Biology subjects

Hand, T. W.

Publications and source records attributed to Hand, T. W..

4 recordsLinked to original sources

bioRxiv2025

Single-cell quantification of the microbiota by flow cytometry: MicFLY

The intestinal microbiota regulates multiple host functions, including digestion and immune development. Our knowledge of the microbiota has been shaped by available technology that primarily measures relative abundance. However, understanding the basis of shifts in microbiota composition requires single cell, absolute abundance measurements. In response to this problem, we developed Microbiota Flow Cytometry (MicFLY), a single cell technology that directly quantifies and characterizes total bacterial abundances with species-level resolution in the microbiota. Using MicFLY, we can identify all major intestinal taxa, discriminate live from dead bacteria, perform single cell measurements of heterogeneous bacterial mRNA expression and concurrently quantify Immunoglobulin (Ig) A and G binding to intestinal bacteria. Using longitudinal species-resolved, quantitative analysis of the preterm infant microbiota, we identify that E. coli unbound by IgG and IgA associates with the development of necrotizing enterocolitis. The application of MicFLY single cell technology permits measurement of the microbiota at a finer scale and with deeper mechanistic understanding of compositional changes.

microbiology↗

bioRxiv2024

The microbiota extends the reproductive lifespan by safeguarding the ovarian reserve

Infertility is a devastating condition affecting one in six people globally. In many cases, the underlying causes are unknown. Emerging evidence suggests that the microbiota influences reproduction, yet the mechanistic link between the microbiota, ovarian function, and length of the fertile lifespan remain unexplored. Here we report that the microbiota controls the length of the reproductive lifespan by maintaining the primordial follicle pool, a process mediated by microbiota-derived short chain fatty acids modulating gene regulatory networks crucial for the survival of the ovarian reserve. Dietary perturbation of the microbiota during a critical developmental window is sufficient to diminish the ovarian reserve, reduce oocyte retrieval, and impair preimplantation embryo viability, mirroring challenges in human fertility treatments. Targeted interventions to restore microbiota improve assisted reproductive outcomes, particularly when implemented early. These findings reveal a novel contribution of host-microbe interactions in mammalian reproduction and demonstrate that the microbiota impacts ovarian function and fertility.

developmental biology↗

bioRxiv2023

Stability and heterogeneity in the anti-microbiota reactivity of human milk-derived Immunoglobulin A

Immunoglobulin A (IgA) is secreted into breast milk and is critical to both protecting against enteric pathogens and shaping the infant intestinal microbiota. The efficacy of breast milk-derived maternal IgA (BrmIgA) is dependent upon its specificity, however heterogeneity in BrmIgA binding ability to the infant microbiota is not known. Using a flow cytometric array, we analyzed the reactivity of BrmIgA against bacteria common to the infant microbiota and discovered substantial heterogeneity between all donors, independent of preterm or term delivery. We also observed intra-donor variability in the BrmIgA response to closely related bacterial isolates. Conversely, longitudinal analysis showed that the anti-bacterial BrmIgA reactivity was relatively stable through time, even between sequential infants, indicating that mammary gland IgA responses are durable. Together, our study demonstrates that the anti-bacterial BrmIgA reactivity displays inter-individual heterogeneity but intra-individual stability. These findings have important implications for how breast milk shapes the development of the infant microbiota and protects against Necrotizing Enterocolitis. SummaryWe analyze the ability of breast milk-derived Immunoglobulin A (IgA) antibodies to bind the infant intestinal microbiota. We discover that each mother secretes into their breast milk a distinct set of IgA antibodies that are stably maintained over time.

immunology↗

bioRxiv2020

Enteropathy-induced regulatory T cells inhibit intestinal CD4+ T cell responses against oral vaccines

Environmental Enteric Dysfunction (EED) is an intestinal disease caused by malnutrition and infection that leads to malabsorption and stunting. EED is also associated with a reduced efficacy of oral vaccines. We show in a microbiota and diet-dependent model of EED that oral vaccine-specific CD4+ T cell responses fail in the small intestine but responses in the draining lymph node were unaffected. Accordingly, the number of immunosuppressive ROR{gamma}T+FOXP3+ Tregs in the small intestine inversely correlated with the response to oral vaccination. Depletion of ROR{gamma}T+FOXP3+ Tregs indicated that they were necessary for EED-associated inhibition of the vaccine response. Additionally, ROR{gamma}T+FOXP3+ Tregs are important to regulate EED-associated inflammation as their depletion significantly worsened stunting. We have shown that EED-associated intestinal inflammation leads to a localized intestinal blockade of CD4 T cell immunity. These results support a modular model for immunity where tissue responses can be regulated independently of systemic immunity to prevent autoinflammation.

immunology↗