Immune Suppression in Premalignant Respiratory Papillomas: Enriched Functional CD4+Foxp3+ Regulatory T Cells and PD-1/PD-L1/L2 Expression

Abstract

Purpose Respiratory papillomas, caused by human papillomaviruses types 6 and 11 (HPV6/11), are premalignant lesions with potential for malignant conversion. The cytokine and chemokine micromilieu of papillomas is TH2-like with a marked absence of IFN-γ expression. To illuminate why patients with recurrent respiratory papillomatosis (RRP) fail to effectively control their disease, we further investigated the suppressive cellular microenvironment in papillomas. Experimental Design CD4+CD25+CD127low/−Foxp3+ Tregs, and CD4+CD25−CD127low/−Foxp3− T-cells within papillomas were characterized and isolated. Their suppressor function was measured by inhibition of PBMC proliferation. Expression of PD-1, CD69, and Helios was identified on these T-cells. PD-L1, PD-L2, CCL17, and CCL22 mRNA was also identified in papillomas. by QPCR. Results Functional Tregs were markedly enriched in papillomas and strongly inhibited anti-CD3 and anti-CD28 antibody activated PBMC proliferation. The natural Treg marker Helios was reduced on Tregs from papillomas, indicating that the majority of Tregs in papillomas are adaptive. The majority of the papilloma-derived CD4+ T-cells expressed the CD4+CD25−CD127low/−Foxp3−PD1+CD69+ phenotype and failed to suppress PBMC proliferation, suggesting that they are chronically activated and exhausted. The Treg-attracting chemokine CCL22 was equally expressed by all laryngeal tissues examined. However CCL17 was robustly expressed by papillomas compared to unaffected laryngeal tissues from RRP patients and individuals without RRP. PD-L1 was elevated in papillomas compared to control laryngeal tissues. Conclusions Papilloma CD4+ T-cells are enriched with functional Tregs, and the adaptive Helios− Treg fraction was increased within the TH2-like papilloma micromilieu. CD4+CD25−CD127low/−Foxp3− T-cells failed to suppress PBMC proliferation and may be exhausted. The PD-1/PDL-1 pathway may represent an additional immunosuppressive mechanism that contributes to defective HPV6/11 clearance in RRP.

Differential control of Helios+/− Treg development by monocyte subsets through disparate inflammatory cytokines

“…20,21 For example, Helios 1 Treg frequencies are increased in the peripheral blood of cancer patients, and most carcinoma-infiltrating Tregs are Helios positive. [8][9][10][11][12] In contrast, in premalignant tumors, such as nasal polyposis 13 and respiratory papillomas, 14 most infiltrating Tregs were shown to be Helios negative. Moreover, in type 2 diabetes mellitus, peripheral blood Helios 2 Treg numbers were decreased, although Helios 1 Treg counts were normal, 18 whereas in patients with myasthenia gravis, Helios 1 Treg frequency was lower.…”

“…6,7 In mice and man, Helios 1 Tregs represent about 70%, whereas Helios 2 Tregs constitute around 30% of Foxp3 1 T cells in the periphery. 5 However, these frequencies appear differently in malignancies, [8][9][10][11][12][13][14] autoimmunity, [15][16][17][18][19] and after infection. 20,21 For example, Helios 1 Treg frequencies are increased in the peripheral blood of cancer patients, and most carcinoma-infiltrating Tregs are Helios positive.…”

Pembrolizumab: the value of PDL1 biomarker in head and neck cancer

“…Moreover, the therapeutic strategy of creating an immune checkpoint blockade has recently been shown to enable the effective treatment of a variety of tumors [5]. Increased PD-L1 expression has been demonstrated in cases of actinic cheilitis, a premalignant condition of the oral cavity, as well as in respiratory HPV infections, which can produce lesions that progress to laryngeal cancers [6]. Immunosuppressed patients are more likely to develop head and neck cancers [7] and the tumors that occur in these individuals tend to have a poor response to treatment.…”

Immunity in Head and Neck Cancer

“…Increased PD-L1 expression has been demonstrated on actinic chelitis, a premalignant condition of the oral cavity (14), as well as respiratory papilloma, lesions that can progress into larynx cancers (19). Although not necessarily indicative of a premalignant condition, a systemic antibody response directed against the oncogenic HPV E6 and E7 proteins has been demonstrated to be highly specific for the eventual diagnosis of oropharyngeal cancer (8).…”