Abstract 693: TGFβ-mediated targeting of the extracellular matrix enhances the migration and cytotoxicity of CAR-T cells in 3D models of ovarian cancer

We have assessed the utility of 3-dimensional (3D) in vitro human cell models to understand barriers to chimeric antigen receptor (CAR)-T cell activity in high-grade serous ovarian cancer, (HGSOC) a disease with a poor response to immunotherapy. We defined mucin-1 (MUC1) as a potential target in HGSOC biopsies and the HGSOC cell lines, OvCAR3 and G164. We then generated CAR-T cells against MUC1 and tested them in spheroid and collagen gel cultures. In spheroids, although CAR-T cells killed OvCAR3 cells, G164 cells failed to induce CAR-T cell activation or cytotoxicity. However, when we added primary omental fibroblasts from ovarian cancer patients to G164 spheroids, CAR-T cells were activated and cytotoxic. Fibroblast conditioned medium also activated CAR-T cells to kill G164 cells in spheroids and this was due to their production of C-C motif chemokine ligand 2 (CCL2). Further experiments revealed that CCL2 produced by fibroblast stimulated CCR2/4 positive CAR-T cells to a higher state of activation, which enhanced the cytotoxicity of CAR-T cells against G164 cells. We then investigated CAR-T cell activity in co-cultures of OvCAR3 or G164 cells and primary fibroblasts embedded in collagen. CAR-T cells migrated into OvCAR3 gels and killed the malignant cells during a three-day period. However, CAR-T cells failed to migrate into gels with G164 cells and there was no malignant cell killing. Gels containing G164 cells had denser extracellular matrix (ECM) than OvCAR3 gels, as measured by staining for collagens and fibronectin. Previously, we showed that transforming growth factor-beta (TGFβ) secreted by HGSOC cells acted on fibroblasts to induce the production of ECM in collagen gels.1 Treating G164 gels with the TGFβ receptor inhibitor SB431542 reduced ECM density, stimulated CAR-T cell migration and restored CAR-T cell cytotoxicity against G164 cells. Using these different human 3D models we have demonstrated that malignant cell intrinsic factors can cause resistance to CAR-T cells. Sensitivity to CAR-T cell killing can be modulated both positively and negatively by fibroblasts. Targeting ECM along with CAR-T cell therapy might improve the efficiency of CAR-T cells in solid tumors.

1Delaine-Smith et al, iScience, 2021

Citation Format: Joash Dominic Joy, Beatrice Malacrida, Florian Laforêts, Panoraia Kotantaki, Eleni Maniati, Sarah Hopkins, Ianire Calleja, Sara Brett, Takis Athanasopoulos, Sadfer Ali, Peter Emery-Billcliff, Ida Ricciardelli, Charlotte Kay, Jayne Colebrook, Magda Ali, Katherine Strong, Frances Balkwill. TGFβ-mediated targeting of the extracellular matrix enhances the migration and cytotoxicity of CAR-T cells in 3D models of ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 693.

The Landscape of Early Clinical Gene Therapies outside of Oncology

The field of cell and gene therapy (GT) is expanding rapidly and there is undoubtedly a wave of enthusiasm and anticipation for what these treatments could achieve next. Here we assessed the worldwide landscape of GT assets currently in early clinical development (clinical trial phase 1/2 or about to enter clinical trial). We included all gene therapies, i.e., strategies that modify an individual's protein make-up by introducing exogenous nucleic acid or nucleic acid modifiers, regardless of delivery. Unmodified cell therapies, oncology therapies (reviewed elsewhere), and vaccine programs (distinct therapeutic strategy) were not included. Using a December 31, 2018 cutoff date, we identified 336 gene therapies being developed for 138 different indications covering 165 genetic targets. In all, we found that the early clinical GT landscape comprises a very disparate group of drug candidates in terms of indications, organizations, and delivery methods. We also highlight interesting trends, revealing the evolution of the field toward in vivo therapies and adeno-associated virus vector-based delivery systems. It will be interesting to witness what proportion of this current list effectively translates into new medicines.

T-cell gene therapy for perforin deficiency corrects cytotoxicity defects and prevents hemophagocytic lymphohistiocytosis manifestations

BACKGROUND

Mutations in the perforin 1 (PRF1) gene account for up to 58% of familial hemophagocytic lymphohistiocytosis syndromes. The resulting defects in effector cell cytotoxicity lead to hypercytokinemia and hyperactivation with inflammation in various organs.

OBJECTIVE

We sought to determine whether autologous gene-corrected T cells can restore cytotoxic function, reduce disease activity, and prevent hemophagocytic lymphohistiocytosis (HLH) symptoms in in vivo models.

METHODS

We developed a gammaretroviral vector to transduce murine CD8 T cells in the Prf-/- mouse model. To verify functional correction of Prf-/- CD8 T cells in vivo, we used a lymphocytic choriomeningitis virus (LCMV) epitope-transfected murine lung carcinoma cell tumor model. Furthermore, we challenged gene-corrected and uncorrected mice with LCMV. One patient sample was transduced with a PRF1-encoding lentiviral vector to study restoration of cytotoxicity in human cells.

RESULTS

We demonstrated efficient engraftment and functional reconstitution of cytotoxicity after intravenous administration of gene-corrected Prf-/- CD8 T cells into Prf-/- mice. In the tumor model infusion of Prf-/- gene-corrected CD8 T cells eliminated the tumor as efficiently as transplantation of wild-type CD8 T cells. Similarly, mice reconstituted with gene-corrected Prf-/- CD8 T cells displayed complete protection from the HLH phenotype after infection with LCMV. Patients' cells showed correction of cytotoxicity in human CD8 T cells after transduction.

CONCLUSION

These data demonstrate the potential application of T-cell gene therapy in reconstituting cytotoxic function and protection against HLH in the setting of perforin deficiency.

Transfer of gene-corrected T cells corrects humoral and cytotoxic defects in patients with X-linked lymphoproliferative disease

BACKGROUND

X-linked lymphoproliferative disease 1 arises from mutations in the SH2D1A gene encoding SLAM-associated protein (SAP), an adaptor protein expressed in T, natural killer (NK), and NKT cells. Defects lead to abnormalities of T-cell and NK cell cytotoxicity and T cell-dependent humoral function. Clinical manifestations include hemophagocytic lymphohistiocytosis, lymphoma, and dysgammaglobulinemia. Curative treatment is limited to hematopoietic stem cell transplantation, with outcomes reliant on a good donor match.

OBJECTIVES

Because most symptoms arise from defective T-cell function, we investigated whether transfer of SAP gene-corrected T cells could reconstitute known effector cell defects.

METHODS

CD3+ lymphocytes from Sap-deficient mice were transduced with a gammaretroviral vector encoding human SAP cDNA before transfer into sublethally irradiated Sap-deficient recipients. After immunization with the T-dependent antigen 4-hydroxy-3-nitrophenylacetly chicken gammaglobulin (NP-CGG), recovery of humoral function was evaluated through germinal center formation and antigen-specific responses. To efficiently transduce CD3+ cells from patients, we generated an equivalent lentiviral SAP vector. Functional recovery was demonstrated by using in vitro cytotoxicity and T follicular helper cell function assays alongside tumor clearance in an in vivo lymphoblastoid cell line lymphoma xenograft model.

RESULTS

In Sap-deficient mice 20% to 40% engraftment of gene-modified T cells led to significant recovery of germinal center formation and NP-specific antibody responses. Gene-corrected T cells from patients demonstrated improved cytotoxicity and T follicular helper cell function in vitro. Adoptive transfer of gene-corrected cytotoxic T lymphocytes from patients reduced tumor burden to a level comparable with that seen in healthy donor cytotoxic T lymphocytes in an in vivo lymphoma model.

CONCLUSIONS

These data demonstrate that autologous T-cell gene therapy corrects SAP-dependent defects and might offer an alternative therapeutic option for patients with X-linked lymphoproliferative disease 1.

Targeting the T cell receptor β-chain constant region for immunotherapy of T cell malignancies

Mature T cell cancers are typically aggressive, treatment resistant and associated with poor prognosis. Clinical application of immunotherapeutic approaches has been limited by a lack of target antigens that discriminate malignant from healthy (normal) T cells. Unlike B cell depletion, pan-T cell aplasia is prohibitively toxic. We report a new targeting strategy based on the mutually exclusive expression of T cell receptor β-chain constant domains 1 and 2 (TRBC1 and TRBC2). We identify an antibody with unique TRBC1 specificity and use it to demonstrate that normal and virus-specific T cell populations contain both TRBC1⁺ and TRBC2⁺ compartments, whereas malignancies are restricted to only one. As proof of concept for anti-TRBC immunotherapy, we developed anti-TRBC1 chimeric antigen receptor (CAR) T cells, which recognized and killed normal and malignant TRBC1⁺, but not TRBC2⁺, T cells in vitro and in a disseminated mouse model of leukemia. Unlike nonselective approaches targeting the entire T cell population, TRBC-targeted immunotherapy could eradicate a T cell malignancy while preserving sufficient normal T cells to maintain cellular immunity.

Thymus transplantation for complete DiGeorge syndrome: European experience

Background

Thymus transplantation is a promising strategy for the treatment of athymic complete DiGeorge syndrome (cDGS).

Methods

Twelve patients with cDGS underwent transplantation with allogeneic cultured thymus.

Objective

We sought to confirm and extend the results previously obtained in a single center.

Results

Two patients died of pre-existing viral infections without having thymopoiesis, and 1 late death occurred from autoimmune thrombocytopenia. One infant had septic shock shortly after transplantation, resulting in graft loss and the need for a second transplant. Evidence of thymopoiesis developed from 5 to 6 months after transplantation in 10 patients. Median circulating naive CD4 counts were 44 × 10⁶/L (range, 11-440 × 10⁶/L) and 200 × 10⁶/L (range, 5-310 × 10⁶/L) at 12 and 24 months after transplantation and T-cell receptor excision circles were 2,238/10⁶ T cells (range, 320-8,807/10⁶ T cells) and 4,184/10⁶ T cells (range, 1,582-24,596/10⁶ T cells). Counts did not usually reach normal levels for age, but patients were able to clear pre-existing infections and those acquired later. At a median of 49 months (range, 22-80 months), 8 have ceased prophylactic antimicrobials, and 5 have ceased immunoglobulin replacement. Histologic confirmation of thymopoiesis was seen in 7 of 11 patients undergoing biopsy of transplanted tissue, including 5 showing full maturation through to the terminal stage of Hassall body formation. Autoimmune regulator expression was also demonstrated. Autoimmune complications were seen in 7 of 12 patients. In 2 patients early transient autoimmune hemolysis settled after treatment and did not recur. The other 5 experienced ongoing autoimmune problems, including thyroiditis (3), hemolysis (1), thrombocytopenia (4), and neutropenia (1).

Conclusions

This study confirms the previous reports that thymus transplantation can reconstitute T cells in patients with cDGS but with frequent autoimmune complications in survivors.

Rapid generation of EBV-specific cytotoxic T lymphocytes resistant to calcineurin inhibitors for adoptive immunotherapy

Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder (PTLD) remains a major cause of morbidity and mortality after hematopoietic stem cell (HSCT) or solid organ transplant (SOT). Strategies to reconstitute immunity by adoptive transfer of EBV-specific cytotoxic T lymphocyte (CTL) therapy while highly effective in the HSCT setting where immunosuppression can be withdrawn have been less successful in the SOT setting where continued immunosuppression therapy is necessary. Additionally, the complexity and time taken to generate EBV-CTLs for adoptive transfer limit the clinical applicability. We have developed a system for the rapid generation of EBV-CTLs resistant to immunosuppression based on selection of interferon-gamma (IFN-γ) secreting EBV-CTLs and retroviral transduction with a calcineurin B mutant. With this methodology, EBV-CTLs resistant to the calcineurin inhibitor Tacrolimus (TAC) can be produced in 14 days. These CTLs show high specificity for EBV with negligible alloreactivity in both proliferation and cytotoxicity assays and are able to proliferate and secrete IFN-γ in response to antigen stimulation in the presence of therapeutic doses of TAC. This strategy will substantially facilitate clinical application of this approach for the treatment of PTLD in SOT recipients.

Optimization of methodology for production of CD25/CD71 allodepleted donor T cells for clinical use

BACKGROUND AIMS

Immunotherapy with allodepleted donor T cells improves immunity after T cell-depleted hematopoietic stem cell transplantation. We developed a methodology for selective depletion of alloreactive T cells after activation with host antigen-presenting cells by targeting T cells up-regulating CD25 and CD71. Combined depletion of these cells yields a pool of allodepleted donor T cells with antiviral properties with minimal capacity to cause graft-versus-host disease.

METHODS

Mature dendritic cells were irradiated and used to stimulate donor peripheral blood mononuclear cells for 4 days. The co-culture was stained with anti-CD71-biotin followed by CliniMACS CD25 and Anti-Biotin Reagents (Miltenyi Biotec GmbH; Bergisch Gladbach, Germany) before depletion on the CliniMACS Plus (Miltenyi Biotec GmbH). Residual alloreactivity was tested by flow cytometry, a secondary mixed lymphocyte reaction and limiting dilution analysis, and specific anti-viral immunity with pentamer staining. The large-scale protocol was tested under current good manufacturing practice conditions in five donor-recipient pairs of human leukocyte antigen-matched volunteer donors.

RESULTS

We developed a closed-system methodology using cell differentiation bags for cell culture and the COBE2991 Cell Processor (CaridianBCT, Lakewood, CO, USA). We also validated an anti-CD71-biotin generated for ex vivo clinical use. In five large-scale runs, the depleted fraction demonstrated excellent viability (99.9%), minimal residual expression of CD3/CD25 and CD3/CD71 (<0.2%) and passed tests for Mycoplasma, endotoxin, bacterial and fungal sterility. In secondary mixed lymphocyte reaction assays, the median response to host after allodepletion was 0%, whereas responses to third-party peripheral blood mononuclear cells were preserved (median, 105%; range 37%-350%). Limiting dilution analysis assays also demonstrated a reduction in response to host (median, -1.11 log) with preservation of third-party responses, and testing with human leukocyte antigen-restricted pentamers showed that populations of Epstein-Barr virus-specific and cytomegalovirus-specific CD8(+) T cells were retained after depletion.

CONCLUSIONS

We optimized a protocol for the combined immunomagnetic depletion of alloreactive CD25/CD71 T cells under current good manufacturing practice conditions and tested the efficacy in five donor-recipient pairs.

Anti tumour necrosis-alpha therapy increases the number of FOXP3 regulatory T cells in children affected by Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract. Its pathogenesis is not completely understood, though the prevailing model is that the intestinal flora drives a strong intestinal T helper 1 (Th1)/Th17 type immune response and inflammation in the genetically susceptible host. This leads to overly aggressive T-cell responses to normal bacteria causing tissue damage. Intestinal homeostasis and maintenance of tolerance to harmless antigens in the intestine has been shown to be maintained by CD4+ CD25+ T regulatory cells (Treg) in animal models of inflammatory bowel diseases. Here we investigated whether Infliximab, a chimeric monoclonal antibody directed against tumour necrosis factor (TNF)-alpha shown to be highly effective in the treatment of CD, has any effect on mucosal CD4+ CD25+ (FOXP3+) Tregs. Colonic mucosal biopsies from children with active Crohn's disease treated in vivo with Infliximab and controls were analysed to determine FOXP3 expression by immunofluorescence and reverse transcription-polymerase chain reaction. We observed that FOXP3+ T cells were significantly reduced in mucosa of CD patients with active disease compared with controls and restored to normal following Infliximab treatment. The frequency of FOXP3+ cells and mRNA expression was significantly increased in CD mucosa from patients treated in vivo with Infliximab compared with CD patients treated with conventional therapies. In conclusion, we show that Infliximab treatment does not solely neutralize soluble TNF-alpha, but also affects activation and possibly expansion of mucosal regulatory T cells. We suggest that anti TNF-alpha immunotherapy can also restore mucosal homeostasis in Crohn's disease.

Unexpected role of surface transglutaminase type II in celiac disease

BACKGROUND & AIMS

In celiac disease (CD), transglutaminase type II (TG2) has 2 fundamental roles: (1) as the autoantigen recognized by highly specific autoantibodies and (2) the modifier of pathogenic gliadin T-cell epitopes. It follows that inhibition of TG2 might represent an attractive strategy to curb the toxic action of gliadin. Here we studied the validity of this strategy using the organ culture approach.

METHODS

Duodenal biopsy specimens from 30 treated patients with CD, 33 untreated patients with CD, and 24 controls were cultured with or without gliadin peptides p31-43, palpha-9, and deamidated palpha-9 for 20 minutes, 3 hours, and 24 hours. In 31 patients with CD and 16 controls, TG2 inhibitor R283 or anti-TG CUB 7402 or anti-surface TG2 (6B9) mAbs were used in cultures. T84 cells were also cultured with or without peptides with or without TG inhibitors. Mucosal modifications after culture were assessed by immunofluorescence, in situ detection of TG activity, confocal microscopy, and fluorescence-activated cell sorter analysis.

RESULTS

The enzymatic inhibition of TG2 only controlled gliadin-specific T-cell activation. The binding of surface TG2 contained gliadin-specific T-cell activation and p31-43-induced actin rearrangement, epithelial phosphorylation, and apoptosis, both in organ cultures and T84 cells.

CONCLUSIONS

These data indicate a novel and unexpected biological role for surface TG2 in the pathogenesis of CD suggesting a third role for TG2 in CD. These results have a specific impact for celiac disease, with wider implications indicating a novel biologic function of TG2 with possible repercussions in other diseases.

Inhibition of p38 mitogen activated protein kinase controls airway inflammation in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) airways are characterised by chronic inflammation, increased interleukin (IL)-8 secretion, and neutrophil activation which are considered the principal factors of morbidity and mortality in CF patients. Optimising management of this chronic inflammatory response is therefore a key issue of basic and clinical CF research. Several reports have addressed ways to manage CF airways inflammation, and an attractive therapeutic strategy may be the inhibition of the p38-mitogen activated protein kinase (p38-MAP-k) pathway.

METHODS

A new ex vivo model was used to study the mucosal inflammatory response to environmental airways stimuli. Nasal biopsy tissues from CF patients and controls were cultured ex vivo for 20 minutes, 4 hours, and 24 hours in the presence of lipopolysaccharide (LPS) from Pseudomonas aeruginosa (PA) with and without the p38-MAP-k inhibitor SB203580. Quantitative mRNA assessment, immunohistochemistry, and Western blots were used to detect the expression and modulation of inflammatory markers.

RESULTS

PA-LPS challenge induced a time dependent mucosal inflammation indicated by rapid epithelial activation, IL-8 release, COX-2 upregulation, and neutrophil migration to the upper mucosal layers. Some of these LPS induced changes (IL-8 release and neutrophil migration) were specific to CF tissues. SB203580 significantly controlled all LPS induced mucosal changes in CF tissues.

CONCLUSION

These findings provide a rationale and proof of principle for the potential use of p38-MAP-k inhibitors to control inflammation in patients with CF.

Gliadin as a stimulator of innate responses in celiac disease

In celiac disease (CD) we have the prototype of an immune mediated response dominated by the activation of the adaptive immune system and in particular of CD4+ HLA class II restricted T cells. Various seminal studies have established the precise mechanism of how antigen (prolamine) specific activation of CD4+ mucosal T cells occurs. Thus, CD is a condition in which T cells and their activation is the essential hinge in the pathogenic process. These functional studies have provided the explanation for the genetic association between CD and certain HLA alleles (HLA DQ2 and DQ8). These genetic, molecular and functional studies have permitted the clarification of a powerful Th1 dominated pro-inflammatory response that characterises the small intestine of active CD patients. Despite this unassailable set of information and reports there are some intriguing points that have been raised by a series of studies which have indicated that CD is not only defined by an aberrant prolamine-induced activation of the adaptive immune system. New evidence and re-assessments of old studies, point to a more complex pathogenic cascade, which may help to unravel some of the residual obscure points of CD pathogenesis. Here, we outline the current concepts that indicate a direct involvement of the adaptive immune system and we discuss all the evidence supporting a direct activation of the innate immune system by fragments of prolamines, which are not recognized T cell epitopes and how they could influence CD. The gliadin-induced activation of the 'innate' immune system might also have a significant role in the induction and persistence of many CD complications and most definitively for the most aggressive one, namely mucosal T cell lymphomas. We further suggest a novel way to harness the unwanted immune response to toxic prolamine, and thus indicate new potential therapeutic strategies to treat or at least control CD.

Association between innate response to gliadin and activation of pathogenic T cells in coeliac disease

BACKGROUND

The adaptive immune system is central to the development of coeliac disease. Adaptive immune responses are, however, controlled by a preceding activation of the innate immune system. We investigated whether gliadin, a protein present in wheat flour, could activate an innate as well as an adaptive immune response in patients with coeliac disease.

METHODS

Duodenal biopsy samples from 42 patients with untreated coeliac disease, 37 treated patients, and 18 controls, were cultured in vitro for 3 h or 24 h, in the presence of either immunodominant gliadin epitopes (p(alpha)-2 and p(alpha)-9) or a non-immunodominant peptide (p31-43) known to induce small intestine damage in coeliac disease. We also incubated biopsy samples from nine untreated and six treated patients with a non-immunodominant peptide for 3 h, before incubation with immunodominant gliadin epitopes. Different combinations of interleukin-15 or signal transduction inhibitors were added to selected incubations.

FINDINGS

Only the non-immunodominant peptide induced rapid expression of interleukin-15, CD83, cyclo-oxygenase (COX)-2, and CD25 by CD3- cells (p=0.005 vs medium alone) and enterocyte apoptosis (p<0.0001). Only the non-immunodominant peptide induced p38 MAP kinase activation in CD3- cells. Pre-incubation with the non-immunodominant peptide enabled immunodominant epitopes to induce T-cell activation (p=0.001) and enterocyte apoptosis. Inhibition of interleukin-15 or of p38 MAP kinase controlled such activity.

INTERPRETATION

A gliadin fragment can activate the innate immune system, affecting the in situ T-cell recognition of dominant gliadin epitopes. Although our findings emphasise the key role of gliadin-specific T cells, they suggest a complex pathogenic situation, and show that inhibition of interleukin-15 or p38 MAP kinase might have the potential to control coeliac disease.

FAS engagement drives apoptosis of enterocytes of coeliac patients

BACKGROUND

Villus atrophy is the most distinctive sign of untreated coeliac disease (CD) and epithelial apoptosis is considered to be involved in this stage of the coeliac lesion. The extent of villus atrophy is, however, not homogeneous and patients with patchy or mild lesions have been described.

AIMS

To address: (a) the degree of "patchiness" in untreated CD patients; and (b) to clarify if apoptosis, and eventually which trigger drives it, causes epithelial damage.

PATIENTS

Twenty of 40 untreated, 14 treated coeliac patients, and 15 controls received five or more multiple duodenal biopsies; the remaining 20 untreated CD patients had no more than three biopsies.

METHODS

All biopsies were analysed to monitor the presence of a "flat" mucosa. Biopsies of 14 untreated, 10 treated coeliacs, and seven controls were cultured with or without gliadin. DNA fragmentation was studied by terminal deoxynucleotidyl transferase (TdT) mediated dUTP digoxigenin nick end labelling (TUNEL), and FAS and Ki67 expression by immunohistochemistry. Antiendomysium antibodies (EMA) were surveyed in biopsy culture supernatants.

RESULTS

A pattern of patchy duodenal lesions was observed in all untreated CD patients biopsied up to five times. High enterocyte FAS expression, and a high number of TUNEL+ and Ki67+ enterocytes were detected in areas with villus atrophy but not in those with a normal morphology (p<0.001). Conversely, EMA in culture supernatants and signs of immunological activation were present in all untreated CD biopsies. In vitro gliadin challenge increased the number of TUNEL+ and Ki67+ enterocytes (p<0.001 v cultures with medium alone) only in "flat" biopsies. Neutralising anti-FAS monoclonal antibodies were found to control gliadin induced enterocyte apoptosis (p>0.01) while agonist anti-FAS monoclonal antibody increased it (p<0.001).

CONCLUSIONS

Patchy lesions are observed in untreated CD mucosa and epithelial FAS engagement is a key trigger in driving villus atrophy in CD.

IL-15 drives the specific migration of CD94+ and TCR-gammadelta+ intraepithelial lymphocytes in organ cultures of treated celiac patients

OBJECTIVES

Celiac disease (CD) is an under-diagnosed but extremely frequent disease, triggered by the ingestion of gliadin. The pathogenic mechanisms of CD are still poorly understood, but intraepithelial lymphocytes are considered to have a key role. We intended to define the subsets of T lymphocytes migrating upon gliadin challenge in organ cultures of treated celiac patients and establish the type of factor(s) driving such an infiltration.

METHODS

Duodenum biopsies from 10 treated celiacs and 7 controls were cultured in vitro with/without gliadin digest (1 mg/ml) or interleukin (IL)-15 (10 ng/ml). In 7 treated celiacs IL-7, IL-4, and IL-2 were similarly tested. Intraepithelial CD3, CD8, TCR-gammadelta, and CD94 were detected by immunohistochemistry and numbered per mm epithelium.

RESULTS

IL-15 but not IL-7, IL-4, or IL-2 induced intraepithelial increase of CD3+ and CD8+ cells in celiac and control intestine (p < 0.001 vs cultures with medium). IL-15 induced increases in the number of intraepithelial TCR- gammadelta+ and CD94+ cells only in celiacs (p < 0.001). IL-7 was also effective in increasing intraepithelial TCR-gammadelta+ (but not CD94+) cells in celiac biopsies (p < 0.001). Gliadin induced intraepithelial migration of CD3+, CD8+ (p < 0.001), and CD94+ (p < 0.05) cells in celiacs, but not in controls.

CONCLUSIONS

The results we describe in this report indicate that IL-15 might have a key role in modulating and driving intraepithelial infiltration and ultimately in the pathogenesis of CD.