Neuroprotective effects of food restriction on autonomic innervation of the lacrimal gland in the rat

Klotho Null Mutation Indirectly Leads to Age-Related Lacrimal Gland Degeneration in Mutant Mice

The Klotho null mutation is known to lead to accelerated aging in many organs, but its effects on tear secretion and lacrimal gland (LG) senescence have not been addressed. This study investigated whether the Klotho null mutation would lead to a dry eye status and the outcome of LG without Klotho function. The Klotho (-/-) mutant mice showed reduced LG size and tear volume on the 8th week, as compared to their littermates (+/+, +/-). Hematoxylin-Eosin and Masson's trichrome staining were performed to determine morphological changes and collagen deposition. Traits of LG aging, including acinar atrophy, thickened capsules, and more collagen depositions, were observed. Immunohistochemical detections for Klotho, α-SMA, MDA, 8-OHdG, vasoactive intestinal polypeptide (VIP), tyrosine hydroxylase (TH), MMP-2, MMP-9, and FGF-23 were performed and compared among the three genotypes (+/+, +/-, -/-) at 6 and 8 weeks of age for mechanism analyses. Unexpectedly, the Klotho protein was not detected in the LG of all the three genotypes, indicating indirect effects from the Klotho null mutation. Further analyses showed abundant MDA and 8-OHdG detected in the Klotho (-/-) LG on the 8th week, indicating elevated oxidative stress. In addition, both sympathetic and parasympathetic neural transducing activities, as represented by TH and VIP expression, respectively, and α-SMA were increased in LGs with Klotho mutations. Furthermore, MMP-2 and MMP-9 expression were elevated, with FGF-23 expression being decreased on the 8th week in the Klotho (-/-) LG. In conclusion, characteristics of age-related LG degeneration were found in the Klotho null mutant mice. These traits support the use of Klotho mutant mice as a model of age-related dry eye disease.

Food restriction reduces hepatic alterations associated with experimental periodontitis

BACKGROUND

Periodontitis is a chronic inflammatory and multifactorial disease that affects the periodontal structures and can cause alterations in the hepatic tissue. The aim of the present study was to evaluate whether a diet with food restriction can decrease oral and liver alterations associated with ligature-induced periodontitis.

METHODS

Twenty-four female Wistar rats were used in this study, randomized into three groups (n = 8 for each group): control (regular food); periodontitis (regular food + periodontitis induced with ligatures); and food restriction (diet with food restriction and periodontitis induction). The following periodontium parameters were analyzed tooth mobility (TM), probing pocket depth (PPD), gingival bleeding index (GBI), and alveolar bone height (ABH). In the liver, the levels of oxidative stress markers-malondialdehyde (MDA), glutathione (GSH), total cholesterol, and levels of myeloperoxidase (MPO) activity were measured. Liver samples were analyzed for histopathological score. In the blood tissue, the levels of enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose, total cholesterol, and the high-density lipoprotein (HDL) were also evaluated.

RESULTS

The animals that received a diet with food restriction + periodontitis showed a decrease in hepatic histopathological score (P < 0.05) when compared with the periodontitis group, the same for glucose, total cholesterol, ALT, AST, and ABH data. The group with food restriction + periodontitis showed a decrease in the histopathological liver score (P < 0.05) compared with the group with periodontitis.

CONCLUSION

This study revealed that food restriction reduced oral damages, as well as hepatic, blood and alveolar bone alterations associated with ligature-induced periodontitis in rats.

Age-related Autoimmune Changes in Lacrimal Glands

Aging is a complex process associated with dysregulation of the immune system and low levels of inflammation, often associated with the onset of many pathologies. The lacrimal gland (LG) plays a vital role in the maintenance of ocular physiology and changes related to aging directly affect eye diseases. The dysregulation of the immune system in aging leads to quantitative and qualitative changes in antibodies and cytokines. While there is a gradual decline of the immune system, there is an increase in autoimmunity, with a reciprocal pathway between low levels of inflammation and aging mechanisms. Elderly C57BL/6J mice spontaneously show LGs infiltration that is characterized by Th1 but not Th17 cells. The aging of the LG is related to functional alterations, reduced innervation and decreased secretory activities. Lymphocytic infiltration, destruction, and atrophy of glandular parenchyma, ductal dilatation, and secretion of inflammatory mediators modify the volume and composition of tears. Oxidative stress, the capacity to metabolize and eliminate toxic substances decreased in aging, is also associated with the reduction of LG functionality and the pathogenesis of autoimmune diseases. Although further studies are required for a better understanding of autoimmunity and aging of the LG, we described anatomic and immunology aspects that have been described so far.