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Hypovitaminosis D is a worldwide disorder, with a high prevalence in the general population of both Western and developing countries. In HIV patients, several studies have linked vitamin D status with bone disease, neurocognitive impairment, depression, cardiovascular disease, high blood pressure, metabolic syndrome, type 2 diabetes mellitus, infections, autoimmune diseases like type 1 diabetes mellitus, and cancer. In this review, we focus on the most recent epidemiological and experimental data dealing with the relationship between vitamin D deficiency and HIV infection. We analysed the extent of the problem, pathogenic mechanisms, clinical implications, and potential benefits of vitamin D supplementation in HIV-infected subjects.

Human rickettsial diseases comprise a variety of clinical entities caused by microorganisms belonging to the genera Rickettsia, Orientia, Ehrlichia, and Anaplasma. These microorganisms are characterized by a strictly intracellular location which has, for long, impaired their detailed study. In this paper, the critical steps taken by these microorganisms to play their pathogenic roles are discussed in detail on the basis of recent advances in our understanding of molecular Rickettsia-host interactions, preferential target cells, virulence mechanisms, three-dimensional structures of bacteria effector proteins, upstream signalling pathways and signal transduction systems, and modulation of gene expression. The roles of innate and adaptive immune responses are discussed, and potential new targets for therapies to block host-pathogen interactions and pathogen virulence mechanisms are considered.

Summary Leishmaniasis is a vector-borne protozoan infection whose clinical spectrum ranges from asymptomatic infection to fatal visceral leishmaniasis. Over the last decades, an increase in imported leishmaniasis cases in developed, non-endemic countries, have been pointed-out from a review of the international literature. Among the possible causes are increasing international tourism, influx of immigrants from endemic regions and military operations. The main area for the acquisition of cutaneous leishmaniasis, especially for adventure travelers on long-term trips in highly-endemic forested areas, is represented from South America, whereas popular Mediterranean destinations are emerging as the main areas to acquire visceral variant. Leishmaniasis should be considered in the diagnostic assessment of patients presenting with a compatible clinical syndrome and a history of travel to an endemic area, even if this occurred several months or years before. Adventure travelers, researchers, military personnel, and other groups of travelers likely to be exposed to sand flies in endemic areas, should receive counseling regarding leishmaniasis and appropriate protective measures. ª

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Irritable bowel syndrome (IBS) is a condition characterized by abdominal pain, bloating, flatus, and altered bowel habits. The role of dietary components in inducing IBS symptoms is difficult to explore. To date, foods are not considered a cause but rather symptom-triggering factors. Particular interest has been given to the so-called FODMAPs (fermentable oligo-, di-, and monosaccharides and polyols). We aimed to summarize the evidence from the most common approaches to manage suspected food intolerance in IBS, with a particular interest in the role of FODMAPs and the effects of a low FODMAP diet. We reviewed literature, consulting PubMed and Medline by using the search terms FODMAP(s), fructose, lactose, fructans, galactans, polyols (sorbitol, mannitol, maltitol, xylitol, erythritol, polydextrose, and isomalt), irritable bowel syndrome, and functional gastrointestinal symptoms. FODMAP-restricted diets have been used for a long time to manage patients with IBS. The innovation in the so-called FODMAP concept is that a global restriction should have a more consistent effect than a limited one in preventing abdominal distension. Even though all the potential low FODMAP diets provide good relief of symptoms in many patients, there is just a little relief in others. Several studies highlight the role of low FODMAP diets to improve symptoms in patients with IBS. The evidence on this dietary approach supports the hypothesis that a low FODMAP diet should be the first dietary approach. However, many points remain to be clarified, including the evaluation of possibly significant nutrition concerns.

Key words: non-celiac gluten sensitivity, celiac disease, wheat allergy, food allergy, HLA, flow cytometric basophil activation test, innate immune response Background: A significant percentage of the general population report problems caused by wheat and/or gluten ingestion, even though they do not have celiac disease (CD) or wheat allergy (WA), because they test negative both for CD-specific serology and histopathology and for immunoglobulin E (IgE)-mediated assays. Most patients report both gastrointestinal and nongastrointestinal symptoms, and all report improvement of symptoms on a gluten-free diet. This clinical condition has been named non-celiac gluten sensitivity (NCGS).Aim: We attempt to define the current pathogenic, clinical, and diagnostic criteria of this "new" disease, to provide a practical view that might be useful to evaluate, diagnose, and manage NCGS patients.Methods: We reviewed the international literature through PubMed and Medline, using the search terms "wheat (hyper)sensitivity," "wheat allergy," "wheat intolerance," "gluten (hyper)sensitivity," and "gluten intolerance," and we discuss current knowledge about NCGS.Results: It has been demonstrated that patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. NCGS diagnosis can be reached only by excluding CD and WA. Recent evidence shows that a personal history of food allergy in infancy, coexistent atopy, positive for immunoglobulin G (IgG) antigliadin antibodies and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients.Conclusions: Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroups. Key teaching points:• Most patients report both gastrointestinal and nongastrointestinal symptoms, and all agree that there is an improvement of symptoms on a gluten-free diet.• NCGS diagnosis can be reached only by excluding celiac disease and wheat allergy.• Patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course.• A personal history of food allergy in infancy, coexistent atopy, positive IgG antigliadin antibodies (AGA) and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients.• Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroup. Abbreviations: CD = celiac disease, WA = wheat allergy, NCGS = non-celiac gluten sensitivity, GFD = gluten-free diet, IBS = irritable bowel syndrome, HLA = human leukocyte antigen, tTg = antitissue transglutaminase, AGA = antigliadin antibodies, EMA = endomysial antigen, DGP = deami...

Summary Background Lymphoid aggregates are normally found throughout the small and large intestine. Known as lymphoid nodular hyperplasia (LNH), these aggregates are observed especially in young children and are not associated with clinical symptoms being considered ‘physiological’. In children presenting with gastrointestinal symptoms the number and size of the lymphoid follicles are increased. Patients suffering from gastrointestinal symptoms (i.e. recurrent abdominal pain) should systematically undergo gastroduodenoscopy and colonoscopy. With these indications LNH, especially of the upper but also of the lower gastrointestinal tract has been diagnosed, and in some children it may reflect a food hypersensitivity (FH) condition. Aim To review the literature about the relationship between LNH and FH, particularly focusing on the diagnostic work‐up for LNH related to FH. Methods We reviewed literature using Pubmed and Medline, with the search terms ‘lymphoid nodular hyperplasia’, ‘food hypersensitivity’, ‘food allergy’ and ‘food intolerance’. We overall examined 10 studies in detail, selecting articles about the prevalence of LNH in FH patients and of FH in LNH patients. Results Collected data showed a median of 49% (range 32–67%) LNH in FH patients and a median of 66% (range 42–90%) FH in LNH patients. Literature review pointed out that the most important symptom connected with LNH and/or FH was recurrent abdominal pain, followed by diarrhoea and growth retardation. Both LNH and FH are associated with an increase in lamina propria γ/δ+ T cells, but the mechanisms by which enhanced local immune responses causing gastrointestinal symptoms still remain obscure. Conclusions When assessing FH, we rely on clinical evaluation, including elimination diet and challenge tests, and endoscopic and immunohistochemical findings. Considering the possible co‐existence of duodenal and ileo‐colonic LNH, upper endoscopy can be recommended in children with suspected FH, especially in those presenting with additional upper abdominal symptoms (i.e. vomiting). Likewise, lower endoscopy might be additionally performed in patients with suspected FH and LNH of the duodenal bulb, also presenting with lower abdominal symptoms (i.e. recurrent abdominal pain).