Transient neonatal Cryptosporidium parvum infection triggers long-term jejunal hypersensitivity to distension in immunocompetent rats

Cryptosporidium and irritable bowel syndrome

Cryptosporidium is an apicomplexan parasite that causes gastrointestinal disease in a wide variety of hosts and is associated with waterborne outbreaks. Nonetheless, the parasite is underdiagnosed. Cryptosporidium has been proposed as an etiological cause of irritable bowel syndrome (IBS) in several studies. However, the exact mechanism of pathogenesis is unknown, and no direct link has been discovered. This review will discuss several parasite-induced modifications, such as immunological, microbiome, and metabolite modifications, as well as their interactions. To summarize, Cryptosporidium causes low inflammation, dysbiosis, and unbalanced metabolism, which leads to a lack of homeostasis in the intestine in a comparable pattern to postinfectious IBS.

Gut Microbiota Shifting in Irritable Bowel Syndrome: The Mysterious Role of Blastocystis sp

Irritable bowel syndrome (IBS) is a chronic disorder, which its causative agent is not completely clear; however, the interaction between microorganisms and gastrointestinal (GI) epithelial cells plays a critical role in the development of IBS and presenting symptoms. During recent decades, many studies have highlighted the high prevalence of Blastocystis sp. in patients with IBS and suggested a probable role for this protist in this disease. Recent studies have documented changes in the gut microbiota composition in patients with IBS regarding the presence of Blastocystis sp., but it is not clear that either disturbance of the gut during GI disorders is a favorable condition for Blastocystis sp. colonization or the presence of this protist may lead to alteration in the gut microbiota in IBS patients. In this review, we comprehensively gather and discuss scientific findings covering the role of Blastocystis sp. in IBS via gut microbiota shifting.

Potential therapeutic and prophylactic effects of Asafoetida in murine cryptosporidiosis

Cryptosporidium parvum is an important coccidian parasite that could infect the intestine, respiratory and biliary tracts of man and animals. This study aims to test the potential therapeutic and prophylactic effects of a natural herbal agent (Asafoetida) versus the nowadays drug of choice (Nitazoxanide). Fifty bred female, white Albino mice of CDI strain were divided into 5 groups; group I (GI): immunosuppressed, infected with C. parvum and treated with Asafoetida, group II (GII): immunosuppressed, prophylactically treated with Asafoetida for 7 days prior to infection, group III (GIII): immunosuppressed, infected and treated with Nitazoxanide, group IV (GIV): immunosuppressed and infected (Positive control), group V (GV): immunosuppressed and non infected (Negative control). Parasitological and histopatholgical examinations of the stool, ileocaecal and liver specimens were performed for the study groups. GI showed reduction of the mean oocyst count in stool with improvement of the pathological changes at the ileocaecal region with preservation of hepatic architecture. Results of GI were better than GII and GIV but not as good as GIII. GII showed the least improvement among the test groups. GIII showed the best response between the test groups. GIV show no statistical significant difference between the mean oocyst count in the mice stool at the time of infection and 7 days after infection. It was therefore concluded that Asafoetida is a promising natural therapeutic and prophylactic agent against cryptosporidiosis while, Nitazoxanide is the best chemotherapeutic agent against cryptosporidiosis.

Chronic colitis-induced visceral pain is associated with increased anxiety during quiescent phase

Inflammatory bowel diseases (IBD) are characterized by repetition of flares and remission periods leading to chronic postinflammatory sequelae. Among postinflammatory sequelae, one-third of patients with IBD are suffering from functional symptoms or psychological comorbidities that persist during remission. The aim of our study was to assess functional and behavioral sequelae of chronic colitis in rats with quiescent intestinal inflammation. Chronic colitis was induced by a weekly intrarectal injection of increasing concentrations of trinitrobenzene sulfonic acid (TNBS) for 3 wk (15-45 mg of TNBS) in 30 rats, whereas the control rats (n = 24) received the vehicle. At 50 days post-TNBS, visceral sensitivity was assessed by visceromotor response to colorectal distension, and transient receptor potential vanilloid type 1 (TRPV1) expression was also quantified in the colon and dorsal root ganglia. Barrier function and inflammatory response were assessed by studying intestinal permeability, tight junction protein, myeloperoxidase activity, histological score, and cytokine production (IL-6, IL-10, and TNF-α). Anxiety behavioral tests were performed from 50 to 64 days after the last TNBS injection. Chronic TNBS induced 1) a visceral hypersensitivity (P = 0.03), 2) an increased colon weight-to-length ratio (P = 0.01), 3) higher inflammatory and fibrosis scores (P = 0.0390 and P = 0.0016, respectively), and 4) a higher colonic IL-6 and IL-10 production (P = 0.008 and P = 0.005, respectively) compared with control rats. Intestinal permeability, colonic production of TNF-α, myeloperoxidase activity, and TRPV1 expression did not differ among groups. Chronic TNBS increased anxiety-related behavior in the open-field test and in the acoustic stress test. In conclusion, chronic colitis induced functional sequelae such as visceral hypersensitivity and increased anxiety with a low-grade intestinal inflammation. Development of a representative animal model will allow defining novel therapeutic approaches to achieve a better management of IBD-related sequelae. NEW & NOTEWORTHY Patients with inflammatory bowel diseases have impaired quality of life. Therapeutic progress to control mucosal inflammation provides us an opportunity to develop novel approaches to understand mechanisms behind postinflammatory sequelae. We used a chronic colitis model to study long-term sequelae on visceral pain, gut barrier function, and psychological impact. Chronic colitis induced functional symptoms and increased anxiety in the remission period. It might define novel therapeutic approaches to achieve a better inflammatory bowel disease-related sequelae management.

Octreotide modulates the expression of somatostatin receptor subtypes in inflamed rat jejunum induced by Cryptosporidium parvum

Somatostatins are proteins that are involved in gastrointestinal function. However, little is known with regard to somatostatin receptor subtype (SSTR) expression changes that occur in the jejunum during low-grade inflammation and during subsequent octreotide treatment. The aim of the present study was to investigate the expression of SSTRs in the jejunums of Cryptosporidium parvum (C. parvum)-infected rats by immunohistochemisty, reverse transcription (RT) PCR and quantitative real-time RT-PCR assays. Five-day-old suckling Sprague-Dawley rats (n = 15 for each group) were orally gavaged with 105 Nouzilly isolate (NoI) oocysts. Rats then received 50 μg/kg/day of octreotide by intraperitoneal injection from day 10 to day 17 post-infection. Animals were sacrificed on days 7 and 14 post-infection for immunohistochemical analysis and on days 14, 35 and 50 for mRNA expression analysis of SSTR subtypes. Histological analysis of jejunum tissues demonstrated infection of C. parvum along the villus brush border on day 7 post-infection and infection clearance by day 14 post-infection. Real-time PCR analysis indicated that in the inflamed jejunum, a significant increase in SSTR1 and SSTR2 expression was observed on day 14 post-infection. Octreotide therapy down-regulated the expression of SSTR2 on day 37 post-infection but significantly increased expression of SSTR1, SSTR2 and SSTR3 on day 50 post-infection. The results indicate that specific SSTRs may regulate the inflammatory pathway in the rat intestinal inflammation model.

Protozoan parasites in irritable bowel syndrome: A case-control study

AIM

To investigate the putative role of protozoan parasites in the development of irritable bowel syndrome (IBS).

METHODS

The study included 109 IBS consecutive adult patients fulfilling the Rome III criteria and 100 healthy control subjects. All study subjects filled a structured questionnaire, which covered demographic information and clinical data. Fresh stool samples were collected from patients and control subjects and processed within less than 2 h of collection. Iodine wet mounts and Trichrome stained smears prepared from fresh stool and sediment concentrate were microscopically examined for parasites. Blastocystis DNA was detected by polymerase chain reaction, and Cryptosporidium antigens were detected by ELISA.

RESULTS

A total of 109 IBS patients (31 males, 78 females) with a mean age ± SD of 27.25 ± 11.58 years (range: 16 -60 years) were enrolled in the study. The main IBS subtype based on the symptoms of these patients was constipation-predominant (88.7% of patients). A hundred healthy subjects (30 males, 70 females) with a mean ± SD age of 25.0 ± 9.13 years (range 18-66 years) were recruited as controls. In the IBS patients, Blastocystis DNA was detected in 25.7%, Cryptosporidium oocysts were observed in 9.2%, and Giardia cysts were observed in 11%. In the control subjects, Blastocystis, Cryptosporidium and Giardia were detected in 9%, 0%, and 1%, respectively. The difference in the presence of Blastocystis (P = 0.0034), Cryptosporidium (P = 0.0003), and Giardia (P = 0.0029) between IBS patients and controls was statistically significant by all methods used in this study.

CONCLUSION

Prevalence of Blastocystis, Cryptosporidium and Giardia is higher in IBS patients than in controls. These parasites are likely to have a role in the pathogenesis of IBS.

Long-term health effects after resolution of acute Cryptosporidium parvum infection: a 1-year follow-up of outbreak-associated cases

We describe a longitudinal study carried out in an adult outbreak-associated cohort to investigate health effects, including post-infectious irritable bowel syndrome, occurring after resolution of acute Cryptosporidium parvum infection. New symptoms self-reported up to 12 months included: weight loss (31 %), abdominal pain (38 %), diarrhoea (33 %), eye pain (9 %), joint pain (33 %), fatigue (22 %) and symptoms consistent with irritable bowel syndrome (IBS) (28 %). Two people were medically diagnosed with IBS. This study describes for the first time sequelae reported by patients up to 12 months after infection with C. parvum, which appear to be similar to those described with C. hominis.

Human cryptosporidiosis in Europe

Cryptosporidium has emerged as a significant cause of diarrhoeal disease worldwide, with severe health consequences for very young, malnourished children living in endemic areas and for individuals with highly impaired T-cell functions. In Europe, as elsewhere, the burden of disease has been difficult to measure as a result of the lack of appropriate, standardized surveillance and monitoring systems. The recent occurrence of large water- and foodborne outbreaks in several EU countries, as well as the results of many surveys of human and animal cryptosporidiosis, indicate that this parasite is widespread. Specific subtypes of the zoonotic Cryptosporidium parvum and the anthroponotic C. hominis are responsible for the majority of human cases in Europe. No treatment is currently available to clear the infection, but recent progress in genetic engineering of the parasite, coupled with advances in genomics, have opened important avenues for future research. Here we explore the possible reasons for underascertainment of cryptosporidiosis and the importance of accurate diagnosis in clinical management, the epidemiology of human cryptosporidiosis and key messages from recent outbreaks to highlight important interventions and emerging public health issues.

Infection of cattle with Cryptosporidium parvum: mast cell accumulation in small intestine mucosa

Mast cells might play an important role as the major effector cells in the immune response against Cryptosporidium parvum. C. parvum is a protozoan parasite that causes cryptosporidiosis in animals and humans worldwide. To investigate the interaction between C. parvum and mast cells during infection, nine 3-day-old male calves were orally challenged with 10(6) oocysts of C. parvum per calf. The distribution of mast cells in the mucosa of the small intestine was analyzed by toluidine blue staining. The concentrations of histamine and the cytokines interferon-γ, interleukin-4, interleukin-2, and interleukin-12 were measured in the serum, and the histamine levels were also determined from the intestinal contents. The following clinical signs were monitored: nausea, watery diarrhea, dehydration, and weight loss. Oocysts were shed in the feces during the infection period. C. parvum infection induced an increase in mast cell numbers in the mucosa of the small intestine in distinct temporal and spatial patterns. Infection with C. parvum can induce mastocytosis in the entire small intestinal mucosa in immune-competent calves, and the presence of the parasites influences the distribution profile of the mast cells.

Gastric electrical stimulation decreases gastric distension-induced central nociception response through direct action on primary afferents

Background & Aims

Gastric electrical stimulation (GES) is an effective therapy to treat patients with chronic dyspepsia refractory to medical management. However, its mechanisms of action remain poorly understood.

Methods

Gastric pain was induced by performing gastric distension (GD) in anesthetized rats. Pain response was monitored by measuring the pseudo-affective reflex (e.g., blood pressure variation), while neuronal activation was determined using c-fos immunochemistry in the central nervous system. Involvement of primary afferents was assessed by measuring phosphorylation of ERK1/2 in dorsal root ganglia.

Results

GES decreased blood pressure variation induced by GD, and prevented GD-induced neuronal activation in the dorsal horn of the spinal cord (T9–T10), the nucleus of the solitary tract and in CRF neurons of the hypothalamic paraventricular nucleus. This effect remained unaltered within the spinal cord when sectioning the medulla at the T5 level. Furthermore, GES prevented GD-induced phosphorylation of ERK1/2 in dorsal root ganglia.

Conclusions

GES decreases GD-induced pain and/or discomfort likely through a direct modulation of gastric spinal afferents reducing central processing of visceral nociception.

Effects of octreotide on jejunal hypersensitivity triggered by Cryptosporidium parvum intestinal infection in an immunocompetent suckling rat model

BACKGROUND

Similar to other bacterial or protozoan infections, human cryptosporidiosis may trigger postinfectious irritable bowel syndrome (IBS)-like symptoms, a condition in which enhanced visceral perception of pain during intestinal distension plays a pivotal role. In an immunocompetent suckling rat model which mimicks features of postinfectious IBS, Cryptosporidium parvum infection induces long-lasting jejunal hypersensitivity to distension in association with intestinal activated mast cell accumulation. The aim of the present study was to explore in this model whether octreotide, a somatostatin agonist analog, could prevent the development of jejunal hypersensitivity and intestinal mast cell/nerve fiber accumulation.

METHODS

Five-day-old Sprague-Dawley rats were infected with C. parvum and treated 10 days later with octreotide (50 g kg(-1) day(-1), i.p.) for 7 days.

KEY RESULTS

Compared with untreated infected rats, octreotide treatment of infected rats resulted in increased weight gain [day 23 postinfection (PI)], decreased food intake (day 16 PI), and a reduction in jejunal villus alterations (day 14 PI), CD3(+) IEL (day 37 PI) and mast cell (days 37 and 50 PI) accumulations, nerve fiber densities (day 50 PI), and hypersensitivity to distension (day 120 PI). In uninfected rats, the effects of octreotide treatment were limited to higher weight gain (days 16 and 23 PI) and decreased food intake (day 23 PI) compared with uninfected-untreated rats.

CONCLUSIONS & INFERENCES

Data confirms the relevance of the present rat model to postinfectious IBS studies and prompt further investigation of somatostatin-dependent regulatory interactions in cryptosporidiosis.

Mechanisms underlying gut dysfunction in a murine model of chronic parasitic infection

Irritable bowel syndrome (IBS) is common in countries where chronic parasitic infestations are endemic. However, the relationship between parasitic infection and IBS is not clear. The aim of this study was to examine whether chronic parasitic infection is accompanied by gut dysfunction and whether the continued presence of the parasite is required for the maintenance of the dysfunction. We used chronic Trichuris muris infection in Th1-biased susceptible AKR mice to evaluate this relationship. AKR mice were infected with T. muris and were euthanized on various days postinfection (pi) to examine worm burden, muscle function, and immune and inflammatory responses. Mice were treated with the anthelmintic oxantel pamoate to assess the effect of eradication of infection on muscle function. Infection resulted in persistence of the parasite, elevated IFN-γ, and increased MPO activity evident at 45 days pi. This was accompanied by a reduction in muscle contractility and excitatory innervation. Whereas parasite eradication at 7 days pi normalized IFN-γ and muscle contractility, eradication at 28 days pi failed to normalize muscle contractility. Administration of dexamethasone after parasite eradication normalized all parameters. Anthelmintic treatment improved histology except for eosinophils, which were normalized by subsequent dexamethasone therapy. Persistent gut dysfunction is independent of the continued presence of the parasite and is maintained by inflammatory process that includes eosinophils. Thus data in this preclinical model suggest that parasitic infection could be a cause of IBS, and the lack of symptomatic improvement following eradication is insufficient evidence to refute a causal relationship between the infection and IBS.

Cryptosporidium parvum isolate-dependent postinfectious jejunal hypersensitivity and mast cell accumulation in an immunocompetent rat model

Cryptosporidium spp. are a cause of self-limited diarrhea in immunocompetent hosts. In immunocompetent rats, Cryptosporidium parvum infection induced digestive hypersensitivity, a key pathophysiological factor in functional digestive disorders such as irritable bowel syndrome (IBS). In such a rat model, we sought to document whether jejunal hypersensitivity depends on C. parvum isolate and is associated with a mast cell accumulation. Five-day-old rats were orally administered 10(5) oocysts of either Nouzilly (NoI) or Iowa (IoI) C. parvum isolate. NoI-infected rats exhibited the lowest food intake on days 7 and 14 postinfection (p.i.). On day 7 p.i., small intestine villus atrophy, crypt hyperplasia, and inflammatory cell infiltration were prominent in NoI-infected rats, with higher numbers of Cryptosporidium forms than in IoI-infected rats. Compared to uninfected control rats, jejunal intraepithelial lymphocytes (IELs) were increased only in NoI-infected rats on day 14 p.i. On day 50 p.i., jejunal hypersensitivity to distension was found only in NoI-infected rats; this hypersensitivity is associated with activated mast cell accumulation. The number of mast cells in the jejunal lamina propria was increased from day 36 p.i. in NoI-infected rats and only at day 120 p.i. in IoI-infected rats. Our data suggest that both the severity of infection (weight loss, reduced food intake, villus atrophy, and IEL accumulation) and the onset of a jejunal hypersensitivity after infection in association with an activated mast cell accumulation are isolate dependent and related to NoI infection. This cryptosporidiosis rat model is a relevant model for the study of underlying mechanisms of postinfectious IBS-like symptoms.

Nitazoxanide: a review of its use in the treatment of gastrointestinal infections

Nitazoxanide (Alinia, Daxon, Dexidex, Paramix, Kidonax, Colufase, Annita) has in vitro activity against a variety of microorganisms, including a broad range of protozoa and helminths. Nitazoxanide is effective in the treatment of protozoal and helminthic infections, including Cryptosporidium parvum or Giardia lamblia, in immunocompetent adults and children, and is generally well tolerated. Nitazoxanide is a first-line choice for the treatment of illness caused by C. parvum or G. lamblia infection in immunocompetent adults and children, and is an option to be considered in the treatment of illnesses caused by other protozoa and/or helminths.