Human cytomegalovirus (HCMV) infection is associated with renal allograft failure. Allograft damage in animal models is accelerated by CMV‐induced T helper 17 (Th17) cell infiltrates. However, the mechanisms whereby CMV promotes Th17 cell‐mediated pathological organ inflammation are uncharacterized. Here we demonstrate that murine CMV (MCMV)‐induced intragraft Th17 cells have a Th1/17 phenotype co‐expressing IFN‐γ and/or TNF‐α, but only a minority of these cells are MCMV specific. Instead, MCMV promotes intragraft expression of CCL20 and CXCL10, which are associated with recruitment of CCR6+CXCR3+ Th17 cells. MCMV also enhances Th17 cell infiltrates after ischemia–reperfusion injury, independent of allogeneic responses. Pharmacologic inhibition of the Th17 cell signature cytokine, IL‐17A, ameliorates MCMV‐associated allograft damage without increasing intragraft viral loads or reducing MCMV‐specific Th1 cell infiltrates. Clinically, HCMV DNAemia is associated with higher serum IL‐17A among renal transplant patients with acute rejection, linking HCMV reactivation with Th17 cell cytokine expression. In summary, CMV promotes allograft damage via cytokine‐mediated Th1/17 cell recruitment, which may be pharmacologically targeted to mitigate graft injury while preserving antiviral T cell immunity.

Background Infants with congenital cytomegalovirus infection (cCMV) are at risk for neurodevelopmental impairment (NDI). Antiviral therapy has been shown to improve neurodevelopmental outcomes but is not recommended for all infected infants. There are currently no predictive markers for NDI in infants with cCMV. Our objective was to compare neonatal T cell differentiation and memory phenotypes in CMV-infected infants with and without subsequent NDI. Methods Blood samples were collected from infants with cCMV and age-matched healthy controls. Peripheral blood mononuclear cells were analyzed by flow cytometry for CD4 and CD8 T cells expressing CD28, CD57, PD, CD45RA/RO, and CCR7. Demographic and clinical data were collected. NDI was defined as Bayley III/IV testing below the average range in at least one domain in infants for whom this developmental testing was available or based on diagnosis by infectious disease physician or primary care provider. Outcomes for infants with follow-up at least 6 months of age were included. Infants with isolated speech delay associated with hearing loss were not considered to have NDI. Results Samples were analyzed from 18 infants (Table 1) at time of diagnosis (≤ 60 days of age) and 5 uninfected age-matched controls. The frequencies of CD8+ T cells expressing CD28low (differentiation), CD57+ (terminal differentiation/senescence), PD1hi (inhibitory or exhausted phenotype) and CD45RO± (memory) phenotypes were higher for the cCMV group without NDI compared to that with NDI (Figure 1). The cCMV group without NDI had lower proportions of naïve (CCR7+/CD45RA+) effector memory, TEM (CCR7-/CD45RA-), and effector memory RA, TEMRA (CCR7-/CD45RA+) CD8+ T cells than those with NDI (Figure 2). There was no difference in memory distribution or surface marker expression of CD4+ T cells. Table 1 Demographic and clinical characteristics of the infants with congenital cytomegalovirus infection (cCMV) with and without neurodevelopmental impairment (NI) and age-matched controls. Continuous variables are compared using the Mann Whitney U test and categorical variables with the Fischer’s Exact test. There were no significant differences between infants with and without NI. Figure 1.CD8+ T cell phenotypes in cCMV groups with and without Neurodevelopmental Impairment (NDI) Frequencies of CD8+ T cells lacking expression of CD28 (A), or expressing CD57 (B), PD-1 (C), or CD45RO (D) are shown at age ≤ 60 days. Infants with congenital CMV (cCMV) and normal neurodevelopmental outcome are shown in blue, infants with neurodevelopmental impairment are shown in red, and uninfected age-matched controls are shown in black. Data are shown as medians [interquartile range]. Groups were compared using the Mann Whitney U Test. Infants with no NDI had significantly higher frequencies of CD28- (p = 0.002), CD57+ (p = 0.001), PD-1+ (p = 0.01) and CD45RO+ (p = 0.01) CD8 T cells. * p ≤ 0.05; ** p ≤ 0.01. Figure 2.T cell memory subset distributions among cCMV groups and uninfected controls Proportions of CD4+ (A) and CD8+ (B) naïve (CCR7+/CD45RA+), central memory, TCM (CCR7+/CD45RA-), effector memory, TEM (CCR7-, CD45RA-), and effector memory RA, TEMRA (CCR7-/CD45RA+) T cells. Infants with congenital CMV (cCMV) and normal neurodevelopmental outcome are shown in blue, infants with neurodevelopmental impairment (NI) are shown in red while uninfected age-matched controls are shown in black and gray. Comparisons between T cell groups were made using the Mann Whitney U test. Infants with cCMV without NI had significantly fewer naïve (p = 0.0001), greater TEM (p = 0.0001), and TEMRA (p = 0.005) CD8+ T cells than those with NI. The distributions of CD4+ T cells were not significantly different. Conclusion In this small cohort of infants infected with CMV, these data suggest that a more differentiated memory CD8+ T cell phenotype in the neonatal period may correlate with normal neurodevelopmental outcomes. Disclosures Alexandra K. Medoro, MD, Merck: Grant/Research Support.

Congenital CMV (cCMV) infection can affect infants born to mothers with preconceptional seroimmunity. To prevent cCMV due to nonprimary maternal infection, vaccines eliciting responses exceeding natural immunity may be required. Anti-gM/gN antibodies have neutralizing capacity in-vitro and in animal models, but anti-gM/gN antibodies have not been characterized among seroimmune pregnant women. Paired maternal and infant cord sera from 92 CMV seropositive mothers and their full-term or preterm infants were tested for anti-gM/gN antibody titers in comparison with anti-gB titers and neutralizing activity. Anti-gM/gN titers were significantly lower than anti-gB titers for all groups and did not correlate with serum neutralizing capacity. Further study is needed to determine if higher anti-gM/gN antibody titers might enhance serum neutralizing capacity among seropositive adults.