# PspA binds necroptotic cells to cause disease and transmit

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2020 · $407,836

## Abstract

Influenza A virus (IAV) profoundly enhances the susceptibility of lung epithelial cells for pneumolysin-mediated
necroptosis. Briefly, pneumolysin is the pore-forming toxin produced by Streptococcus pneumoniae (Spn),
whereas necroptosis is a caspase-independent form of programmed cell death that results in cell lysis. Herein,
we will determine the molecular basis and full biological consequence of a new key observation: Spn binds to
necroptotic respiratory epithelial cells via Pneumococcal surface protein A (PspA). Briefly, our
preliminary results show that PspA binds to host-derived (h)GAPDH on dying cells and this property directly
contributes to IAV/Spn disease severity. Furthermore, Spn/sloughed epithelial cell aggregates formed in the
nasopharynx likely promote Spn transmission to a naive host. Herein we test the hypothesis that during
IAV/Spn superinfection a high level of epithelial cell necroptosis occurs that promotes PspA-mediated
binding to cells. This property directly enhances Spn outgrowth and promotes Spn transmission.
AIM 1: Determine the molecular basis for PspA-mediated adhesion to necroptotic lung epithelial cells
(LEC). Spn adhesion to LEC is PspA-dependent, enhanced when cells undergo necroptosis, and mediated by
PspA binding to hGAPDH found on the surface of dying cells. We will identify the domain of PspA responsible
for hGAPDH binding, how conserved this domain is across sequenced strains of Spn, and the affinity of
representative PspA variants to hGAPDH. We will create and test the ability of isogenic mutants in the PspA
hGAPDH binding motif to bind dying LEC. We will identify the region of hGAPDH that is bound by PspA.
AIM 2: Determine the biological impact of PspA-mediated adhesion on IAV/Spn pneumonia severity.
PspA is required for the enhanced disease severity that occurs during IAV superinfection. We will determine if
hGAPDH binding alters the canonical role of PspA, which is inhibiting lactoferricin-mediated killing. We will
determine how PspA-binding influences the localization of Spn within the airway and how this is impacted by
co-infection with IAV, neutralization of pneumolysin, or blocking of necroptosis. We will determine if PspA-
mediated binding of Spn to dying LEC promotes their outgrowth in otherwise nutrient restricted conditions. We
will determine how antibody against the hGAPDH-binding motif of PspA alters overall disease progression.
AIM 3: Determine the requirement of PspA mediated adhesion to colonization and transmission. Spn
binds to dying mucosal epithelial cells during colonization and they are together expelled in nasal secretions.
Sloughed Spn/host cell aggregates are infectious and thought to promote Spn survival on fomites. We will
determine the requirement for PspA on the formation of Spn/host cell aggregates, moreover, how pneumolysin,
IAV superinfection, and necroptosis inhibition influences their number in secretions. We will determine the
requirement of PspA hGAPDH binding for transmiss...

## Key facts

- **NIH application ID:** 10133428
- **Project number:** 1R01AI156898-01
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** Carlos J Orihuela
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $407,836
- **Award type:** 1
- **Project period:** 2020-09-24 → 2025-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10133428

## Citation

> US National Institutes of Health, RePORTER application 10133428, PspA binds necroptotic cells to cause disease and transmit (1R01AI156898-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10133428. Licensed CC0.

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