Inflammation is a key process in normal wound repair. Upon wounding, cytokines are activated and chemoattract leukocytes, including macrophages, to the wound site. Macrophages are key for the proper formation of granulation tissue because they clean up dead cells in the wound and produce a plethora of cytokines that initiate formation of the healing tissue. While many detailed mechanisms involved early in inflammation are known, those involved in resolution of inflammation are poorly understood. Understanding how inflammation ends is as important as understanding its beginning because prolongation of inflammation leads to impaired healing and chronic inflammatory conditions. VEGF is a key factor in wound healing and is primarily known for its role in angiogenesis. However, recently VEGF is emerging as a regulator of immunity and inflammation. We have discovered that VEGF contributes to resolution of macrophage- induced inflammation during wound healing and that it stimulates macrophage apoptosis in culture. We have also shown that VEGF stimulates the expression of TNFSF14/LIGHT in human macrophages. LIGHT is a member of the TNF superfamily of cytokines known to regulate co-stimulation of T cells as well as apoptosis in mucosal tumors. Our findings point to a novel cytokine-modulated pathway involved in resolution of the inflammatory response. In the work proposed here we address the consequences of these newly discovered functions of VEGF in resolution of inflammation during wound healing. We hypothesize that a novel function of VEGF in the healing process is modulation of macrophage survival in the damaged tissue and that LIGHT is a critical mediator of this process. Specifically, we will: (1) Determine whether VEGF induces macrophage apoptosis in vivo and stimulates LIGHT expression during healing and (2) Determine the relationship between VEGF-induced macrophage cell death and LIGHT. We will use a combination of cultured human macrophages, normal and genetically-modified mice, coupled with agonists/antagonists of VEGF- and LIGHT-dependant pathways. Histochemical and immunological techniques, ELISA, multiplex RT-PCR and siRNA technology will be used. The work proposed is novel because it reveals previously unknown functions of VEGF and it is important because it may facilitate the development of new therapies for poorly-healing wounds as well as other conditions characterized by excessive inflammation and for tumors in which VEGF is upregulated. Because resolution of inflammation occurs poorly or not at all in most abnormal healing situations, this line of investigation is significant for health because it identifies a novel strategy for improving impaired healing, a critical medical area.

Public Health Relevance

Inflammation is a key process in normal wound repair. Upon wounding, cytokines are activated and chemoattract leukocytes, including macrophages, to the wound site. Macrophages are key for the proper formation of granulation tissue because they clean up dead cells in the wound and produce a plethora of cytokines that initiate formation of the healing tissue. Understanding how inflammation ends is as important as understanding its beginning because prolongation of inflammation leads to impaired healing and chronic inflammatory conditions. We have discovered that VEGF contributes to resolution of macrophage-induced inflammation during wound healing and that it stimulates macrophage death. The studies proposed here are to test the possibility that VEGF is a player in resolution of inflammation and that LIGHT mediates the VEGF effects on resolution of inflammation. Because resolution of inflammation occurs poorly or not at all in most abnormal healing situations, this line of investigation is significant for heath because it identifies a potentially novel strategy for improving impaired healing, a critical medical area.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI078208-01A2
Application #
7740319
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Leitner, Wolfgang W
Project Start
2009-06-01
Project End
2011-05-31
Budget Start
2009-06-01
Budget End
2010-05-31
Support Year
1
Fiscal Year
2009
Total Cost
$186,120
Indirect Cost
Name
University of California Riverside
Department
Anatomy/Cell Biology
Type
Schools of Earth Sciences/Natur
DUNS #
627797426
City
Riverside
State
CA
Country
United States
Zip Code
92521
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Liu, Yan; Chen, Xue Lian; Wang, Lei et al. (2017) Insulin Antagonizes Thrombin-Induced Microvessel Leakage. J Vasc Res 54:143-155
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Dhall, Sandeep; Do, Danh; Garcia, Monika et al. (2014) A novel model of chronic wounds: importance of redox imbalance and biofilm-forming bacteria for establishment of chronicity. PLoS One 9:e109848
Petreaca, Melissa L; Do, Danh; Dhall, Sandeep et al. (2012) Deletion of a tumor necrosis superfamily gene in mice leads to impaired healing that mimics chronic wounds in humans. Wound Repair Regen 20:353-66