Isolation of Lymphocytes from Human Skin and Murine Tissues: A Rapid and Epitope-Preserving Approach

Tissue-resident immune cells have been shown to play an important role in skin health and disease. However, owing to limited access to human skin samples and time-consuming, technically demanding protocols, the characterization of tissue-derived cells remains challenging. For this reason, blood-derived leukocytes are frequently used as a surrogate specimen, although they do not necessarily reflect local immune responses in the skin. Therefore, we aimed to establish a rapid protocol to isolate a sufficient number of viable immune cells from 4-mm skin biopsies that can be directly used for a deeper characterization such as comprehensive phenotyping and functional studies of T cells. In this optimized protocol, only two enzymes, type IV collagenase and DNase I, were used to achieve both the highest possible cellular yield and marker preservation of leukocytes stained for multicolor flow cytometry. We further report that the optimized protocol may be used in the same manner for murine skin and mucosa. In summary, this study allows a rapid acquisition of lymphocytes from human or mouse skin suitable for comprehensive analysis of lymphocyte subpopulations, for disease surveillance, and for identification of potential therapeutic targets or other downstream applications.

Dupilumab Effects on Innate Lymphoid Cell and Helper T Cell Populations in Patients with Atopic Dermatitis

Group 2 innate lymphoid cells (ILCs) are thought to contribute to the pathogenesis of atopic dermatitis (AD). IL-4 stimulates T helper type 2 (Th2) cells and ILC2s to proliferate and produce cytokines. Dupilumab, an antibody against the IL-4 receptor, is used in AD therapy. We speculated that its efficacy might involve blocking the activation of Th2 cells and ILC2s via IL-4. Here, we examined circulating Th2 cells and ILC2s in 27 Japanese patients with AD before and after the administration of dupilumab. Between 0 and 4 months after dupilumab administration, the percentages of Th2 cells and ILC2s were decreased. Notably, ILC2/3 ratio was decreased after dupilumab treatment. Interestingly, ILC2/3 ratio before dupilumab treatment were significantly higher in high responders than in low responders to dupilumab. To resolve the molecular signatures of the Th2 and ILC2s in AD, we sorted CD4⁺ T cells and ILCs from peripheral blood and analyzed their transcriptomes using the BD Rhapsody Single-cell RNA sequencing system. Between 0 and 4 months after dupilumab administration, the Th2 and ILC2 cluster gene signatures were downregulated. Thus, dupilumab might improve dermatitis by suppressing the Th2 cell and ILC2 populations and altering the Th2 and ILC2 repertoire in patients with AD.

Toll-Like Receptor 7 Agonist-Induced Dermatitis Causes Severe Dextran Sulfate Sodium Colitis by Altering the Gut Microbiome and Immune Cells

BACKGROUND & AIMS

Psoriasis and inflammatory bowel disease (IBD) are both chronic inflammatory diseases occurring in the skin and gut, respectively. It is well established that psoriasis and IBD have high concordance rates, and similar changes in immune cells and microbiome composition have been reported in both conditions. To study this connection, we used a combination murine model of psoriatic dermatitis and colitis in which mice were treated topically with the Toll-like receptor 7 agonist imiquimod (IMQ) and fed dextran sulfate sodium (DSS).

METHODS

We applied IMQ topically to B6 mice (IMQ mice) and subsequently fed them 2% DSS in their drinking water. Disease activity and immune cell phenotypes were analyzed, and the microbial composition of fecal samples was investigated using 16S ribosomal RNA sequencing. We transplanted feces from IMQ mice to germ-free IQI/Jic (IQI) mice and fed them DSS to assess the effect of the gut microbiome on disease.

RESULTS

We first confirmed that IMQ mice showed accelerated DSS colitis. IMQ mice had decreased numbers of IgD⁺ and IgM⁺ B cells and increased numbers of non-cytokine-producing macrophages in the gut. Moreover, the gut microbiomes of IMQ mice were perturbed, with significant reductions of Lactobacillus johnsonii and Lactobacillus reuteri populations. Germ-free mice transplanted with feces from IMQ mice, but not with feces from untreated mice, also developed exacerbated DSS colitis.

CONCLUSIONS

These results suggest that skin inflammation may contribute to pathogenic conditions in the gut via immunologic and microbiological changes. Our finding of a novel potential skin-gut interaction provides new insights into the coincidence of psoriasis and IBD.

IL22 Inhibits Epithelial Stem Cell Expansion in an Ileal Organoid Model

Background & Aims

Crohn's disease is an inflammatory bowel disease that affects the ileum and is associated with increased cytokines. Although interleukin (IL)6, IL17, IL21, and IL22 are increased in Crohn's disease and are associated with disrupted epithelial regeneration, little is known about their effects on the intestinal stem cells (ISCs) that mediate tissue repair. We hypothesized that ILs may target ISCs and reduce ISC-driven epithelial renewal.

Methods

A screen of IL6, IL17, IL21, or IL22 was performed on ileal mouse organoids. Computational modeling was used to predict microenvironment cytokine concentrations. Organoid size, survival, proliferation, and differentiation were characterized by morphometrics, quantitative reverse-transcription polymerase chain reaction, and immunostaining on whole organoids or isolated ISCs. ISC function was assayed using serial passaging to single cells followed by organoid quantification. Single-cell RNA sequencing was used to assess Il22ra1 expression patterns in ISCs and transit-amplifying (TA) progenitors. An IL22-transgenic mouse was used to confirm the impact of increased IL22 on proliferative cells in vivo.

Results

High IL22 levels caused decreased ileal organoid survival, however, resistant organoids grew larger and showed increased proliferation over controls. Il22ra1 was expressed on only a subset of ISCs and TA progenitors. IL22-treated ISCs did not show appreciable differentiation defects, but ISC biomarker expression and self-renewal-associated pathway activity was reduced and accompanied by an inhibition of ISC expansion. In vivo, chronically increased IL22 levels, similar to predicted microenvironment levels, showed increases in proliferative cells in the TA zone with no increase in ISCs.

Conclusions

Increased IL22 limits ISC expansion in favor of increased TA progenitor cell expansion.

Functional Characterization of Inflammatory Bowel Disease-Associated Gut Dysbiosis in Gnotobiotic Mice

BACKGROUND & AIMS

Gut dysbiosis is closely involved in the pathogenesis of inflammatory bowel disease (IBD). However, it remains unclear whether IBD-associated gut dysbiosis contributes to disease pathogenesis or is merely secondary to intestinal inflammation. We established a humanized gnotobiotic (hGB) mouse system to assess the functional role of gut dysbiosis associated with 2 types of IBD: Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

Germ-free mice were colonized by the gut microbiota isolated from patients with CD and UC, and healthy controls. Microbiome analysis, bacterial functional gene analysis, luminal metabolome analysis, and host gene expression analysis were performed in hGB mice. Moreover, the colitogenic capacity of IBD-associated microbiota was evaluated by colonizing germ-free colitis-prone interleukin 10-deficient mice with dysbiotic patients' microbiota.

RESULTS

Although the microbial composition seen in donor patients' microbiota was not completely reproduced in hGB mice, some dysbiotic features of the CD and UC microbiota (eg, decreased diversity, alteration of bacterial metabolic functions) were recapitulated in hGB mice, suggesting that microbial community alterations, characteristic for IBD, can be reproduced in hGB mice. In addition, colonization by the IBD-associated microbiota induced a proinflammatory gene expression profile in the gut that resembles the immunologic signatures found in CD patients. Furthermore, CD microbiota triggered more severe colitis than healthy control microbiota when colonized in germ-free interleukin 10-deficient mice.

CONCLUSIONS

Dysbiosis potentially contributes to the pathogenesis of IBD by augmenting host proinflammatory immune responses. Transcript profiling: GSE73882.

GATA-3 augmentation down-regulates Connexin43 in Helicobacter pylori associated gastric carcinogenesis

Helicobacter pylori (H. pylori) is a risk factor of gastric carcinoma, and inflammation with H.pylori infection has widely been suggested to trigger gastric carcinogenesis through "inflammation-carcinoma chain" (non-atrophic gastritis (NAG) → chronic atrophic gastritis (CAG) → intestinal metaplasia (IM) → dysplasia (DYS) and gastric carcinoma (GC)). Connexin43 (Cx43) is a major constituent of gap junction in normal gastric mucosa (NGM) and it is continuously down-regulated from normal gastric mucosa to precancerous lesions or ultimate gastric carcinoma, which shows novel target against gastric carcinoma by preventing the Cx43 decline. Our previous studies demonstrated that H. pylori infection in gastric mucosa down-regulates Cx43 expression, but its mechanism remains unknown. The transcriptional factor, GATA binding protein 3 (GATA-3) is the key to regulate adaptive immune response, which possibly relates to inflammation toward malignant transformation. Here the substantial rising of GATA-3 was screened by transcriptional factor microarray along the developmental stages of H. pylori associated gastric carcinoma. Moreover, the increased GATA-3 and inhibited Cx43 were confirmed in clinical specimens, Mongolian gerbils and normal gastric epithelial cell line GES-1 with H. pylori infection. GATA-3 silencing generated the Cx43 restoration both in intermediate differentiation gastric cancer cells BGC-803 and in H. pylori infected GES-1 cells. Dual-luciferase reporter assay further revealed the GATA-3 as one of Cx43 down-regulators by directly binding to its promoters. Together, the incremental GATA-3 is found in H. pylori associated gastric carcinogenesis, which is responsible for Cx43 inhibition as well.

IL33 Is a Stomach Alarmin That Initiates a Skewed Th2 Response to Injury and Infection

BACKGROUND & AIMS

Interleukin (IL)33 is a recently described alarmin that is highly expressed in the gastric mucosa and potently activates Th2 immunity. It may play a pivotal role during Helicobacter pylori infection. Here, we delineate the role of IL33 in the normal gastric mucosa and in response to gastropathy.

METHODS

IL33 expression was evaluated in mice and human biopsy specimens infected with H pylori and in mice after dosing with aspirin. IL33 expression was localized in the gastric mucosa using immunofluorescence. Mice were given 1 or 7 daily doses of recombinant IL33 (1 μg/dose), and the stomach and the spleen responses were quantified morphologically, by flow cytometry and using quantitative reverse-transcription polymerase chain reaction and immunoblotting.

RESULTS

In mice, the IL33 protein was localized to the nucleus of a subpopulation of surface mucus cells, and co-localized with the surface mucus cell markers Ulex Europaeus 1 (UEA1), and Mucin 5AC (Muc5AC). A small proportion of IL33-positive epithelial cells also were Ki-67 positive. IL33 and its receptor Interleukin 1 receptor-like 1 (ST2) were increased 4-fold after acute (1-day) H pylori infection, however, this increase was not apparent after 7 days and IL33 expression was reduced 2-fold after 2 months. Similarly, human biopsy specimens positive for H pylori had a reduced IL33 expression. Chronic IL33 treatment in mice caused systemic activation of innate lymphoid cell 2 and polarization of macrophages to the M2 phenotype. In the stomach, IL33-treated mice developed transmural inflammation and mucous metaplasia that was mediated by Th2/signal transducer and activator of transcription 3 signaling. Rag-1^-/- mice, lacking mature lymphocytes, were protected from IL33-induced gastric pathology.

CONCLUSIONS

IL33 is highly expressed in the gastric mucosa and promotes the activation of T helper 2-cytokine-expressing cells. The loss of IL33 expression after prolonged H pylori infection may be permissive for the T helper 1-biased immune response observed during H pylori infection and subsequent precancerous progression.