Cytotoxic T cells in AIDS colonic cryptosporidiosis

Dual transcriptomics to determine interferon-gamma independent host response to intestinal Cryptosporidium parvum infection

Animals with a chronic infection of the parasite Toxoplasma gondii are protected against lethal secondary infection with other pathogens. Our group previously determined that soluble T. gondii antigens (STAg) can mimic this protection and be used as a treatment against several lethal pathogens. Because treatments are limited for the parasite Cryptosporidium parvum, we tested STAg as a C. parvum therapeutic. We determined that STAg treatment reduced C. parvum Iowa II oocyst shedding in gamma interferon knockout (IFN-γ-KO) mice. Murine intestinal sections were then sequenced to define the IFN-γ-independent transcriptomic response to C. parvum infection. Gene Ontology and transcript abundance comparisons showed host immune response and metabolism changes. Transcripts for type I interferon-responsive genes were more abundant in C. parvum-infected mice treated with STAg. Comparisons between phosphate-buffered saline (PBS) and STAg treatments showed no significant differences in C. parvum gene expression. C. parvum transcript abundance was highest in the ileum and mucin-like glycoproteins and the GDP-fucose transporter were among the most abundant. These results will assist the field in determining both host- and parasite-directed future therapeutic targets.

Increased inherent intestinal granzyme B expression may be associated with SIV pathogenesis in Asian non-human primates

BACKGROUND

Unlike Asian non-human primates, chronically SIV-infected African non-human primates (NHP) display a non-pathogenic disease course. The different outcomes may be related to the development of an SIV-mediated breach of the intestinal mucosa in the Asian species that is absent in the African animals.

METHODS

To examine possible mechanisms that could lead to the gut breach, we determined whether the colonic lamina propria (LP) of SIV-naïve Asian monkeys contained more granzyme B (GrB) producing CD4 T cells than did that of the African species. GrB is a serine protease that may disrupt mucosal integrity by damaging tight junction proteins.

RESULTS

We found that the colonic LP of Asian NHP contain more CD4(+) /GrB(+) cells than African NHP. We also observed reduced CD4 expression on LP T cells in African green monkeys.

CONCLUSION

Both phenotypic differences could protect against SIV-mediated damage to the intestinal mucosa and could lead to future therapies in HIV(+) humans.

Global distribution, public health and clinical impact of the protozoan pathogen cryptosporidium

Cryptosporidium spp. are coccidians, oocysts-forming apicomplexan protozoa, which complete their life cycle both in humans and animals, through zoonotic and anthroponotic transmission, causing cryptosporidiosis. The global burden of this disease is still underascertained, due to a conundrum transmission modality, only partially unveiled, and on a plethora of detection systems still inadequate or only partially applied for worldwide surveillance. In children, cryptosporidiosis encumber is even less recorded and often misidentified due to physiological reasons such as early-age unpaired immunological response. Furthermore, malnutrition in underdeveloped countries or clinical underestimation of protozoan etiology in developed countries contribute to the underestimation of the worldwide burden. Principal key indicators of the parasite distribution were associated to environmental (e.g., geographic and temporal clusters, etc.) and host determinants of the infection (e.g., age, immunological status, travels, community behaviours). The distribution was geographically mapped to provide an updated picture of the global parasite ecosystems. The present paper aims to provide, by a critical analysis of existing literature, a link between observational epidemiological records and new insights on public health, and diagnostic and clinical impact of cryptosporidiosis.

An early intestinal mucosal source of gamma interferon is associated with resistance to and control of Cryptosporidium parvum infection in mice

Resistance to and control of Cryptosporidium parvum infection in mice in the absence of adaptive immunity appears to be gamma interferon (IFN-gamma) dependent. Using an IFN-gamma-neutralizing antibody in a murine model, we demonstrated increased susceptibility to infection within 24 h. We correlated this early resistance and control with increased mucosal expression of IFN-gamma and demonstrate that CD8+ T-cell receptor alphabeta intestinal intraepithelial lymphocytes express and secrete this cytokine shortly after infection. The rapid kinetics of IFN-gamma expression and secretion by naive CD8+ T cells in response to a protozoan pathogen have not previously been demonstrated.

Recent advances in cryptosporidiosis: the immune response

An increased understanding of host immune responses to Cryptosporidium parvum which are responsible for clearance of primary infection and resistance to reinfection, and characterization of the parasite molecules to which they are directed, are essential for discovery of effective active and passive immunization strategies against cryptosporidiosis. In this article, recent advances in knowledge of humoral and cellular immune responses to C. parvum, their antigen specificities, and mechanisms of protection are briefly reviewed.

Chronic intestinal graft-versus-host disease: clinical, histological and immunohistochemical analysis of 17 children

Graft-versus-host disease (GVHD) can be acute or chronic. The pathogenesis of chronic GVHD is unclear. Chronic GVHD affects mainly skin, liver and digestive tract. Intestinal involvement is uncommon and histological features are poorly described. We report here the clinical, histological and immunohistochemical features of chronic GVHD with intestinal involvement. Intestinal biopsies from children with chronic GVHD (n=17) were compared to control children (n=21: 10 non-transplant cases, four non-GVHD transplant cases, seven acute GVHD). We evaluated clinical outcome, histological features and characterized immunohistochemically the immune cells involved locally. Chronic GVHD with intestinal involvement was usually multisystemic (88.2%) and preceded by acute GVHD in 88.2% of cases. The outcome was severe with complete recovery in only 58.8% of cases, and death related to chronic GVHD in 17.6% of cases. Histological features were characterized by (1) villous atrophy and (2) glandular lesions, mainly apoptotic with variable intensity and (3) lamina propria infiltrate with cytotoxic T lymphocytes (CD3+, CD8+, TiA1+, granzyme B-) which were significantly (P<0.001) increased compared to non-GVHD transplant and non-transplant controls. Therefore in chronic intestinal GVHD, the apoptotic process could be related to cytotoxic T lymphocytes.

Gastrointestinal infections in the immunocompromised host

Immunocompromised patients, including patients with AIDS, solid organ and bone marrow transplant recipients, patients with leukemia and lymphoma, patients with inherited immune deficiencies, and patients on immunosuppressive therapy for a variety of disorders, are at risk for infections-particularly opportunistic infections, which, by definition, do not infect the healthy host. All systems of the body, including the gastrointestinal tract, are susceptible. The esophagus, stomach, small intestine, and large intestine are sites of infection for viruses, bacteria, fungi, and protozoa. Symptoms can range in severity from fevers of unknown etiology to life-threatening hemorrhage and perforation. This review summarizes recent case reports, clinical studies, and reviews pertaining to pathogens that uniquely cause disease, more frequently cause disease, or cause more severe disease in the immunocompromised host than in the immunocompetent host.