The Salmonella pathogenicity island (SPI)-2 and SPI-1 type III secretion systems allow Salmonella serovar typhimurium to trigger colitis via MyD88-dependent and MyD88-independent mechanisms.

Salmonella typhimurium can colonize the gut, invade intestinal tissues, and cause enterocolitis. In vitro studies suggest different mechanisms leading to mucosal inflammation, including 1) direct modulation of proinflammatory signaling by bacterial type III effector proteins and 2) disruption or penetration of the intestinal epithelium so that penetrating bacteria or bacterial products can trigger innate immunity (i.e., TLR signaling). We studied these mechanisms in vivo using streptomycin-pretreated wild-type and knockout mice including MyD88(-/-) animals lacking an adaptor molecule required for signaling via most TLRs. The Salmonella SPI-1 and the SPI-2 type III secretion systems (TTSS) contributed to inflammation. Mutants that retain only a functional SPI-1 (M556; sseD::aphT) or a SPI-2 TTSS (SB161; DeltainvG) caused attenuated colitis, which reflected distinct aspects of the colitis caused by wild-type S. typhimurium: M556 caused diffuse cecal inflammation that did not require MyD88 signaling. In contrast, SB161 induced focal mucosal inflammation requiring MyD88. M556 but not SB161 was found in intestinal epithelial cells. In the lamina propria, M556 and SB161 appeared to reside in different leukocyte cell populations as indicated by differential CD11c staining. Only the SPI-2-dependent inflammatory pathway required aroA-dependent intracellular growth. Thus, S. typhimurium can use two independent mechanisms to elicit colitis in vivo: SPI-1-dependent and MyD88-independent signaling to epithelial cells and SPI-2-dependent intracellular proliferation in the lamina propria triggering MyD88-dependent innate immune responses.

Molecular Analyses Define Vα7.2-Jα33+ MAIT Cell Depletion in HIV Infection: A Case-Control Study

Mucosal-associated invariant T (MAIT) cells are an abundant antibacterial innate-like lymphocyte population. There are conflicting reports as to their fate in HIV infection. The objective of this study was to determine whether MAIT cells are truly depleted in HIV infection.In this case-control study of HIV-positive patients and healthy controls, quantitative real-time polymerase chain reaction was used to assess the abundance of messenger RNA (mRNA) and genomic DNA (gDNA) encoding the canonical MAIT cell T cell receptor (Vα7.2-Jα33). Comparison was made with flow cytometry.Significant depletion of both Vα7.2-Jα33 mRNA and gDNA was seen in HIV infection. Depletion of Vα7.2+CD161++ T cells was confirmed by flow cytometry. In HIV infection, the abundance of Vα7.2-Jα33 mRNA correlated most strongly with the frequency of Vα7.2+CD161++ cells. No increase was observed in the frequency of Vα7.2+CD161- cells among CD3+CD4- lymphocytes.MAIT cells are depleted from blood in HIV infection as confirmed by independent assays. Significant accumulation of a CD161- MAIT cell population is unlikely. Molecular approaches represent a suitable alternative to flow cytometry-based assays for tracking of MAIT cells in HIV and other settings.

Genome-Wide Analyses Suggest Mechanisms Involving Early B-Cell Development in Canine IgA Deficiency.

Immunoglobulin A deficiency (IgAD) is the most common primary immune deficiency disorder in both humans and dogs, characterized by recurrent mucosal tract infections and a predisposition for allergic and other immune mediated diseases. In several dog breeds, low IgA levels have been observed at a high frequency and with a clinical resemblance to human IgAD. In this study, we used genome-wide association studies (GWAS) to identify genomic regions associated with low IgA levels in dogs as a comparative model for human IgAD. We used a novel percentile groups-approach to establish breed-specific cut-offs and to perform analyses in a close to continuous manner. GWAS performed in four breeds prone to low IgA levels (German shepherd, Golden retriever, Labrador retriever and Shar-Pei) identified 35 genomic loci suggestively associated (p <0.0005) to IgA levels. In German shepherd, three genomic regions (candidate genes include KIRREL3 and SERPINA9) were genome-wide significantly associated (p <0.0002) with IgA levels. A ~20kb long haplotype on CFA28, significantly associated (p = 0.0005) to IgA levels in Shar-Pei, was positioned within the first intron of the gene SLIT1. Both KIRREL3 and SLIT1 are highly expressed in the central nervous system and in bone marrow and are potentially important during B-cell development. SERPINA9 expression is restricted to B-cells and peaks at the time-point when B-cells proliferate into antibody-producing plasma cells. The suggestively associated regions were enriched for genes in Gene Ontology gene sets involving inflammation and early immune cell development.

Mosaic pattern of sucrase isomaltase deficiency in two brothers

The pathophysiology of mucosal changes observed in infants with chronic protracted diarrhea is poorly understood. We report on two brothers suffering from a special form of sucrase isomaltase (SI) deficiency. The children presented with weight loss and dyspepsia after sucrose exposition. We performed an H respiration test, which showed a pathologic result in the younger brother. Analysis of the brush border enzyme activities showed low expression of lactase and SI. Immunoelectron microscopy of duodenal biopsies showed an isolated SI deficiency in a mosaic pattern [e.g., 42% (14%) crypt enterocytes and 64% (59%) villus enterocytes with decreased amounts of SI on microvilli], whereas lactase and aminopeptidase n (ApN) were present at the apical membrane of all cells in a normal range. The SI mosaic pattern of these patients shows that the enterocytes contain low amounts of SI on the apical membrane but express normal quantities of other disaccharidases. These findings suggest the existence of different clonal expressions or specific (posttranslational) mechanisms of postGolgi transportation for individual brush border enzymes. It remains unresolved whether the mosaic distribution is part of a normal maturation process or caused by a lack of an overall control mechanism in the expression of brush border hydrolases.

Bone loss after ridge expansion with or without reflection of the periosteum.

OBJECTIVE To evaluate the role of the periosteum in preserving the buccal bone after ridge splitting and expansion with simultaneous implant placement. MATERIAL AND METHODS In 12 miniature pigs, the mandibular premolars and first molars were removed together with the interdental bone septa and the buccal bone. Three months later, ridge splitting and expansion of the buccal plate was performed with simultaneous placement of two titanium implants per quadrant. Access by a mucosal flap (MF) was prepared on test sides, while a mucoperiosteal flap (MPF) with complete denudation of the buccal bone was increased on control sides. After healing periods of six and 12 weeks, the animals were sacrificed for histologic and histometric evaluation. RESULTS In the MF group, all 16 implants were osseointegrated, while in the MPF group, four of 16 implants were lost. Noticeable differences of bone levels on the implant surface and of the bone crest (BC) were found between the MF and the MPF group. Buccally after 6 weeks, the median distance between the implant shoulder (IS) and the coronal-most bone on the implant (cBIC) was for the MF group -1.42 ± 0.42 mm and for the MPF group -4.80 ± 2.72 mm (P = 0.15). The median distance between the IS and the buccal BC was -1.24 ± 0.51 mm and -2.78 ± 1.98 mm (P = 0.12) for the MF and MPF group, respectively. After 12 weeks, median IS-cBIC was -2.12 ± 0.84 mm for MF and -7.19 mm for MPF, while IS-BC was -2.08 ± 0.79 mm for MF and -5.96 mm for MPF. After 6 weeks, the median buccal bone thickness for MF and MPF was 0.01 and 0 mm (P < 0.001) at IS, 1.48 ± 0.97 mm and 0 ± 0.77 mm (P = 0.07) at 2 mm apical to IS, and 2.12 ± 1.19 mm and 1.72 ± 01.50 mm (P = 0.86) at 4 mm apical to IS, respectively. After 12 weeks, buccal bone thickness in the MF group was 0 mm at IS, 0.21 mm at 2 mm apical to IS, and 2.56 mm at 4 mm apical to IS, whereas complete loss of buccal bone was measured from IS to 4 mm apical to IS for the MPF group. CONCLUSIONS In this ridge expansion model in miniature pigs, buccal bone volume was significantly better preserved when the periosteum remained attached to the bone.

CD4 T cells are required for both development and maintenance of disease in a new mouse model of reversible colitis

Current therapies to treat inflammatory bowel diseases have limited efficacy, significant side effects, and often wane over time. Little is known about the cellular and molecular mechanisms operative in the process of mucosal healing from colitis. To study such events, we developed a new model of reversible colitis in which adoptive transfer of CD4(+)CD45RB(hi) T cells into Helicobacter typhlonius-colonized lymphopenic mice resulted in a rapid onset of colonic inflammation that was reversible through depletion of colitogenic T cells. Remission was associated with an improved clinical and histopathological score, reduced immune cell infiltration to the intestinal mucosa, altered intestinal gene expression profiles, regeneration of the colonic mucus layer, and the restoration of epithelial barrier integrity. Notably, colitogenic T cells were not only critical for induction of colitis but also for maintenance of disease. Depletion of colitogenic T cells resulted in a rapid drop in tumor necrosis factor α (TNFα) levels associated with reduced infiltration of inflammatory immune cells to sites of inflammation. Although neutralization of TNFα prevented the onset of colitis, anti-TNFα treatment of mice with established disease failed to resolve colonic inflammation. Collectively, this new model of reversible colitis provides an important research tool to study the dynamics of mucosal healing in chronic intestinal remitting-relapsing disorders.Mucosal Immunology advance online publication 16 September 2015; doi:10.1038/mi.2015.93.

Epithelial-intrinsic IKKα expression regulates group 3 innate lymphoid cell responses and antibacterial immunity

Innate lymphoid cells (ILCs) are critical for maintaining epithelial barrier integrity at mucosal surfaces; however, the tissue-specific factors that regulate ILC responses remain poorly characterized. Using mice with intestinal epithelial cell (IEC)-specific deletions in either inhibitor of κB kinase (IKK)α or IKKβ, two critical regulators of NFκB activation, we demonstrate that IEC-intrinsic IKKα expression selectively regulates group 3 ILC (ILC3)-dependent antibacterial immunity in the intestine. Although IKKβ(ΔIEC) mice efficiently controlled Citrobacter rodentium infection, IKKα(ΔIEC) mice exhibited severe intestinal inflammation, increased bacterial dissemination to peripheral organs, and increased host mortality. Consistent with weakened innate immunity to C. rodentium, IKKα(ΔIEC) mice displayed impaired IL-22 production by RORγt(+) ILC3s, and therapeutic delivery of rIL-22 or transfer of sort-purified IL-22-competent ILCs from control mice could protect IKKα(ΔIEC) mice from C. rodentium-induced morbidity. Defective ILC3 responses in IKKα(ΔIEC) mice were associated with overproduction of thymic stromal lymphopoietin (TSLP) by IECs, which negatively regulated IL-22 production by ILC3s and impaired innate immunity to C. rodentium. IEC-intrinsic IKKα expression was similarly critical for regulation of intestinal inflammation after chemically induced intestinal damage and colitis. Collectively, these data identify a previously unrecognized role for epithelial cell-intrinsic IKKα expression and TSLP in regulating ILC3 responses required to maintain intestinal barrier immunity.

Jejunitis and brown bowel syndrome with multifocal carcinogenesis of the small bowel

This is the first report describing a case where prolonged, severe malabsorption from brown bowel syndrome progressed to multifocally spread small bowel adenocarcinoma. This case involves a female patient who was initially diagnosed with chronic jejunitis associated with primary diffuse lymphangiectasia at the age of 26 years. The course of the disease was clinically, endoscopically, and histologically followed for 21 years until her death at the age 47 due to multifocal, metastasizing adenocarcinoma of the small bowel. Multiple lipofuscin deposits (so-called brown bowel syndrome) and severe jejunitis were observed microscopically, and sections of the small bowel showed dense lymphoplasmacytic infiltration of the lamina propria as well as blocked lymphatic vessels. After several decades, multifocal nests of adenocarcinoma cells and extensive, flat, neoplastic mucosal proliferations were found only in the small bowel, along with a loss of the mismatch repair protein MLH1 as a long-term consequence of chronic jejunitis with malabsorption. No evidence was found for hereditary nonpolyposis colon carcinoma syndrome. This article demonstrates for the first time multifocal carcinogenesis in the small bowel in a malabsorption syndrome in an enteritis-dysplasia-carcinoma sequence.

Fish Immune Responses to Myxozoa

Myxozoans evoke important economic losses in aquaculture production, but there is almost a total lack of disease control methods as no vaccines or commercial treatments are currently available. Knowledge of the immune responses that lead to myxozoan elimination and subsequent disease resistance is vital for shaping the future development of disease control measures. Different fish immune factors triggered by myxozoan parasites are reviewed in this chapter. Detailed information on the phenotypic and underlying molecular aspects of innate and adaptive responses, at both cellular and humoral levels, is provided for some well-studied fishmyxozoan systems. The importance of the local immune response, mainly at mucosal sites, is also highlighted. Myxozoan tactics to disable or avoid immune responses, such as modulation of immune gene transcription and immune evasion, are also reviewed. The existence of innate and acquired resistance to some myxozoan species suggest promising possibilities for controlling myxozooses through immune-based strategies, such as genetic selection for host resistance, vaccination, immune therapies and administration of immunostimulants.

Is "milk crust" a transient form of golden retriever ichthyosis?

BACKGROUND A recessive inherited form of lamellar ichthyosis is well recognized in golden retrievers. In this breed, young puppies demonstrate a self-limiting scaling disorder which is commonly recognized by breeders, who use the term "milk crust" to describe this syndrome. HYPOTHESIS/OBJECTIVES To determine whether "milk crust" is a new keratinization disorder or a self-limiting form of golden retriever ichthyosis. ANIMALS A total of 179 golden retriever dogs (21 dams and 158 puppies) were examined. METHODS Dermatological examination and assessment of the patatin-like phospholipase-1 (PNPLA1) genotype by PCR testing of buccal mucosal swabs. Skin biopsies from one affected puppy were evaluated for histopathological abnormalities. RESULTS Forty-five of 158 (28%) puppies exhibited scaling at 8 weeks of age; 113 of 158 (72%) were dermatologically normal. Of 144 analysed samples, 40 of 144 (28%) puppies demonstrated a homozygous mutation of the PNPLA1 genotype [of which, 36 of 40 (90%) had signs of scaling], 77 of 144 (53%) demonstrated a heterozygous mutation and 27 of 144 (19%) were a normal wild-type. In six of 17 (35%) dams, a homozygous mutation of the PNPLA1 genotype was found, eight of 17 (47%) demonstrated a heterozygous mutation and three of 17 (18%) were normal wild-type. Dams with a homozygous mutation were clinically unaffected. A 1 year follow-up revealed that 23 of 28 (82%) puppies affected with this syndrome failed to develop typical signs of ichthyosis. In five of 28 (18%) dogs there was persistence of mild scaling. CONCLUSIONS AND CLINICAL IMPORTANCE We hypothesize that the clinical syndrome termed "milk crust" could represent a transient form of golden retriever ichthyosis. Remission is not fully linked to PNPLA1 genotype, suggesting that unknown factors may contribute to the clinical disease.

Erosive esophageal reflux vs. non erosive esophageal reflux: oral findings in 71 patients.

BACKGROUND The purpose of this clinical study was to assess the prevalence of acidic oral mucosal lesions and periodontal conditions in patients suffering from erosive esophageal reflux disease (ERD) compared with non erosive esophageal reflux disease (NERD) patients, both treated with long term proton pump inhibitors (PPI). METHODS Seventy-one patients with diagnosed GERD were studied: i.e. 29 ERD and 42 NERD patients. Thorough visual examination of the oral mucosa and a periodontal evaluation was performed. The primary outcome was defined as a statistically significant difference, between the two groups, in the presence of acidic lesions of the oral mucosa and specific periodontal parameters. RESULTS This study failed to demonstrate statistically significant differences between ERD and NERD patients with respect to the prevalence of oral mucosal lesions. However, significantly more ERD patients suffered from severe periodontitis (CAL ≥ 5 mm) as compared to NERD patients. Accordingly, it may be assumed that PPI-use had no adverse effects on the prevalence of acidic oral mucosal lesions and on periodontal destruction. CONCLUSIONS Within the limitations of this study it may be concluded that ERD and NERD patients need separate evaluation with respect to periodontal destruction. Moreover, long term PPI medication had no adverse clinical impact on acidic oral mucosal lesions and periodontal destruction. Further studies are necessary to elucidate the role of reflux in the periodontal destruction of ERD individuals.

Comparative dendritic cell biology of veterinary mammals.

Dendritic cells (DC) have a main function in innate immunity in that they sense infections and environmental antigens at the skin and mucosal surfaces and thereby critically influence decisions about immune activation or tolerance. As professional antigen-presenting cells, they are essential for induction of adaptive immune responses. Consequently, knowledge on this cell type is required to understand the immune systems of veterinary mammals, including cattle, sheep, pigs, dogs, cats, and horses. Recent ontogenic studies define bona fide DC as an independent lineage of hematopoietic cells originating from a common precursor. Distinct transcription factors control the development into the two subsets of classical DC and plasmacytoid DC. These DC subsets express a distinguishable transcriptome, which differs from that of monocyte-derived DC. Using a comparative approach based on phenotype and function, this review attempts to classify DC of veterinary mammals and to describe important knowledge gaps.

Regulation of Neutrophil Serine Proteases by Intracellular Serpins

Neutrophil granules contain serine proteases that are central components of the antimicrobial weapons of the innate immune system. Neutrophil proteases also contribute to the amplification and resolution of inflammatory responses through defined proteolytic cleavage of mediators, cell surface receptors, and extracellular matrix proteins. In the blood and at mucosal surfaces, neutrophil serine proteases are regulated by serpins found in plasma and by non-serpin secreted inhibitors. Distinct mechanisms leading to neutrophil cell death have been described for the granule serine proteases, neutrophil elastase, cathepsin G, and proteinase-3. Granule leakage in neutrophils triggers death pathways mediated by cathepsin G and proteinase-3, and both proteases are tightly regulated by their inhibitor SERPINB1 in a cell intrinsic manner. Although stored in the same types of granules, neutrophil elastase does not significantly contribute to cell death following intracellular release from granules into the cytoplasm. However, heterozygous mutations in ELANE, the gene encoding elastase, are the cause of severe congenital neutropenia, a life-threatening condition characterized by the death of neutrophils at an early precursor stage in the bone marrow. This chapter focuses on recent work exploring the biology of clade B intracellular serpins that inhibit neutrophil serine proteases and their functions in neutrophil homeostasis and serine protease control at sites of inflammation.

Attenuated portal hypertension in germ-free mice: Function of bacterial flora on the development of mesenteric lymphatic and blood vessels

Intestinal bacterial flora may induce splanchnic hemodynamic and histological alterations that are associated with portal hypertension (PH). We hypothesized that experimental PH would be attenuated in the complete absence of intestinal bacteria. We induced prehepatic PH by partial portal vein ligation (PPVL) in germ-free (GF) or mice colonized with altered Schaedler's flora (ASF). After 2 or 7 days, we performed hemodynamic measurements, including portal pressure (PP) and portosystemic shunts (PSS), and collected tissues for histomorphology, microbiology, and gene expression studies. Mice colonized with intestinal microbiota presented significantly higher PP levels after PPVL, compared to GF, mice. Presence of bacterial flora was also associated with significantly increased PSS and spleen weight. However, there were no hemodynamic differences between sham-operated mice in the presence or absence of intestinal flora. Bacterial translocation to the spleen was demonstrated 2 days, but not 7 days, after PPVL. Intestinal lymphatic and blood vessels were more abundant in colonized and in portal hypertensive mice, as compared to GF and sham-operated mice. Expression of the intestinal antimicrobial peptide, angiogenin-4, was suppressed in GF mice, but increased significantly after PPVL, whereas other angiogenic factors remained unchanged. Moreover, colonization of GF mice with ASF 2 days after PPVL led to a significant increase in intestinal blood vessels, compared to controls. The relative increase in PP after PPVL in ASF and specific pathogen-free mice was not significantly different. CONCLUSION In the complete absence of gut microbial flora PP is normal, but experimental PH is significantly attenuated. Intestinal mucosal lymphatic and blood vessels induced by bacterial colonization may contribute to development of PH.