Pfit is a structurally novel Crohn's disease-associated superantigen

The Immunologic Profiles of Kawasaki Disease Triggered by Mycoplasma pneumoniae Infection

OBJECTIVE

We compared the immunologic characteristics of mycoplasma pneumoniae-triggered Kawasaki disease (MP-KD) with Kawasaki disease (KD) not associated with mycoplasma pneumoniae (MP), with mycoplasma pneumoniae-triggered Henoch-Schönlein purpura (MP-HSP), and with healthy controls.

METHODS

Complement levels, cellular and humoral immunity were assessed in KD, in MP-KD, in MP-HSP, and in healthy children.

RESULTS

Of 622 children with KD, 74 had MP-KD. Complement C3 and CD4/CD8 ratio were significantly increased in MP-KD compared to KD. C3, C4, and the ratio of CD4/CD8 in the MP-KD group were higher than those in the MP-HSP group. IgA and CD56 were lower in the MP-KD group than the MP-HSP group.

CONCLUSIONS

Both C3 and polyclonal CD4+ T lymphocytes may be activated in the patients with MP-KD.

Autoimmunity and the microbiome: T-cell receptor mimicry of "self" and microbial antigens mediates self tolerance in holobionts: The concepts of "holoimmunity" (TcR-mediated tolerance for the holobiont) and "holoautoimmunity" (loss of tolerance for the holobiont) are introduced

I propose a T-cell receptor (TcR)-based mechanism by which immunity mediates both "genetic self" and "microbial self" thereby, connecting microbiome disease with autoimmunity. The hypothesis is based on simple principles. First, TcR are selected to avoid strong cross-reactivity with "self," resulting in selection for a TcR repertoire mimicking "genetic self." Second, evolution has selected for a "microbial self" that mimics "genetic self" so as to share tolerance. In consequence, our TcR repertoire also mimics microbiome antigenicity, providing a novel mechanism for modulating tolerance to it. Also, the microbiome mimics the TcR repertoire, acting as a secondary immune system. I call this TcR-microbiome mimicry "holoimmunity" to denote immune tolerance to the "holobiont self." Logically, microbiome-host mimicry means that autoimmunity directed at host antigens will also attack components of the microbiome, and conversely, an immunological attack on the microbiome may cross-react with host antigens producing "holoautoimmunity."

Comparative genomics of Pseudomonas fluorescens subclade III strains from human lungs

Background

While the taxonomy and genomics of environmental strains from the P. fluorescens species-complex has been reported, little is known about P. fluorescens strains from clinical samples. In this report, we provide the first genomic analysis of P. fluorescens strains in which human vs. environmental isolates are compared.

Results

Seven P. fluorescens strains were isolated from respiratory samples from cystic fibrosis (CF) patients. The clinical strains could grow at a higher temperature (>34 °C) than has been reported for environmental strains. Draft genomes were generated for all of the clinical strains, and multi-locus sequence analysis placed them within subclade III of the P. fluorescens species-complex. All strains encoded type- II, −III, −IV, and -VI secretion systems, as well as the widespread colonization island (WCI). This is the first description of a WCI in P. fluorescens strains. All strains also encoded a complete I2/PfiT locus and showed evidence of horizontal gene transfer. The clinical strains were found to differ from the environmental strains in the number of genes involved in metal resistance, which may be a possible adaptation to chronic antibiotic exposure in the CF lung.

Conclusions

This is the largest comparative genomics analysis of P. fluorescens subclade III strains to date and includes the first clinical isolates. At a global level, the clinical P. fluorescens subclade III strains were largely indistinguishable from environmental P. fluorescens subclade III strains, supporting the idea that identifying strains as ‘environmental’ vs ‘clinical’ is not a phenotypic trait. Rather, strains within P. fluorescens subclade III will colonize and persist in any niche that provides the requirements necessary for growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2261-2) contains supplementary material, which is available to authorized users.