For decades, neurologic and other extra glandular manifestations have been described in Sjögren’s syndrome (SS). More recently, neuropathic, psychological and cognitive alterations are being considered part of the disease. The lacrimal glands (LG), the ocular surface (OS), salivary glands (SG) and the central nervous system (CNS) are integrated to modulate the autonomic functions and, not just those organs, but also the hippocampus, which is linked to the autonomic nervous system, and modulate behavior responses appears to be compromised in the SS. Recent studies confirm that the tryptophan/kynurenine pathway (TKP) can be stimulated by interferon-γ (IFN-γ) and other cytokines, activating the indoleamine-pyrrole 2,3-dioxygenase (IDO) in SS. This pathway interferes on serotonergic and glutamatergic neurotransmission, mostly in the hippocampus, and other structures of the CNS. Although not demonstrated, it is plausible that this constant interference induces clinical signs of SS, and contributes to the discrepancy between symptoms and signs, towards manifestations of hyperalgesia and depression in patients with SS. Therapeutic strategies are being reexamined and new options designed and tested to regulate the involved steps of the TKP. In the future, the application of this concept may offer a clue to the mosaic of manifestations of SS.

The study evaluated the regenerative responses of the lacrimal functional unit (LFU) after Lacrimal Gland (LG) ablation. The LG of Wistar rats were submitted to G1) partial LG ablation, G2) partial ablation and transplantation of an allogeneic LG, or G3) total LG ablation, (n=7-10/group). The eye wipe test, slit-lamp image, tear flow, and histology were evaluated. RT-PCR analyzed inflammatory and proliferation mediators. The findings were compared to naïve controls after 1 and 2 months (M1 and M2). G3 presented increased corneal sensitivity, and the 03 groups have shown corneal neovascularization. Histology revealed changes in LG, and corneal inflammation. In the LG, there was an increase in MMP-9 mRNA of G1 and G2 at M1 and M2 and RUNX-1 at M1 and M2 in G1 and RUNX-3 mRNA at M1 in G1, and in G2 at M2. TNF-α mRNA rose in the corneas of G1 and G2 at M2. There was an increase in the IL-1β mRNA in the Trigeminal Ganglion of G1 at M1. Without changes in tear flow or evidence of LG regeneration, LG ablation or grafting are unreliable models for dry eye or LG repair in rats. The surgical manipulation extended inflammation to the LFU.