Distinctive gut microbiomes of ankylosing spondylitis and inflammatory bowel disease patients suggest differing roles in pathogenesis and correlate with disease activity

BACKGROUND

Multiple studies have confirmed dysbiosis in ankylosing spondylitis (AS) and inflammatory bowel disease (IBD); however, due to methodological differences across studies, it has not been possible to determine if these diseases have similar or different gut microbiomes.

RESULTS

In this study, faecal and intestinal biopsies were obtained from 33 Australian AS patients (including 5 with concomitant IBD, 'AS-IBD'), 59 IBD patients and 105 healthy controls. Stool samples were also obtained from 16 Italian AS patients and 136 Swedish AS patients. Focusing on the Australian cohort, AS, AS-IBD and IBD patients differed from one another and from healthy controls in both alpha and beta diversity. AS patients with and without clinical IBD could be distinguished from one another with moderate accuracy using stool microbiome (AUC=0.754). Stool microbiome also accurately distinguished IBD patients from healthy controls (AUC=0.757). Microbiome composition was correlated with disease activity measured by BASDAI and faecal calprotectin (FCP) levels. Enrichment of potentially pathogenic Streptococcus was noted in AS, AS-IBD and IBD patients. Furthermore, enrichment of another potentially pathogenic genus, Haemophilus, was observed in AS, AS-IBD, IBD, AS patients with increased BASDAI, and IBD patients with faecal calprotectin >100 μg/mg. Apart from these genera, no other taxa were shared between AS and IBD patients.

CONCLUSIONS

In conclusion, the distinct gut microbiome of AS and AS-IBD patients compared to IBD patients and healthy controls is consistent with immunological and genetic evidence suggesting that the gut plays a different role in driving AS compared with IBD. However, enrichment of two potentially pathogenic genera in both diseases suggests that the presence of a shared/common microbial trigger of disease cannot be discounted.

SAT0361 HEALTHY HUMAN SPINAL PROCESSES PERI-ENTHESEAL T-CELLS EXHIBIT A TR1 RATHER THAN A FOXP3 REGULATORY PHENOTYPE

Background:

We have previously reported that the normal spinal enthesis has populations of conventional T-cells including CD4+ & CD8+ T-cells that could be induced to produce IL-17A and TNF following anti-CD3/CD28 stimulation. The biology of such cells in health including their normal function and antigen reactivity is completely unknown. The purpose of this work was to define the phenotype, functionality and TCR reactivity of such T-cells in health.

Objectives:

To investigate whether the T-cells at the normal enthesis were regulatory in nature and to determine the type of regulatory T-cell as Tr1 or FOXP3 regulatory T-cell and to determine T-cell reactivity.

Methods:

Healthy interspinous ligament and spinous process with matched peripheral blood were harvested from patients undergoing elective spinal surgery (n=20). Entheseal soft tissue (EST) & peri-entheseal bone (PEB) was enzymatically digested and then sorted. Tr1 and Treg phenotypes were investigated using flow cytometry. Analysis of cytokines, growth factors and chemokines was performed by qRT-PCR, ELISA and flow cytometry. TCR sequencing was performed and a search for putative T-cell reactivity was done using TCR3 database.

Results:

Pro-inflammatory cytokine transcripts including IL-17A, IL-17F, IL-22, IL-23 (p19) & TNF were very low or undetectable in the Enthesis T-cells (Fig 1). Flow cytometry confirmed entheseal T-cells had a Tr1 phenotype (CD4+ LAG3+ CD49b+). Intracellular flow cytometry showed enthesis T-cells had very low FOXP3 expression, when compared to their blood counterparts. Intracellular flow cytometry and gene expression showed high basal expression of growth factors and regulatory proteins such as IL-10 & TGFβ, when compared to blood T-cells. RNA-Seq data, showed 13 potential TCR clonal sequences the most common of which are predicted to be reactive viral infection was CMV present in 8 sequences and Influenza A virus present in 2 sequences.

Conclusion:

The healthy human enthesis has regulatory T-cells of a Tr1 phenotype rather than a FOXP3 Treg phenotype. Many clones have antigen specificity indicating reactivity to prior infection. These findings suggest that conventional entheseal T-cells have a role in enthesis immune homeostasis.

Disclosure of Interests:

Hannah Rowe Grant/research support from: Novartis UK Investigator Initiated non-clinical research funding support, Abdulla Watad: None declared, Tobias Russell Grant/research support from: Novartis UK Investigator Initiated non-clinical research funding support, Kassem Sharif: None declared, Darren Newton: None declared, Miriam Wittmann: None declared, Qiao Zhou Grant/research support from: Funded by the PARTNER fellowship program, Almas Khan: None declared, Peter Loughenbury: None declared, Robert Dunsmuir: None declared, Abhay S Rao: None declared, Peter Millner: None declared, Tony Kenna: None declared, Matthew Brown: None declared, Charlie Bridgewood: None declared, Dennis McGonagle Grant/research support from: Janssen Research & Development, LLC

A potent nonporphyrin class of photodynamic therapeutic agent: cellular localisation, cytotoxic potential and influence of hypoxia

We have developed a totally new class of nonporphyrin photodynamic therapeutic agents with a specific focus on two lead candidates azadipyrromethene (ADPM)01 and ADPM06. Confocal laser scanning microscopy imaging showed that these compounds are exclusively localised to the cytosolic compartment, with specific accumulation in the endoplasmic reticulum and to a lesser extent in the mitochondria. Light-induced toxicity assays, carried out over a broad range of human tumour cell lines, displayed EC₅₀ values in the micro-molar range for ADPM01 and nano-molar range for ADPM06, with no discernable activity bias for a specific cell type. Strikingly, the more active agent, ADPM06, even retained significant activity under hypoxic conditions. Both photosensitisers showed low to nondeterminable dark toxicity. Flow cytometric analysis revealed that ADPM01 and ADPM06 were highly effective at inducing apoptosis as a mode of cell death. The photophysical and biological characteristics of these PDT agents suggest that they have potential for the development of new anticancer therapeutics.

Creatine kinase release not associated with myocardial necrosis after short periods of coronary artery occlusion in conscious baboons

The effects of 15 minute periods of coronary artery occlusion on plasma creatine kinase (CK) and CK-MB isoenzyme activity, regional myocardial function and subsequent myocardial necrosis were studied in six conscious baboons 2 to 3 weeks after recovery from instrumentation. Mid left anterior descending coronary artery occlusion induced complete loss of systolic wall thickening (ultrasound transit time technique) and decreases in epicardial (-93%) and endocardial (-96%) blood flows (microsphere technique). Reperfusion after 15 minutes resulted in complete recovery of regional function 24 hours later. Serial plasma enzyme activity revealed a significant increase in total CK from 71 +/- 11 to 976 +/- 158 U/liter and in CK-MB from levels that were too low to measure to 21.4 +/- 2.9 U/liter. At autopsy, neither gross pathologic evidence (triphenyltetrazolium chloride staining technique) nor histologic evidence of myocardial necrosis was observed. Thus, in the conscious baboon short episodes of myocardial ischemia are associated with a significant appearance of CK and CK-MB in the blood in the absence of cellular necrosis.