Sperling Leonard C, Hussey Sean, Sorrells Timothy, Wang Ji-an, Darling Thomas
Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
J Cutan Pathol. 2010 Feb;37(2):243-8. doi: 10.1111/j.1600-0560.2009.01330.x. Epub 2009 Jul 10.
Premature desquamation of the inner root sheath (IRS) is an important histological marker for central, centrifugal, cicatricial alopecia (CCCA), and an inherently defective IRS may be responsible. Cytokeratin 75 (K75; formerly K6hf) is an appealing candidate for study because K75 is specifically expressed in the companion layer of the hair follicle, the interface for IRS desquamation. Also, K75 abnormalities have been found in other hair diseases bearing similarities to CCCA.
We used a commercially available antibody to K75 on formalin-fixed, paraffin-embedded tissue from clinically and histologically "normal" scalp (n=9); clinically diseased scalp from patients with CCCA (n=15); and clinically "normal" scalp from patients with CCCA (n=6).
K75 expression disappears during the process of IRS desquamation, and loss of expression begins even when IRS desquamation is in its incipient phase. Also, K75 has a characteristic pattern of expression in telogen follicles.
K75 expression is closely associated with the process of desquamation of the IRS. This process occurs prematurely (below the isthmus) in many follicles from patients with, but not without, CCCA. K75 expression highlights premature desquamation of the IRS in CCCA, but may not be directly involved in disease pathogenesis.
内根鞘（IRS）过早脱屑是中央性、离心性瘢痕性秃发（CCCA）的一个重要组织学标志物，可能是由内在缺陷的IRS所致。细胞角蛋白75（K75；原称K6hf）是一个有吸引力的研究对象，因为K75在毛囊的伴层中特异性表达，而伴层是IRS脱屑的界面。此外，在其他与CCCA相似的毛发疾病中也发现了K75异常。
我们使用一种市售的抗K75抗体，对来自临床和组织学上“正常”头皮（n = 9）、CCCA患者的临床病变头皮（n = 15）以及CCCA患者的临床“正常”头皮（n = 6）的福尔马林固定、石蜡包埋组织进行检测。
K75表达在IRS脱屑过程中消失，甚至在IRS脱屑处于初始阶段时表达就开始丧失。此外，K75在休止期毛囊中有特征性的表达模式。
K75表达与IRS脱屑过程密切相关。在CCCA患者的许多毛囊中，这个过程（在峡部以下）过早发生，而非CCCA患者则不然。K75表达突出了CCCA中IRS的过早脱屑，但可能不直接参与疾病发病机制。
