686 - Elevations in TNFα and IL-18 are Associated with Increased Risk of Probable Cytomegalovirus Tissue Invasive Disease in Solid Organ Transplant Recipients

Background: Human cytomegalovirus (CMV) continues to cause significant morbidity and mortality in solid organ transplant (SOT) recipients despite prophylaxis. Tissue invasive CMV disease (TI-CMV) can lead to end-organ damage and graft loss. Diagnosing TI-CMV can be challenging as CMV viral load in the blood does not always correlate with episodes of TI-CMV and therefore definitive diagnosis often requires an invasive procedure such as bronchoscopy or colonoscopy. The purpose of this study was to determine if proinflammatory cytokines, including IL-18, are elevated in SOT recipients with probably TI-CMV as a way to identify patients at risk for this severe form of CMV disease.

Methods: The electronic medical record was searched for adult SOT recipients who were tested for CMV via blood qPCR during an 11-month period.Twenty-nine SOT recipients were identified that had episodes of CMV DNAemia without other concomitant infections during this time period. Patients were divided into those that had probable TI-CMV and those with CMV DNAemia alone, by chart review. Inflammatory cytokines (IFNγ, TNFα, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-18, and IL-1RA) were measured in residual plasma from these patients using a commercially available multiplex assay for at least two time points during the study period. Wilcoxon-Rank-Sum, logistic regression, and principal component analysis was performed comparing patients with and without probable TI-CMV.

Results: Patients with probable TI-CMV had significantly higher IL-18, TNFα, and IL-1β than patients with CMV DNAemia alone (p < 0.001, < 0.001, and < 0.05 respectively). When adjusting for transplant type and CMV recipient serostatus, elevations in TNFα (OR 1.43, 95% CI 1.07-1.92) and IL-18 (OR 2.00, 95% CI 1.06-3.75) were associated with increased odds of having probable TI-CMV. In principal component analysis the combination of CMV viral load, IL-18, TNFa, and IL-1β accounted for 80% of the variance in the data.

Conclusion: TNFα and IL-18 in combination with CMV viral load may be useful in predicting likelihood of TI-CMV. This is important in situations where tissue biopsies are not feasible, and adds to our diagnostic capability for TI-CMV in SOT recipients.