# The Role of Macrophages in Immune Responses to Giardia

> **NIH NIH R15** · GEORGETOWN UNIVERSITY · 2021 · $453,551

## Abstract

Abstract
 Giardia lamblia is the most common protozoan cause of diarrhea in the world. It infects ~500 million
people worldwide, often resulting in nutrient malabsorption which can lead to physical and cognitive
developmental defects in children. Paradoxically, recent data also indicate that the presence of Giardia is
associated with reduced levels of moderate-to-severe diarrhea in children. The infection is transmitted by
ingestion of cysts and the cyst wall contains large amounts of N-acetyl galactosamine (GalNAc) polymer. The
macrophage galactose-binding lectin (MGL) is the dominant lectin capable of recognizing GalNAc. Our
hypothesis is that recognition of cyst wall material by MGL plays a significant role in determining the outcome
of infections by modulating both innate and adaptive immune responses. Specifically, we hypothesize that
stimulation of macrophages through MGL1 potentiates the production of IL-10 in response to other activating
signals such as the presence of bacteria. This IL-10 may enhance parasite persistence, but also limits
pathology and decreases disease severity. We will address these hypotheses utilizing in vitro cultures of
macrophages derived from MGL1 deficient mice. We will also analyze infections with Giardia, alone and in
combination with another parasite known to induce severe inflammatory pathology in mice, using mice
deficient in MGL1 as well as mice lacking macrophages. We will assay the parasite burdens and markers of
pathology during infections. Bone marrow chimeras will be used to identify roles of MGL1 on specific cell types.

## Key facts

- **NIH application ID:** 10291848
- **Project number:** 2R15AI109591-03A1
- **Recipient organization:** GEORGETOWN UNIVERSITY
- **Principal Investigator:** STEVEN M SINGER
- **Activity code:** R15 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $453,551
- **Award type:** 2
- **Project period:** 2014-07-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10291848

## Citation

> US National Institutes of Health, RePORTER application 10291848, The Role of Macrophages in Immune Responses to Giardia (2R15AI109591-03A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10291848. Licensed CC0.

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