Altered Immune Response to Decellularized Porcine Small Intestinal Sub- Mucosa (DPSIS) Graft in Dogs Suffering from Keratoconjunctivitis Sicca

Study was conducted to explore immune response to decellularised porcine small intestinal sub-mucosa (DPSIS) graft though clinical evaluation and mRNA expression of selected genes of ocular surface epithelium after corneal surface reconstruction in dogs suffering from Keratoconjunctivitis sicca (KCS). Sixteen client-owned dogs that underwent deep lamellar keratoplasty (DALK) and DPSIS graft for corneal surface reconstruction were selected; seven dogs with corneal ulcer were included in group A as control and nine dogs with corneal ulcer as a complication of KCS were included in group B as treatment group. Healing of corneal ulcer under graft was evaluated clinically and by digital photographs. Gene expression of ICAM-1, VCAM-1, PD-L1 and FASL before and after grafting was done by real-time polymerase chain reaction (qRT-PCR) at definite intervals post graft. DPSIS graft promoted effective healing of corneal defect of partial/full thickness in group A and preserved corneal integrity whereas fibrosis and corneal pigmentation ensued in group B post DPSIS graft. Gene expression of ICAM-1 and VCAM-1 were found elevated in group B before and after PSIS grafting. PD-L1 mRNA expression was significantly increased in group B. Protein and gene expression of ICAM-1 and VCAM-1 varied with severity of inflammation in corneal surface post DPSIS grafting. Enhanced mRNA expression of PD- L1 and inflammatory mediators ICAM-1 and VCAM-1 in the ocular surface epithelial cells suggested an altered immune response to DPSIS graft and warranted strategies to modify them for successful repair of corneal epithelial defects in KCS affected dogs.

• Ocular surface epithelial cells of dogs with KCS showed increased gene expression of PD-L1, ICAM-1, and VCAM-1

• Fate of DPSIS graft in cornea of KCS affected dogs is influenced by its altered immune status