Aging-associated shifts in functional status of mast cells located by adult and aged mesenteric lymphatic vessels

Abstract

We had previously proposed the presence of permanent stimulatory influences in the tissue microenvironment surrounding the aged mesenteric lymphatic vessels (MLV), which influence aged lymphatic function. In this study, we performed immunohistochemical labeling of proteins known to be present in mast cells (mast cell tryptase, c-kit, prostaglandin D(2) synthase, histidine decarboxylase, histamine, transmembrane protein 16A, and TNF-α) with double verification of mast cells in the same segment of rat mesentery containing MLV by labeling with Alexa Fluor 488-conjugated avidin followed by toluidine blue staining. Additionally, we evaluated the aging-associated changes in the number of mast cells located by MLV and in their functional status by inducing mast cell activation by various activators (substance P; anti-rat DNP Immunoglobulin E; peptidoglycan from Staphyloccus aureus and compound 48/80) in the presence of ruthenium red followed by subsequent staining by toluidine blue. We found that there was a 27% aging-associated increase in the total number of mast cells, with an ∼400% increase in the number of activated mast cells in aged mesenteric tissue in resting conditions with diminished ability of mast cells to be newly activated in the presence of inflammatory or chemical stimuli. We conclude that higher degree of preactivation of mast cells in aged mesenteric tissue is important for development of aging-associated impairment of function of mesenteric lymphatic vessels. The limited number of intact aged mast cells located close to the mesenteric lymphatic compartments to react to the presence of acute stimuli may be considered contributory to the aging-associated deteriorations in immune response.

Aged Lymphatic Contractility: Recent Answers and New Questions

“…35 In this study, we performed immunohistochemical labeling of proteins known to be present in mast cells (mast cell tryptase, c-kit, prostaglandin D2 synthase, histidine decarboxylase, histamine, transmembrane protein 16A, and tumor necrosis factor-alpha) with double verification of mast cells in the same segment of rat mesentery containing MLV by labeling with Alexa Fluor 488-conjugated avidin, followed by toluidine blue staining. Additionally, we evaluated the agingassociated changes in the number of mast cells located by MLV and in their functional status by inducing mast cell AGED LYMPHATIC CONTRACTILITYactivation by various activators (substance P, anti-rat DNP Immunoglobulin E, peptidoglycan from Staphyloccus aureus, and compound 48/80) in presence of Ruthenium Red, followed by staining by toluidine blue.…”

“…[48][49][50][51] Historically studies on mast cells in aging have been limited to dermal and lung mast cells in context of studies on allergy and asthma. [52][53][54] In this study, 35 we have for the first time analyzed the agingassociated changes in mast cell number and their behavior in rat mesentery near lymphatic vessels. In this study, we also have compared the responses of mesenteric mast cells to different acute stimuli in adult and aged animals.…”

Mast Cell-Directed Recruitment of MHC Class II Positive Cells and Eosinophils Towards Mesenteric Lymphatic Vessels in Adulthood and Elderly

“…6,7 Furthermore, we proposed that such high levels of pre-existing activation of MCs would alter the initial phases of acute inflammation and immune response in elderly. 13 While considering potential interactions between MLVs and MCs in aged mesenteric tissues during initial phases of acute inflammation and immune response, we attempted to answer the question on general importance of mesenteric MCs located near MLVs for these processes. It is well established that cells of the immune system are required to communicate between each other through secretion of soluble mediators and direct cell-cell interaction to develop an effective immune response.…”

“…13 Being located at the border between the biologically aggressive environment of the gut lumen and inner compartments of the abdomen, the inner surface of these vessels provide much greater surface area for initial contact and interaction with inflammatory mediators, products of tissue metabolism, and various foreign and selfantigens than the inner surface of downstream lymph nodes located far from the gut wall. MCs as sentinel cells being localized by MLVs may be considered as ideal candidates to provide an important functional link between MLVs and other immune cells located in the mesenteric tissue.…”

“…There is evidence of increased number of MCs in dermis of skin, 27 lung vessels, 28 and mesentery with increased degree of basal activation of aged MCs in the mesentery. 13 MCs were shown to undergo aging-induced reprogramming, and aged dermal MCs in mice were prone to degranulation with PGE2 unlike that in young mice. 29 We hypothesized that acute activation of MCs located near MLVs induce activation and recruitment of MHC class II positive APCs, as well as recruitment of eosinophils towards these collecting lymph vessels, and that there is an aging-related decrease in such acute MC-dependent immune cell mobilization near MLVs in aged mesenteric tissues due to the pre-existing sustained activation of MCs confirmed by us earlier.…”