Gianfranco Abbate

We demonstrate that CD161 is a highly up-regulated gene in human interleukin (IL) 17 T helper cell (Th17) clones and that all IL-17-producing cells are contained in the CD161(+) fraction of CD4(+) T cells present in the circulation or in inflamed tissues, although they are not CD1-restricted natural killer T cells. More importantly, we show that all IL-17-producing cells originate from CD161(+) naive CD4(+) T cells of umbilical cord blood, as well as of the postnatal thymus, in response to the combined activity of IL-1 beta and IL-23. These findings implicate CD161 as a novel surface marker for human Th17 cells and demonstrate the exclusive origin of these cells from a CD161(+)CD4(+) T cell progenitor.

Asthma is a complex inflammatory disease of the lung characterized by variable airflow obstruction, bronchial hyperresponsiveness, and airway inflammation. Inflammation in asthma consists of airway infiltration by mast cells, lymphocytes, and eosinophils. There is accumulating evidence that CD4+ lymphocytes with a Th2-cytokine pattern play a pivotal role in the pathogenesis of asthma. These cells orchestrate the recruitment and activation of the primary effector cells of the allergic response (mast cells and eosinophils), through the release of cytokines such as IL-4, IL-5, and IL-13. Allergic inflammation is also implicated in airway epithelium changes, although the mechanisms by which inflammatory cells and, in particular, T cells interact with the epithelium are not completely clarified. This paper explores the role of T cells in the allergic inflammation of asthma.

BACKGROUND: Recent studies indicate that T-cell activation may play an important role in the pathophysiology of acute coronary syndromes (ACS). However, although those studies detected T-cell expansion in peripheral blood cells, demonstration of specific T-cell expansion within the plaque of patients with ACS is lacking. The present study aims to address whether a specific, immune-driven T-lymphocyte recruitment occurs within the unstable plaque of patients with ACS. METHODS AND RESULTS: We simultaneously examined the T-cell repertoire using CDR3 size analysis both in coronary plaques (obtained by directional atherectomy) and in peripheral blood of patients with either ACS (n=11) or chronic stable angina (n=10). Unstable plaques showed a 10-fold increase in T-cell content by quantitative PCR. Using spectratyping analysis, we found several specific T-cell clonotype expansions only in unstable plaque from each patient with ACS, indicating a specific, antigen-driven recruitment of T cells within unstable lesions. CONCLUSIONS: For the first time, T-cell repertoire was investigated directly into coronary plaques; using this approach, we demonstrate that coronary plaque instability in the setting of ACS is associated with immune-driven T-cell recruitment, specifically within the plaque.

Sphingosine 1-phosphate (S1P) is a sphingolipid mediator that is involved in diverse biological functions. Local administration of S1P causes inflammation coupled to a large eosinophil (EO) recruitment in the rat-paw tissue. The inflammatory response is accompanied by an increase in S1P receptors, namely S1P(1), S1P(2), S1P(3), and by an enhanced expression of CCR3, which is the main chemokine receptor known to be involved in EO function. Human EOs constitutively express S1P(1) and, at a lower extent, S1P(2), S1P(3) receptors. S1P in vitro causes cultured human EO migration and an increase in S1P receptor mRNA copies and strongly up-regulates CCR3 and RANTES (regulated on activation, normal T cell-expressed and secreted) message levels; in particular CCR3 is up-regulated 18,000-fold by S1P. A blocking anti-CCR3 Ab inhibits S1P-induced chemotaxis, implying that S1P acts as specific recruiting signal for EOs not only through its own receptors but also through CCR3. These results show that S1P is involved in EO chemotaxis and contribute to shed light on the complex mechanisms underlying EO recruitment in several diseases such as asthma and some malignancies.