(905) Gut Microbial Translocation may drive NK cell Reprogramming in Adolescents Living with Perinatally Acquired HIV

Introduction/Rationale: Natural killer (NK) cell dysregulation contributes to chronic inflammation in people living with HIV, yet underlying mechanisms remain unclear. Gut microbial translocation (GMT), driven by impaired gut barrier integrity, is a source of systemic immune activation in HIV. We explored whether GMT influences NK cell phenotype and function in adolescents with perinatally acquired HIV (PHIV) on long-term antiretroviral therapy.

Methods: PHIV (n = 10) were compared to age-matched healthy controls (HC, n = 11). High dimensional flow cytometry was employed for immune profiling, including stimulation with HIV gag peptide pool. Plasma biomarkers were measured by ELISA. UMAP and FlowSOM were used for Phenotypic clustering. Data were analyzed using Mann-Whitney U test and Pearson correlation coefficient.

Results: Six of 15 NK clusters expressing TLR2, TLR4 and HLA-DR were upregulated in PHIV; two KLRG1+ clusters were downregulated (p < 0.05). Conventional gating revealed increased TLR2 in CD16+CD56- NK subset with elevated HLA-DR (p < 0.05) alongside NKG2D in CD16+CD56bright subset (p < 0.005), indicating persistent activation. KLRG1+ effector memory-like NK cells were downregulated (p < 0.05) in three of five NK subsets. Upon stimulation, NK cells from PHIV secrete more TNFα (p < 0.05), while KLRG1+ NK cells produced less Granzyme B (p < 0.005). This reflects a pro-inflammatory yet less cytotoxic phenotype.
Plasma intestinal fatty acid binding protein, a marker of gut integrity, was elevated in PHIV (p < 0.05) and positively correlated with TLR2+/TLR4+/HLA-DR+ NK subsets (R > 0.5) and inversely correlated with KLRG1+ NK subsets (R < -0.5).

Conclusion: Our findings suggest that GMT may promote NK cell activation via TLR2/TLR4 signaling, driving a pro-inflammatory yet less cytotoxic phenotype. This may contribute to the development of HIV-associated comorbidities. Strategies to restore gut barrier integrity or/and modulation of NK cells could mitigate chronic inflammation and improve long-term outcomes in PHIV.