An Intracameral Injection of Antigen Induces In Situ Chemokines and Cytokines Required for the Generation of Circulating Immunoregulatory Monocytes

Abstract

Anterior Chamber-Associated Immune Deviation (ACAID) induced by an intracameral injection of antigen generates antigen-specific regulatory splenic T cells that suppress specifically cell-mediated immunity specific for the injected antigen. Circulating F4/80+ cells recovered from mice receiving an intracameral injection of antigen are thought to be ocular in origin and induce the development of thymic and splenic regulatory T cells. We have shown previously that after the intracameral injection of antigen there is a CCR2/CCL2-dependent infiltration of circulating F4/80+ cells into the anterior chamber associated with the generation of circulating, ACAID-inducing F4/80+ monocytes. Here we tested the hypothesis that the intracameral injection of antigen induces events in the anterior chamber that are associated with the induction of circulating immunoregulatory monocytes that induce the suppression of cell-mediated immunity. The intracameral injection of antigen resulted in aqueous humor (i) a time- dependent increase of CCL2 and CCL7, (ii) a transient increase in TNF-α, and (iii) an infiltration of CD11bhi, Gr1hi and F4/80+ as well as F4/80− and Gr1hi peripheral blood cells into the anterior chamber. Further characterization of these F4/80+ cells revealed that they are Ly 6Chi, LY6Glo or negative, 7/4 (LY6B)hi, CD115+, CD45+, CD49B+, and CD62 L+. Antibody-mediated neutralization of TGF-β in situ in the anterior chamber prevented the induction of circulating, ACAID-inducing monocytes and ACAID. These cells did not increase in the irides of ACAID-refractory CCR2–/– and CCL2–/– mice that received an intracameral injection of antigen. Our results extend our suggestion that ACAID is initiated as the result of a mild proinflammatory response to intracameral injection that results in the infiltration of a CCR2+ subset of monocytes into the anterior chamber where there is a TGF-β-dependent induction of an immunosuppressive phenotype in the infiltrated monocytes that recirculate to induce antigen-specific regulatory T cells.

Anterior chamber associated immune deviation used as a neuroprotective strategy in rats with spinal cord injury

“…For the induction of ACAID, thirty-day old rats were anesthetized with an intra-peritoneal injection of ketamine/xylazine, and then one drop of lidocaine (1% dilution PISA laboratory, Mexico) was applied topically on each eye before injection to reduce corneal reflex [ 16 ]. Under a dissecting microscope, a 30-G disposable needle (BD Co., Mexico) attached to a manually controlled Hamilton syringe (701LTSYR, Hamilton Co., USA), was inserted into the AC and the aqueous humor was allowed to drain [ 17 ]. Approximately 10 microliters of PBS alone or containing antigens (50 micrograms of OVA or MBP), were injected into the AC of both eyes respectively for each group [ 18 ].…”

Mammalian non-classical major histocompatibility complex I and its receptors: Important contexts of gene, evolution, and immunity

“…[ 79 ] (a) Schematic representation of ACAID model, which illustrate ACAID mediated suppression of antigen mediated DTH in mice. (b) Suggested role of CD94/NKG2A-Qa-1 system for CD8 + immunosuppressive Tregs in ACAID[ 79 ], where transforming growth factor beta may influence the generation of CD8 + Tregs[ 104 105 106 107 ]…”

Cellular and Molecular Mechanisms of Anterior Chamber-Associated Immune Deviation (ACAID): What We Have Learned from Knockout Mice

“…As demonstrated in different animal models, an antigen (e.g., ovalbumin) injected into the anterior chamber of the eye is taken up and processed by antigen-presenting cells (APCs) that migrate via the blood to the thymus and the spleen (Figure 1 ). The source of these APCs is still controversial: they may be recruited as monocytes from the blood after the injection ( 3 ) or, alternatively, could be resident APCs. In any case, these F4/80 + CD11b + ocular APCs migrate to the thymus and induce the generation of NKT cells (NK1.1 + CD4 − CD8 − ), which, in turn, play a role in producing splenic suppressor cells.…”