. In contrast, when RTX was administered on day 1 p.i., the parasite burden decreased significantly (P < 0.05). In the present study TLC of T. spiralis was performed on late treated subgroups, which started treatment on day 21 p.i. (G IIIc, IVc, Vc). It has been found that in relation to TLC of the infected non-treated mice, there was a highly significant decrease in the mean TLC of the infected mice treated with albendazole with 55% reduction rate, albendazole and RTX with 64% reduction rate and albendazole and Dexa with 60%reduction rate (P = 0.001) with no significant difference between the three groups. 2913 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 Regarding the histopathological study performed on day 6 p.i., small intestinal sections of T. spiralis infected non-treated mice revealed edema and elongation of the villous core with severe inflammatory cellular infiltrate. The infiltrate was in the form of lymphocytes, eosinophils and neutrophils giving a mean inflammatory score of 5.40 ± 0.55. In addition, there were goblet cell hyperplasia, high mitotic activity and hyperplasia of the payer's patches. In the present study, as regard to mice treated with albendazole only, there were moderately elongated villi, moderate edema and inflammatory cellular infiltrate with a mean inflammatory score of 3.20 ± 0.84 (P = 0.001). However, in the infected mice treated with albendazole and RTX, there was mild inflammation and even there was almost normal intestinal epithelium in some mice with a mean inflammatory score of 0.80 ± 0.45 (P = 0.001). Also, in the infected mice treated with albendazole and Dexa, there were mild inflammatory cellular infiltrate with lymphoid hyperplasia, shortening of the villi and mild edema with a mean inflammatory score of 1.40 ± 0.55 (P = 0.001). Similar results were obtained by MunozCarrillo et al., (2016) who found a marked reduction in the intestinal pathology in RTX and Dexa treated subgroups on day 1 p.i. with a dose (20 μg/kg) and (1mg/kg) respectively. There was a reduction in the intestinal crypts hyperplasia and reconstitution of the intestinal villi (P < 0.05 and P < 0.01 respectively). However, adult females of T. spiralis were still observed in both duodenum and jejunum. In addition, the infected groups treated with RTX and Dexa with the same doses on day 7 p.i. did not show any intestinal pathology, the intestine was almost normal. In the current study, the histopathological examination of muscle sections of T. spiralis infected non-treated mice on day 35 p.i., revealed multiple encapsulated larvae surrounded by severe inflammatory cellular infiltrate between the muscle fibers and around the encapsulated larvae. The infiltrate was in the form of plasma cells, lymphocytes, macrophages and neutrophils giving a mean inflammatory score of 5.60 ± 0.55. There was loss of the myofibrils. Regarding mice treated with albendazole only, there was a less number of encapsulated larvae surrounded by moderate inflammatory cellular infiltrate in the early treated subgroups (b)with a mean inflammatory score of 2.80 ± 0.84 (P= 0.001). On the other hand El-Gendy et al., (2015) detected mild inflammatory cellular infilteration around the encapsulated muscle larvae five weeks p.i. in T. spiralis infected mice treated with albendazole. As regards the infected mice treated with albendazole and RTX showed mild inflammatory cells and minimal amount of larvae and some showed absent larvae with normal striation with a mean inflammatory score of 0.80 ± 0.84 (P= 0.001). However in the infected mice treated with albendazole and Dexa, there were nurse cells with mild to moderate inflammatory cellular infiltrate giving a mean inflammatory score of 2.40 ± 0.89 (P= 0.001). In the late treated subgroups (c), the infected mice treated with albendazole only showed moderate to severe inflammatory cellular infiltrate, remnants of the larvae and hyaline degeneration of some nurse cells with a mean inflammatory score of 4.20 ± 0.84 (P = 0.008). In the infected mice treated with albendazole and RTX, mild to moderate inflammatory infiltrate, remnants of the larva and hyaline degeneration of the nurse cells were detected giving a mean inflammatory score of (1.60 ± 0.55) (P = 0.001). Also, in the 2914 Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 2906-2922 infected mice Dexa, there inflammatory encapsulated inflammatory 0.001). treated with albendazole and was mild to moderate cellular infiltrate around the larvae giving a mean score of 2.40 ± 0.89 (P = IFN-γ is a cytokine that forms an important part of both innate and adaptive immunity in T. spiralis infection. It has important protective effects against the newly born larvae that in turn may restrict the number of larvae entering the blood circulation (Helmby and Grencis, 2003). Moreover, IFN-γ increases the development and differentiation of Th1 cells, induces the expression of iNOS and regulates the production of pro-inflammatory cytokines, such as TNF-α. In the immune response against T. spiralis infection, IFN-γ has a key role in the pathogenesis of inflammatory diseases, as it participates in the activation of a cascade of pro-inflammatory cytokines, especially IL-1β, IL-6 and IL-8 (Muhl and Pfeilschifter, 2003). In the current study, the mean serum levels of IFN-γ in both early and late treated subgroups were determined on days 6 and 25 p.i. respectively. The results showed a significant increase in the mean serum level of IFN-γ in the infected non-treated group (P < 0.05). These results were in agreement with the results of many studies. Bakir et al., (2017) showed a significant difference between the levels of IFN-γ in the infected non-treated group through days of infection with a significant peak of expression on day 5 p.i.. Chen et al., (2013) showed that there was a significant increase in the serum levels of IFN-γ during the early phase of infection especially on day 7 p.i.. Stolley and Campbell (2016) detected an increase about 2.5 fold in the IFN-γ expression at the mRNA level. In the serum, IFN-γ increased also during the early days of infection. In the present work, there was an insignificant increase in the mean serum IFN-γ levels of the infected mice treated with albendazole alone in comparison to the infected nontreated mice (P > 0.05).This was explained by Du et al., (2003) who declared that albendazole is a benzimidazole derivative that inhibits microtubule synthesis in the parasite and modifies the cytokine responses changing the immune response from Th2 to Th1 dominance and increases IFN-γ levels.On the other hand, in the present study, there was a significant decrease in the mean serum levels of IFN-γ in the infected mice treated with (albendazole and RTX) (P < 0.05). There was no significant difference in the mean serum level between the subgroup treated with (albendazole and RTX) and the subgroup treated with (albendazole and Dexa) (P > 0.05).In agreement with these results, MunozCarrillo et al., (2017-a) compared between the effect of RTX and cortisone on the intestinal phase of T. spiralis in mice. They detected that in the RTX treated group with a dose 20 μg/kg for two doses on day 1 and 3 p.i., it was observed that the serum levels of IFN-γ were decreased significantly (P < 0.05) to a level similar to that of the groups treated with Dexa (1mg/kg) at the same time. The results of the present study concerning the marked decrease in the serum level of IFN-γ in RTX treated groups declared the improvement of the histopathological changes in the small intestine and the muscle by modulation of the immune response with decrease of other proinflammatory cytokines involved in the inflammatory process as well as the decrease in iNOS level with decrease in oxidative stress (Munoz-Carrillo et al., 2017). NO is produced from arginine by the action of iNOS produced from activated T-helper cells. It is one of the most important secretory products of macrophages that participate in the host defense function. It destroys and suppresses many parasites (Ascenzi and Gradoni, 2002). 2915