Effects Of Follicular Helper T Cells, IL-21 And B Cells On The Proliferation And Cell Cycle Of HaCaT Cells

Objective:To observe the effects of T follicular helper cells and the main functional cytokines IL-21 and B lymphocytes on the proliferation and cell cycle of HaCaT cells cultured in vitro in patients with psoriasis.Through the co-culture of Tfh cells and B lymphocytes with HaCaT cells in vitro and the addition or blockage of IL-21 to verify whether Tfh cells secrete IL-21 on keratinocytes resulting in excessive proliferation and activation,mediating the occurrence and development of psoriasis,and to explore the role and clinical significance of Tfh cells,IL-21 and B lymphocytes in the immune pathogenesis of psoriasis.Method:Fifteen patients with psoriasis vulgaris and 10 healthy controls were defined as psoriasis group and healthy control group respectively.The clinical information such as PASI score and DLQI score were collected.CD4+CXCR5+Tfh cells and CD19+B lymphocytes from psoriatic patients and healthy controls were separated by flow cytometry and co-cultured with HaCaT cells at 1:1.At the same time,IL-21 or IL-21 neutralizing antibodies were added to the Tfh cell co-culture group,and the cells were collected after 3 days of culture.The cell survival rate was detected by CCK-8 method,the cell cycle and Ki-67 expression of HaCaT cells were detected by flow cytometry,and the effects of Tfh cells,IL-21 and B lymphocytes on the proliferation and activation of keratinocytes were observed.Results:When HaCaT cells were co-cultured with IL-21 in vitro,the results showed that IL-21 could promote the proliferation of HaCaT cells and increase the proportion of HaCaT cells in S phase and decrease the proportion of cells in G0/G1 phase(P<0.05).For B cells co-cultured with HaCaT cells,the absorbance of HaCaT cells at 450nm was increased in psoriasis group and healthy control group,but the promoting effect was stronger in psoriasis group(P<0.0001).In psoriasis group,the proportion of cells in S phase increased,the proportion of cells in G0/G1 phase decreased,and the proliferation index PI increased(P<0.0001),but the healthy control group did not have this ability to regulate cell cycle.When Tfh cells were co-cultured with HaCaT cells,the proliferation activity of HaCaT cells in psoriasis group and healthy control group was significantly higher than that in control group(P<0.0001),and the proliferation activity of HaCaT cells in psoriasis group was higher than that in IL-21 neutralization antibody group(P<0.0001).In psoriasis group,IL-21 neutralizing antibody group compared with Tfh+HaCaT co-culture group show that it could block HaCaT cells in G0/G1 phase,reduce the number of cells in S phase,and then inhibit the proliferation of HaCaT cells.Conclusion:1.The quality of life in patients with psoriasis is positively correlated with the area and severity of skin lesions.2.IL-21 may promote the pathogenesis of psoriasis by promoting the proliferation of keratinocytes.3.Tfh cells can promote the proliferation of keratinocytes,and blocking IL-21 can inhibit this promoting effect.4.The ability of B cells to promote the proliferation of keratinocytes in the psoriasis group was stronger than that in the healthy control group.