Innate T cell responses in human gut

Epstein-Barr virus-associated enteritis with multiple ulcers: The first autopsy case

Epstein-Barr virus (EBV)-associated enteritis is extremely rare and has not been well characterized. Herein, we present the first autopsy case of EBV-associated enteritis with multiple ulcers in a 73-year-old Japanese male. The patient had abdominal pain and was clinically diagnosed with enteritis. An endoscopic examination revealed multiple ulcers at the terminal ileum. His condition worsened due to serosanguinous bowel discharge and the patient was then admitted to the hospital. Ileocecal and subtotal small intestinal resection was performed for repetitive hemorrhage from ulcers. However, the patient died due to uncontrolled hemorrhage. An autopsy was then performed in order to explore the cause of ulcers in the small intestine. Macroscopic findings revealed multiple ulcers with occasional cobblestone-like appearance of the ileum. Histological analysis revealed marked infiltration of lymphocytes and plasma cells around the ulcer. EBV-encoded RNA in situ hybridization (EBER-ISH) revealed positive inflammatory cells. Cytomegalovirus was immunohistochemically negative. Macroscopic and microscopic findings obtained from autopsy specimens showed no foci of inflammation and EBER-ISH-positive stromal cells in the esophagus, stomach, and colorectum. EBV-associated enteritis can cause uncontrolled repetitive hemorrhage from ulcers and result in critical condition of the patient, which can be used for differential diagnosis.

Human dental follicle mesenchymal stem cells alleviate T cell response in inflamed tissue of Crohn's patients

BACKGROUND/AIMS

Crohn's Disease (CD) is a chronic inflammatory condition characterized by various abnormalities that lead to overly aggressive T-cell responses. Our in vitro experiments aimed to investigate the potential use of Dental Follicle Mesenchymal Stem Cells (DF-MSCs) to suppress the exaggerated immune response in inflamed and non-inflamed tissue of Crohn's Disease (CD).

MATERIAL AND METHODS

Dental follicle tissues were obtained from extracted third molar teeth of 3 healthy volunteers who have no abscess or inflammatory diseases. Eleven patients included the experiment who had been diagnosed with CD and not received steroid maintenance therapy for more than 1 month. Mononuclear Cells (MNCs) were isolated from inflamed and non-inflamed tissue of CD. Isolated cells were stimulated with anti-CD3/anti-CD28 monoclonal antibodies in the presence and absence of DF-MSCs and analyzed for lymphocytes proliferation capacity and viability, T lymphocyte subsets, CD4+IL22BP and CD4+CD25+Foxp3+ regulatory T cell (Tregs) frequencies and cytokine levels.

RESULTS

A significant downregulation of lymphocyte proliferation and CD4+IL22BP T cell ratio were found in inflamed cultures with DF-MSCs (p<0,005). Also, the frequency of Tregs increased with DF-MSCs (p<0,05). Pro-inflammatory cytokine levels (TNF-α and IL-6) were decreased (p<0,05) and IL-10 levels were increased (p<0,05) in the supernatant of inflamed cultures.

CONCLUSION

DF-MSCs reduced the inflammatory immune response, induced Tregs and downregulated CD4+IL22BP T cell ratio in inflamed samples of CD patients, which may be exploited for significant therapeutic use.

Duodenal mucosal immune cells in treatment-naive adult patients with celiac disease having different histological grades and controls

Background

It is hypothesized that the duodenal mucosal damage in patients with celiac disease (CeD) is caused by the mucosa-infiltrating lymphoid cells. This study aimed to analyze the immune effective and regulatory T (Treg) cells in duodenal biopsies from treatment-naive adult patients with CeD having different histological grades and controls.

Patients and Methods

Dual-color immunohistochemical staining was done in a total of 234 duodenal biopsies, including 132 controls and 102 adult patients with CeD using CD20, CD3:CD4, CD3:CD8, CD4:FoxP3, CD8:FoxP3, and TCRαβ:TCRγδ antibodies. The density of these lymphoid cells in lamina propria and mucosal epithelium was compared between controls and CeD, with different modified Marsh grades.

Results

Densities of CD4+ T cells in lamina propria and CD8+γδ intraepithelial lymphocytes (IELs) were significantly more in biopsies from patients with CeD, than in controls. An increasing linear pattern of IELs, CD3+ T cells, and CD20+ B cells was observed with increasing grades of villous abnormalities. Although CD8+ FoxP3+ Treg cells were significantly more in biopsies from patients with CeD, there was no significant difference in CD4+ FoxP3+ Treg cell infiltrate between both the groups.

Conclusion

Our finding in this observational study generates interest to study the local intestinal mucosal immunity in CeD in detail. A study to prove the failure of CD4+ FoxP3+ Treg cell recruitment in CeD and its direct functional impact may yield valuable information regarding loss of mucosal tolerance.

Fish Lymphocytes: An Evolutionary Equivalent of Mammalian Innate-Like Lymphocytes?

Lymphocytes are the responsible of adaptive responses, as they are classically described, but evidence shows that subpopulations of mammalian lymphocytes may behave as innate-like cells, engaging non-self rapidly and without antigen presentation. The innate-like lymphocytes of mammals have been mainly identified as γδT cells and B1-B cells, exert their activities principally in mucosal tissues, may be involved in human pathologies and their functions and tissue(s) of origin are not fully understood. Due to similarities in the morphology and immunobiology of immune system between fish and mammals, and to the uniqueness of having free-living larval stages where the development can be precisely monitored and engineered, teleost fish are proposed as an experimental model to investigate human immunity. However, the homology between fish lymphocytes and mammalian innate-like lymphocytes is an issue poorly considered in comparative immunology. Increasing experimental evidence suggests that fish lymphocytes could have developmental, morphological, and functional features in common with innate-like lymphocytes of mammals. Despite such similarities, information on possible links between conventional fish lymphocytes and mammalian innate-like lymphocytes is missing. The aim of this review is to summarize and describe available findings about the similarities between fish lymphocytes and mammalian innate-like lymphocytes, supporting the hypothesis that mammalian γδT cells and B1-B cells could be evolutionarily related to fish lymphocytes.

T-cell repertoires in refractory coeliac disease

OBJECTIVE

Refractory coeliac disease (RCD) is a potentially hazardous complication of coeliac disease (CD). In contrast to RCD type I, RCD type II is a precursor entity of enteropathy-associated T-cell lymphoma (EATL), which is associated with clonally expanding T-cells that are also found in the sequentially developing EATL. Using high-throughput sequencing (HTS), we aimed to establish the small-intestinal T-cell repertoire (TCR) in CD and RCD to unravel the role of distinct T-cell clonotypes in RCD pathogenesis.

DESIGN

DNA extracted from duodenal mucosa specimens of controls (n=9), active coeliacs (n=10), coeliacs on a gluten-free diet (n=9), RCD type I (n=8), RCD type II (n=8) and unclassified Marsh I cases (n=3) collected from 2002 to 2013 was examined by TCRβ-complementarity-determining regions 3 (CDR3) multiplex PCR followed by HTS of the amplicons.

RESULTS

On average, 10⁶ sequence reads per sample were generated consisting of up to 900 individual TCRβ rearrangements. In RCD type II, the most frequent clonotypes (ie, sequence reads with identical CDR3) represent in average 42.6% of all TCRβ rearrangements, which was significantly higher than in controls (6.8%; p<0.01) or RCD type I (6.7%; p<0.01). Repeat endoscopies in individual patients revealed stability of clonotypes for up to several years without clinical symptoms of EATL. Dominant clonotypes identified in individual patients with RCD type II were unique and not related between patients. CD-associated, gliadin-dependent CDR3 motifs were only detectable at low frequencies.

CONCLUSIONS

TCRβ-HTS analysis unravels the TCR in CD and allows detailed analysis of individual TCRβ rearrangements. Dominant TCRβ sequences identified in patients with RCD type II are unique and not homologous to known gliadin-specific TCR sequences, supporting the assumption that these clonal T-cells expand independent of gluten stimulation.

Mucosal and Systemic γδ+ T Cells Associated with Control of Simian Immunodeficiency Virus Infection

γδ T cells act as a first line of defense against invading pathogens. However, despite their abundance in mucosal tissue, little information is available about their functionality in this compartment in the context of HIV/SIV infection. In this study, we evaluated the frequency, phenotype, and functionality of Vδ1 and Vδ2 T cells from blood, rectum, and the female reproductive tract (FRT) of rhesus macaques to determine whether these cells contribute to control of SIV infection. No alteration in the peripheral Vδ1/Vδ2 ratio in SIV-infected macaques was observed. However, CD8⁺ and CD4⁺CD8⁺ Vδ1 T cells were expanded along with upregulation of NKG2D, CD107, and granzyme B, suggesting cytotoxic function. In contrast, Vδ2 T cells showed a reduced ability to produce the inflammatory cytokine IFN-γ. In the FRT of SIV⁺ macaques, Vδ1 and Vδ2 showed comparable levels across vaginal, ectocervical, and endocervical tissues; however, endocervical Vδ2 T cells showed higher inflammatory profiles than the two other regions. No sex difference was seen in the rectal Vδ1/Vδ2 ratio. Several peripheral Vδ1 and/or Vδ2 T cell subpopulations expressing IFN-γ and/or NKG2D were positively correlated with decreased plasma viremia. Notably, Vδ2 CD8⁺ T cells of the endocervix were negatively correlated with chronic viremia. Overall, our results suggest that a robust Vδ1 and Vδ2 T cell response in blood and the FRT of SIV-infected macaques contribute to control of viremia.

Gut Microbiota and Celiac Disease

Recent evidence regarding celiac disease has increasingly shown the role of innate immunity in triggering the immune response by stimulating the adaptive immune response and by mucosal damage. The interaction between the gut microbiota and the mucosal wall is mediated by the same receptors which can activate innate immunity. Thus, changes in gut microbiota may lead to activation of this inflammatory pathway. This paper is a review of the current knowledge regarding the relationship between celiac disease and gut microbiota. In fact, patients with celiac disease have a reduction in beneficial species and an increase in those potentially pathogenic as compared to healthy subjects. This dysbiosis is reduced, but might still remain, after a gluten-free diet. Thus, gut microbiota could play a significant role in the pathogenesis of celiac disease, as described by studies which link dysbiosis with the inflammatory milieu in celiac patients. The use of probiotics seems to reduce the inflammatory response and restore a normal proportion of beneficial bacteria in the gastrointestinal tract. Additional evidence is needed in order to better understand the role of gut microbiota in the pathogenesis of celiac disease, and the clinical impact and therapeutic use of probiotics in this setting.

Primary and Chronic HIV Infection Differently Modulates Mucosal Vδ1 and Vδ2 T-Cells Differentiation Profile and Effector Functions

Gut-associated immune system has been identified as a major battlefield during the early phases of HIV infection. γδ T-cells, deeply affected in number and function after HIV infection, are able to act as a first line of defence against invading pathogens by producing antiviral soluble factors and by killing infected cells. Despite the relevant role in mucosal immunity, few data are available on gut-associated γδ T-cells during HIV infection. Aim of this work was to evaluate how primary (P-HIV) and chronic (C-HIV) HIV infection affects differentiation profile and functionality of circulating and gut-associated Vδ1 and Vδ2 T-cells. In particular, circulating and mucosal cells were isolated from respectively whole blood and residual gut samples from HIV-infected subjects with primary and chronic infection and from healthy donors (HD). Differentiation profile and functionality were analyzed by multiparametric flow cytometry. P-HIV and C-HIV were characterized by an increase in the frequency of effector Vδ1-T cells both in circulating and mucosal compartments. Moreover, during P-HIV mucosal Vδ1 T-cells expressed high levels of CD107a, suggesting a good effector cytotoxic capability of these cells in the early phase of infection that was lost in C-HIV. P-HIV induced an increase in circulating effector Vδ2 T-cells in comparison to C-HIV and HD. Notably, P-HIV as well as HD were characterized by the ability of mucosal Vδ2 T-cells to spontaneously produce IFN-γ that was lost in C-HIV. Altogether, our data showed for the first time a functional capability of mucosal Vδ1 and Vδ2 T-cells during P-HIV that was lost in C-HIV, suggesting exhaustion mechanisms induced by persistent stimulation.

Update on ankylosing spondylitis: current concepts in pathogenesis

Ankylosing spondylitis is an insidiously progressive and debilitating form of arthritis involving the axial skeleton. The long delay in diagnosis and insufficient response to currently available therapeutics both advocate for a greater understanding of disease pathogenesis. Genome-wide association studies of this highly genetic disease have implicated specific immune pathways, including the interleukin (IL)-17/IL-23 pathway, control of nuclear factor kappa B (NF-κB) activation, amino acid trimming for major histocompatibility complex (MHC) antigen presentation, and other genes controlling CD8 and CD4 T cell subsets. The relevance of these pathways has borne out in animal and human subject studies, in particular, the response to novel therapeutic agents. Genetics and the findings of autoantibodies in ankylosing spondylitis revisit the question of autoimmune vs. autoinflammatory etiology. As environmental partners to genetics, recent attention has focused on the roles of microbiota and biomechanical stress in initiating and perpetuating inflammation. Herein, we review these current developments in the investigation of ankylosing spondylitis pathogenesis.

Harnessing the antibacterial and immunological properties of mucosal-associated invariant T cells in the development of novel oral vaccines against enteric infections

Enteric infections are a major cause of mortality and morbidity with significant social and economic implications worldwide and particularly in developing countries. An attractive approach to minimizing the impact of these diseases is via the development of oral vaccination strategies. However, oral vaccination is challenging due to the tolerogenic and hyporesponsive nature of antigen presenting cells resident in the gastrointestinal tract. The inclusion of adjuvants in oral vaccine formulations has the potential to overcome this challenge. To date no oral adjuvants have been licenced for human use and thus oral adjuvant discovery remains a key goal in improving the potential for oral vaccine development. Mucosal-associated invariant T (MAIT) cells are a recently discovered population of unconventional T cells characterized by an evolutionarily conserved αβ T cell receptor (TCR) that recognizes antigens presented by major histocompatibility complex (MHC) class I-related (MR1) molecule. MAIT cells are selected intra-thymically by MR1 expressing double positive thymocytes and enter the circulation with a naïve phenotype. In the circulation they develop a memory phenotype and are programmed to home to mucosal tissues and the liver. Once resident in these tissues, MAIT cells respond to bacterial and yeast infections through the production of chemokines and cytokines that aid in the induction of an adaptive immune response. Their abundance in the gastrointestinal tract and ability to promote adaptive immunity suggests that MAIT cell activators may represent attractive novel adjuvants for use in oral vaccination.

CD4(+) T-cell subsets in intestinal inflammation

Intestinal CD4⁺ T cells are essential mediators of immune homeostasis and inflammation. Multiple subsets of CD4⁺ T cells have been described in the intestine, which represents an important site for the generation and regulation of cells involved in immune responses both within and outside of the gastrointestinal tract. Recent advances have furthered our understanding of the biology of such cells in the intestine. Appreciation of the functional roles for effector and regulatory populations in health and disease has revealed potential translational targets for the treatment of intestinal diseases, including inflammatory bowel disease. Furthermore, the role of dietary and microbiota-derived factors in shaping the intestinal CD4⁺ T-cell compartment is becoming increasingly understood. Here, we review recent advances in understanding the multifaceted roles of CD4⁺ T cells in intestinal immunity.

NKG2D/Ligand dysregulation and functional alteration of innate immunity cell populations in pediatric IBD

BACKGROUND

Dysregulated innate immune responses play an important role in inflammatory bowel disease (IBD). NKG2D innate immunity receptor is a major sensor of tissue damage that, by recognizing multiple stress-induced, cell-associated ligands (MIC-A/B and ULBP1-5), potentiates the effector functions of "innate-like" (γ/δ TcR+, and natural killer receptor+ [NKR+]) T-cell populations. We analyzed the representivity, NKG2D/ligand expression pattern, and functional ability of the major innate immunity cell populations in pediatric IBD patients.

METHODS

We analyzed 41 Crohn's disease (CD) patients, 33 ulcerative colitis (UC) patients, and 51 age-matched non-IBD controls. The expression of NKG2D and its ligands, interferon-gamma (IFN-γ) production, and cytotoxic granule release were assessed by immunostaining and multiparameter cytofluorimetric analysis on circulating and mucosal mononuclear subsets; the inflammatory infiltrate was also characterized by immunohistochemistry.

RESULTS

The expression pattern of NKG2D receptor and its ligands on mucosal and circulating innate immunity populations is severely disturbed in IBD; NKG2D and ligands are upregulated on immune infiltrate in both CD and UC active lesions; receptor/ligand upregulation also occurs on circulating leukocyte populations, where it depends on both disease activity and type (UC vs. CD). Finally, the frequency and effector capability of peripheral blood "innate-like" T-cell populations are also altered in IBD patients.

CONCLUSIONS

The circulating and mucosal innate immunity compartment is phenotypically and functionally altered in pediatric IBD; some alterations may represent a distinctive feature of the pediatric disease condition. The disturbance of NKG2D/ligand pathway may play a role in sustaining immune activation which leads to chronic inflammatory tissue damage.

Celiac disease: an immunological jigsaw

Celiac disease (CD) is a chronic enteropathy induced by dietary gluten in genetically predisposed people. The keystone of CD pathogenesis is an adaptive immune response orchestrated by the interplay between gluten and MHC class II HLA-DQ2 and DQ8 molecules. Yet, other factors that impair immunoregulatory mechanisms and/or activate the large population of intestinal intraepithelial lymphocytes (IEL) are indispensable for driving tissue damage. Herein, we summarize our current understanding of the mechanisms and consequences of the undesirable immune response initiated by gluten peptides. We show that CD is a model disease to decipher the role of MHC class II molecules in human immunopathology, to analyze the mechanisms that link tolerance to food proteins and autoimmunity, and to investigate how chronic activation of IEL can lead to T cell lymphomagenesis.

Size and dynamics of mucosal and peripheral IL-17A+ T-cell pools in pediatric age, and their disturbance in celiac disease

Mucosal interleukin (IL)-17A-producing T cells contribute to protective antimicrobial responses and to epithelial barrier integrity; their role in celiac disease (CD) is debated. We analyzed the frequency and developmental dynamics of mucosal (intraepithelial lymphocytes (IEL)) and circulating (peripheral blood (PB)) IL-17A (T17) and/or interferon (IFN)-γ-producing (T1, T1/T17) T-cell populations in 86 pediatric controls and 116 age-matched CD patients upon phorbol myristate acetate/ionomycin or CD3/CD28 stimulation. T17 and T1/17 are physiologically present among IEL and PB populations, and their frequency is selectively and significantly reduced in CD IEL. The physiological age-dependent increase of Th17 IEL is also absent in CD, while IFN-γ-producing PB-T cells significantly accumulate with patient's age. Finally, the amplitude of IL-17A+ and IFN-γ+ T-cell pools are significantly correlated in different individuals; this relationship only applies to CD4+ T cells in controls, while it involves also the CD4- counterpart in CD patients. In conclusion, both size and dynamics of mucosa-associated and circulating IL-17A+ T-cell pools are finely regulated in human pediatric subjects, and severely disturbed in CD. The impaired IL-17A+ IEL-T pool may negatively impact on epithelial barrier efficiency, and contribute to CD mucosa damage; the disturbed dynamics of circulating IL-17A+ and IFN-γ+ T-cell pools may be involved in the extraintestinal autoimmune manifestations associated with CD.

The suckling rat as a model for immunonutrition studies in early life

Diet plays a crucial role in maintaining optimal immune function. Research demonstrates the immunomodulatory properties and mechanisms of particular nutrients; however, these aspects are studied less in early life, when diet may exert an important role in the immune development of the neonate. Besides the limited data from epidemiological and human interventional trials in early life, animal models hold the key to increase the current knowledge about this interaction in this particular period. This paper reports the potential of the suckling rat as a model for immunonutrition studies in early life. In particular, it describes the main changes in the systemic and mucosal immune system development during rat suckling and allows some of these elements to be established as target biomarkers for studying the influence of particular nutrients. Different approaches to evaluate these immune effects, including the manipulation of the maternal diet during gestation and/or lactation or feeding the nutrient directly to the pups, are also described in detail. In summary, this paper provides investigators with useful tools for better designing experimental approaches focused on nutrition in early life for programming and immune development by using the suckling rat as a model.

The enteropathy associated with common variable immunodeficiency: the delineated frontiers with celiac disease

OBJECTIVES

The enteropathy associated with common variable immunodeficiency (CVID) is poorly characterized, and its possible relationships with well-defined causes of enteropathy, such as celiac sprue (CS), remain debated. We aimed to assess the clinical and histopathological features of the enteropathy associated with CVID.

METHODS

The medical files of 50 CVID patients with gastrointestinal symptoms were analyzed retrospectively. Histological, phenotypic, and molecular analysis of intestinal endoscopic specimens was centrally performed.

RESULTS

Chronic diarrhea was the most frequent gastrointestinal symptom (92%), and biological evidence of malabsorption was observed in 54% of patients. Chronic gastritis associated or not with pernicious anemia and microscopic colitis were the most frequently observed histopathological features in gastric and colonic mucosa, respectively. Small-bowel biopsies available in 41 patients showed moderate increase in intestinal intraepithelial lymphocytes in 31 patients (75.6%) and villous atrophy in 21 patients (51%). Distinctive features from CS were a profound depletion in plasma cells and follicular lymphoid hyperplasia. Presence of peripheral blood CD8+ hyperlymphocytosis was predictive of intestinal intraepithelial hyperlymphocytosis. Intravenous (i.v.) immunoglobulin (Ig) therapy had no effect on enteropathy-related symptoms. Gluten-free diet improved only two out of 12 patients with villous atrophy, whereas all patients (7/7) responded to steroid therapy.

CONCLUSIONS

Several distinctive features differentiate CVID enteropathy from other causes of enteropathy including CS. Replacement i.v. Ig therapy is insufficient to improve gastrointestinal symptoms. Steroids are effective in reducing inflammation and restoring mucosal architecture.

Krüppel-like factor 2 regulates trafficking and homeostasis of gammadelta T cells

gammadelta T cells are generated in the thymus and traffic to secondary lymphoid organs and epithelial surfaces, where they regulate immune responses. alphabeta T cells require sphingosine 1-phosphate receptor type 1 (S1P(1)) and CD62L for thymic emigration and circulation through secondary lymphoid organs. Both of these genes are regulated by the transcription factor Krüppel-like factor 2 (KLF2) in conventional alphabeta T cells. It is unclear if gammadelta T cells use similar mechanisms. In this study, we show that thymic gammadelta T cells express S1P(1) and that it is regulated by KLF2. Furthermore, KLF2 and S1P(1)-deficient gammadelta T cells accumulate in the thymus and fail to populate the secondary lymphoid organs or gut, in contrast to the expectation from published work. Interestingly, KLF2 but not S1P(1) deficiency led to the expansion of a usually rare population of CD4(+) promyelocytic leukemia zinc finger(+) "gammadelta NKT" cells. Thus, KLF2 is critically important for the homeostasis and trafficking of gammadelta T cells.

Homeostasis and inflammation in the intestine

The gut is home to our largest collection of microbes. The ability of the immune system to coevolve with the microbiota during postnatal life allows the host and microbiota to coexist in a mutually beneficial relationship. Failure to achieve or maintain equilibrium between a host and its microbiota has negative consequences for both intestinal and systemic health. In this Review, we consider the many cellular and molecular methods by which inflammatory responses are regulated to maintain intestinal homeostasis and the disease states that can ensue when this balance is lost.

The immunopathogenesis of Entamoeba histolytica

Amebiasis is the disease caused by the enteric dwelling protozoan parasite Entamoeba histolytica. The WHO considers amebiasis as one of the major health problems in developing countries; it is surpassed by only malaria and schistosomiasis for death caused by parasitic infection. E. histolytica primarily lives in the colon as a harmless commensal, but is capable of causing devastating dysentery, colitis and liver abscess. What triggers the switch to a pathogenic phenotype and the onset of disease is unknown. We are becoming increasingly aware of the complexity of the host-parasite interaction. During chronic stages of amebiasis, the host develops an immune response that is incapable of eliminating tissue resident parasites, while the parasite actively immunosuppresses the host. However, most individuals with symptomatic infections succumb only to an episode of dysentery. Why most halt invasion and a minority progress to chronic disease remains poorly understood. This review presents a current understanding of the immune processes that shape the outcome of E. histolytica infections during its different stages.

Celiac disease: from pathogenesis to novel therapies

Celiac disease has become one of the best-understood HLA-linked disorders. Although it shares many immunologic features with inflammatory bowel disease, celiac disease is uniquely characterized by (1) a defined trigger (gluten proteins from wheat and related cereals), (2) the necessary presence of HLA-DQ2 or HLA-DQ8, and (3) the generation of circulating autoantibodies to the enzyme tissue transglutaminase (TG2). TG2 deamidates certain gluten peptides, increasing their affinity to HLA-DQ2 or HLA-DQ8. This generates a more vigorous CD4(+) T-helper 1 T-cell activation, which can result in intestinal mucosal inflammation, malabsorption, and numerous secondary symptoms and autoimmune diseases. Moreover, gluten elicits innate immune responses that act in concert with the adaptive immunity. Exclusion of gluten from the diet reverses many disease manifestations but is usually not or less efficient in patients with refractory celiac disease or associated autoimmune diseases. Based on the advanced understanding of the pathogenesis of celiac disease, targeted nondietary therapies have been devised, and some of these are already in phase 1 or 2 clinical trials. Examples are modified flours that have been depleted of immunogenic gluten epitopes, degradation of immunodominant gliadin peptides that resist intestinal proteases by exogenous endopeptidases, decrease of intestinal permeability by blockage of the epithelial ZOT receptor, inhibition of intestinal TG2 activity by transglutaminase inhibitors, inhibition of gluten peptide presentation by HLA-DQ2 antagonists, modulation or inhibition of proinflammatory cytokines, and induction of oral tolerance to gluten. These and other experimental therapies will be discussed critically.