Comparison of commercially available serologic kits for the detection of celiac disease.

BACKGROUND: The sensitivity and specificity of current antihuman tissue transglutaminase (tTG) IgA assays used to detect celiac disease reportedly approach 100%. In addition, the sensitivity of new generation deamidated gliadin peptide (alpha-DGP) antibody assays has also been reported to be similar to the tTG IgA assays. In routine clinical practice, however, the sensitivities and specificities of these tests for diagnosing celiac disease seem to be lower. AIM: We analyzed sensitivities and specificities of 4 IgA tTG and 3 deamidated gliadin peptide (alpha-DGP) kits. METHODS: The performance of 4 tTG IgA assays, A: Inova (Hu red blood cell), B: Binding site (rHu Ag), C: Eurospital (rHu Ag), D: Immco (rHu Ag) and 3 Inova alpha-DGP assays, E: alpha-DGP-IgA, F: alpha-DGP-IgG, and G: alpha-DGP-IgA+G was evaluated using sera from different subsets of celiac disease patients and controls; group 1: active celiac disease n=28, group 2: gluten-free diet n=54, group 3: healthy controls n=40, group 4: disease controls n=57(Crohn's disease n=17, chronic hepatitis n=40). RESULTS: Using the manufacturer's cut-off values, the sensitivities and specificities of different kits ranged from 71.4% to 96.4% and 87.5% to 100%, respectively. When group 1 was compared with disease controls, sensitivities remained the same but specificities decreased. Receiver operating characteristic plot derived cut-off values modified decision thresholds in all assays except kit (G). Kappa analysis demonstrated variable degrees of agreement. All assays demonstrated higher sensitivities for patients with higher grades of villous atrophy. CONCLUSIONS: Overall sensitivity was at or below 90%, which is lower than that reported in the literature. Performance of the recombinant and red blood cell antigen-based tTG assays was similar, whereas the alpha-DGP assays demonstrated lower values. Receiver operating characteristic plot derived cut-off values altered test results. Many factors affect the results of these tests and clinicians should be aware of their limitations.

Tissue transglutaminase antibodies in individuals with celiac disease bind to thyroid follicles and extracellular matrix and may contribute to thyroid dysfunction.

BACKGROUND: Individuals with active celiac disease (CD+) have an increased incidence of thyroid dysfunction, which improves on a gluten-free diet (CD-). We investigated whether tissue transglutaminase-2 IgA antibodies (anti-TGase II) present in sera of patients with celiac disease react with thyroid tissue and possibly contribute to thyroid disease. METHODS: Serum from 40 active celiac patients taken before a gluten-free diet (CD+), 46 patients on a gluten-free diet (CD-), 40 normal controls (NC), and 25 with Crohn's disease (CROHN) was used. All sera were screened for antithyroperoxidase antibodies (TPO-AB) and thyroglobulin antibodies (TG-AB), and indirect immunofluorescence (IIF) was performed on primate thyroid tissue sections using TPO-AB- and TG-AB-negative sera. RESULTS: IIF with thyroid seronegative, anti-TGase II-positive CD+ sera (n = 23) demonstrated staining of thyroid follicular cells and extracellular matrix, in an identical pattern with monoclonal anti-human TGase II antibody. Evidence of TGase II as the antigen in thyroid tissue was supported by elimination of the IIF pattern when sera were depleted of anti-TGase II by pretreatment with human recombinant TGase II. No staining of thyroid tissue was observed when sera from CD+ patients that were negative for TGase II antibodies, or sera from NC subjects were used. Thyroid antibodies were found in 43% of CD+ patients, significantly higher than NC and CROHN patients (p < 0.0001). In addition, a positive correlation was observed between anti-TGase II and TPO-AB titers (p = 0.0001; r = 0.63). CONCLUSIONS: Anti-TGase II antibodies bind to TGase II in thyroid tissue, and titers correlate with TPO antibody titers. These findings suggest that anti-TGase II antibodies could contribute to the development of thyroid disease in celiac disease.

Economic benefits of increased diagnosis of celiac disease in a national managed care population in the United States.

OBJECTIVES: To estimate the rate of celiac disease diagnosis and evaluate the economic benefits of diagnosis by analyzing retrospective cohorts from a national managed-care-population database. METHODS: We identified patients who received a new diagnosis of celiac disease. We also identified 3 control groups, persons without a diagnosis of celiac disease but who exhibited 1, 2, or 3 or more symptoms associated with the disease. Using claims, encounter, and eligibility data of approximately 10.2 million managed care members across the United States between January 1999 and December 2003, we measured and compared direct standardized relative value based (RVU) medical costs and utilization of selected health care services among the 4 study cohorts. RESULTS: The rate of new diagnosis for celiac disease more than doubled over the 4-year period. The celiac disease cohort had a significant trend reduction in direct standardized medical costs relative to the three control groups. RVU-based medical costs in the celiac cohort were 24%, 33%, and 27% lower than cohort 1 (p<0.05), 29.0%, 38%, and 24% lower than cohort 2 (p<0.05), and 38%, 33%, and 31% lower than cohort 3 (p<0.01) for the 12-month, 24-month and 36-month post-diagnosis periods, respectively. The reductions in costs were attributable to decreasing trends in utilization of office visits, lab, diagnostic, imaging, and endoscopy procedures relative to the 3 comparative cohorts over the 3-year follow-up period. CONCLUSIONS: There was an increase in the rate of celiac disease diagnosis, which was associated with significant reduction in direct standardized RVU-based medical costs and utilization of selected health care services over time.

Small intestinal CD8+TCRgammadelta+NKG2A+ intraepithelial lymphocytes have attributes of regulatory cells in patients with celiac disease.

Intraepithelial lymphocytes (IELs) bearing the gammadelta TCR are more abundant in the small intestinal mucosa of patients with celiac disease (CD) compared with healthy individuals. However, their role in disease pathogenesis is not well understood. Here, we investigated the functional attributes of TCRgammadelta+ IELs isolated from intestinal biopsies of patients with either active celiac disease (ACD) or those on a gluten-free diet (GFD). We found that compared with individuals with ACD, individuals on GFD have a higher frequency of CD8+TCRgammadelta+ IELs that express the inhibitory NK receptor NKG2A and intracellular TGF-beta1. TCR triggering as well as cross-linking of NKG2A increased both TGF-beta1 intracellular expression and secretion in vitro. Coculture of sorted TCRgammadelta+NKG2A+ IELs, IL-15-stimulated TCRalphabeta+ IELs, and HLA-E+ enterocytes resulted in a decreased percentage of cytotoxic CD8+TCRalphabeta+ IELs expressing intracellular IFN-gamma and granzyme-B and surface NKG2D. This inhibition was partially abrogated by blocking either TGF-beta alone or both NKG2A and HLA-E. Thus, our data indicate that suppression was at least partially mediated by TGF-beta secretion as a result of engagement of NKG2A with its ligand, HLA-E, on enterocytes and/or TCRalphabeta+ IELs. These findings demonstrate that human small intestinal CD8+TCRgammadelta+ IELs may have regulatory potential in celiac disease.

Chronic hepatitis C virus and celiac disease, is there an association?

Celiac disease (CD) has been epidemiologically associated with chronic hepatitis C (HCV), and CD activation after the initiation of interferon (IFN-alpha) in patients with HCV is documented. However, clear association of CD and HCV is lacking. A prospectively maintained database of 878 CD patients showed a prevalence of 0.68% (six patients). Symptoms of diarrhea, weight loss, and depression prompted the diagnosis of CD during or after IFN-alpha therapy in four cases. Also, 294 subjects with liver disease (195 with HCV, 80 normal controls and 19 disease controls) were prospectively screened for CD. The mean age of the subjects was 50.1 years (SD 12.3), 58% males:42% females. A total of 30% received IFN-alpha therapy (16% at the time of testing for CD). Two HCV patients (1%) had positive tTG-IgA but these had negative endomysial antibody (EMA) and normal duodenal biopsies. CD prevalence is not increased in patients with HCV. Routine screening of CD in HCV patients is not warranted, however, the presence of CD should be considered in the setting of clinical deterioration during or after IFN-alpha therapy.

Molecular characterization of allospecific T suppressor and tolerogenic dendritic cells: review.

T suppressor and regulatory cells have been shown to play an important role in the maintenance of central and peripheral tolerance thereby preventing allograft rejection, autoimmunity and allergy. We have previously described a distinct population of antigen-specific CD8(+)CD28(-) T suppressor cells (T(S)). These CD8(+)CD28(-) T(S) cells can be generated in vitro after multiple rounds of stimulation of human peripheral blood mononuclear cells (PBMCs) with either allogenic- or xenogeneic-donor APCs. CD8(+)CD28(-) T(S) cells are FOXP3+, MHC class I-restricted and tolerize both professional antigen presenting cells, such as dendritic cells (DC) and nonprofessional APC such as endothelial cells (EC) by up-regulating the cell surface expression of inhibitory receptors immunoglobulin-like transcript (ILT)-3 and ILT4 and down-regulating the expression of costimulatory molecules such as CD58 and CD86. Tolerized ILT3(high), ILT4(high) APC anergize CD4(+) T(H) cells and can induce the generation of antigen-specific CD4(+)CD25(+) T regulatory cells (T(R)) cells and CD8(+)CD28(-) T(S) cells. In this review, we present our recent studies on the molecular characterization of these antigen specific T suppressor cells and tolerogenic APC.

Alloantigen specific CD8+CD28- FOXP3+ T suppressor cells induce ILT3+ ILT4+ tolerogenic endothelial cells, inhibiting alloreactivity.

Endothelial cells have been shown to activate T cell responses to alloantigens, triggering transplant rejection. However, they may also play a role in tolerance induction. Using RT-PCR we show here that alloantigen specific CD8(+)CD28(-) T suppressor cells generated in vitro are FOXP3 positive and interact with human endothelial cells. This interaction results in the induction of inhibitory receptors and down-regulation of costimulatory and adhesion molecules, thus rendering endothelial cells tolerogenic. In turn, tolerized endothelial cells elicit the differentiation of CD8(+)CD28(-) FOXP3(+) T suppressor cells. Taken together our data demonstrate a functional and phenotypic overlap between tolerogenic dendritic cells and endothelial cells. Furthermore, alloantigen specific CD8(+)CD28(-) FOXP3(+) T cells, which trigger the upregulation of inhibitory receptors in endothelial cells, are present in the circulation of heart allograft recipients in quiescence as demonstrated by flow cytometry, RT-PCR and luciferase transcription assays. Their detection facilitates the identification of patients who may benefit from partial or complete cessation of immunosuppressive therapy, a goal of obvious importance given the morbidity and mortality associated with chronic immunosuppression. Modulation of endothelial cells in favor of promoting tolerance may be important for long-term survival of organ allografts.

Multiple stages of malignant transformation of human endothelial cells modelled by co-expression of telomerase reverse transcriptase, SV40 T antigen and oncogenic N-ras.

We have modelled multiple stages of malignant transformation of human endothelial cells (ECs) by overexpressing the catalytic subunit of human telomerase (hTERT), together with SV40 T antigen (SV40T) and oncogenic N-ras. Transfection with hTERT alone, led to the immortalization of two out of three cultures of bone marrow-derived ECs (BMECs). One hTERT transduced BMEC culture underwent a long proliferative lag before resuming proliferation. BMECs transfected with hTERT alone were functionally and phenotypically normal. BMECs transfected with SV40T (BMSVTs) had an extended lifespan, but eventually succumbed to crisis. BMSVTs exhibited a partially transformed phenotype, demonstrating growth factor independence, altered antigen expression and forming tiny, infrequent colonies in vitro. Transduction of BMSVTs with hTERT resulted in immortalization of 4 out of 4 cultures. BMSVTs immortalized with hTERT formed large colonies in vitro and small transient tumours in vivo. BMECs co-expressing SV40T, hTERT and N-ras exhibited an overtly transformed phenotype; forming very large colonies with an altered morphology and generating rapidly growing tumours in vivo. These investigations demonstrate transformation of human ECs to an overtly malignant phenotype. This model will be useful for understanding mechanisms underlying vascular and angiogenic neoplasias, as well as for testing drugs designed to curtail aberrant EC growth.