Isolation and culture of fibroblasts from endoscopic duodenal biopsies of celiac patients

ROS release by PPARβ/δ-null fibroblasts reduces tumor load through epithelial antioxidant response

Tumor stroma has an active role in the initiation, growth, and propagation of many tumor types by secreting growth factors and modulating redox status of the microenvironment. Although PPARβ/δ in fibroblasts was shown to modulate oxidative stress in the wound microenvironment, there has been no evidence of a similar effect in the tumor stroma. Here, we present evidence of oxidative stress modulation by intestinal stromal PPARβ/δ, using a FSPCre-Pparb/d^−/− mouse model and validated it with immortalized cell lines. The FSPCre-Pparb/d^−/− mice developed fewer intestinal polyps and survived longer when compared with Pparb/d^fl/fl mice. The pre-treatment of FSPCre-Pparb/d^−/− and Pparb/d^fl/fl with antioxidant N-acetyl-cysteine prior DSS-induced tumorigenesis resulted in lower tumor load. Gene expression analyses implicated an altered oxidative stress processes. Indeed, the FSPCre-Pparb/d^−/− intestinal tumors have reduced oxidative stress than Pparb/d^fl/fl tumors. Similarly, the colorectal cancer cells and human colon epithelial cells also experienced lower oxidative stress when co-cultured with fibroblasts depleted of PPARβ/δ expression. Therefore, our results establish a role for fibroblast PPARβ/δ in epithelial–mesenchymal communication for ROS homeostasis.

Isolation of CD 90+ Fibroblast/Myofibroblasts from Human Frozen Gastrointestinal Specimens

Fibroblasts/myofibroblasts (MFs) have been gaining increasing attention for their role in pathogenesis and their contributions to both wound healing and promotion of the tumor microenvironment. While there are currently many techniques for the isolation of MFs from gastrointestinal (GI) tissues, this protocol introduces a novel element of isolation of these stromal cells from frozen tissue. Freezing GI tissue specimens not only allows the researcher to acquire samples from worldwide collaborators, biobanks, and commercial vendors, it also permits the delayed processing of fresh samples. The described protocol will consistently yield characteristic spindle-shaped cells with the MF phenotype that express the markers CD90, α-SMA and vimentin. As these cells are derived from patient samples, the use of primary cells also confers the benefit of closely mimicking MFs from disease states-namely cancer and inflammatory bowel diseases. This technique has been validated in gastric, small bowel, and colonic MF primary culture generation. Primary MF cultures can be used in a vast array of experiments over a number of passage and their purity assessed by both immunocytochemistry and flow cytometry analysis.

Non-celiac gluten sensitivity: Time for sifting the grain

In the last few years, a new nomenclature has been proposed for the disease induced by the ingestion of gluten, a protein present in wheat, rice, barley and oats. Besides celiac disease and wheat allergy, the most studied forms of gluten-related disorders characterized by an evident immune mechanism (autoimmune in celiac disease and IgE-mediated in wheat allergy), a new entity has been included, apparently not driven by an aberrant immune response: the non-celiac gluten sensitivity (NCGS). NCGS is characterized by a heterogeneous clinical picture with intestinal and extraintestinal symptoms arising after gluten ingestion and rapidly improving after its withdrawal from the diet. The pathogenesis of NCGS is largely unknown, but a mixture of factors such as the stimulation of the innate immune system, the direct cytotoxic effects of gluten, and probably the synergy with other wheat molecules, are clues for the complicated puzzle. In addition, the diagnostic procedures still remain problematic due to the absence of efficient diagnostic markers; thus, diagnosis is based upon the symptomatic response to a gluten-free diet and the recurrence of symptoms after gluten reintroduction with the possibility of an important involvement of a placebo effect. The temporary withdrawal of gluten seems a reasonable therapy, but the timing of gluten reintroduction and the correct patient management approach are have not yet been determined.

Restricted VH/VL usage and limited mutations in gluten-specific IgA of coeliac disease lesion plasma cells

Coeliac disease (CD), an enteropathy caused by cereal gluten ingestion, is characterized by CD4(+) T cells recognizing deamidated gluten and by antibodies reactive to gluten or the self-antigen transglutaminase 2 (TG2). TG2-specific immunoglobulin A (IgA) of plasma cells (PCs) from CD lesions have limited somatic hypermutation (SHM). Here we report that gluten-specific IgA of lesion-resident PCs share this feature. Monoclonal antibodies were expression cloned from single PCs of patients either isolated from cultures with reactivity to complex deamidated gluten antigen or by sorting with gluten peptide tetramers. Typically, the antibodies bind gluten peptides related to T-cell epitopes and many have higher reactivity to deamidated peptides. There is restricted VH and VL combination and usage among the antibodies. Limited SHM suggests that a common factor governs the mutation level in PCs producing TG2- and gluten-specific IgA. The antibodies have potential use for diagnosis of CD and for detection of gluten.

microRNA profiles in coeliac patients distinguish different clinical phenotypes and are modulated by gliadin peptides in primary duodenal fibroblasts

CD (coeliac disease) is a frequent autoimmune disorder of the small bowel, which is characterized by an immunological reaction against gluten and transglutaminase in genetically predisposed subjects. However, the molecular determinants underpinning CD pathogenesis are yet to be fully elucidated and little data are available about the involvement of miRNAs (microRNAs) in CD. In the present study, the duodenal mucosa miRNA expression was profiled in adult untreated CD presenting with a classic phenotype or iron-deficiency anaemia, treated patients with or without duodenal normalization, and non-CD subjects as controls. Deregulation of seven miRNAs (miR-31-5p, miR-192-3p, miR-194-5p, miR-551a, miR-551b-5p, miR-638 and miR-1290) was determined in a larger series of CD patients with different clinical phenotypes compared with non-CD subjects. These seven microRNAs were then analysed in duodenal fibroblasts obtained from CD patients and incubated with gliadin peptides (13- and 33-mer). The miRNA cluster miR-192/194, involved in matrix remodelling, was deregulated in CD according to the different clinical presentations, and miR-192-3p levels were modulated by gliadin peptides in vitro. In conclusion, the analysis of miRNAs deserves further consideration for its potential use in the treatment and management of CD.

Extracellular matrix proteins and displacement of cultured fibroblasts from duodenal biopsies in celiac patients and controls

BACKGROUND

Celiac disease (CD) is mainly characterised by villous atrophy and mucosal architectural rearrangement. The fibroblasts (FBs) are the most abundant mesenchymal cell type in the intestinal mucosa and are responsible for both the architectural arrangement of the villi and the formation of the extracellular matrix (ECM). This study aimed at the evaluation of both the intracellular distribution of different proteins involved in ECM and FBs characterisation, and the cellular displacement of primary FBs obtained from duodenal endoscopic biopsies of healthy subjects and celiac patients.

METHODS

Primary healthy and celiac duodenal FBs were evaluated by means of immuno-fluorescence assay for collagen type I and IV, fibronectin, actin, alpha-Smooth Muscle Actin (alpha-SMA), Fibroblast Surface Protein (FSP) and transglutaminase type 2 (TG2). The geometric indexes of the fluorescence signals were investigated by image analysis software (Image J, NIH). Both morphology and kinetic were evaluated during a 72 hours time course movie. TG2 medium activity was evaluated by means of ELISA.

RESULTS

All the cells examined were immunopositive for FSP, alpha-SMA, actin, collagen I, collagen IV and TG2. CD cells showed a signet collagen-I and collagen-IV pattern, as compared to the controls being characterised by a spindle geometry. Moreover, the collagen signals in CD FBs showed a significantly higher circularity index (major orthogonal diameter ratio) than the controls (p<0.0001), whereas the perimeter and area ratio were significantly lower (p<0.0001). The TG2 signal had a decreased area (p<0.05), but a two-fold increased medium activity. The time course highlighted a reduction of the displacement of CD FBs.

CONCLUSIONS

The isolated primary CD FBs showed a different collagen and TG2 pattern of distribution associated with a different cellular displacement. The reasons for such CD cell peculiar characteristics are yet unknown but they might represent a factor in the progression of the intestinal damage.

Immunohistochemical expression of oncological proliferation markers in the hearts of rats during normal pregnancy

Aim: Pregnancy is characterized by left ventricular hypertrophy that is potentially accounted for by cardiomyocyte proliferation, although no such evidence is currently available. This study investigates if the left ventricular mass (LVM) increase during pregnancy implies cell hyperplasia. Materials & methods: In nonpregnant and late-pregnant rats, cardiac function and LVM were evaluated by MRI, and cardiomyocyte dimensions and proliferations were assessed quantitatively by morphometric analysis and immunohistochemistry using oncological markers (Ki67 and MCM2). Results: In late-pregnant rats, LVM and cardiomyocyte area were greater. No mitotic figures were found nor was there any significant difference between groups in Ki67 expression. MCM2 expression was related to LVM. Conclusion: During pregnancy, rat cardiomyocytes undergo hypertrophy but not hyperplasia; the expression of MCM2, related to LVM, suggests it could be a marker of protein synthesis. The application of oncological markers to physiological contexts may provide insight into their role within the cell cycle.

Congestive heart failure effects on atrial fibroblast phenotype: differences between freshly-isolated and cultured cells

Introduction

Fibroblasts are important in the atrial fibrillation (AF) substrate resulting from congestive heart failure (CHF). We previously noted changes in in vivo indices of fibroblast function in a CHF dog model, but could not detect changes in isolated cells. This study assessed CHF-induced changes in the phenotype of fibroblasts freshly isolated from control versus CHF dogs, and examined effects of cell culture on these differences.

Methods/Results

Left-atrial fibroblasts were isolated from control and CHF dogs (ventricular tachypacing 240 bpm×2 weeks). Freshly-isolated fibroblasts were compared to fibroblasts in primary culture. Extracellular-matrix (ECM) gene-expression was assessed by qPCR, protein by Western blot, fibroblast morphology with immunocytochemistry, and K⁺-current with patch-clamp. Freshly-isolated CHF fibroblasts had increased expression-levels of collagen-1 (10-fold), collagen-3 (5-fold), and fibronectin-1 (3-fold) vs. control, along with increased cell diameter (13.4±0.4 µm vs control 8.4±0.3 µm) and cell spreading (shape factor 0.81±0.02 vs. control 0.87±0.02), consistent with an activated phenotype. Freshly-isolated control fibroblasts displayed robust tetraethylammonium (TEA)-sensitive K⁺-currents that were strongly downregulated in CHF. The TEA-sensitive K⁺-current differences between control and CHF fibroblasts were attenuated after 2-day culture and eliminated after 7 days. Similarly, cell-culture eliminated the ECM protein-expression and shape differences between control and CHF fibroblasts.

Conclusions

Freshly-isolated CHF and control atrial fibroblasts display distinct ECM-gene and morphological differences consistent with in vivo pathology. Culture for as little as 48 hours activates fibroblasts and obscures the effects of CHF. These results demonstrate potentially-important atrial-fibroblast phenotype changes in CHF and emphasize the need for caution in relating properties of cultured fibroblasts to in vivo systems.

Immunological comorbity in coeliac disease: associations, risk factors and clinical implications

PURPOSE

Coeliac disease is frequently associated with other immunomediated diseases. Our aim was to identify immunological comorbidities and possible risk factors for their development in coeliac patients.

METHODS

We recruited a cohort of 1,015 coeliac patients followed from 0 to 46 years in a single tertiary referral centre. Data were collected from the yearly scheduled clinical and serological evaluations. Possible risk factors such as demographic parameters, type of symptomatic presentation, gluten exposure, gluten-free diet compliance and family history were all evaluated. Subjects (848,606) from the regional health registry were investigated as controls.

RESULTS

The prevalence of immunomediated diseases was higher in patients with coeliac disease compared to the registry population (23 % vs 0.4 %, p < 0.001). Diagnosis during paediatric age represented a risk factor for the presence of at least an immunomediated disease (hazard ratio = 1.62, 95 % confidence interval 1.15-2.29, p = 0.0061). Type of presentation and dietetic compliance did not represent risk factors. Long-standing gluten exposure reduced the risk of developing immunomediated diseases in coeliac subjects (hazard ratio for 1 year longer exposure 0.23, 95 % confidence interval 0.16-0.33, p < 0.0001). A familiar background characterized by the presence of immunological disorders was not a risk factor, although 419 (13 %) first degree relatives of coeliac patients out of 3,195 had an immunomediated disease.

CONCLUSIONS

Our study suggests the need to investigate coeliac patients for other associated immunomediated diseases, independently of sex, gluten exposure and compliance to therapy; also subjects diagnosed in paediatric age should be carefully screened during follow up.