ABSTRACT
Objective@#To explore the effects of dendritic epidermal T cells (DETC) on proliferation and apoptosis of epidermal cells in wound margin of mice and its effects on wound healing.@*Methods@#Twenty-eight healthy specific pathogen free (SPF) C57BL/6 wild-type (WT) male mice aged 8-12 weeks and 60 SPF T lymphocyte receptor δ-knockout (TCR δ-/-) male mice aged 8-12 weeks were selected to conduct the following experiments. (1) Eight WT mice were selected to isolate epidermal cells and primarily culture DETC according to the random number table. Morphological observation and purity identification of DETC by flow cytometer were detected immediately after culture and on culture day (CD) 15 and 30, respectively. (2) According to the random number table, 5 WT mice and 5 TCR δ-/- mice were selected and enrolled into WT control group and TCR δ-/- group. Round full-thickness skin defect with diameter of 6 mm was made on the back of each mouse. The wound healing condition was observed immediately after injury and on post injury day (PID) 2, 4, 6, 8, 10, and the percentage of residual wound area was calculated. (3) Mice were selected to group and reproduce model of full-thickness skin defect as in experiment (2). On PID 3, the tissue of wound margin was collected for hematoxylin eosin staining, and the length of new epithelium was measured. (4) Mice were selected to group and reproduce model of full-thickness skin defect as in experiment (2). On PID 3, epidermal tissue of wound margin was collected to determine expression of proliferating cell nuclear antigen (PCNA) using Western blotting for evaluation of proliferation of epidermal cell. (5) Mice were selected to group and reproduce model of full-thickness skin defect as in experiment (2). On PID 3, epidermal tissue of wound margin was selected and digested into single-cell suspension, and apoptosis of cells was detected by flow cytometer. (6) Forty TCR δ-/- mice were selected to carry out the same treatment as in experiments (2)-(5). According to the random number table, these mice were enrolled into TCR δ-/- control group and TCR δ-/-+ DETC group, with 5 mice in each group for each experiment. Round full-thickness skin defect was made on the back of each mouse. DETC in the number of 1×105 (dissolution in 100 μL phosphate with buffer purity above 90%) were injected through multiple points of wound margin of mice in TCR δ-/-+ DETC group immediately after injury, and equal volume of phosphate buffer was injected into mice of TCR δ-/- control group with the same method as above. Data were processed with one-way analysis of variance for repeated measurement, t test, and Bonferroni correction.@*Results@#(1) Along with the culture time elapse, the number of dendritic structures of DETC increased gradually. The percentage of T lymphocytes was 4.67% and 94.1% of these T lymphocytes were DETC. The purity of DETC on CD 15 was 18.50% and the purity of DETC on CD 30 was 98.70%. (2) Immediately after injury, the wound healing condition of mice in WT control group and TCR δ-/- group was similar. The wound healing speed of mice in TCR δ-/- group was slower than that in WT control group on PID 2-10. The percentages of residual wound area of mice in TCR δ-/- group on PID 2, 4, 6, 8, and 10 were increased significantly compared with those in WT control group (t=3.492, 4.425, 4.170, 4.780, 7.318, P<0.01). (3) The length of new epithelium of mice in TCR δ-/- group on PID 3 was (359 ± 15) μm, which was obviously shorter than that in WT control group [(462±26) μm, t=3.462, P<0.01]. (4) Immediately after injury, wound condition of mice in TCR δ-/-+ DETC group and TCR δ-/- control group was similar. Compared with TCR δ-/-+ DETC group, the wound healing speed of mice in TCR δ-/- control group were obviously slower on PID 2-10. The percentages of residual wound area of mice in TCR δ-/-+ DETC group on PID 2, 4, 6, 8, and 10 were decreased significantly compared with those in TCR δ-/- control group (t=2.308, 3.725, 2.698, 3.707, 6.093, P<0.05 or P<0.01). (5) On PID 3, the length of new epithelium of mice in TCR δ-/-+ DETC group was (465±31) μm, which was obviously longer than that in TCR δ-/- control group [(375±21) μm, t=2.390, P<0.05]. (6) On PID 3, PCNA expression of epidermal cell in wound margin of mice in TCR δ-/- group was 1.25±0.04, which was obviously lower than that in WT control group (2.01±0.09, t=7.415, P<0.01). (7) On PID 3, PCNA expression of epidermal cell in wound margin of mice in TCR δ-/-+ DETC group was 1.62±0.08, which was significantly higher than that in TCR δ-/- control group (1.05±0.14, t=3.561, P<0.05). (8) On PID 3, apoptosis rate of epidermal cell in wound margin of mice in TCR δ-/- group was (16.1±1.4)%, which was higher than that in WT control group [(8.1±0.6)%, t=5.363, P<0.01]. (9) On PID 3, apoptosis rate of epidermal cell in wound margin of mice in TCR δ-/-+ DETC group was (11.4±1.0)%, which was obviously lower than that in TCR δ-/- control group [(15.4±1.4)%, t=2.377, P<0.05].@*Conclusions@#DETC participates in the process of wound healing though promoting the proliferation of epidermal cells in wound margin and inhibit the apoptosis of these cells.
ABSTRACT
Objective@#To explore effects of dendritic epidermal T cells (DETCs) and Vγ4 T lymphocytes on proliferation and differentiation of mice epidermal cells and the effects in wound healing of mice.@*Methods@#(1) Six C57BL/6 male mice aged 8 weeks were collected and divided into control group and wound group according to random number table (the same grouping method below), with 3 mice in each group. A 4 cm long straight excision with full-thickness skin defect was cut on back of each mouse in wound group, while mice in control group received no treatment. On post injury day (PID) 3, mice in 2 groups were sacrificed, and skin within 5 mm from the wound margin on back of mice in wound group and normal skin on corresponding part of mice in control group were collected to make single cell suspensions. The percentage of Vγ4 T lymphocyte expressing interleukin-17A (IL-17A) and percentage of DETCs expressing insulin-like growth factor Ⅰ (IGF-Ⅰ) were detected by flow cytometer. (2) Ten C57BL/6 male mice aged 8 weeks were collected and divided into control group and Vγ4 T lymphocyte depletion group with 5 mice in each group. Mice in Vγ4 T lymphocyte depletion group were injected with 200 g Vγ4 T lymphocyte monoclonal neutralizing antibody of Armenian hamster anti-mouse intraperitoneally, and mice in control group were injected with the same amount of Armenian hamster Ig intraperitoneally. One hole with full-thickness skin defect was made on each side of spine of back of each mice. The wound healing was observed on PID 1-8, and percentage of remaining wound area was calculated. (3) Six C57BL/6 male mice aged 8 weeks were grouped and treated in the same way as in experiment (2), with 3 mice in each group. On PID 3, expressions of IL-17A and IGF-Ⅰ in epidermis on margin of wound were detected with Western blotting. (4) Thirty C57BL/6 male mice aged 3 days were sacrificed, and epidermal cells were extracted. The keratin 14 positive cell rate was examined by flow cytometer (the same detecting method below). (5) Another batch of mouse epidermal cells were collected and divided into control group, IGF-Ⅰ group, and IL-17A group, with 3 wells in each group (the same well number below). Cells in IGF-Ⅰ group and IL-17A group were added with 1 mL recombinant mouse IGF-Ⅰ and IL-17A with final mass concentration of 100 ng/mL respectively, while cells in control group were added with the same amount of sterile phosphate buffered saline (PBS). On post culture day (PCD) 5, keratin 14 negative cell rate was examined. Another batch of mouse epidermal cells were collected, grouped, and treated in the same way as aforementioned experiment, and keratin 10 positive cell rate was examined on PCD 10. (6) Another batch of mouse epidermal cells were collected and added with 4 mmol/L 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) solution, and divided into control 0 d group, control 7 d group, IGF-Ⅰ group, and IL-17A group. Cells in IGF-Ⅰ group and IL-17A group were treated in the same way as the corresponding groups in experiment (5), and cells in control 0 d group and control 7 d group were treated in the same way as the control group in experiment (5). The CFSE fluorescence peaks were examined on PCD 0 of control 0 d group and PCD 7 of the other 3 groups. (7) Another batch of mouse epidermal cells were collected and divided into control group and IGF-Ⅰ group. Cells in IGF-Ⅰ group were added with 1 mL recombinant mouse IGF-Ⅰ with final mass concentration of 100 ng/mL, and cells in control group were added with the same amount of sterile PBS. On PCD 5, cells were underwent keratin 14 staining and CFSE staining as aforementioned, and keratin 14 negative cell rate of CFSE positive cells was examined. Another batch of mouse epidermal cells were collected and divided into control group and IL-17A group. Cells in IL-17A group were added with 1 mL recombinant mouse IL-17A with final mass concentration of 100 ng/mL, and cells in control group were added with the same amount of sterile PBS. On PCD 5, keratin 14 negative cell rate of CFSE positive cells was examined. Data were processed with one-way analysis of variance and t test.@*Results@#(1) On PID 3, percentage of DETC expressing IGF-Ⅰ in normal epidermis of control group was (9.9±0.8)%, significantly lower than (19.0±0.6)% of epidermis around margin of wound group (t=8.70, P<0.01); percentage of Vγ4 T lymphocyte expressing IL-17A in normal epidermis of control group was (0.123±0.024)%, significantly lower than (8.967±0.406)% of epidermis around margin of wound group (t=21.77, P<0.01). (2) On PID 1-4, there was obvious inflammatory reaction around wounds of mice in control group, and on PID 5-8, the wound area was still large. On PID 1-4, there was slight inflammatory reaction around wounds of mice in Vγ4 T lymphocyte depletion group, and on PID 5-8, the wound area was significantly reduced. On PID 3-7, percentages of residual wound area in Vγ4 T lymphocyte depletion group were significantly lower than those in control group (t=5.92, 5.74, 7.17, 5.38, 5.57, P<0.01), while percentages of residual wound area in two groups on PID 1, 2, 6 were similar (t=1.46, 3.17, 3.10, P>0.05). (3) On PID 3, compared with those in control group, expression of IL-17A and IGF-Ⅰ in epidermis around wound margin of mice in Vγ4 T lymphocyte depletion group was markedly decreased and increased respectively (t=8.47, 19.24, P<0.01). (4) The keratin 14 positive cell rate of mouse epidermal cells was 94.7%. (5) On PCD 5, the keratin 14 negative cell rate of mice in control group was markedly higher than that of IGF-Ⅰ group, while significantly lower than that of IL-17A group (t=7.25, 5.64, P<0.01). On PCD 10, the keratin 10 positive cell rate of mice in control group was significantly higher than that of IGF-Ⅰ group, while significantly lower than that of IL-17A group (t=3.99, 10.82, P<0.05 or P<0.01). (6) Compared with that of control 0 d group, CFSE fluorescence peaks of mouse epidermal cells in control 7 d group, IGF-Ⅰ group, and IL-17A group on PCD 7 shifted to the left. Compared with that of control 7 d group, CFSE fluorescence peaks of mouse epidermal cells in IGF-Ⅰ group and IL-17A group on PCD 7 shifted to the left. (7) On PCD 5, keratin 14 negative cell rate of CFSE positive cells of mice in control group was significantly higher than that in IGF-Ⅰ group (t=9.91, P<0.01), and keratin 14 negative cell rate of CFSE positive cells of mice in control group was markedly lower than that in IL-17A group (t=6.49, P<0.01).@*Conclusions@#In the process of wound healing, IGF-Ⅰ secreted by DETC can promote the proliferation of mouse keratin 14 positive epidermal cells and inhibit their terminal differentiation, while IL-17A secreted by Vγ4 T lymphocyte can promote the proliferation and terminal differentiation of mouse keratin 14 positive epidermal cells, thus both IGF-Ⅰ and IL-17A can affect wound healing.