Role of cytomegalovirus in the expansion of CD4+CD28– T cells in patients with ANCA-associated vasculitis: a proof-of-concept, randomised controlled trial

Abstract

BackgroundCD4+CD28– T-cell expansion is linked to increased infection and mortality in patients with ANCA-associated vasculitis (AAV), and cardiovascular disease in other inflammatory conditions. We aimed to characterise these cells in AAV, assess their contribution to arterial stiffness, a marker of cardiovascular disease risk, and in a proof-of-concept, open-label, randomised controlled clinical trial determine whether subclinical cytomegalovirus (CMV) reactivation leads to expansion of CD4+CD28– T cells in AAV. MethodsPeripheral blood mononuclear cells from 53 patients with AAV and 30 age-matched healthy volunteers (all CMV positive) were stimulated with CMV lysate. Arterial stiffness was measured by pulse wave velocity (Vicorder, Skidmore Medical Ltd, Bristol, UK). 38 CMV-positive AAV patients were computer randomised (1:1) to 6 months' valaciclovir (2 g four times a day) or no additional treatment (19 in each group). Primary outcome was proportion of patients with CMV reactivation at 6 months, assessed by plasma and urine real-time PCR. Secondary outcome was change in proportion of CD4+CD28– T cells from baseline to 6 months. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01633476. FindingsCD4+CD28– cells expressed endothelial receptors CX3CR1, CD49d, and CD11b, and cytotoxic molecules perforin and granzymeB, and secreted interferon γ and tumour necrosis factor α after CMV lysate stimulation. The proportion of CD4+CD28– cells was independently associated with increased pulse wave velocity in AAV after controlling for relevant confounders. No CMV reactivation was detected in valaciclovir-treated patients whereas reactivation was detected in controls (4/19 [21·1%], p=0·037). At 6 months there was a significant reduction in both percentage (mean reduction 23%, 95% CI 3–39; p=0·039) and absolute count (27%, 7–42; p=0·013) of CD4+CD28– cells in treated patients with no significant change in controls. CD4+CD28– cell reduction in the treated group persisted 6 months after cessation of treatment. Valaciclovir was well tolerated. InterpretationCD4+CD28– cells are a CMV-specific, cytotoxic, proinflammatory subset that possess endothelial targeting receptors and are independently associated with increased arterial stiffness in inflammatory disease. Blocking subclinical CMV reactivation led to a persistent reduction in CD4+CD28– cells; this finding suggests that CMV subclinical reactivation causes the expansion of this cytotoxic T-cell subset and offers novel therapeutic opportunities in AAV to reduce the risk of infection, cardiovascular disease, and mortality. FundingWellcome Trust (research training fellowship for DC), Vasculitis UK.