A comprehensive molecular characterization of a claudin-low luminal B breast tumor.

Breast cancer is the most common cause of death from cancer in women. Here, we present the case of a 43-year-old woman, who received a diagnosis of claudin-low luminal B breast cancer. The lesion revealed to be a poorly differentiated high-grade infiltrating ductal carcinoma, which was strongly estrogen receptor (ER)/progesterone receptor (PR) positive and human epidermal growth factor receptor (HER2) negative. Her tumor underwent in-depth chromosomal, mutational and gene expression analyses. We found a pathogenic protein truncating mutation in the TP53 gene, which is predicted to disrupt its transcriptional activity. The patient also harbors germline mutations in some mismatch repair (MMR) genes, and her tumor displays the presence of immune infiltrates, high tumor mutational burden (TMB) status and the apolipoprotein B mRNA editing enzyme catalytic polypeptide 3 (APOBEC3) associated signatures, which, overall, are predictive for the use of immunotherapy. Here, we propose promising prognostic indicators as well as potential therapeutic strategies based on the molecular characterization of the tumor.

The impact of CLDN18.2 expression on effector cells mediating antibody-dependent cellular cytotoxicity in gastric cancer.

Activating antibody-dependent cellular cytotoxicity (ADCC) by targeting claudin-18 isoform 2 (CLDN18.2) using zolbetuximab, a monoclonal antibody against CLDN18.2, has been considered a promising novel therapeutic strategy for gastric cancer (GC). However, the impact of CLDN18.2 expression on natural killer (NK) cells and monocytes/macrophages-crucial effector cells of ADCC-in GC has not been fully investigated. In the present study, we assessed the impact of CLDN18.2 expression on clinical outcomes, molecular features, and the frequencies of tumor-infiltrating NK cells and macrophages, as well as peripheral blood NK cells and monocytes, in GC by analyzing our own GC cohorts. The expression of CLDN18.2 did not significantly impact clinical outcomes of GC patients, while it was significantly and positively associated with Epstein-Barr virus (EBV) status and PD-L1 expression. The frequencies of tumor-infiltrating NK cells and macrophages, as well as peripheral blood NK cells and monocytes, were comparable between CLDN18.2-positive and CLDN18.2-negative GCs. Importantly, both CLDN18.2 expression and the number of tumor-infiltrating NK cells were significantly higher in EBV-associated GC compared to other molecular subtypes. Our findings support the effectiveness of zolbetuximab in CLDN18.2-positive GC, and offer a novel insight into the treatment of this cancer type, highlighting its potential effectiveness for CLDN18.2-positive/EBV-associated GC.

Heterogeneity of claudin 18.2 expression in metastatic gastric cancer.

Claudin 18.2 has emerged as a viable therapeutic target in gastric cancer (GC), but little is known about the heterogeneity of its expression in GC. This study investigated the heterogeneity of claudin 18.2 expression in 166 patients with metastatic GC whose surgical or paired primary-metastatic specimens were available. The prevalence of claudin 18.2 positivity (moderate-to-strong expression in ≥ 75% by the 43-14A clone) was 47.0%. Claudin 18.2-positive tumors exhibited more frequent peritoneal metastasis and a lower incidence of hepatic and distant lymph node involvement. Survival outcomes were comparable between patients with claudin 18.2-positive and -negative tumors. Intratumoral heterogeneity was noted in 38.5% of surgical specimens. Paired primary-metastatic site analysis revealed that 25.2% of patients had discordant results for claudin 18.2 positivity. Across different metastatic organ categories, peritoneal lesions showed the highest positivity rate (44.3%) and positive concordance rate (31.4%), whereas liver lesions had the lowest positivity rate (17.9%) and concordance rate (12.8%). In conclusion, claudin 18.2 expression exhibits intratumoral and intrapatient spatial heterogeneity in metastatic GC. Claudin 18.2 positivity is associated with more frequent peritoneal metastasis, and peritoneal lesions are more likely to have positively concordant claudin 18.2 results with the primary site than other metastatic sites.

Intestinal epithelial Cldn-7 regulates intestinal inflammation by altering the gut microbiota.

BACKGROUND AND AIM: Tight junctions maintain gut homeostasis by forming a physical barrier that protects the gut from invasion by microbiota. Cldn-7 is an important component involved in this protection, but the relationship between Cldn-7, intestinal inflammation, and gut microbiota has not been clarified. Here, we hypothesize that Cldn-7 depletion affects intestinal inflammation by altering the gut microbiota. METHODS: Based on the induced intestinal condition of Cldn-7 knockout mice (Cldn7fl/fl;villin-CreaERT2), we established the intestinal flora depletion model and colitis model by antibiotic drinking and feeding with dextran sodium sulfate (DSS). The environment of Cldn-7 gene deletion mice was changed by co-housing experiment. AB-PAS staining and Muc2 were used to detect the effect of co-housing and Cldn-7 deficiency on the mucus layer after flora depletion. qRT-PCR was used to detect the expression of intestinal inflammatory factors and AMPs in mice. Feces were collected and proportions of microbiota were analyzed by 16 S rRNA amplicon sequencing. RESULTS: Mice in the co-housing experiment had altered intestinal microbiota, including diversity, composition, and functional prediction, compared to controls. Intestinal inflammation was restored to some extent following altered intestinal microbiota. The intestinal inflammation caused by Cldn-7 deficiency and susceptibility to DSS could be reduced after antibiotic administration compared to controls, in terms of phenotype, pathological changes, inflammatory factors, mucus barrier, and expression of AMPs. CONCLUSIONS: In analyses of intestinal tissues, colitis induction, and gut microbiota in mice with intestinal disruption of Cldn-7, we found this protein to prevent intestinal inflammation by regulating the gut microbiota. Cldn-7might therefore be an important mediator of host-microbiome interactions. Our research has revealed that Cldn-7 plays an indispensable role in maintaining intestinal homeostasis by regulating the gut microbiota and impacting intestinal inflammation. These findings provide new insights into the pathogenesis of ulcerative colitis.

Prinsepia utilis Royle polysaccharides promote skin barrier repair through the Claudin family.

BACKGROUND: Plant polysaccharides have various biological activities. However, few studies have been conducted on the skin barrier of Prinsepia utilis Royle polysaccharide extract (PURP). MATERIALS AND METHODS: The proportions of polysaccharides, monosaccharides and proteins were determined by extracting polysaccharides from fruit meal using water. The healing rate was measured by cell scratch assays. SDS-damaged reconstructed human epidermal models, an acetone-ether-induced mouse model and an IL-4-induced cellular inflammation model were used to detect the effects of polysaccharides on the phenotype, HA, TEWL, and TEER, with further characterizations performed using QRT-PCR, Western blotting, immunofluorescence (IF) assays. RESULTS: PURP contained 35.73% polysaccharides and 11.1% proteins. PURP promoted cell migration and increased skin thickness in a reconstructed human epidermis model. The TEWL significantly decreased, and the HA content significantly increased. PURP significantly increased the TEER and decreased the permeability of the SDS-damaged reconstructed human epidermis model. Claudin-3, Claudin-4, and Claudin-5 were significantly upregulated. IF and Western blot analysis revealed that the Claudin-4 level significantly increased after treatment with PURP. Claudin-1, Claudin-3, Claudin-4, and Claudin-5 gene expression and IF and immunohistochemical staining were significantly increased in mice treated with acetone-ether. PURP promoted the expression of Claudin-1, Claudin-3, Claudin-4, and Claudin-5 after treatment with 100 ng/mL IL-4. PURP also downregulated the expression of NO, IL6, TNFα and NFκB in Raw 264.7 cells and in a mouse model. CONCLUSION: We hypothesize that PURP may repair the skin barrier by promoting the expression of the claudin family and can assist in skin therapy.

Comparative morphology of tumour microenvironment in claudin-low and claudin-high breast cancers.

BACKGROUND: Claudin-low breast cancers (BCs) exhibit more aggressive behaviour compared to claudin-high types. Claudin-low BCs are often characterized by features such as a higher grade, enrichment of stemness characteristics, and a propensity for metastasis. Tumour microenvironment (TME) defined as the intricate network of surrounding cells, blood vessels, and extracellular matrix components influences the behaviour of cancer cells within the breast tissue. Understanding the TME is crucial for comprehending the aggressive characteristics of claudin-low BCs. METHODS: In this study, we have studied the morphology of immune and non-immune TME using Haematoxylin and eosin (H&E)-stained slides of 15 claudin-low and 12 claudin-high tissue samples of BC. RESULTS: TME of claudin-low BCs was observed to have a significantly higher frequency of retraction clefts (66.6 %; n = 10/15), immature desmoplastic response (40 %; n = 6/15), higher stromal cellularity (60 %; n = 9/15); and fibroblastic proliferation (53.3 %; n = 8/15) with a low prevalence of elastosis (66.6 %; n = 10/15). The immune microenvironment revealed a higher frequency of total (80 %; n = 12/15) as well as stromal (86.67 %; n = 13/15) and intra-tumoural TILs (60 %; n = 9/15) in them. CONCLUSION: The above morphology-based study revealed that claudin-low tumours have unique immune and non-immune TME as compared to claudin-high tumours. Future studies exploring the molecular correlates of each of the above morphological features can help in identifying novel therapeutic targets for the treatment of claudin-low BCs.

Sinuous Is a Claudin Required for Locust Molt in Locusta migratoria.

The epidermal cells of insects are polarized epithelial cells that play a pivotal role in the insect's molting process. Sinuous, a pivotal structural protein involved in the formation of septate junctions among epithelial cells, is essential for its physiological function. In this study, to determine whether sinuous participates in the regulation of insect molting, we identified the sinuous gene, Lmsinu, in Locusta migratoria, which encodes a protein belonging to the claudin family and shares 62.6% identity with Drosophila's sinuous protein. Lmsinu is expressed in multiple tissues, and its expression level in the integument significantly increases prior to molting. Knockdown of Lmsinu in L. migratoria results in larval mortality during molting. Furthermore, hematoxylin and eosin and chitin staining demonstrate that the downregulation of Lmsinu led to a prolonged degradation process of the old cuticle during the molting process. Electron microscopy analysis further revealed that knockdown of Lmsinu disrupts the formation of septate junctions among epidermal cells, which are a monolayer of polarized epithelial cells, which may hinder the functionality of epidermal cells during the process of molting. In summary, these findings suggest that Lmsinu plays a role in nymph molting by regulating the formation of septate junctions among epidermal cells.

Global prevalence of claudin 18 isoform 2 in tumors of patients with locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma.

BACKGROUND: Limited data exist for global prevalence of claudin 18 isoform 2 (CLDN18.2) positivity and association of CLDN18.2 status with clinical and tumor characteristics in patients with locally advanced (LA) unresectable or metastatic gastric or gastroesophageal junction (mG/GEJ) adenocarcinoma. We report prevalence of CLDN18.2 positivity (phase 3; SPOTLIGHT, NCT03504397; GLOW, NCT03653507) and concordance of CLDN18.2 status between a subset of pair-matched tumor samples (phase 2, ILUSTRO, NCT03505320; phase 1, NCT03528629) from clinical studies of zolbetuximab. METHODS: Tumor samples from patients with LA unresectable or mG/GEJ adenocarcinoma were tested for CLDN18.2 status by immunohistochemistry. Human epidermal growth factor receptor 2 (HER2) expression was tested per central or local assessment. RESULTS: Across SPOTLIGHT and GLOW, the prevalence of CLDN18.2 positivity (≥ 75% of tumor cells demonstrating moderate-to-strong membranous CLDN18 staining) was 38.4%. Prevalence was similar in gastric versus GEJ adenocarcinoma samples and regardless of collection method (biopsy versus resection) or collection site (primary versus metastatic). CLDN18.2 positivity was most prevalent in patients with diffuse-type tumors. In ILUSTRO and the phase 1 study, concordance of CLDN18.2 positivity was 61.1% between archival (i.e., any time before treatment) and baseline (i.e., ≤ 3 months before first treatment) samples, and concordance of any CLDN18 staining (≥ 1% of tumor cells demonstrating moderate-to-strong membranous CLDN18 staining) was 88.9%. CONCLUSIONS: CLDN18.2 was a highly prevalent biomarker in patients with HER2-negative, LA unresectable or mG/GEJ adenocarcinoma. CLDN18.2 positivity remained relatively stable over time in many patients. Biomarker testing for CLDN18.2 should be considered in standard clinical practice in these patients.

Preparation of Radiolabeled Zolbetuximab Targeting CLDN18.2 and Its Preliminary Evaluation for Potential Clinical Applications.

Claudin18.2 (CLDN18.2), due to its high expression in various gastric cancer tissues, is considered an optimal target for antitumor drug molecules. In this study, we obtained the labeled compounds of [125I]I-zolbetuximab using the Iodogen method. Under the optimum labeling conditions, the molar activity of [125I]I-zolbetuximab was 1.75 × 102 GBq/µmol, and the labeling efficiency was more than 99%. The labeled compounds exhibited excellent in vitro stability in both phosphate buffer saline (PBS, pH = 7.4) and fetal bovine serum systems (FBS) (radiochemical purity >90% at 72 h). The uptake percentage of [125I]I-zolbetuximab in MKN45-CLDN18.2 cells is 24.69 ± 0.84% after 6 h. The saturation binding assay and specificity assay further demonstrated the high specificity of [125I]I-zolbetuximab for CLDN18.2. The long retention at the tumor site and rapid metabolic clearance at other organ sites of [125I]I-zolbetuximab were observed in small-animal SPECT-CT imaging. The same trend was also observed in the biodistribution study. Due to the excellent targeting ability of zolbetuximab for CLDN18.2, [125I]I-zolbetuximab exhibits strong specific binding and retention with cells and tumors highly expressing CLDN18.2. However, the balance between mAb's longer cycle time in vivo and targeting binding and retention ability should be intensively considered for using this kind of radiopharmaceutical in the diagnosis and treatment of CLDN18.2-positive gastric cancer.

Characteristics of Retinal Vascular Degeneration and the Expression of Vessel-Related Claudin Proteins in Retinal Degeneration Mouse.

INTRODUCTION: This study aimed to investigate the characteristics of retinal vascular degeneration and the expression of vessel-related claudin (CLD) proteins in retinal degeneration mouse (Pde6ßrd1/rd1 rd1 mouse). METHODS: Retinas from wild-type (WT) mice and rd1 mice at postnatal day 3 (P3), P5, P8, P11, P13, P15, P18, and P21 were collected. Immunofluorescence staining was used to assess the retinal vascular plexus, cell proliferation, CLD expression, and retinal ganglion cells (RGCs). The distribution of retinal superficial and deep vessels was determined by isolectin B4 fluorescence staining of retinal flat mounts and frozen sections. Hematoxylin and eosin staining and terminal deoxynucleotidyl transferase-mediated dNTP nick-end labeling were used to investigate retinal histological degeneration and apoptosis in rd1 mice, respectively. Quantitative real-time PCR and Western blot were used to measure the expression of vessel-related CLD-1, -2, -3, and -5, vascular endothelial growth factor A (VEGFA), and vascular endothelial growth factor receptor 2 (VEGFR2) in the retinas. RESULTS: Compared to the WT mice, the rd1 mice displayed delayed but completed progressive development in the retinal superficial vascular plexuses (SVPs) and deep vascular plexuses (DVPs). In the rd1 mice, the thickness of retinal layers gradually decreased and the retinas underwent progressive atrophy and degeneration. The deterioration got worse at the late developmental stage. The declined vessel density of SVP and DVP correlated with the decreased thickness of the full and inner parts of the retina and the reduced number of RGCs. DVP degeneration and the thinning of the outer nuclear layer exhibited an obvious reduction at P15. The expression levels of CLD-1, CLD-2, CLD-3, CLD-5, VEGFA, and VEGFR2 decreased and were consistently lower in the rd1 mice than in WT mice since P15. CONCLUSION: Rd1 mice exhibited progressive vascular degeneration of retinal SVP and DVP, the thinning and atrophy of retinal ONL and RGC, and the downregulation of vessel-related CLD proteins during the late developmental period. Thus, the rd1 mouse is a useful model of not only retinal neuro-degeneration but also retinal vascular degeneration.

Molecular SPECT/CT Profiling of Claudin18.2 Expression In Vivo: Implication for Patients with Gastric Cancer.

Zolbetuximab (IMAB362), a monoclonal antibody targeting Claudin18.2 (CLDN 18.2), demonstrates a significant clinical benefit in patients with advanced gastroesophageal cancers. The noninvasive assessment of CLDN18.2 expression through molecular imaging offers a potential avenue for expedited monitoring and the stratification of patients into risk groups. This study elucidates that CLDN18.2 is expressed at a noteworthy frequency in primary gastric cancers and their metastases. The iodogen method was employed to label IMAB362 with 123I/131I. The results demonstrated the efficient and reproducible synthesis of 123I-IMAB362, with a specific binding affinity to CLDN18.2. Immuno-single-photon emission computed tomography (SPECT) imaging revealed the rapid accumulation of 123I-IMAB362 in gastric cancer xenografts at 12 h, remaining stable for 3 days in patient-derived tumor xenograft models. Additionally, tracer uptake of 123I-IMAB362 in MKN45 cells surpassed that in MKN28 cells at each time point, with tumor uptake correlating significantly with CLDN18.2 expression levels. Positron emission tomography/computed tomography imaging indicated that tumor uptake of 18F-FDG and the functional/viable tumor volume in the 131I-IMAB362 group were significantly lower than those in the 123I-IMAB362 group on day 7. In conclusion, 123I-IMAB362 immuno-SPECT imaging offers an effective method for direct, noninvasive, and whole-body quantitative assessment of tumor CLDN18.2 expression in vivo. This approach holds promise for accelerating the monitoring and stratification of patients with gastric cancer.

Claudin 18 turns up the heat in cancer.

A major barrier to antitumor immunity in solid tumors is T cell exclusion. In this issue of Immunity, De Sanctis et al.1 elucidate how CLDN18 on pancreatic and lung cancer cells enhances infiltration, immunological synapse formation, and activation of cytotoxic T lymphocytes.

Downregulation of chemoresistance by claudin-14 silencing in human colorectal cancer cells.

An exceptional expression of claudins (CLDNs), tight junction (TJ) proteins, is observed in various solid cancer tissues. However, the pathophysiological roles of CLDNs have not been clarified in detail. CLDN14 is highly expressed in human colorectal cancer (CRC) tissues and cultured cancer epithelial cells. We found CLDN14 silencing decreased cell viability without affecting spheroid size in the three-dimensional (3D) spheroid model of DLD-1 cells derived from human CRC. Mitochondria activity and oxidative stress level were reduced by CLDN14 silencing. Furthermore, CLDN14 silencing decreased the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and its target antioxidative genes. CLDN14 was colocalized with ZO-1, a scaffolding protein in the TJ. CLDN14 silencing induced the disruption of TJ barrier such as the reduction of transepithelial electrical resistance and elevation of fluxes of small molecules including glucose in two-dimensional (2D) cultured model,. The depletion of glucose induced the elevation of ROS generation, mitochondria activity, and Nrf2 expression. These results suggest that CLDN14 increases Nrf2 expression in spheroids mediated via the formation of paracellular barrier to glucose. The cytotoxicities of doxorubicin, an anthracycline anticancer drug, and oxaliplatin, a platinum-based agent, were augmented by an Nrf2 activator in 2D cultured cells. The anticancer drug-induced toxicity was enhanced by CLDN14 silencing in 3D spheroids. We suggest that CLDN14 may potentiate chemoresistance mediated by the suppression of paracellular glucose permeability and activation of the Nrf2 signaling pathway in CRC cells.

The preclinical discovery and development of zolbetuximab for the treatment of gastric cancer.

INTRODUCTION: Gastric cancer remains a formidable challenge in oncology with high mortality rates and few advancements in treatment. Claudin-18.2 (CLDN18.2) is a tight junction protein primarily expressed in the stomach and is frequently overexpressed in certain subsets of gastric cancers. Targeting CLDN18.2 with monoclonal antibodies, such as zolbetuximab (IMAB362), has shown promising efficacy results in combination with chemotherapy. AREAS COVERED: The molecular cell biology of CLDN18.2 is discussed along with studies demonstrating the utility of CLDN18.2 expression as a biomarker and therapeutic target. Important clinical studies are reviewed, including Phase III trials, SPOTLIGHT and GLOW, which demonstrate the efficacy of zolbetuximab in combination with chemotherapy in patients with CLDN18.2-positive advanced gastric cancer. EXPERT OPINION: CLDN18.2 is involved in gastric differentiation through maintenance of epithelial barrier function and coordination of signaling pathways, and its expression in gastric cancers reflects a 'gastric differentiation' program. Targeting Claudin-18.2 represents the first gastric cancer specific 'targeted' treatment. Further studies are needed to determine its role within current gastric cancer treatment sequencing, including HER2-targeted therapies and immunotherapies. Management strategies will also be needed to better mitigate zolbetuximab-related treatment side effects, including gastrointestinal (GI) toxicities.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial final results.

Claudin18.2 (CLDN18.2) is highly expressed with the development of various malignant tumors, especially gastrointestinal cancers, and is emerging as a new target for cancer treatment. Satricabtagene autoleucel (satri-cel)/CT041 is an autologous chimeric antigen receptor (CAR) T cell targeting CLDN18.2, and the interim results of the CT041-CG4006 trial were reported in June 2022. Here we present the final results of this single-arm, open-label, phase 1 trial, which evaluated the safety and efficacy of satri-cel in patients with CLDN18.2-positive advanced gastrointestinal cancers. This trial included a dose-escalation stage (n = 15) and a dose-expansion stage in four different cohorts (total n = 83): cohort 1, satri-cel monotherapy in 61 patients with standard chemotherapy-refractory gastrointestinal cancers; cohort 2, satri-cel plus anti-PD-1 therapy in 15 patients with standard chemotherapy-refractory gastrointestinal cancers; cohort 3, satri-cel as sequential treatment after first-line therapy in five patients with gastrointestinal cancers; and cohort 4, satri-cel monotherapy in two patients with anti-CLDN18.2 monoclonal antibody-refractory gastric cancer. The primary endpoint was safety; secondary endpoints included efficacy, pharmacokinetics and immunogenicity. A total of 98 patients received satri-cel infusion, among whom 89 were dosed with 2.5 × 108, six with 3.75 × 108 and three with 5.0 × 108 CAR T cells. Median follow-up was 32.4 months (95% confidence interval (CI): 27.3, 36.5) since apheresis. No dose-limiting toxicities, treatment-related deaths or immune effector cell-associated neurotoxicity syndrome were reported. Cytokine release syndrome occurred in 96.9% of patients, all classified as grade 1-2. Gastric mucosal injuries were identified in eight (8.2%) patients. The overall response rate and disease control rate in all 98 patients were 38.8% and 91.8%, respectively, and the median progression-free survival and overall survival were 4.4 months (95% CI: 3.7, 6.6) and 8.8 months (95% CI: 7.1, 10.2), respectively. Satri-cel demonstrates therapeutic potential with a manageable safety profile in patients with CLDN18.2-positive advanced gastrointestinal cancer. ClinicalTrials.gov identifier: NCT03874897 .

Heterogenous Gene Expression of Bicellular and Tricellular Tight Junction-Sealing Components in the Human Intestinal Tract.

A major site for the absorption of orally administered drugs is the intestinal tract, where the mucosal epithelium functions as a barrier separating the inside body from the outer environment. The intercellular spaces between adjacent epithelial cells are sealed by bicellular and tricellular tight junctions (TJs). Although one strategy for enhancing intestinal drug absorption is to modulate these TJs, comprehensive gene (mRNA) expression analysis of the TJs components has never been fully carried out in humans. In this study, we used human biopsy samples of normal-appearing mucosa showing no endoscopically visible inflammation collected from the duodenum, jejunum, ileum, colon, and rectum to examine the mRNA expression profiles of TJ components, including occludin and tricellulin and members of the claudin family, zonula occludens family, junctional adhesion molecule (JAM) family, and angulin family. Levels of claudin-3, -4, -7, -8, and -23 expression became more elevated in each segment along the intestinal tract from the upper segments to the lower segments, as did levels of angulin-1 and -2 expression. In contrast, expression of claudin-2 and -15 was decreased in the large intestine compared to the small intestine. Levels of occludin, tricellulin, and JAM-B and -C expression were unchanged throughout the intestine. Considering their segment specificity, claudin-8, claudin-15, and angulin-2 appear to be targets for the development of permeation enhancers in the rectum, small intestine, and large intestine, respectively. These data on heterogenous expression profiles of intestinal TJ components will be useful for the development of safe and efficient intestinal permeation enhancers.

The impact of microplastics polystyrene on the microscopic structure of mouse intestine, tight junction genes and gut microbiota.

Microplastics, which are tiny plastic particles less than 5 mm in diameter, are widely present in the environment, have become a serious threat to aquatic life and human health, potentially causing ecosystem disorders and health problems. The present study aimed to investigate the effects of microplastics, specifically microplastics-polystyrene (MPs-PS), on the structural integrity, gene expression related to tight junctions, and gut microbiota in mice. A total of 24 Kunming mice aged 30 days were randomly assigned into four groups: control male (CM), control female (CF), PS-exposed male (PSM), and PS-exposed female (PSF)(n = 6). There were significant differences in villus height, width, intestinal surface area, and villus height to crypt depth ratio (V/C) between the PS group and the control group(C) (p <0.05). Gene expression analysis demonstrated the downregulation of Claudin-1, Claudin-2, Claudin-15, and Occludin, in both duodenum and jejunum of the PS group (p < 0.05). Analysis of microbial species using 16S rRNA sequencing indicated decreased diversity in the PSF group, as well as reduced diversity in the PSM group at various taxonomic levels. Beta diversity analysis showed a significant difference in gut microbiota distribution between the PS-exposed and C groups (R2 = 0.113, p<0.01), with this difference being more pronounced among females exposed to MPs-PS. KEGG analysis revealed enrichment of differential microbiota mainly involved in seven signaling pathways, such as nucleotide metabolism(p<0.05). The relative abundance ratio of transcriptional pathways was significantly increased for the PSF group (p<0.01), while excretory system pathways were for PSM group(p<0.05). Overall findings suggest that MPs-PS exhibit a notable sex-dependent impact on mouse gut microbiota, with a stronger effect observed among females; reduced expression of tight junction genes may be associated with dysbiosis, particularly elevated levels of Prevotellaceae.

Fetal gut cell-like differentiation in esophageal adenocarcinoma defines a rare tumor subtype with therapeutically relevant claudin-6 positivity and SWI/SNF gene alteration.

Esophageal adenocarcinoma (EAC) is one of the deadliest tumor entities worldwide, with a 5-year survival rate of less than 25%. Unlike other tumor entities, personalized therapy options are rare, partly due to the lack of knowledge about specific subgroups. In this publication, we demonstrate a subgroup of patients with EAC in a large screening cohort of 826 patients, characterized by specific morphological and immunohistochemical features. This subgroup represents approximately 0.7% (6/826) of the total cohort. Morphological features of this subgroup show a striking clear cytoplasm of the tumour cells and the parallel existence of rare growth patterns like yolk sac-like differentiation and enteroblastic differentiation. Immunohistochemistry reveals expression of the fetal gut cell-like proteins Sal-like protein 4 (SALL4), claudin-6, and glypican 3. Interestingly, we find a correlation with alterations of SWI/SNF-complex associated genes, which are supposed to serve as tumor suppressor genes in various tumour entities. Our results suggest a possible implication of rare tumour subtypes in the WHO classification for EACs according to the classification for gastric cancer. Furthermore, claudin-6 positive tumors have shown promising efficacy of CAR T cell therapy in the recently published BNT-211-01 trial (NCT04503278). This represents a personalized therapeutic option for this tumor subtype.

HELIX Syndrome, a Claudinopathy with Relevant Dermatological Manifestations: Report of Two New Cases.

HELIX syndrome (Hypohidrosis-Electrolyte disturbances-hypoLacrimia-Ichthyosis-Xerostomia) (MIM#617671) (ORPHA:528105), described in 2017, is due to an abnormal claudin 10 b protein, secondary to pathogenic CLDN10 variants. So far, only ten families have been described. We aim to describe the phenotype in the first Spanish family identified, highlight the skin anomalies as an important clue, and expand the genotypic spectrum. Two adult brothers from consanguineous parents with suspected ectodermal dysplasia (ED) since early childhood were re-evaluated. A comprehensive phenotypic exam and an aCGH + SNP4 × 180 K microarray followed by Sanger sequencing of the CLDN10 gene were performed. They presented hypohidrosis, xerosis, mild ichthyosis, plantar keratosis, palm hyperlinearity, alacrima, and xerostomia. In adulthood, they also developed a salt-losing nephropathy with hypokalemia and hypermagnesemia. The molecular study in both patients revealed a novel pathogenic homozygous deletion of 8 nucleotides in exon 2 of the CLDN10 gene [CLDN10 (NM_0006984.4): c.322_329delGGCTCCGA, p.Gly108fs*] leading to a premature truncation of the protein. Both parents were heterozygous carriers. Hypohidrosis, ichthyosis, and plantar keratosis associated with alacrima and xerostomia should raise suspicion for HELIX syndrome, which also includes nephropathy and electrolyte disturbances in adults. Given the potential for ED misdiagnosis in infancy, it is important to include the CLDN10 gene in a specific genodermatosis next-generation sequencing (NGS) panel to provide early diagnosis, accurate management, and genetic counseling.