Changes in myeloid-derived suppressor cells (MDSC), Treg and Th17 cells in peripheral blood of patients with cervical human papillomavirus (HPV) infection
Objective 
To investigate the changes in myeloid-derived suppressor cells (MDSC), regulatory T cells (Treg) and T helper 17 (Th17) cells in peripheral blood of patients with HPV infection and cervical diseases including ectopic cervical columnar epithelium (CE), cervical intraepithelial neoplasia (CIN) and cervical squamous cell carcinoma (CC), and to analyze the roles of MDSC, Treg and Th17 cells in the development of cervical diseases. 
 
 
Methods 
This study enrolled 120 HPV-positive patients with cervical diseases (18 cases of CE, 50 cases of CIN, 52 cases of CC), 20 HPV-negative patients with cervical diseases (10 cases of CE and 10 cases of CIN) and 20 healthy subjects from March 2011 to December 2016. Changes in MDSC, Treg and Th17 cells in peripheral blood of all patients were detected by flow cytometry. 
 
 
Results 
Percentages of MDSC, Treg and Th17 cells in peripheral blood of patients who were positive for HPV were significantly higher than those in HPV-negative patients (P<0.05). Besides, percentages of these cells gradually increased with the exacerbation of cervical disease (CE-CINⅠ-CINⅡ-CINⅢ-CC) (P<0.05). Patients who were infected with high-risk HPV had significantly higher percentages of MDSC, Treg and Th17 cells in peripheral blood than those infected with low-risk HPV (P<0.05). Changes of MDSC, Treg and Th17 cells in peripheral blood of HPV-positive patients with cervical cancer were related to International Federation of Gynecology and Obstetrics (FIGO) stage, tumor differentiation, lymph node metastasis and vascular invasion (P<0.05). MDSC, Treg and Th17 cells in peripheral blood of all patients were significantly reduced after treatment (P<0.05). Patients whose status changed from HPV-positive to HPV-negative following treatment also showed significantly decreased MDSC, Treg and Th17 cells in peripheral blood as compared with those who remained HPV-positive (P<0.05). MDSC, Treg and Th17 cells in peripheral blood of HPV-positive patients with cervical diseases were positively correlated (r=0.599, 0.677, 0.648; P<0.05). 
 
 
Conclusion 
MDSC, Treg and Th17 cells in peripheral blood of patients with HPV infection are associated with the pathological process, severity and clinical pathological features of cervical diseases as well as therapeutic effects. Therefore, they can be used as biomarkers to detect the occurrence and development of HPV-positive cervical diseases. 
 
 
Key words: 
Human papillomavirus; Cervical cancer; Myeloid-derived suppressor cell; Regulatory T cell; T helper 17 cell