Limits...
Kruppel-like factor KLF4 facilitates cutaneous wound healing by promoting fibrocyte generation from myeloid-derived suppressor cells.

Ou L, Shi Y, Dong W, Liu C, Schmidt TJ, Nagarkatti P, Nagarkatti M, Fan D, Ai W - J. Invest. Dermatol. (2015)

Bottom Line: Myeloid-derived suppressor cells (MDSCs) accumulate as a result of inflammation and promote cutaneous wound healing by mechanisms that are not fully understood.Recently, MDSCs have been shown to differentiate into fibrocytes, which serve as emerging effector cells that enhance cell proliferation in wound healing.In the current study, by using full-thickness and PU mouse models, we found that Kruppel-like factor 4 (KLF4) deficiency resulted in decreased accumulation of MDSCs and fibrocytes, and wound healing was significantly delayed.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, USA [2] Department of Biopharmaceuticals, School of Biotechnology, Southern Medical University, Guangzhou, People's Republic of China.

ABSTRACT
Pressure ulcers (PUs) are serious skin injuries whereby the wound healing process is frequently stalled in the inflammatory phase. Myeloid-derived suppressor cells (MDSCs) accumulate as a result of inflammation and promote cutaneous wound healing by mechanisms that are not fully understood. Recently, MDSCs have been shown to differentiate into fibrocytes, which serve as emerging effector cells that enhance cell proliferation in wound healing. We postulate that in wound healing MDSCs not only execute their immunosuppressive function to regulate inflammation but also stimulate cell proliferation once they differentiate into fibrocytes. In the current study, by using full-thickness and PU mouse models, we found that Kruppel-like factor 4 (KLF4) deficiency resulted in decreased accumulation of MDSCs and fibrocytes, and wound healing was significantly delayed. Conversely, KLF4 activation by the plant-derived product Mexicanin I increased the number of MDSCs and fibrocytes and accelerated the wound healing. Collectively, our study revealed a previously unreported function of MDSCs in cutaneous wound healing and identified Mexicanin I as a potential agent to accelerate PU wound healing.

Show MeSH

Related in: MedlinePlus

Hair loss and decreased fibrocyte generation in FSP-1-Cre/KLF4(flox) mice(a). Representatives of the wild type (WT) and FSP=1-Cre/KLF4(flox) (KLF4−/−(FSP-1)) mice. Black squares indicate an area in which a severe hair loss was seen in KLF4−/−(FSP-1) mice. (b). Body weights of male and female WT and KLF4−/−(FSP-1) mice. (c). Representative images of KLF4 staining of skin (left) and measurement of KLF4 positive cells (right). (d). Left, representative images of HE staining of skin. The areas between two dotted red lines represent skin suprabasal layers and the red arrow heads are pointing to hair follicles. Right, measurement of epithelial thickness and hair follicles. (e). Measurement of serum cytokines by ELISA (n=3). (f). Quantification of fibrocyte generation (n=5) Scale bars: 100 μm. *p<0.05, **p<0.01.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4402119&req=5

Figure 4: Hair loss and decreased fibrocyte generation in FSP-1-Cre/KLF4(flox) mice(a). Representatives of the wild type (WT) and FSP=1-Cre/KLF4(flox) (KLF4−/−(FSP-1)) mice. Black squares indicate an area in which a severe hair loss was seen in KLF4−/−(FSP-1) mice. (b). Body weights of male and female WT and KLF4−/−(FSP-1) mice. (c). Representative images of KLF4 staining of skin (left) and measurement of KLF4 positive cells (right). (d). Left, representative images of HE staining of skin. The areas between two dotted red lines represent skin suprabasal layers and the red arrow heads are pointing to hair follicles. Right, measurement of epithelial thickness and hair follicles. (e). Measurement of serum cytokines by ELISA (n=3). (f). Quantification of fibrocyte generation (n=5) Scale bars: 100 μm. *p<0.05, **p<0.01.

Mentions: FSP-1-Cre/KLF4(flox) mice showed no obvious abnormalities from birth to 8 weeks of age. After 8 weeks of age, significant hair and weight loss was observed in these KLF4 deficient mice when compared to WT mice (Figure 4a and 4b). Successful KLF4 knockout in monocytes in KLF4 deficient mice (designated as KLF4−/−(FSP-1)) was confirmed by qRT-PCR (Supplementary Figure 1). IHC staining showed that the number of KLF4 positive cells was decreased by 84% in KLF4−/−(FSP-1) mice (Figure 4c). H&E staining showed that the hair follicle density decreased by about 50%, and the suprabasal layer was thicker in KLF4−/−(FSP-1) mice (Figure 4d). To examine the potential immunological defects in FSP-1-Cre/KLF4 (flox) mice, we measured the cytokine/chemokine levels in mouse sera. Expression levels of IL4 and IL5 were significantly increased, but the level of IL-12 (P40), a shared subunit of IL-12 and IL-23 (Quatresooz et al., 2012), was decreased in KLF4−/−(FSP-1) mice (Figure 4e). Interestingly, expression levels of granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory protein 1 alpha (MIP-1α) were also significantly increased in KLF4−/−(FSP-1) mice (Figure 4e). Consistent with the importance of CCR2+ MDSCs in fibrocyte generation (Shi et al., 2014), the number of fibrocytes generated from spleen cells decreased from 112±8 per 105 cells in the WT mice to 46±4 per 105 cells in FSP-1-Cre/KLF4 (flox) mice (Figure 4f).


Kruppel-like factor KLF4 facilitates cutaneous wound healing by promoting fibrocyte generation from myeloid-derived suppressor cells.

Ou L, Shi Y, Dong W, Liu C, Schmidt TJ, Nagarkatti P, Nagarkatti M, Fan D, Ai W - J. Invest. Dermatol. (2015)

Hair loss and decreased fibrocyte generation in FSP-1-Cre/KLF4(flox) mice(a). Representatives of the wild type (WT) and FSP=1-Cre/KLF4(flox) (KLF4−/−(FSP-1)) mice. Black squares indicate an area in which a severe hair loss was seen in KLF4−/−(FSP-1) mice. (b). Body weights of male and female WT and KLF4−/−(FSP-1) mice. (c). Representative images of KLF4 staining of skin (left) and measurement of KLF4 positive cells (right). (d). Left, representative images of HE staining of skin. The areas between two dotted red lines represent skin suprabasal layers and the red arrow heads are pointing to hair follicles. Right, measurement of epithelial thickness and hair follicles. (e). Measurement of serum cytokines by ELISA (n=3). (f). Quantification of fibrocyte generation (n=5) Scale bars: 100 μm. *p<0.05, **p<0.01.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402119&req=5

Figure 4: Hair loss and decreased fibrocyte generation in FSP-1-Cre/KLF4(flox) mice(a). Representatives of the wild type (WT) and FSP=1-Cre/KLF4(flox) (KLF4−/−(FSP-1)) mice. Black squares indicate an area in which a severe hair loss was seen in KLF4−/−(FSP-1) mice. (b). Body weights of male and female WT and KLF4−/−(FSP-1) mice. (c). Representative images of KLF4 staining of skin (left) and measurement of KLF4 positive cells (right). (d). Left, representative images of HE staining of skin. The areas between two dotted red lines represent skin suprabasal layers and the red arrow heads are pointing to hair follicles. Right, measurement of epithelial thickness and hair follicles. (e). Measurement of serum cytokines by ELISA (n=3). (f). Quantification of fibrocyte generation (n=5) Scale bars: 100 μm. *p<0.05, **p<0.01.
Mentions: FSP-1-Cre/KLF4(flox) mice showed no obvious abnormalities from birth to 8 weeks of age. After 8 weeks of age, significant hair and weight loss was observed in these KLF4 deficient mice when compared to WT mice (Figure 4a and 4b). Successful KLF4 knockout in monocytes in KLF4 deficient mice (designated as KLF4−/−(FSP-1)) was confirmed by qRT-PCR (Supplementary Figure 1). IHC staining showed that the number of KLF4 positive cells was decreased by 84% in KLF4−/−(FSP-1) mice (Figure 4c). H&E staining showed that the hair follicle density decreased by about 50%, and the suprabasal layer was thicker in KLF4−/−(FSP-1) mice (Figure 4d). To examine the potential immunological defects in FSP-1-Cre/KLF4 (flox) mice, we measured the cytokine/chemokine levels in mouse sera. Expression levels of IL4 and IL5 were significantly increased, but the level of IL-12 (P40), a shared subunit of IL-12 and IL-23 (Quatresooz et al., 2012), was decreased in KLF4−/−(FSP-1) mice (Figure 4e). Interestingly, expression levels of granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory protein 1 alpha (MIP-1α) were also significantly increased in KLF4−/−(FSP-1) mice (Figure 4e). Consistent with the importance of CCR2+ MDSCs in fibrocyte generation (Shi et al., 2014), the number of fibrocytes generated from spleen cells decreased from 112±8 per 105 cells in the WT mice to 46±4 per 105 cells in FSP-1-Cre/KLF4 (flox) mice (Figure 4f).

Bottom Line: Myeloid-derived suppressor cells (MDSCs) accumulate as a result of inflammation and promote cutaneous wound healing by mechanisms that are not fully understood.Recently, MDSCs have been shown to differentiate into fibrocytes, which serve as emerging effector cells that enhance cell proliferation in wound healing.In the current study, by using full-thickness and PU mouse models, we found that Kruppel-like factor 4 (KLF4) deficiency resulted in decreased accumulation of MDSCs and fibrocytes, and wound healing was significantly delayed.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, USA [2] Department of Biopharmaceuticals, School of Biotechnology, Southern Medical University, Guangzhou, People's Republic of China.

ABSTRACT
Pressure ulcers (PUs) are serious skin injuries whereby the wound healing process is frequently stalled in the inflammatory phase. Myeloid-derived suppressor cells (MDSCs) accumulate as a result of inflammation and promote cutaneous wound healing by mechanisms that are not fully understood. Recently, MDSCs have been shown to differentiate into fibrocytes, which serve as emerging effector cells that enhance cell proliferation in wound healing. We postulate that in wound healing MDSCs not only execute their immunosuppressive function to regulate inflammation but also stimulate cell proliferation once they differentiate into fibrocytes. In the current study, by using full-thickness and PU mouse models, we found that Kruppel-like factor 4 (KLF4) deficiency resulted in decreased accumulation of MDSCs and fibrocytes, and wound healing was significantly delayed. Conversely, KLF4 activation by the plant-derived product Mexicanin I increased the number of MDSCs and fibrocytes and accelerated the wound healing. Collectively, our study revealed a previously unreported function of MDSCs in cutaneous wound healing and identified Mexicanin I as a potential agent to accelerate PU wound healing.

Show MeSH
Related in: MedlinePlus