Macrophages expressing TREM-1 are involved in the progression of HPV16-related oropharyngeal squamous cell carcinoma

Introduction: Many types of research have been performed to improve the diagnosis, therapy, and prognosis of oropharyngeal carcinomas (OP-SCCs). Since they arise in lymphoid-rich areas and intense lymphocytic infiltration has been related to a better prognosis, a TREM-1 putative function in tumour progression and survival has been hypothesized. Materials and methods: Twenty-seven human papillomavirus (HPV) 16⁺ OP-SCC specimens have been analyzed to relate TREM-1 expression with histiocytic and lymphocytic markers, HPV presence and patients’ outcome. Results: No differences have been shown between intratumoral and stromal CD4⁺ cells, while intratumoral CD8⁺ lymphocytes are higher with respect to the tumour stroma (p=.0005). CD68⁺ cells are more than CD35⁺ and TREM-1⁺; their presence is related to CD35^± and TREM-1^± histiocytes (p=.005 and.026, respectively). Intratumoral CD4⁺ lymphocytes are higher in p16⁺ cases (11/27) than in p16⁻ (p=.042); moreover, p16 positivity correlates to a better survival (p=.034). CD4⁺, CD8⁺ and CD35⁺ cells have no impact on survival, while CD68 expression heavily influences progression and bad outcome (p=.037). TREM-1 positivity also leads to worst overall survival (p=.001): peritumoral expression and death-cause relationship are always significant, particularly when the cause is OP-SCC (p=.000). Conclusion: While p16 shows to better stratify HPV16⁺ patients’ outcome, TREM-1⁺ macrophages suggest their key importance in HPV-related OP-SCCs progression.KEY MESSAGES TREM-1 positivity correlates to the worst overall survival of HPV16-positive OPSCCs-affected patients. p16-positive HPV16 related OPSCCs patients have a better prognosis with respect to p16-negative ones.