Biology subjects

Seet, C. S.

Publications and source records attributed to Seet, C. S..

4 recordsLinked to original sources

bioRxiv2026

NK Cells Engineered with a Chimeric Antigen Receptor Delay HIV Rebound and Reshape HIV Reservoir Composition

Durable HIV remission will require strategies that eliminate or permanently silence the latent reservoir that persists despite antiretroviral therapy (ART). Natural killer (NK) cells possess inherent antiviral activity, but unmodified NK cells have limited ability to recognize or clear latently infected cells during ART suppression. We engineered allogeneic human primary NK cells expressing a truncated CD4-based chimeric antigen receptor (D1D2-CAR) that targets the conserved CD4 binding site on HIV Env without permitting viral entry, and evaluated their activities in humanized mice infected with barcoded CCR5-tropic HIV. D1D2-CAR NK cells selectively killed HIV-infected primary CD4 T cells in vitro and significantly delayed viral rebound following ART interruption in humanized mice compared to GFP-NK or no NK control groups. Barcoded HIV tracking showed that CAR-NK treatment reduced the number, diversity, and inter-organ overlap of rebounding viral RNA and proviral DNA lineages, yielding rebound driven by a restricted set of dominant clones. Integration site and chromatin analysis further demonstrated selective depletion of proviruses positioned in genes, enhancers, promoters, and open chromatin. These findings show that CAR-NK cells can target rare reactivation events during ART suppression and reshape the reservoir toward a less rebound-competent, epigenetically repressive state.

immunology↗

bioRxiv2026

Mucosally sourced complement factor B modulates the host response to colitis

Distinct host factors maintain intestinal homeostasis but are incompletely understood. The complement system is primarily liver-derived and serum-operative. However, there is growing recognition for complement-mediated host defense at mucosal surfaces. The alternative pathway, which is constitutively active at low levels and amplifies complement activation independent of antibodies, requires Complement Factor B (CFB). Despite its evolutionary conservation, the spatial, cellular, and functional roles of CFB in the intestine are poorly understood. Here, we show that CFB is produced in the human colon and is increased in patients with active inflammatory bowel disease. To isolate the role of local CFB in mucosal responses, we interrogated a mouse strain that has no circulating, liver-derived CFB but retains intact CFB expression in the gut. Global CFB-deficient mice succumb to colitis compared to these liver-specific knockout mice, suggesting that locally synthesized CFB mitigates colitis. Single-cell analyses identify enterocytes and fibroblasts as key CFB producers in the gut. Compartment-specific deletion of CFB from epithelial or stromal cells abrogates mucosal protection independent of circulating levels, which corroborates with pharmacological CFB inhibition. These findings redefine complement in the intestine as a locally regulated mucosal defense system and establish gut-derived CFB as a critical determinant of intestinal homeostasis. BRIEF SUMMARYThe role of local immune mediators in gut mucosal immune responses is still not entirely understood. In this study, we demonstrate a novel role for complement protein Factor B, a key component of the alternative pathway, which is locally sourced through epithelial and stromal cells. In vivo modeling of impaired local Factor B synthesis results in worse colitis, revealing a key role for mucosal sourced components of the alternative pathway.

immunology↗

bioRxiv2025

IL-9 as a naturally orthogonal cytokine with optimal JAK/STAT signaling for engineered T cell therapy

Arming T cells with a synthetically orthogonal IL-9 receptor (o9R) permits facile engraftment and potent anti-tumor functions. We considered whether the paucity of natural IL-9R expression could be exploited for T cell immunotherapy given that, in mice, high doses of IL-9 were well-tolerated without discernible immune modulation. Compared to o9R, T cells engineered with IL-9R exhibit superior tissue infiltration, stemness, and anti-tumor activity. These qualities are consistent with a stronger JAK/STAT signal, which in addition to STAT1/3/5, unexpectedly includes STAT4 (canonically associated with IL-12 but not common {gamma}-chain cytokines). IL-9R T cells are exquisitely sensitive to perturbations of proximal signaling, including structure-guided attenuation, amplification, and rebalancing of JAK/STAT signals. Biased IL-9R mutants uncover STAT1 as a rheostat between proliferative stem-like and terminally differentiated effector states. In summary, we identify native IL-9/IL-9R as a natural cytokine-receptor pair with near-orthogonal qualities and an optimal JAK/STAT signaling profile for engineered T cell therapy.

immunology↗

bioRxiv2024

Stage-specific CAR-mediated signaling generates naive-like, TCR-null CAR T cells from induced pluripotent stem cells

Genetically modified, induced pluripotent stem cells (iPSCs) offer a promising allogeneic source for the generation of functionally enhanced, chimeric antigen receptor (CAR) T cells. However, the signaling of CARs during early T cell development and the removal of the endogenous T cell receptor required to prevent alloreactivity pose significant challenges to the production of mature conventional CAR T cells from iPSCs. Here, we show that TCR-null, CD8{beta} CAR T cells can be efficiently generated from iPSCs by engineering stage-specific onset of CAR expression and signaling to both permit conventional T cell development and to induce efficient positive selection. CAR T cells produced using this approach displayed a uniform, naive T cell phenotype and demonstrated superior antigen-specific cytotoxicity compared to iPSC-derived effector memory CAR T cells. Multimodal sequencing revealed CAR-mediated positive selection induced the persistent upregulation of key transcription factors involved in naive T cell development. Achieving precise control of CAR expression and signaling in developmentally sensitive T precursors will be critical to realizing the full potential for "off-the-shelf", iPSC-derived cellular therapies.

bioengineering↗