Viral nucleic acid analysis with PCR in lacrimal tissue and nasal swab samples of primary acquired nasolacrimal duct obstruction cases

Yanik, Özge; Hosal, Banu; Tekeli, Alper; Nalci, Hilal

In the present study, two of the patients exhibited the RSV genome in both the nasal mucosal swab and the DCR biopsy specimens. RSV is a segmental, negatively polarized RNA virus. 15 It has the capability of affecting the cytokine production profile of adaptive immune system cells by shifting the T helper (Th) 1 / Th 2 balance toward Th 2 cytokines and immunoglobulin E. 16 It has also been shown to alter the biological activity of macrophages. 17 Furthermore, matrix metalloproteinase 9 (MMP-9), a profibrotic enzyme has been shown to increase in the epithelium after an RSV infection. 18 When all these mechanisms are considered together, RSV has the capability to trigger inflammation and fibrosis development by both shifting the Th balance toward the production of the profibrotic cytokines, interleukin (IL)-4 and IL-13, and increasing the synthesis of connective tissue enzymes, such as MMP-9. 18, 19 Adenovirus DNA was detected in the DCR biopsy specimen from one case and in the nasal swab sample from one case. Adenoviruses, which are common respiratory tract viruses with more than 50 serotypes, have been proven to cause latent infections, especially in lymphoid tissues. [20] [21] [22] Early region 1A, which is a viral gene product of adenoviruses, has been reported to promote the production of profibrotic mediators, such as connective tissue growth factor and transforming growth factor-β mRNA on the bronchial epithelium. 23 In the case of a latent adenovirus infection, the continuous release of these profibrotic mediators may trigger fibrosis development. In addition, the nasolacrimal duct is surrounded by a mucosa-associated lymphoid tissue, which is believed to provide immunomodulation, and damage to this structure has been associated with the development of PANDO. 24, 25 Because adenoviruses have been proven to cause latent infections in lymphoid tissues, 22 a persistent viral infection in this special lymphoid tissue may lead to a chronic inflammatory process resulting in injury and scar formation.