Invariant natural killer T cells in children with eosinophilic esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is an atopic disease characterized by eosinophilic inflammation in which dietary antigens (in particular, milk) play a major role. EoE is most likely a mixed IgE and non-IgE food-mediated reaction in which overexpression of Th2 cytokines, particularly IL-13, play a major role; however, the cells responsible for IL-13 overexpression remain elusive. Th2-cytokines are secreted following the ligation of invariant natural killer T cell receptors to sphingolipids (SLs). Sphingolipids (SLs) are presented via the CD1d molecule on the INKTs surface. Cow's milk-derived SL has been shown to activate iNKTs from children with IgE-mediated food allergies to milk (FA-MA) to produce Th2 cytokines. The role of iNKTs and milk-SL in EoE pathogenesis is currently unknown. OBJECTIVE: The aim of this study was to investigate the role of iNKTs and milk-SL in EoE. METHODS: Peripheral blood mononuclear cells (PBMCs) from 10 children with active EoE (EoE-A), 10 children with controlled EoE (EoE-C) and 16 healthy controls (non-EoE) were measured ex vivo and then incubated with α-galactosylceramide (αGal) and milk-SL. INKTs from peripheral blood (PB) and oesophageal biopsies were studied. RESULTS: EoE-A children had significantly fewer peripheral blood iNKTs with a greater Th2-response to αGal and milk-SM compared with iNKTs of EoE-C and non-EoE children. Additionally, EoE-A children had increased iNKT levels in oesophageal biopsies compared with EoE-C children. CONCLUSION: Milk-SLs are able to activate peripheral blood iNKTs in EoE-A children to produce Th2 cytokines. Additionally, iNKT levels are higher at the site of active oesophageal eosinophilic inflammation. CLINICAL RELEVANCE: This study suggests that sphingolipids (SLs) contained in milk may drive the development of EoE by promoting an iNKT-cell-mediated Th2-type cytokine response that facilitates eosinophil-mediated allergic inflammation.

Dyskeratosis congenita: a combined immunodeficiency with broad clinical spectrum--a single-center pediatric experience.

BACKGROUND: Dyskeratosis Congenita (DKC) is a syndrome characterized by immunodeficiency, bone marrow failure, somatic abnormalities, and cancer predisposition resulting from defective telomere maintenance. The immunologic features of DKC remain under diagnosed and under treated despite the fact that immunodeficiency is a major cause of premature mortality in DKC. METHODS: This study undertook a retrospective review of 7 DKC patients diagnosed at the Children's Hospital of Philadelphia. In parallel, we reviewed previously reported immunologic findings in DKC patients. RESULTS: Immunologic abnormalities (lymphopenia, low B-cell numbers, hypogammaglobulinemia, and decreased T-cell function) were the most frequent laboratory findings at initial presentation, preceding the development of significant anemia or thrombocytopenia. Recurrent sinopulmonary or opportunistic infections were present in 6/7 patients. Infant-onset patients had more severe immunologic and somatic features (particularly severe enteropathy). CONCLUSION: In DKC, development of immunologic abnormalities can precede bone marrow failure, highlighting the importance of proper immunodeficiency management to minimize morbidity and premature mortality in this disease.

Interleukin-6 stimulates thyrotropin receptor expression in human orbital preadipocyte fibroblasts from patients with Graves' ophthalmopathy.

The thyrotropin receptor (TSHR) is the thyroid autoantigen against which stimulating autoantibodies are directed in Graves' hyperthyroidism. Recent evidence suggests that TSHR may also serve as an orbital autoantigen in Graves' ophthalmopathy (GO) and that expression of this protein is increased in the fatty connective tissues of the orbit in this condition. It has been shown that orbital fibroblasts from patients with GO increase thyrotropin (TSH)-dependent cyclic adenosine monophosphate (cAMP) production and TSHR gene expression when cultured under conditions known to stimulate adipocyte differentiation. In the current study, we wanted to determine whether treatment of these cells with particular cytokines (each 1 ng/mL) during differentiation might further augment TSHR expression. We found that exposure to interleukin (IL)-6 increased TSHR expression above control levels in cells from patients with GO. In contrast, this cytokine did not affect TSHR expression in normal orbital cells. Neither IL-4 nor IL-1alpha had a significant stimulatory effect in either normal or Graves' cultures. These findings suggest that IL-6 may play a role in the pathogenesis of GO by increasing expression of the putative autoantigen within the adipose/connective tissues of the orbit.

Effect of tumor necrosis factor-alpha, interferon-gamma, and transforming growth factor-beta on adipogenesis and expression of thyrotropin receptor in human orbital preadipocyte fibroblasts.

Graves' ophthalmopathy (GO) is an orbital autoimmune disease that is closely associated with Graves' hyperthyroidism. Examination of retroorbital tissues in GO reveals an accumulation of glycosaminoglycans, increased fat volume, lymphocytic infiltration, and the presence of several inflammatory cytokines. A subpopulation of human orbital fibroblasts can be differentiated in vitro into cells with the morphologic features of adipocytes. We demonstrated recently that these differentiated cultures show increased expression of functional TSH receptor (TSHr). To determine whether the presence of inflammatory cytokines might impact adipogenesis or TSHr expression in these cultures, we treated orbital fibroblasts from normal individuals or GO patients with tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), or transforming growth factor-beta. We found that each of these cytokines inhibits TSH-dependent cAMP production and TSHr gene expression, and that TNF-alpha and IFN-gamma also inhibit morphological adipocyte differentiation. When cytokines were added after differentiation, the inhibition was less pronounced. Our results suggest that TNF-alpha, IFN-gamma, and transforming growth factor-beta may act within the orbit in GO to modulate expression of the putative orbital autoantigen, TSHr. In addition, the former two cytokines may play a role in determining the extent to which the volume of the orbital adipose tissue increases in this condition.

Differentiation of human orbital preadipocyte fibroblasts induces expression of functional thyrotropin receptor.

Although the autoantigen involved in Graves' hyperthyroidism is known to be the TSH receptor (TSHr), whether this antigen plays a primary role in the pathogenesis of Graves' ophthalmopathy (GO) is unclear. We sought to determine whether fibroblasts derived from orbital adipose/connective tissue are capable of differentiating into adipocytes that bear immunoreactive and functional TSHr. In addition, we assessed relative levels of TSHr gene expression in normal and GO orbital adipose/connective tissue specimens. GO and normal orbital preadipocyte fibroblasts, cultured under conditions known to stimulate adipocyte differentiation, showed evidence of adipogenesis and positive immunostaining for TSHr protein. In addition, significantly more cAMP was produced in response to TSH stimulation in the differentiated cultures than in undifferentiated cultures derived from the same individuals' cells. Other studies demonstrated relatively greater TSHr gene expression in GO than in normal orbital tissue specimens. These results indicate that orbital preadipocyte fibroblasts increase their TSHr expression with differentiation and suggest that these cells play an important role in the pathogenesis of GO. Furthermore, our studies support the concept that TSHr may be an important target antigen in this condition. Factors that stimulate adipocyte differentiation and TSHr expression in the orbit in GO have yet to be defined.