Defining the role of mSMGP/mPIP as an immunoregulatory molecule in host defense

定义mSMGP作为免疫调节分子在宿主防御中的作用假设：小鼠颌下（下）腺蛋白，mSMGP，是一种重要的免疫调节分子，在先天性和适应性免疫宿主防御中发挥作用。建议：研究mSMGP对适应性免疫系统的影响，并阐明其先天抗菌活性的机制。我的实验室对颌下腺的生物学和生理学感兴趣。与大多数其他哺乳动物一样，小鼠的下颌下腺具有内分泌和外分泌功能，并且是几种生物活性多肽（包括激素、生长因子和消化酶）的合成部位。这些蛋白质中的许多都得到了很好的研究和表征，然而，其他几种蛋白质的功能仍然难以捉摸。我已经确定了一个基因，这是高度表达的腺体和蛋白质，我们称之为小鼠颌下腺蛋白（mSMGP）。mSMGP的功能尚未阐明。在这一初步发现之后，我们随后发现mSMGP不仅在唾液腺中表达，而且在病原体的免疫学重要入口处表达，如皮肤、眼睛和耳朵，以及在这些组织产生的体液中发现的分泌蛋白，如唾液、眼泪和汗液。我们进一步证明了mSMGP结合并聚集细菌，包括几种人和小鼠口腔菌株，阻止其增殖和传播。这些观察使我们假设mSMGP在先天宿主防御中起作用。然而，mSMGP可能在免疫中具有更广泛作用的线索来自于对人类同源物进行的其他研究，该人类同源物如mSMGP不仅具有结合细菌菌株的能力，而且能够结合CD4分子并抑制T淋巴细胞凋亡。此外，使用mSMGP敲除模型，我们产生的一种工具，以解决蛋白质的功能，我们证明，敲除小鼠有异常淋巴细胞，表现出异常的增殖率，受损的Th1和可能的，Th2免疫反应，并增加了对利什曼原虫感染的易感性。我们首次证明了mSMGP参与细胞介导的免疫。我们还表明，KO小鼠唾液在聚集口腔细菌方面效果较差，并且口腔植物群的组成与其野生型对应物不同，具有来自链球菌属的优势代表。此外，我们发现mSMGP功能的丧失导致了一类唾液蛋白的上调，这些蛋白最近被鉴定为疾病的推定标志物。我们目前的目标是研究mSMGP在细胞介导的免疫中的作用，并阐明mSMGP抗菌活性的机制。迄今为止，对防止入侵生物或感染，特别是通过口腔污染的保护知之甚少。提出的研究是从口腔角度探讨感染现象的极少数研究之一。我预计这项研究将对mSMGP的功能和生物学产生重要的见解，并将进一步有助于增加我们对颌下腺生物学和免疫的理解。

Defining a role for mSMGP as an immunoregulatory molecule in host defense HYPOTHESIS: The mouse submaxillary (submandibular) gland protein, mSMGP, is an important immunoregulatory molecule that plays a role in both innate and adaptive immune host defense. PROPOSAL: To examine mSMGP’s influence on the adaptive immune system and to delineate the mechanisms of its innate antimicrobial activities. My laboratory is interested in the biology and physiology of the submandibular gland. The submandibular gland in the mouse, as in most other mammals, exhibits both endocrine and exocrine functions, and is the site of synthesis of several biologically active polypeptides, including hormones, growth factors, and digestive enzymes. Many of these proteins are well studied and characterized, however, the function of several others remain elusive. I have identified a gene that is highly expressed in this gland and whose protein we termed the mouse submaxillary gland protein (mSMGP). The function of mSMGP has not been delineated. Following this initial discovery, we subsequently found that not only was mSMGP expressed in salivary glands, but was also expressed at immunologically important ports of entry for pathogens, such as skin, eyes and ears and the secreted protein found in the bodily fluids produced by these tissues such as saliva, tears and sweat. We further demonstrated that mSMGP binds to and aggregates bacteria including several human and mouse oral strains, prohibiting their multiplication and spread. These observations led us to hypothesize that mSMGP plays a role in innate host defense. However, clues that mSMGP may have a broader role in immunity have come from other studies carried out on a human homologue which was shown, like mSMGP, not only to possess the ability to bind to bacterial strains but was capable of binding to the CD4 molecule and inhibit T lymphocyte apoptosis. Furthermore, using a mSMGP knockout model which we generated as a tool to address protein function, we demonstrated that knockout mice had abnormal lymphocytes that exhibited abnormal proliferation rates, had impaired Th1 and possibly, Th2 immune responses and had increased susceptibility to Leishmania major infection. We demonstrated for the first time that mSMGP was involved in cell mediated immunity. We also showed that KO mice saliva was less effective in aggregating oral bacteria and that the composition of the oral flora was different from its wild type counterpart, with a preponderance of representation from the genus Streptococcus. Additionally we showed that loss of mSMGP function resulted in the up regulation of a class of salivary proteins recently identified as putative markers of disease. Our current objectives are to investigate the role of the mSMGP in cell mediated immunity and to delineate the mechanism of mSMGP antimicrobial activities. Protection against invading organisms or infection, particularly via oral contamination is to date, poorly understood. The proposed studies are among the very few that approach the infection phenomenon from an oral perspective. I anticipate this study will yield critical insights into the function and biology of the mSMGP, and will further contribute to increasing our understanding of submandibular gland biology and immunity.