Tumour infiltrating CD25+ FoxP3+ regulatory T cells (Tregs) relate to tumour grade and stromal inflammation in oral squamous cell carcinoma

Abstract

This research is aimed to quantitate and characterize the subtypes of tumour infiltrating lymphocytes (TILs), in particular the presence of FoxP3+ Tregs in different grades of oral squamous cell carcinoma using monospecific antibody staining of formalin-fixed, paraffin-embedded tissue sections. The correlation between tumour grade and the intensity of tumour infiltrating lymphocytes was tried to be tested, to assume a putative linkage between them. Thirty-four cases of histologically proven primary oral squamous cell carcinoma (OSCC) of different grades of differentiation were assorted to groups 1-3. Three-micron sections of tissue were cut and captured on electrically charged slides (Vision BioSystem, Mount Waverley, Australia) and stained using monospecific antibody against FoxP3+ Treg phenotype (dilution 1:40, Mouse monoclone No: 236A/E7, Ab 20034, IgG1; Abcam, Cambridge, UK). Automated protocols were employed for staining and scoring of staining intensity using Bond™ system (Vision BioSystem). Significant difference in staining intensities (Tregs) was noted among the histologic grades of tumour, where well-differentiated OSCC had significantly low expression of FoxP3+ Tregs in comparison with moderately and poorly differentiated tumours. A significant linear correlation was established between tumour grade and the intensity of TILs, where high grade tumours (poor differentiation) were more markedly infiltrated. There was also a significant positive correlation between FoxP3+ Tregs and TILs in cases studied. The correlation of these three variables noted in the study (FoxP3+ Tregs, tumour grade and TILs) and their significance in a meta-analysis may prove useful in targeting patients with high-risk neoplasms for more aggressive treatment protocols and management strategies.

T-helper and T-regulatory cells modulation in head and neck squamous cell carcinoma

“…Four independent studies have studied the immunolocalized Treg cells in HNSCC and they all highlighted a marked presence of cells in the tumor microenvironment. 20,37,39,42 Two studies prevalently found Tregs at the tumor margins, 39,42 thus sustaining the hypothesis that these cells might oversee the interactions between SCC cells and effector immune cells at the border between tumor and normal tissue.…”

“…Several data strongly sustained a negative prognostic index associated to high levels of Tregs, 10,39,41 but other studies described a completely different situation, with high numbers of Treg associated to an improved loco-regional control and better overall survival. 12,42,45,46 These apparent contradictions might be explained, in part by the difficulties to proper identify Treg cells and in part by the tissue dependent modulation of Treg levels; indeed, tumors arising in the rich lymphoid tissue oropharynx have higher level of infiltrating Treg than cancer types arising in larynx.…”

“…12,20,27,29,35,37,[39][40][41][42] Furthermore, Treg levels increase accordingly with tumor staging and they are particularly elevated in patients with active disease. 20,35,39 A murine model of oral carcinogenesis demonstrated a cancer cells promoted skew toward Treg, probably due to the decreased levels of IL-23, also observed in the late phase of HNSCC development in humans. 32 Accordingly, Treg would increase in advanced stage HNSCC as a result of the unbalance of Th17-promoting cytokines.…”

Immunohistochemical analysis of FoxP3+ regulatory T cells in lower lip squamous cell carcinomas

“…13,15 Therefore, research into the cellular and molecular features of the immune response to tumors has intensified in recent years in an attempt to obtain a better understanding of the process of tumor progression, to identify more reliable prognostic factors, and to eventually define potential targets for immunotherapeutic strategies. 6,13,22,23 Within the context of immune responses to tumors, studies have highlighted the participation of Treg cells, which can suppress the functions of different immune system cells. 5,9 In this respect, an increase in the number of Treg cells in the tumor microenvironment has been associated with a poorer prognosis of head and neck carcinomas, including SCC of the oral cavity.…”

“…These tumors represented a higher proportion in the group of early-stage LLSCCs (data not shown). Although they used the World Health Organization grading system, Al-Qahtani et al 22 also found a positive correlation between the intensity of inflammatory infiltration and the number of Treg cells in the microenvironment of SCCs of the oral cavity.…”