Varicella-zoster virus vasculopathy: immune characteristics of virus-infected arteries

Abstract

Objective: Pathologic changes in varicella-zoster virus (VZV)-infected arteries include inflammation, thickened intima, and paucity of smooth muscle cells. Since no criteria have been established for early vs late VZV vasculopathy, we examined inflammatory cells and their distribution in 6 normal arteries, and 2 VZV-infected arteries 3 days after onset of disease (early) and 10 months after protracted neurologic disease (late).

Methods: VZV-infected temporal artery obtained 3 days after onset of ischemic optic neuropathy from an 80-year-old man, VZV-infected middle cerebral artery (MCA) obtained 10 months after protracted disease from a 73-year-old man, and 5 MCAs and 1 temporal artery from normal subjects, age 22-60 years, were examined histologically and immunohistochemically using antibodies against VZV and inflammatory cell subsets.

Results: In both early and late VZV vasculopathy, T cells, activated macrophages, and rare B cells were found in adventitia and intima. In adventitia of early VZV vasculopathy, neutrophils and VZV antigen were abundant and a thickened intima was associated with inflammatory cells in vaso vasorum vessels. In media of late VZV vasculopathy, viral antigen, but not leukocytes, was found. VZV was not seen in inflammatory cells. Inflammatory cells were absent in control arteries.

Conclusions: Both VZV and neutrophils exclusively in adventitia in early VZV vasculopathy indicate that disease begins there. Late VZV vasculopathy is distinguished by viral antigen without inflammation in media, revealing a human virus in an immunoprivileged arterial media. Association of thickened intima and inflammation in vaso vasorum vessels in early VZV vasculopathy support the role of virus-induced inflammation in vessel wall remodeling.

Figure 1. Distribution of varicella-zoster virus (VZV) antigen and leukocytes expressing CD45 in cerebral arteries from normal subjects and from patients with VZV vasculopathy

(A-I) Hematoxylin & eosin (H&E) staining shows normal artery morphology in a normal artery (A) with a single layer of endothelial cells in the intima (I), smooth muscle cells in the media (M), and fibroblasts and connective tissue in the outer adventitia (Adv). A thickened intima (I) was seen in both early (D) and late (G) VZV vasculopathy. VZV antigen was not seen in the normal artery (B), but was present in the adventitia (E) in early VZV vasculopathy and in the media (H) in late VZV vasculopathy (black arrows, pink color). Leukocytes expressing CD45 were not present in the normal artery (C), but were seen in the adventitia (F, black arrows, brown color), where VZV antigen was found in early VZV vasculopathy. In late VZV vasculopathy, leukocytes expressing CD45 were seen predominantly in the luminal surface of the thickened intima and to a lesser degree in the adventitia (I, black arrows, brown color). In contrast to the presence of both VZV antigen and leukocytes in the adventitia in early VZV vasculopathy, the media in late VZV vasculopathy contained only VZV antigen. Magnification = ×200 in panels A–C and G–I; ×100 in panels D–F.

Figure 2. Cells in cerebral arteries containing varicella-zoster virus (VZV) antigen do not express CD45

Cerebral arteries from subjects with early and late VZV vasculopathy were dual-stained with antibodies directed against VZV antigen and CD45. In the adventitia of early VZV vasculopathy, immunofluorescent staining identified cells containing VZV antigen (A, arrows, green color) but not expressing CD45. Leukocytes that expressed CD45 were devoid of VZV antigen (B, arrows, red color). The merged image also shows VZV-infected cells that did not express CD45 (C, arrows, green color). In the media of late VZV vasculopathy, cells expressing VZV antigen (D, arrow, green color) did not express CD45 (E, arrows, red color). The merged image in late VZV vasculopathy also shows VZV-infected cells (F). Nonspecific green and red autofluoresence is seen in the arterial folds (A–C, long thin arrows) and in the internal elastic lamina (D–F, long thin arrows). Magnification = ×200.

Figure 3. T-cell subsets in varicella-zoster virus (VZV) vasculopathy

Cells expressing CD3 were seen primarily in the adventitia (A, black line, thin black arrows, brown color) as well as in the thickened intima (A, white line, thick black arrows, brown color) in early VZV vasculopathy, whereas cells expressing CD3 were found primarily in the thickened intima (D, white line, thick black arrows, brown color) and much less in the adventitia (D, black line, thin black arrows, brown color) in late VZV vasculopathy. Cells expressing CD4 were present in the adventitia and intima in early and late VZV vasculopathy (B and E, thin black arrows in adventitia; thick black arrows in intima, brown color). Similarly, cells expressing CD8 were present in the adventitia and intima in early and late VZV vasculopathy (C and F, thin black arrows in adventitia, thick black arrows in intima; brown color). Magnification = ×100 in panels A–C and ×200 in panels D–F.

Figure 4. B cells, activated macrophages, and neutrophils in varicella-zoster virus (VZV) vasculopathy

In early (A) and late (D) VZV vasculopathy, rare or no B cells expressing CD20 were seen in the adventitia (black line, thin black arrows, brown color) and intima (white line, thick black arrows, brown color). Activated macrophages expressing CD68 were seen in the adventitia and intima in early (B) and late (E) VZV vasculopathy (thin black arrows in adventitia; thick black arrows in intima, brown color). In early VZV vasculopathy, activated macrophages expressing CD68 were found within the lumen of the vaso vasorum that extended into the media (B, thick white arrows). Abundant neutrophils expressing CD15 were present predominantly in the adventitia and rarely in the intima in early VZV vasculopathy (C, thin black arrows in adventitia; thick black arrow in intima, brown color), whereas only rare or no neutrophils were seen in the intima in late VZV vasculopathy (F, thick black arrow, brown color). Magnification = ×100 in panels A–C and ×200 in panels D–F.

Figure 5. In early varicella-zoster virus (VZV) vasculopathy, the thickened intima is associated with inflammatory cells in the vaso vasorum

Within the adventitia of the early VZV vasculopathy artery, 2 vaso vasorum vessels contained T cells expressing CD3 (long black arrows, brown color) adjacent to the thickened intima (black bars). Short black arrows in areas where the intima is not thickened were devoid of cells expressing CD3. A thickened intima was also associated with cells expressing CD4, CD8, CD20, and CD68 (not shown). Magnification = ×100.