Lacrimal Gland Innervation Is Not Altered with the Onset and Progression of Disease in a Murine Model of Sjögren's Syndrome

The lacrimal glands of patients with Sjögren's syndrome develop extensive lymphocytic infiltration, but also contain a large number of seemingly healthy looking acinar and ductal cells. Despite this, the secretory function of this tissue is impaired, leading to aqueous tear-deficient dry eye. This raises the possibility that there is a defect in the neural innervation of the remaining portion of the lacrimal gland. To test for this possibility, we used antibodies specific to various markers of the parasympathetic, sympathetic, and sensory nerves and performed immunohistochemical analyses of lacrimal glands from a murine model of Sjögren's syndrome, the MRL/Mp-Fas-lpr/lpr(MRL/lpr) and the control mice MRL/Mp−+/+ (MRL/+). Our results show that the MRL/lpr, but not the MRL/+, lacrimal glands become infiltrated with lymphocytes starting at 8 weeks of age which worsens by 12 and 18 weeks. The density and the pattern of parasympathetic, sympathetic, and sensory innervation of the noninflamed acinar tissue of MRL/lpr lacrimal glands, at 4, 8, 12, and 18 weeks, is indistinguishable from that of age-matched control MRL/+ lacrimal glands. We conclude that the loss of the secretory function in Sjögren's syndrome lacrimal glands is not due to a loss or decrease of its innervation.