Connecting the innate and adaptive immune responses in mouse choroidal neovascularization via the anaphylatoxin C5a and γδT-cells

Sci Rep. 2016 Mar 31:6:23794. doi: 10.1038/srep23794.

Abstract

Neovascular age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV). An overactive complement system is associated with AMD pathogenesis, and serum pro-inflammatory cytokines, including IL-17, are elevated in AMD patients. IL-17 is produced by complement C5a-receptor-expressing T-cells. In murine CNV, infiltrating γδT- rather than Th17-cells produce the IL-17 measurable in lesioned eyes. Here we asked whether C5a generated locally in response to CNV recruits IL-17-producing T-cells to the eye. CNV lesions were generated using laser photocoagulation and quantified by imaging; T-lymphocytes were characterized by QRT-PCR. CNV resulted in an increase in splenic IL-17-producing γδT- and Th17-cells; yet in the CNV eye, only elevated levels of γδT-cells were observed. Systemic administration of anti-C5- or anti-C5a-blocking antibodies blunted the CNV-induced production of splenic Th17- and γδT-cells, reduced CNV size and eliminated ocular γδT-cell infiltration. In ARPE-19 cell monolayers, IL-17 triggered a pro-inflammatory state; and splenocyte proliferation was elevated in response to ocular proteins. Thus, we demonstrated that CNV lesions trigger a systemic immune response, augmenting local ocular inflammation via the infiltration of IL-17-producing γδT-cells, which are presumably recruited to the eye in a C5a-dependent manner. Understanding the complexity of complement-mediated pathological mechanisms will aid in the development of an AMD treatment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptive Immunity
  • Animals
  • Antibodies, Neutralizing / pharmacology
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / pathology
  • Cell Line
  • Cell Movement / drug effects
  • Choroid / immunology*
  • Choroid / pathology
  • Choroidal Neovascularization / drug therapy
  • Choroidal Neovascularization / etiology
  • Choroidal Neovascularization / genetics
  • Choroidal Neovascularization / immunology*
  • Complement C5a / antagonists & inhibitors
  • Complement C5a / genetics*
  • Gene Expression
  • Humans
  • Immunity, Innate
  • Injections, Intravenous
  • Interleukin-17 / genetics
  • Interleukin-17 / immunology
  • Light Coagulation / adverse effects
  • Mice
  • Mice, Inbred C57BL
  • Receptor, Anaphylatoxin C5a / genetics
  • Receptor, Anaphylatoxin C5a / immunology
  • Receptors, Antigen, T-Cell, gamma-delta / genetics
  • Receptors, Antigen, T-Cell, gamma-delta / immunology*
  • Retinal Pigment Epithelium / cytology
  • Retinal Pigment Epithelium / drug effects
  • Retinal Pigment Epithelium / immunology
  • Spleen / immunology
  • Spleen / pathology
  • Th17 Cells / immunology*
  • Th17 Cells / pathology

Substances

  • Antibodies, Neutralizing
  • Interleukin-17
  • Receptor, Anaphylatoxin C5a
  • Receptors, Antigen, T-Cell, gamma-delta
  • Complement C5a