Cryptosporidiosis and the follicle-associated epithelium over the ileal Peyer's patch in calves

Using Twitter (X) to Mobilize Knowledge for First Contact Physiotherapists: Qualitative Study

BACKGROUND

Twitter (now X) is a digital social network commonly used by health care professionals. Little is known about whether it helps health care professionals to share, mobilize, and cocreate knowledge or reduce the time between research knowledge being created and used in clinical practice (the evidence-to-practice gap). Musculoskeletal first contact physiotherapists (FCPs) are primary care specialists who diagnose and treat people with musculoskeletal conditions without needing to see their general practitioner (family physician) first. They often work as a sole FCP in practice; hence, they are an ideal health care professional group with whom to explore knowledge mobilization using Twitter.

OBJECTIVE

We aimed to explore how Twitter is and can be used to mobilize knowledge, including research findings, to inform FCPs' clinical practice.

METHODS

Semistructured interviews of FCPs with experience of working in English primary care were conducted. FCPs were purposively sampled based on employment arrangements and Twitter use. Recruitment was accomplished via known FCP networks and Twitter, supplemented by snowball sampling. Interviews were conducted digitally and used a topic guide exploring FCP's perceptions and experiences of accessing knowledge, via Twitter, for clinical practice. Data were analyzed thematically and informed by the knowledge mobilization mindlines model. Public contributors were involved throughout.

RESULTS

In total, 19 FCPs consented to the interview (Twitter users, n=14 and female, n=9). Three themes were identified: (1) How Twitter meets the needs of FCPs, (2) Twitter and a journey of knowledge to support clinical practice, and (3) factors impeding knowledge sharing on Twitter. FCPs described needs relating to isolated working practices, time demands, and role uncertainty. Twitter provided rapid access to succinct knowledge, the opportunity to network, and peer reassurance regarding clinical cases, evidence, and policy. FCPs took a journey of knowledge exchange on Twitter, including scrolling for knowledge, filtering for credibility and adapting knowledge for in-service training and clinical practice. Participants engaged best with images and infographics. FCPs described misinformation, bias, echo chambers, unprofessionalism, hostility, privacy concerns and blurred personal boundaries as factors impeding knowledge sharing on Twitter. Consequently, many did not feel confident enough to actively participate on Twitter.

CONCLUSIONS

This study explores how Twitter is and can be used to mobilize knowledge to inform FCP clinical practice. Twitter can meet the knowledge needs of FCPs through rapid access to succinct knowledge, networking opportunities, and professional reassurance. The journey of knowledge exchange from Twitter to clinical practice can be explained by considering the mindlines model, which describes how FCPs exchange knowledge in digital and offline contexts. Findings demonstrate that Twitter can be a useful adjunct to FCP practice, although several factors impede knowledge sharing on the platform. We recommend social media training and enhanced governance guidance from professional bodies to support the use of Twitter for knowledge mobilization.

Roles of M cells in infection and mucosal vaccines

The mucosal immune system plays a crucial part in the control of infection. Exposure of humans and animals to potential pathogens generally occurs through mucosal surfaces, thus, strategies that target the mucosa seem rational and efficient vaccination measures. Vaccination through the mucosal immune system can induce effective systemic immune responses simultaneously with mucosal immunity compared with parenteral vaccination. M cells are capable of transporting luminal antigens to the underlying lymphoid tissues and can be exploited by pathogens as an entry portal to invade the host. Therefore, targeting M-cell-specific molecules might enhance antigen entry, initiate the immune response, and induce protection against mucosal pathogens. Here, we outline our understanding of the distribution and function of M cells, and summarize the advances in mucosal vaccine strategies that target M cells.

Innate immune responses against Cryptosporidium parvum infection

Cryptosporidium parvum infects intestinal epithelial cells and is commonly the parasite species involved in mammalian cryptosporidiosis, a major health problem for humans and neonatal livestock. In mice, immunologically mediated elimination of C. parvum requires CD4+ T cells and IFN-γ. However, innate immune responses also have a significant protective role in both adult and neonatal mice. NK cells and IFN-γ have been shown to be important components in immunity in T and B cell-deficient mice, but IFN-γ-dependent resistance has also been demonstrated in alymphocytic mice. Epithelial cells may play a vital role in immunity as once infected these cells have increased expression of inflammatory chemokines and cytokines and demonstrate antimicrobial killing mechanisms, including production of NO and antimicrobial peptides. Toll-like receptors facilitate the establishment of immunity in mice and are involved in the development of inflammatory responses of infected epithelial cells and also dendritic cells.

The role of bacteria in the pathogenesis of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) have features that suggest bacterial involvement, and all genetic models of inflammatory bowel disease (IBD) require the presence of commensal bacteria. CD is associated with innate immune response genes such as NOD2/CARD15 and the autophagy genes ATG16L1 and IRGM. However, IBD responds to immunosuppression, suggesting that any bacteria involved are not acting as conventional pathogens. Molecular techniques are rapidly advancing our knowledge of the gut microbiota. In CD there is reduced diversity, and notably a reduction in the probiotic Faecalibacterium prausnitzii, the presence of which in the terminal ileum is associated with a reduced risk of recurrence following surgery. There is also a consistent increase in mucosa-associated Escherichia coli with an "adherent and invasive" phenotype, which allows them to replicate inside macrophages and induce granulomas. Speculation that CD could be caused by the Mycobacterium avium subspecies paratuberculosis (MAP) continues. The response to antitumor necrosis factor treatments suggests that, if relevant at all, MAP is not acting as a conventional pathogen. However, there is increased colonization by MAP in CD, and there is evidence that it could have an indirect effect mediated by the suppression of macrophage function. UC relapse is frequently associated with infection by pathogens, but there is less evidence for involvement of a specific bacterial species. Poor barrier integrity followed by an inflammatory reaction to bacterial components, with chronicity maintained by an autoimmune process, seems a plausible pathogenic model. Bacterial theories of pathogenesis are now becoming testable by targeted therapeutic interventions.

MALT structure and function in farm animals

Mucosa-associated lymphoid tissue (MALT) is defined as an organized lymphoid tissue in the mucosa that samples antigens. The morphological characteristics that distinguish MALT from lymphoid infiltrates are discussed. MALT has been extensively investigated in laboratory animals, while knowledge in cattle, sheep, goats, pigs and horses that are summarized under the term farm animals in this review is fragmentary. Literature data about the distribution, morphology, function and involvement in infectious diseases of MALT in farm animals are described. The understanding of specific features of MALT in other species than laboratory animals is important for comparative research, in order to understand pathological and immunological processes in the respective species and as a potential route of vaccination of mucosal surfaces.

Lymphocyte depletion in ileal Peyer's patch follicles in lambs infected with Eimeria ovinoidalis

A total of 14 lambs were experimentally infected with Eimeria ovinoidalis in two separate experiments in two consecutive years. Nine lambs served as uninoculated controls. Material was collected from the ileum 2 weeks after infection in eight lambs and 3 weeks after infection in six lambs. Lambs examined 2 weeks after infection had normal follicles. After three weeks, the follicle-associated epithelium covering the lymphoid follicles of the ileal Peyer's patches showed fusions with adjacent absorptive epithelium, focal hyperplasia, and occasionally necrosis. Macrogametes, microgamonts, and oocysts were often found in the follicle-associated epithelium and the dome region. Various degrees of lymphocyte depletion were present in the ileal lymphoid follicles in all six infected lambs 3 weeks after infection, and four lambs had decreased follicle size. Reduced staining for leukocyte common antigen (CD45), B-cell markers, and the proliferation marker Ki-67 was present in these lambs. Application of the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling method for apoptotic cells revealed decreased staining in the ileal lymphoid follicles 3 weeks after infection. A marker of follicular dendritic cells, 5'- nucleotidase, showed increased reactivity, probably due to condensation of reticular cells following loss of follicle lymphocytes. Reduced staining for carbonic anhydrase in the follicle-associated epithelium and the domes was present in all six lambs examined 3 weeks after infection, indicating decreased production of carbonic anhydrase-reactive 50-nm particles and a decreased lymphoproliferative stimulus. In conclusion, the present study shows that severe E. ovinoidalis infection in lambs causes lesions of the follicle-associated epithelium and may result in lymphocyte depletion and atrophy of the ileal Peyer's patch follicles.

Uptake of ferritin by follicle-associated epithelium in the colon of calves

Uptake of macromolecules (e.g., ferritin) by M cells in follicle-associated epithelium in small and large intestine was investigated in three healthy, conventionally raised, 2- to 3-week-old, female Holstein Frisian calves. A 2.5% solution of ferritin was injected into the ligated loops in mid-jejunum, in terminal ileum, in the ascending colon adjacent to the ileocecal junction, and in the proximal loop of the ascending colon containing gut-associated lymphoid tissue. After exposure times that ranged from 82 to 165 minutes, ferritin was detected in M cells of domes in the small intestine, as well as in cells in follicle-associated epithelium of proprial lymphoid nodules and lymphoglandular complexes of colon that morphologically resembled M cells of small intestine. Ferritin was found in apical invaginations, apical vesicles, multivesicular bodies, basal vesicles, and adjacent intercellular spaces. In addition to ferritin, apical vesicles, multivesicular bodies, and intercellular spaces contained 50-nm membrane-bound particles. More ferritin was endocytosed by M cells of the small intestine than by M cells of the large intestine. In the large intestine, higher amounts of ferritin were found in M cells of follicle-associated epithelium overlying proprial lymphoid nodules than in M cells of follicle-associated epithelium in the depth of lymphoglandular complexes. Based on these results, we concluded that M cells of follicle-associated epithelium in the colon of calves provide a route for antigen uptake into the intestinal lymphoid system.

Immuno-histochemical and -cytochemical evidence suggesting the presence of Campylobacter jejuni and Campylobacter coli in cases of porcine intestinal adenomatosis

Antisera against a number of Campylobacter species were used in immuno-histochemical and -cytochemical studies on cases of porcine intestinal adenomatosis. Avidin-biotin-complex (ABC) and streptavidin immunoperoxidase methods were used on formalin-fixed, paraffin-embedded and frozen sections. Protein A gold method was used on formaldehyde fixed and frozen sections for immuno-cytochemistry. The antisera used were raised in rabbits by subcutaneous or intravenous injection of living or formalin treated organisms. Anti-sera against different serotypes of the thermotolerant, catalase positive campylobacters, Campylobacter jejuni and Campylobacter coli, gave positive reactions in the immuno-histochemical studies. The staining was found in intestinal epithelial cells both in the ileum and in the colon and was restricted to the apical cytoplasm of adenomatous epithelial cells. The staining had a granular pattern, the positive structures sometimes having the shape of Campylobacter. Epithelial cells in areas with normal differentiation of goblet cells did not stain. In contrast, no staining resulted with antisera against Campylobacter sputorum subsp. mucosalis and Campylobacter hyointestinalis. Immuno-cytochemistry, using antisera against Campylobacter jejuni, showed that the positive staining in altered epithelial cells were restricted to intracellular organisms having a structure resembling Campylobacter spp.

The intestinal habitat for organized lymphoid tissues in ruminants; comparative aspects of structure, function and development

Unlike the Peyer's patches of rats and mice, which are considered to be secondary lymphoid organs, the ileal Peyer's patch of sheep is thought to be responsible for the primary generation of B cells, like the bursa of Fabricius of birds. The ileal Peyer's patch of sheep shows prenatal maturation, antigen-independent lymphopoiesis, a rate of lymphocyte production larger than that of the thymus, and involution at a young age. Follicles contain few T cells and have an IgM+, relatively immature B lymphocyte population, as judged by B-cell differentiation markers. The follicle-associated epithelium of the ileal Peyer's patch is of a special type that sheds carbonic anhydrase-rich, 50-nanometer membrane-bounded particles (carbonic anhydrase-reactive particles; CAP) into the intercellular spaces. The CAP filter into the follicle centre and are taken up by lymphocytes. They represent the epithelial (bursa-like) element in an otherwise mesenchymal stroma of reticular cells embedding the follicle lymphocytes. Transepithelial transport of macromolecules, with the formation of multivesicular body-like cytoplasmic vacuoles, appears to be the basis for CAP formation. The jejunal Peyer's patches are devoid of CAP, persist in the adult animal, contain M cells with clusters of B cells in the follicle-associated epithelium, and have many CD4+ lymphocytes in the follicles and in the interfollicular areas. Aggregates of lymphoid follicles in the large intestine resemble the jejunal Peyer's patches with respect to their lymphocyte population and the ileal Peyer's patch with respect to their follicle-associated epithelium.

Cryptosporidiosis and AIDS

Cryptosporidiosis in patients with AIDS presents as a chronic enteritis, with biliary complications in about 10% of sufferers. The disease is persistent and progressively fatal. Due to the widespread prevalence of the parasite in the community and amongst domesticated animals, persons with AIDS are constantly at risk. Treatment is extremely difficult in view of the apparent lack of a specific anticryptosporidial drug. Methods of immunomodulation are worth considering, but the main recourse may have to be a prolonged regimen of rehydration and parenteral nutrition. However, if T helper cell function improves, the disease may go into remission or the parasite could be eliminated. Vaccination of those at risk is not feasible at present.

Immuno-histochemical and -cytochemical evidence suggesting the presence of Campylobacter jejuni and Campylobacter coli in cases of porcine intestinal adenomatosis

Antisera against a number of Campylobacter species were used in immuno-histochemical and -cytochemical studies on cases of porcine intestinal adenomatosis. Avidin-biotin-complex (ABC) and streptavidin immunoperoxidase methods were used on formalin-fixed, paraffin-embedded and frozen sections. Protein A gold method was used on formaldehyde fixed and frozen sections for immuno-cytochemistry. The antisera used were raised in rabbits by subcutaneous or intravenous injection of living or formalin treated organisms. Anti-sera against different serotypes of the thermotolerant, catalase positive campylobacters, Campylobacter jejuni and Campylobacter coli, gave positive reactions in the immuno-histochemical studies. The staining was found in intestinal epithelial cells both in the ileum and in the colon and was restricted to the apical cytoplasm of adenomatous epithelial cells. The staining had a granular pattern, the positive structures sometimes having the shape of Campylobacter. Epithelial cells in areas with normal differentiation of goblet cells did not stain. In contrast, no staining resulted with antisera against Campylobacter sputorum subsp. mucosalis and Campylobacter hyointestinalis. Immuno-cytochemistry, using antisera against Campylobacter jejuni, showed that the positive staining in altered epithelial cells were restricted to intracellular organisms having a structure resembling Campylobacter spp.