CD64 plays a key role in diabetic wound healing

Abstract

Introduction: Wound healing poses a clinical challenge in diabetes mellitus (DM) due to compromised host immunity. CD64, an IgG-binding Fcgr1 receptor, acts as a pro-inflammatory mediator. While its presence has been identified in various inflammatory diseases, its specific role in wound healing, especially in DM, remains unclear.

Objectives: We aimed to investigate the involvement of CD64 in diabetic wound healing using a DM animal model with CD64 KO mice.

Methods: First, we compared CD64 expression in chronic skin ulcers from human DM and non-DM skin. Then, we monitored wound healing in a DM mouse model over 10 days, with or without CD64 KO, using macroscopic and microscopic observations, as well as immunohistochemistry.

Results: CD64 expression was significantly upregulated (1.25-fold) in chronic ulcerative skin from DM patients compared to non-DM individuals. Clinical observations were consistent with animal model findings, showing a significant delay in wound healing, particularly by day 7, in CD64 KO mice compared to WT mice. Additionally, infiltrating CD163⁺ M2 macrophages in the wounds of DM mice decreased significantly compared to non-DM mice over time. Delayed wound healing in DM CD64 KO mice correlated with the presence of inflammatory mediators.

Conclusion: CD64 seems to play a crucial role in wound healing, especially in DM conditions, where it is associated with CD163⁺ M2 macrophage infiltration. These data suggest that CD64 relies on host immunity during the wound healing process. Such data may provide useful information for both basic scientists and clinicians to deal with diabetic chronic wound healing.

Keywords: CD163+ M2 macrophage; CD64; CD68/CD80 M1 macrophages; diabetes mellitus; wound healing.

Figure 1

CD64⁺ cells in the wounds across different groups from Wt. The representing photos are presented in (A), while the quantification is presented in (B). The X-axis denotes the days post-surgery, while the Y-axis represents the number of CD64⁺ cells per high power field.

Figure 2

Expression of CD64 in diabetic and non-diabetic skin detected by immunohistochemistry. Data are presented as mean ± standard deviation in the left graph (A). The correlation between %CD64⁺ cells and FBG, HbA1c and GA was analysed (B).

Figure 3

Wound closure of mice in each group. The mean ± standard deviation of wound closure rate was demonstrated (A). The inset shows data for day 7. The macroscopic wound closure at the days post-surgery was showed in the photographs (B).

Figure 4

Expression of CD163⁺ macrophages in wounds across different groups detected by immunohistochemistry. CD163⁺ macrophages infiltration at the day 7 post-surgery was showed in the photomicrographs (A). The mean ± standard deviation of CD163⁺ cells/filed was showed (B). The inset shows data for days 3 and 7. The X-axis denotes the days post-surgery, while the Y-axis represents the expression of CD163⁺ macrophages in image units.

Figure 5

It illustrates the presence of macrophages in wounds among different groups, as detected by immunofluorescence double staining. Photomicrographs (A) showcase immunofluorescence staining of CD80 (in red) and F4/80 (in green) on day 7 post-surgery. Similarly, photomicrographs (B) display immunofluorescence staining of CD163 (in red) and F4/80 (in green) on the same day. Quantitative analysis reveals the mean ± standard deviation of F4/80⁺ cells per field (C), CD80⁺ cells per field (D), and CD163⁺ cells per field (E). The X-axis denotes the days post-surgery, while the Y-axis represents the positive cells per field in image units.

Figure 6

Expression of TGFβ1 in wounds across different groups detected by immunohistochemistry. TGFβ1 expression at the day 7 post-surgery was showed in the photomicrographs (A). The mean ± standard deviation of TGFβ1⁺ cells/filed was showed (B). The inset shows data for day 7. The X-axis denotes the days post-surgery, while the Y-axis represents the expression of TGFβ1 in image units.

Figure 7

Expression of CD31 in wounds across different groups detected by immunohistochemistry. CD31⁺ microvessels at the days post-surgery was showed in the photomicrographs (A). The mean ± standard deviation of CD31⁺ microvessels area rate was showed (B). The inset shows data for day 7. The X-axis denotes the days post-surgery, while the Y-axis represents the area rate of CD31⁺ microvessels in image units.

Figure 8

Collagen deposition in the wounds across different groups detected by Trichrome staining. The collagen deposition at the days post-surgery was showed in the photographs (A). The mean ± standard deviation of CVF was showed (B). The inset shows data for day 7 and 14. The X-axis denotes the days post-surgery, while the Y-axis represents the collagen volume fraction in image units.