Search

Background: Due to their "natural immune privilege" and immunoregulatory properties human fibroblast-like limbal stem cells (f-LSCs) have acquired great interest as a potential tool for achieving immunotolerance. Hashimoto's thyroiditis (HT) is the most common thyroid autoimmune disease and cause of hypothyroidism. To date, conventional hormone replacement therapy and unspecific immunosuppressive regimens cannot provide a definitive cure for HT subjects. We explored the immunosuppressant potential of human f-LSCs on circulating lymphomonocytes (PBMCs) collected from healthy donors and female HT patients. Methods: We assessed the immunophenotyping of f-LSCs, both untreated and after 48 h of proinflammatory cytokine exposure, by means of quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and flow cytometry. The immunosuppressant effects of f-LSCs on healthy activated PBMCs were investigated in cell-cell contact and transwell settings through cell cycle assay, acridine orange staining, and caspase-3 detection. We also studied T-cell responses and possible Treg conversion by means of flow cytometry. Functional assays were conducted in activated HT lymphocytes cocultured with f-LSCs after carboxyfluorescein succinimidyl ester labeling and intracellular detection of pro- and antiinflammatory cytokines. Results: The hypo-immunogenicity of the f-LSC population depended on both cell contact and soluble factors produced, as well as the undetectable expression of all those molecules required to fully activate T lymphocytes. Following exposure to Th1 cytokines, f-LSCs augmented expression of programmed death-ligand 1 and 2 (PDL-1 and -2), indoleamine-pyrrole-2,3-dioxygenase (IDO), interleukin (IL)-6, and monocyte chemotactic protein 1 (MCP-1) while maintaining their negative phenotype for major histocompatibility (MHC) class II and costimulatory molecules. During coculture, f-LSCs suppressed up to 40% of proliferation in healthy activated PBMCs, arrested them in the G0/G1 cell cycle phase without inducing apoptosis cascade, inverted the CD4/CD8 ratio, and promoted sustained expression of the immunomodulator marker CD69. Under coculture conditions the Th imbalance of autoreactive T cells from female HT patients was fully restored. Conclusions: Our study describes an in vitro coculture system able to prevent inappropriate activation of autoreactive T lymphocytes of female HT patients and to generate a tolerogenic environment even in an inflammatory background. Further investigations are necessary to establish whether this stem cell-based therapy approach in HT could avoid lifetime hormone replacement therapy by inducing T-cell education. [ABSTRACT FROM AUTHOR]

Background: Neck lymph nodes may be involved in the pathogenesis of chronic autoimmune thyroiditis (CAT). This study was undertaken to identify which of the sonographic features of cervical lymph nodes are readily applicable to patients affected by CAT compared to healthy control subjects. Methods: We recruited 106 patients (92 females and 14 males) with CAT and 70 control subjects (53 females and 17 males) without clinical, biochemical, and ultrasonographic evidence of thyroid and neck diseases. We performed laboratory tests (thyrotropin, antithyroperoxidase antibodies, antithyroglobulin antibodies, and ultrasonography) to evaluate in each group: (i) thyroid function, autoimmunity, and morphology; (ii) number, topographic distribution (levels I-VI), and morphology of neck nodes (long-axis diameter; short-axis diameter; short-axis/long-axis ratio; absence or presence of hilus). Results: Total number of neck nodes with long-axis diameter >10 mm was significantly higher in the CAT group than in the control group (mean±standard deviation [SD]: 3.7±2.4 vs. 0.8±1.3; p<0.001) with significantly increased differences in levels II (1.4±0.8 vs. 0.3±0.5; p<0.001), III (2±1.2 vs. 0.3±0.7; p<0.001), and IV (0.7±0.7 vs. 0.07±0.2; p<0.001). More nodes with a hilus were found in the CAT group than in the control group (mean number of nodes±SD: 2.8±1.9 vs. 0.7±1.1; p<0.001). Short-axis diameter of level III (4.4±1 vs. 3.7±1.2 mm; p=0.002) and level IV nodes (3.9±1 vs. 3.1±0.5 mm p=0.030) was increased in CAT patients when compared with healthy controls. Conclusions: The present study is the first one aiming at a systematic description of the sonographic pattern of cervical lymph nodes in CAT. An increased number of benign hyperplastic neck nodes, especially in levels II-IV, appears to be a characteristic sonographic finding associated with CAT. [ABSTRACT FROM AUTHOR]

Proposes that differences in the production of cytokines by infiltrating lymphocytes can explain the differences in thyroid follicular cell (TFC) apoptosis being observed in Hashimoto's thyroiditis (HT) and Grave's disease (GD). Evidence of higher apoptosis in HT than in GD thyroids; Other mechanisms affecting the apoptosis; Higher Fas expression in HT and lower in GD thyrocytes; Proposal for the promotion of lymphocyte apoptosis by FasL expression in GD thyrocytes.