Table 2.
Method and markers used to detect Tregs, and reported role of Tregs in HNC.
| References | Method for detecting Treg | Treg markers | Changes in Tregs observed with treatment | Changes in Tregs observed with disease progression | Suggested role of Tregs |
|---|---|---|---|---|---|
| Stasikowska-Kanicka et al. (20) | IHC, morphometry | Foxp3+ | N/A | The mean number of Foxp3+ cells was significantly increased in poor prognosis group in comparison to the better prognosis and control groups | Higher mean numbers of Tregs associated with poorer prognosis |
| Hussaini et al. (31) | IHC, IF | FoxP3+, TLR2 | N/A | Significantly more single-stained FoxP3+ cells and double-stained FoxP3+TLR2+ cells in the OSCC than in the control group | FoxP3+TLR2+ cells may represent dendritic cell dependent pathway of inhibiting Treg suppression. Exact role in disease progression not disclosed |
| Ihara et al. (17) | FC | CD4, CCR4, CD127low, CD45RA-, Foxp3high | Low frequency of CD45RA–Foxp3 High Tregs before treatment showed a better clinical outcome, even in patients with advanced stage tumors | High frequency of CD45RA–Foxp3high Tregs correlated with a poor prognosis and recurrence | |
| Ma et al. (32) | FC, IHC, IF, WB | CD4, Foxp3, A2AR | A2AR blockade reduces CD4+ Foxp3+ Tregs in HNSCC mouse model. A2AR blockade enhances the anti-tumor response of CD8+ T cells in HNSCC mouse model | A2AR was correlated with higher pathological grade and significantly correlated with Foxp3 | A2AR blockade reduces CD4+ Foxp3+ Tregs in HNSCC mouse model and enhances the anti-tumor response of CD8+ T cells |
| Zhou et al. (33) | IHC | CD4, FoxP3 | N/A | Increased number of Tregs in SCC and metastatic lymph nodes Tissue in comparison to adjacent tissues | Expression of Tregs in SCC lesions was inversely associated with overall survival and associated with worse prognosis |
| Nguyen et al. (25) | IHC | FoxP3 | N/A | N/A | Higher levels of FoxP3 infiltrates were associated with improved overall survival but not for relapse free or disease specific outcomes |
| Miki et al. (34) | Histopath, RT-PCR, IHC | Foxp3 | No difference in the number of Foxp3+ cells between the control group and the groups treated with the COX-2 inhibitor regardless of the dose of COX-2 inhibitor | Foxp3 expression in the tongues of mice treated with 4NQO was significantly higher than normal control group (weeks 15 and 20), but significantly decreased with tumor progression | The authors could not conclude the exact role of Tregs in SCC |
| da Cunha Filho et al. (35) | Histopath, IHC | FoxP3+ | N/A | Decrease in FoxP3+ T Cells with more advanced lesions and lymph node metastasis | Tregs are probably involved in early stages of lip carcinogenesis. Exact role not concluded |
| Montler et al. (36) | IHC, FC | CD25, Foxp3, OX40, PD-1, CTLA-4 | N/A | N/A | High expression of OX40, as well as CTLA-4 and PD-1 in the TIL Tregs. Role in SCC not concluded |
| Takahashi et al. (37) | FC | CD3, CD4, CD25, CD127low | The proportion of Tregs decreased significantly at day 6 following treatment, but the activation marker increased at day 21 | The proportion of Tregs was significantly higher in SCC patients compared to healthy donors | Chemotherapy can trigger a transient reduction of Tregs associated with an activation of CD8 T cells suggesting a tumor progressive role of Tregs in HNC |
| Jie et al. (18) | FC | CD4+, CD25hi,Foxp3+, CTLA-4, TGF-β, CD39 | Cetuximab significantly increased the frequency of intratumoral Treg expressing CTLA-4, CD39, and TGF-β. significant increase was only observed in circulating Treg expressing CTLA-4 | The frequency of CTLA-4+ Treg were significantly increased among the non-responder patients | |
| Partlova et al. (38) | FC, RT-PCR | CD4+, CD25+, CD127low | N/A | N/A | No statistically significant differences were observed in the numbers and proportions of Tregs were observed between HPV+ and HPV– tumors. The role of Treg could not be concluded |
| Wolf et al. (29) | IHC | Foxp3 | N/A | Levels of Tregs were higher in early stage cancers. Mean TIL levels for CD4, CD8, and FoxP3 cells were significantly correlated with each other and were higher in surviving patients | The findings suggest that Tregs are associated with better survival |
| Sun et al. (39) | FC | CD3, CD4, CD45RA–, Foxp3, CD25 | N/A | Tregs increase in the peripheral circulation of HNSCC patients, and correlate with tumor stage and nodal status | The findings suggest a role for Treg in tumor progression |
| Schipmann et al. (40) | IHC, RT-PCR | Foxp3 | N/A | Foxp3 expression much higher in SCC compared to normal controls | Oral and skin SCC recruit Tregs into the tumor microenvironment to suppress immunosurveillance |
| Lim et al. (23) | FC, ELISA | CD4+CD25hiCD127low | N/A | Tregs increased in SCC compared to normal controls | High levels of CD4+CD25highCD127low Tregs is associated with better survival |
| Hanakawa et al. (16) | IHC | Foxp3 | N/A | N/A | High intraepithelial and stromal infiltration of Tregs correlated with significantly worse 5-year disease-free survival |
| Ward et al. (28) | IHC | Foxp3 | N/A | The proportion of Foxp3+ cells was reduced in HPV+ compared with HPV– tumors | Tregs were associated with improved survival, but might be a reflection of the overall increase in TIL |
| Lukesova et al. (24) | FC, PCR, IHC | CD4, CD3, CD25 | N/A | Higher numbers of Tregs in oral tumors than oropharyngeal tumors | High level of Tregs in blood is associated with better survival |
| Zhao et al. (41) | FC | CD4+ CD25+ FoxP3+ | N/A | Tregs were significantly higher in OSCC than controls and increased with the progression of 4NQO-induced rat tongue carcinogenesis | The results of this study suggest a role for Tregs in tumor progression |
| Jie et al. (42) | FC | CD4+, CD25+, Foxp3+ TGF-β CD39 CTLA-4 | N/A | Intratumoral Treg exhibited more suppressive activity than peripheral blood Treg | The findings of this study suggest a suppressive function associated with disease progression |
| Park et al. (26) | IHC | Foxp3+ CD25+ | N/A | Foxp3 expression is associated positively with p16 expression, and is a favorable prognostic factor for overall survival | Tregs are up-regulated in HPV+ SCC and Foxp3 is related to a favorable prognosis |
| Weed et al. (43) | IF | CD4+, Foxp3+ | N/A | Cytoplasmic Foxp3 is associated with a lower possibility of recurrence, while nuclear Foxp3 is associated with a higher possibility of recurrence | The overall expression of FoxP3 does not Correlate with Clinical Outcome. However, elevated number of TILs expressing Foxp3 in the cytoplasm are indicative of a favorable prognosis while TILs expressing nuclear Foxp3 are associated with recurrence |
| Drennan et al. (44) | FC | CD4+ CD25high CD127low | N/A | Level of peripheral Tregs increased with advanced tumor stage and lymph node involvement | The findings of this study suggest a role for Tregs in tumor progression |
| Bron et al. (22) | IHC | Foxp3 | N/A | Treg more frequent in patients without lymph node involvement | High numbers of total FOXP3+ Tregs within the TIL were significantly associated with prolonged overall survival |
| Judd et al. (19) | FC | CD4+, Foxp3 | Depletion of Tregs using anti-CD25 antibody resulted in a decrease in growth rate | N/A | Tregs contribute to the aggressive tumor growth in the studied model |
| Gaur et al. (45) | FC | CD4+ CD25+ Foxp3+ | N/A | Increase in Th17/Tregs ratio in early stages and a decrease in this ratio in later stages due to a higher frequency of Tregs in later stages and in lymph node metastasis | The findings of this study suggest that Tregs are associated with more advanced disease and promote metastasis |
| Wansom et al. (27) | IHC | FOXP3 | N/A | N/A | Higher levels of Tregs (Foxp3+) in TIL was associated with better disease specific and overall survival |
| Wild et al. (46) | FC, IF, RT-PCR, ELISA | CD4+, CD25+, FoxP3+, CD127low, TLR4 | N/A | HMGB1 promotes suppressive function of Treg in HNSCC patients | The findings of this study suggest a role for Tregs in immune escape and tumor progression |
| Näsman et al. (47) | IHC | Foxp3 | N/A | Higher number of Foxp3+ TILs HPV+ compared to HPV- SCC. No difference in Treg levels between poor and good prognosis | Although a High CD8+/Foxp3+ Ratio is Linked to a Good Clinical Outcome, no diff in Treg levels was observed related to clinical outcomes, indicating that the better prognosis is attributed to the elevated CD8 Levels |
| Lee et al. (48) | FC, IHC, RT-PCR | Foxp3, CD4, CD25, ICOS, TGF-β, CCR6 | N/A | Within the TILs, the percentages of Th17 and Treg cells were inversely correlated. The prevalence of IL-17-producing FOXP3+ CD4+ in TIL is increased in SCC and possess suppressive function similar to Tregs | The findings of this study suggest a tumor promoting role for Tregs (regardless of their IL-17 production ability) |
| Schuler et al. (49) | FC | CD4+, CD25high, Foxp3+ | RCT had diverse effects on Treg frequency | The mean frequency of Tregs was significantly increased SCC prior to Rct compared to healthy controls | Although this study reported unpredictable effect of RCT on Tregs, it reported an increase in Tregs in SCC patients suggesting an active mechanism of immune escape and tumor promotion |
| Alhamarneh et al. (50) | ELISA, FC | CD4+CD25high, GITR, CTLA-4, Foxp3 | Post-treatment Treg levels were significantly higher than pre-treatment levels | Patients had significantly higher percentages of circulating Tregs compared with normal controls | The levels of Treg cells were elevated significantly SCC, however, they failed to correlate with disease progression or tumor burden |
| Al-Qahtani et al. (51) | IHC | Foxp3 | N/A | Treg levels were higher in poorly differentiated SCC. | A linear positive correlation was established between tumor grade and number of Tregs suggesting a role in tumor promotion |
| Tominaga et al. (52) | IF, FC | CD4+, FoxP3+ | N/A | Dogs with MM had increased numbers of circulating Tregs and TILs compared to healthy control dogs | The findings suggest a tumor promoting effect of Tregs |
| Horiuchi et al. (53) | FC | CD4+, Foxp3+ | N/A | The percentage of circulating Treg increased with the tumor stage in dogs with oral MM | The findings of this study suggest Tregs possess a suppressive role for anti-tumor immunity, thus promoting tumor progression |
| Schott et al. (54) | FC | CD4+, CD25high, GITR, CTLA-4, CD122, CD127low, CCR7, Foxp3, CCL22 | Increased Treg levels were found even in patients with no active disease several years after tumor resection | Increased ratio of Tregs within total CD4+ population in SCC patients. Increased level of GITR and CCR4 expression in Tregs from SCC patients | Increased Tregs in SCC patients might correspond to reduced anti-tumor immunity and therefore contribute to tumor progression or recurrence |
| Gasparoto et al. (55) | FC | CD4, CD25, FoxP3, GITR, CD45RO, CD69, TGF-β, CTLA-4, CCR4, IL-10 | N/A | High frequency of Tregs in SCC patient blood with stronger suppressive ability than Tregs from healthy donors | Tregs suppress immune responses both systemically and in the tumor microenvironment, thus promoting tumor progression |
| Boucek et al. (15) | FC | CD3+, CD4+, CD25 | N/A | Treg counts were higher in SCC patients compared to controls and were higher in recurrent disease | The levels of Treg in the peripheral blood correlate with a higher probability of early recurrence of SCC |
| Distel et al. (56) | IHC | Foxp3 | N/A | In the low risk group, CD3+/Foxp3+ ratio had a clear impact on NED-survival with a low ratio being associated with a better prognosis. This was not observed in high risk patients | The results of this study suggest that intratumoral Treg infiltration on its own does not have an impact on tumor control or survival rates. CD3+/Foxp3+ ratio impacted NED-survival in the low risk group |
| Schwarz et al. (57) | IHC | Foxp3, CD25 | N/A | Tregs were significantly elevated in SCC compared to control tissues | The authors could not conclude the role that Tregs play in tumor progression |
| Bergmann et al. (58) | FC, ELISA, WB | CD3, CD4,CD25+, Foxp3, IL-10, CTLA-4 | N/A | overexpression of COX-2 and secretion of PGE2 by tumor cells induce the highly suppressive type 1 Treg (Tr1) subset of suppressor cells | The induction of Tr1 suppressor cells by SCC contribute to carcinogenesis by creating a suppressive microenvironment that promotes tumor growth |
| Chikamatsu et al. (59) | FC | CD4+, CD25+ | N/A | Circulating Tregs are increased in patients with SCC compared to controls | Although there were no associations between Treg and tumor stage or histological differentiation, Treg percentage inversely correlated with that of total CD8+ T cells in cancer patients and was associated with inhibition of cytokine expression in CTLs suggesting a possible role in the downregulation of antitumor immune response |
| Badoual et al. (21) | IF | CD3, CD4, CD25, Foxp3, CD69 | N/A | Overall, high levels of CD4+CD69+, CD4+CD25+ or CD4+Foxp3+ are associated with better survival and locoregional control | The findings of this study suggest that tumor infiltrating Tregs are associated with a better prognosis |
| Schaefer et al. (60) | FC | CD3, CD4+, CD25+, Foxp3, GITR, CCR7 | N/A | Patients had significantly higher percentages of circulating Tregs than controls | Although the effect of Treg on downregulating the immune functions of other T cells subsets was shown, the exact role of Treg on disease progression could not be confirmed in this study |
FC, Flow Cytometry; IHC, Immunohistochemistry; IF, Immunofluorescence; WB, Western Blot.