Head and Neck Medicine by Alexandros G.Sfakianakis

Author(s): Fiona Moghaddas, Ping Zeng, Yuxia Zhang, Heike Schützle, Sebastian Brenner, Sigrun R. Hofmann, Reinhard Berner, Yuanbo Zhao, Bingtai Lu, Xiaoyun Chen, Li Zhang, Suyun Cheng, Stefan Winkler, Kai Lehmberg, Scott W. Canna, Peter E. Czabotar, Ian P. Wicks, Dominic De Nardo, Christian M. Hedrich, Huasong Zeng

Background

Monogenic autoinflammatory disorders are characterized by dysregulation of the innate immune system, for example by gain-of-function mutations in inflammasome-forming proteins, such as NOD-like receptor family CARD-containing 4 protein (NLRC4).

Objective

Here we investigate the mechanism by which a novel mutation in the leucine-rich repeat (LRR) domain of NLRC4 (c.G1965C, p.W655C) contributes to autoinflammatory disease. Methods: We studied 2 unrelated patients with early-onset macrophage activation syndrome harboring the same de novo mutation in NLRC4. In vitro inflammasome complex formation was quantified by using flow cytometric analysis of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 techniques and lentiviral transduction were used to generate THP-1 cells with either wild-type or mutant NLRC4 cDNA. Cell death and release of IL-1β/IL-18 were quantified by using flow cytometry and ELISA, respectively.

Results

The p.W655C NLRC4 mutation caused increased ASC speck formation, caspase-1–dependent cell death, and IL-1β/IL-18 production. ASC contributed to p.W655C NLRC4–mediated cytokine release but not cell death. Mutation of p.W655 activated the NLRC4 inflammasome complex by engaging with 2 interfaces on the opposing LRR domain of the oligomer. One key set of residues (p.D1010, p.D1011, p.L1012, and p.I1015) participated in LRR-LRR oligomerization when triggered by mutant NLRC4 or type 3 secretion system effector (PrgI) stimulation of the NLRC4 inflammasome complex.

Conclusion

This is the first report of a mutation in the LRR domain of NLRC4 causing autoinflammatory disease. c.G1965C/p.W655C NLRC4 increased inflammasome activation in vitro. Data generated from various NLRC4 mutations provides evidence that the LRR-LRR interface has an important and previously unrecognized role in oligomerization of the NLRC4 inflammasome complex.

Graphical abstract

Graphical abstract for this article

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A burning need to redefine airways disease: Biomass smoke exposure identified as a unique risk factor for ACO in low- and middle- income countries

Publication date: Available online 5 December 2018

Source: Journal of Allergy and Clinical Immunology

Author(s): Amir A. Zeki, Cameron H. Flayer, Angela Haczku

https://ift.tt/2SyPDTC

Role of human forkhead box P3 in early thymic maturation and peripheral T-cell homeostasis

Publication date: December 2018

Source: Journal of Allergy and Clinical Immunology, Volume 142, Issue 6

Author(s): Francesca R. Santoni de Sio, Laura Passerini, Silvia Restelli, Maria Maddalena Valente, Aleksandar Pramov, Maria Elena Maccari, Francesca Sanvito, Maria Grazia Roncarolo, Matthew Porteus, Rosa Bacchetta

Background

Forkhead box P3 (FOXP3) is a key transcription factor in regulatory T (Treg) cell function. FOXP3 gene mutations cause immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, a fatal autoimmune syndrome. FOXP3 has also been proposed to act in effector T (Teff) cells, but to date, this role has not been confirmed.

Objective

We sought to evaluate the effect of reduced FOXP3 expression on human Treg and Teff cell development and correlate it with IPEX syndrome immune pathology.

Methods

We developed a model of humanized mice (huMice) in which the human hematopoietic system is stably knocked down or knocked out for the FOXP3 gene (knockdown [KD]/knockout [KO] huMice).

Results

Because FOXP3-KD/KO was not 100% effective, residual FOXP3 expression in hematopoietic stem progenitor cells was sufficient to give rise to Treg cells with normal expression of FOXP3. However, numerous defects appeared in the Teff cell compartment. Compared with control mice, FOXP3-KD/KO huMice showed altered thymocyte differentiation, with KD/KO thymocytes displaying significantly reduced T-cell receptor (TCR) signaling strength and increased TCR repertoire diversity. Peripheral KD/KO Teff cells were expanded and showed signs of homeostatic proliferation, such as a significantly contracted TCR repertoire, a severely reduced naive compartment, decreased telomeric repeat-binding factor 2 expression, and a skew toward a T_H2 profile, resembling an aged immune system. Consistent with results in FOXP3-KD/KO huMice, analysis of patients with IPEX syndrome provided evidence of defects in the Teff cell compartment at both the thymic and peripheral levels.

Conclusions

These findings support an intrinsic role for human FOXP3 in controlling thymocyte maturation and peripheral expansion of Teff cells and reveal a previously undescribed pathogenic mechanism through an altered Teff cell compartment in patients with IPEX syndrome.