Biology subjects

Wallet, M. A.

Publications and source records attributed to Wallet, M. A..

3 recordsLinked to original sources

bioRxiv2021

Use of Induced Pluripotent Stem Cells to Build Isogenic Systems and Investigate Type 1 Diabetes

Type 1 diabetes is a disease that arises due to complex immunogenetic mechanisms. Key cell-cell interactions involved in the pathogenesis of T1D are activation of autoreactive T cells by dendritic cells (DC), migration of T cells across endothelial cells (EC) lining capillary walls into the islets of Langerhans, interaction of T cells with macrophages in the islets, and killing of {beta}-cells by autoreactive CD8+ T cells. Overall, pathogenic cell-cell interactions are likely regulated by the individuals collection of genetic T1D-risk variants. To accurately model the role of genetics, it is essential to build systems to interrogate single candidate genes in isolation during the interactions of cells that are essential for disease development. However, obtaining single-donor matched cells relevant to T1D is a challenge. Sourcing these genetic variants from human induced pluripotent stem cells (iPSC) avoids this limitation. Herein, we have differentiated iPSC from one donor into DC, macrophages, EC, and {beta}-cells. Additionally, we also engineered T cell avatars from the same donor to provide an in vitro platform to study genetic influences on these critical cellular interactions. This proof of concept demonstrates the ability to derive an isogenic system from a single donor to study these relevant cell-cell interactions. Our system constitutes an interdisciplinary approach with a controlled environment that provides a proof-of-concept for future studies to determine the role of disease alleles (e.g. IFIH1, PTPN22, SH2B3, TYK2) in regulating cell-cell interactions and cell-specific contributions to the pathogenesis of T1D.

immunology↗

bioRxiv2021

High-Yield Monocyte, Macrophage, and Dendritic Cell Differentiation from Induced Pluripotent Stem Cells

Differentiation of induced pluripotent stem cells (iPSC) into monocytes, monocyte-derived macrophages (MDM), and monocyte-derived dendritic cells (moDC) represents a powerful tool for studying human innate immunology and developing novel iPSC-derived immune therapies. Challenges include inefficiencies in iPSC-derived cell cultures, labor-intensive culture conditions, low purity of desired cell types, and feeder cell requirements. Here, a highly efficient method for differentiating monocytes, MDMs, and moDCs that overcomes these challenges is described. The process utilizes commercially-available materials to derive CD34+ progenitor cells that are apically released from a hemogenic endothelium. Subsequently, the hemogenic endothelium gives rise to highly pure (>95%), CD34-CD14+ monocytes in 19-23 days and yields 13.5-fold more monocytes by day 35 when compared to previous methods. These iPSC-monocytes are analogous to human blood-derived monocytes and readily differentiate into MDM and moDC. The efficient workflow and increase in monocyte output heightens feasibility for high throughput studies and enables clinical-scale iPSC-derived manufacturing processes.

immunology↗

bioRxiv2020

Harmine enhances the activity of the HIV-1 latency-reversing agents ingenol A and SAHA

Infection of HIV-1 remains incurable because long-lived, latently-infected cells persist during prolonged antiretroviral therapy. Attempts to pharmacologically reactivate and purge the latent reservoir with latency reactivating agents (LRAs) such as protein kinase C (PKC) agonists (e.g. ingenol A) or histone deacetylase (HDAC) inhibitors (e.g. SAHA) have shown promising but incomplete efficacy. Using the J-Lat T cell model of HIV latency, we found that the plant-derived compound harmine enhanced the efficacy of existing PKC agonist LRAs in reactivating latently-infected cells. Treatment with harmine increased not only the number of reactivated cells but also increased HIV transcription and protein expression on a per-cell basis. Importantly, we observed an additive effect when harmine was used in combination with ingenol A and the HDAC inhibitor SAHA. An investigation into the mechanism revealed that harmine, when used with LRAs, increased the availability of transcription factors needed for viral reactivation such as NF{kappa}B, MAPK p38, and ERK1/2. We also found that harmine treatment resulted in reduced expression of HEXIM1, a negative regulator of transcriptional elongation. Despite harmines reported inhibitory effects on DYRK1A and consequent enhancement of NFAT signaling, the HIV reactivating effects of harmine occurred independent of DYRK1A and NFAT. Harmine increases the efficacy of LRAs by increasing the availability of HIV-1 transcription factors and decreasing expression of HEXIM1. Combination therapies with harmine and LRAs could benefit patients by achieving deeper reactivation of the latent pool of HIV provirus.

microbiology↗