# iNKT cells hyperactivate DCs

> **NIH NIH R21** · BRIGHAM AND WOMEN'S HOSPITAL · 2020 · $211,900

## Abstract

Pathogens employ many strategies to evade immune recognition. Correspondingly, the immune system 
has evolved antigen receptors and sensors for molecular patterns to recognize microbial invasion. 
Despite these efforts, microbial detection may be inadequate and severe infection results. IL-1β
release from DCs and macrophages occurs when cytosolic microbial products or cellular stress are 
detected by specialized sensors capable of assembling into inflammasomes. An orchestrated series of 
events occurs since pro-IL-1β must be cleaved to its active form and lacking a signal peptide, must 
be released directly from the cytosol.
Inflammasome assembly results in caspase-1 activation with subsequent cleavage of pro-IL-1β, 
Gasdermin-D and pyroptotic cell lysis that releases bioactive IL-1β. However, many microbes evade 
inflammasome activation and IL-1β release.
A special group of T cells, invariant (i) NKT cells sits at the interface between innate and 
adaptive immunity. They have a semi-invariant T cell receptor that recognizes microbial or 
TLR-activated self-lipid antigens presented by CD1d on DCs. iNKT cells are “cellular adjuvants” 
because they recognize early infection, secrete high levels of cytokines, and trans-activate other 
leukocytes to amplify stronger and more rapid immune responses. Here, we define an axis in which 
iNKT cells drive IL-1β release from DCs when inflammasome activation fails. The mechanism involves 
Fas-FasL engagement that instead of apoptotic cell death, results in a special state of cellular 
activation referred to as “hyperactivation” of DCs, where sustained bioactive IL-1β release occurs 
from living cells.
In Aim 1, we determine how IL-1β is released from TLR-primed DCs following Fas ligation. We 
hypothesize that IL-1β may escape via cell membrane pores resulting from activation of gasdermins 
(besides gasdermin-D). We will use CRISPR/Cas9 and RNAi methods to delete or silence genes 
encoding various caspase and gasdermins to determine those required for pro-IL-1β cleavage, pore 
formation and release. In Aim 2, we determine how DCs escape apoptotic cell death after Fas 
ligation. Based on preliminary data, we hypothesize that this occurs by rapid proteasomal 
degradation of active caspase or gasdermin effectors. We will determine the effects of proteasome 
inhibition and which caspases and related cell death mediators become predominantly K11 and 
K48-ubiquitin-linked to learn how cell death is avoided. In Aim 3, we test commensal (B. fragilis) 
and pathogenic (C. trachomatis and S. typhimurium) live bacterial infection of DCs in vitro in the 
presence or absence of iNKT cells. Based on preliminary data that several of these infections 
result in IL-1β release only if iNKT cells are present, we will determine if the mechanism 
responsible is CD1d dependent, Fas mediated, and if bioactive IL-1β is released through membrane 
pores similar to the mechanism established in the reductionist models in Aims 1 and 2.

## Key facts

- **NIH application ID:** 9878056
- **Project number:** 5R21AI144139-02
- **Recipient organization:** BRIGHAM AND WOMEN'S HOSPITAL
- **Principal Investigator:** Michael B. Brenner
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $211,900
- **Award type:** 5
- **Project period:** 2019-02-20 → 2021-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9878056

## Citation

> US National Institutes of Health, RePORTER application 9878056, iNKT cells hyperactivate DCs (5R21AI144139-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9878056. Licensed CC0.

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