PLoS ONE：揭示神经肌肉障碍和嗅觉缺失的关联

2012年10月18日 讯 /生物谷BIOON/ --寒冷和呼吸道感染可以引发嗅觉和味觉能力的改变，但是嗅觉和味觉的改变或许也是神经变性疾病的初期征兆，如阿尔兹海默症和帕金森疾病等。近日，来自宾夕法尼亚大学的研究者揭示了嗅觉损伤和重症肌无力（MG）疾病之间的关联，重症肌无力是一种慢性的自体免疫神经肌肉疾病，其主要表现为脉动疲劳和肌肉无力等症状。相关研究成果刊登于国际杂志PLoS One上。

这项研究中，研究者发现一种苦味觉受体在上呼吸道细胞中发挥着功能，比如受体-T2R38其通过检测特定的细菌分泌的毒性分子来保护上呼吸道免受感染，这些毒性分子可以指导其它细菌形成生物被膜，从而帮助细菌自我包裹。前期研究中，研究者表示，生物被膜可以刺激免疫系统发生较强的免疫反应，进而导致窦炎、重症肌无力等症状，当受体T2R38检测到细菌毒性分子后，其会激活局部的防御对抗来增加细菌粘液的清除率，并且杀死入侵的细菌。

研究者对病人的窦组织进行检测发现病人的味觉系统并未受到细菌感染。基于这些研究发现，研究者表示其它的苦味受体在抵御细菌感染上也扮演着类似的作用，而且研究者希望将他们的研究成果转化成为个体化的诊断策略来应对慢性鼻窦炎症状。

于此同时，研究小组使用当前的研究结果开发出了一种“品尝测试”方法来指导临床学诊断，我们相信这种检测方法可以帮助预测患者是否会遭受细菌生物膜的影响，由于生物被膜的影响会导致机体免疫系统开启免疫效应，最终导致患者出现肌无力等症状，研究者希望他们的研究成果为新型疗法的开发带来帮助。

Profound Olfactory Dysfunction in Myasthenia Gravis

In this study we demonstrate that myasthenia gravis, an autoimmune disease strongly identified with deficient acetylcholine receptor transmission at the post-synaptic neuromuscular junction, is accompanied by a profound loss of olfactory function. Twenty-seven MG patients, 27 matched healthy controls, and 11 patients with polymiositis, a disease with peripheral neuromuscular symptoms analogous to myasthenia gravis with no known central nervous system involvement, were tested. All were administered the University of Pennsylvania Smell Identification Test (UPSIT) and the Picture Identification Test (PIT), a test analogous in content and form to the UPSIT designed to control for non-olfactory cognitive confounds. The UPSIT scores of the myasthenia gravis patients were markedly lower than those of the age- and sex-matched normal controls [respective means (SDs) = 20.15 (6.40) & 35.67 (4.95); p<0.0001], as well as those of the polymiositis patients who scored slightly below the normal range [33.30 (1.42); p<0.0001]. The latter finding, along with direct monitoring of the inhalation of the patients during testing, implies that the MG-related olfactory deficit is unlikely due to difficulties sniffing, per se. All PIT scores were within or near the normal range, although subtle deficits were apparent in both the MG and PM patients, conceivably reflecting influences of mild cognitive impairment. No relationships between performance on the UPSIT and thymectomy, time since diagnosis, type of treatment regimen, or the presence or absence of serum anti-nicotinic or muscarinic antibodies were apparent. Our findings suggest that MG influences olfactory function to the same degree as observed in a number of neurodegenerative diseases in which central nervous system cholinergic dysfunction has been documented.