HtrA, fatty acids, and membrane protein interplay in Chlamydia trachomatis to impact stress response and trigger early cellular exit

Chlamydia trachomatis is an intracellular bacterial pathogen that undergoes a biphasic developmental cycle, consisting of intracellular reticulate bodies and extracellular infectious elementary bodies. A conserved bacterial protease, HtrA, was shown previously to be essential for Chlamydia during the reticulate body phase, using a novel inhibitor (JO146). In this study, isolates selected for the survival of JO146 treatment were found to have polymorphisms in the acyl-acyl carrier protein synthetase gene (aasC). AasC encodes the enzyme responsible for activating fatty acids from the host cell or synthesis to be incorporated into lipid bilayers. The isolates had distinct lipidomes with varied fatty acid compositions. A reduction in the lipid compositions that HtrA prefers to bind to was detected, yet HtrA and MOMP (a key outer membrane protein) were present at higher levels in the variants. Reduced progeny production and an earlier cellular exit were observed. Transcriptome analysis identified that multiple genes were downregulated in the variants especially stress and DNA processing factors. Here, we have shown that the fatty acid composition of chlamydial lipids, HtrA, and membrane proteins interplay and, when disrupted, impact chlamydial stress response that could trigger early cellular exit.

IMPORTANCE

Chlamydia trachomatis is an important obligate intracellular pathogen that has a unique biphasic developmental cycle. HtrA is an essential stress or virulence protease in many bacteria, with many different functions. Previously, we demonstrated that HtrA is critical for Chlamydia using a novel inhibitor. In the present study, we characterized genetic variants of Chlamydia trachomatis with reduced susceptibility to the HtrA inhibitor. The variants were changed in membrane fatty acid composition, outer membrane proteins, and transcription of stress genes. Earlier and more synchronous cellular exit was observed. Combined, this links stress response to fatty acids, membrane proteins, and HtrA interplay with the outcome of disrupted timing of chlamydial cellular exit.

POS0484 LUNG ORGANOIDS: A NOVEL APPROACH TO STUDY THE MOLECULAR PATHOLOGY OF PULMONARY FIBROSIS IN SYSTEMIC SCLEROSIS

Background

Pulmonary fibrosis is one of the major manifestations in Systemic Sclerosis (SSc) associated with high mortality. Mesenchymal transformation of the airway epithelial cells has been implicated as one of the causes for developing pulmonary fibrosis. Though several animal models shed light towards some of these aspects, an in vitro airway epithelial model would provide a novel experimental platform for the understanding and molecular and genetic changes that occur in SSc associated pulmonary fibrosis.

Objectives

To establish a functional model for airway epithelium from patient with diffuse cutaneous SSc (dSSc)and healthy volunteers derived nasal stem cells. Subsequently to induce Epithelial Mesenchymal transformation (EMT).

Methods

Nasal stem cells harvested from healthy volunteers(HV) and dSSc patients were differentiated into ciliated airway epithelium in an Air -Liquid Interface (ALI) using a transwell system. 4 HV cultures were then stimulated with TGF beta (5ug/ml) for 10 days at a basal stage and when differentiated. Markers of mesenchymal transformation including loss of E cadherin, and gain of N cadherin, fibronectin and vimentin were analysed by flow cytometry and image stream, and mean expression intensities given as (MFI). Secreted Type 1 collagen and fibronectin were measured by ELISA.

Results

Ciliated epithelial cultures could successfully be established from nasal stem cells (Figure 1).

TGF beta induced a phenotypic change in the epithelial cells towards a mesenchymal one in HV cultures. This was observed by significantly increased expression of fibronectin and vimentin and loss of expression of E cadherin on the ciliated cells with 7 days of stimulation with TGF beta at a basal stage (Figure 1b). When cells, stimulated with TGF beta for 7 days, were analysed at Day 35 a similar trend was seen in their Delta MFI (Figure 1c). Stimulating the ALI cultures with TGF beta for 20 days completely repressed epithelial cell growth and disrupted their microstructure.

Figure 1.

Conclusion

This novel ALI differentiated Airway epithelial model serves as a functional organoid to test various pulmonary manifestations of Systemic Sclerosis. The ability to induce Epithelial Mesenchymal Transformation of these cultures provides a proof of concept for TGF beta mediated fibrosis in dSSc. Moreover, this model can be utilized to explore, at the cell and molecular level, the impact of various autoantibodies and therapeutics on epithelial cells.

References

[1]Mehmet Kesimer,1 Sara Kirkham,2 Raymond J. Pickles,3 Ashley G. Henderson,4 Neil E. Alexis,5 Genevieve DeMaria,1 David Knight,2 David J. Thornton,2 and John K. Sheehan1 Tracheobronchial air-liquid interface cell culture: a model for innate mucosal defense of the upper airways?; Am J Physiol Lung Cell Mol Physiol 296: L92–L100, 2009

Disclosure of Interests

None declared.

POS0481 DEFINING DISTINCT RESIDENT AND MIGRATORY FIBROBLAST POPULATIONS FROM SKIN BIOPSIES IN SYSTEMIC SCLEROSIS

Background

Recent studies using single cell RNA sequencing have delineated distinct subpopulations of fibroblasts in skin and other organs. To improve understanding of functional differences between fibroblast subpopulations, we have developed a novel technique to selectively isolate “migratory” fibroblasts, and non-migratory “resident” fibroblasts from heathy control (HC) and SSc skin.

Objectives

To compare migratory and resident populations of dermal fibroblasts in systemic sclerosis by their differential gene or protein expression, and through functional assays of fibrotic potential.

Methods

Forearm skin punch biopsies were collected from dcSSc(n=3), and healthy control skin(n=3).

Migratory fibroblasts were first isolated by standard explant culture, then the residual biopsy fragments underwent collagenase digestion to yield a population of resident fibroblasts that retained in the biopsy fragments. These populations were further expanded for use at passage 3-6.

Functional characterisation included 3-D collagen gel contraction, and migratory scratch-wound assays. Expression of pro-collagen I (Col1), CTGF and αSMA was compared by western blot. Bulk RNAseq on each fibroblast population was performed. Statistical analysis was carried out using Rsoftware “tidyverse”. Criteria for significant differences in gene expression were a fold change of ≥1.5, and adjusted p-value (FDR) of <0.05

Results

Compared with HC, all SSc fibroblast populations showed a hallmark fibrotic phenotype with increased gel contraction, faster migration, and overexpression of Col1, CTGF and αSMA compared with HC. However, SSc resident fibroblasts showed attenuated contraction, migration, and reduced levels of αSMA compared to migratory SSc fibroblasts. Bulk RNAseq performed on each fibroblast population confirmed 5579 significantly differentially expressed genes between SSc resident and SSc migratory fibroblasts, whereas no genes were significantly differentially expressed between HC resident and migratory fibroblasts.

SSc and HC migratory fibroblasts and resident fibroblasts were then compared, to understand disease-related differences between the two fibroblast populations. 739 genes were significantly overexpressed in the migratory fibroblast population (including ASPM, TRIP3), whereas 745 genes were significantly upregulated in the resident fibroblast population. The genes upregulated in resident fibroblasts included CCL2, CXCL8, and ICAM1.

Many genes typically associated with SSc (such as SERPINE1, COMP), were not significantly different between the SSc fibroblast subpopulations, but were significantly elevated in both SSc subpopulations compared to HC fibroblast populations, suggesting that these reflect a more generic SSc phenotype.

Conclusion

Migratory and resident SSc fibroblast populations exhibit distinct functional and transcriptional differences that are much less apparent for HC biopsies. Further work is required to understand the precise contribution these distinct SSc fibroblast populations in pathogenesis, and how they might be targeted therapeutically. Our findings also highlight that conventional explant culture techniques may ignore important fibroblasts populations and highlight the importance of more detailed analysis such as single cell analysis to better understand pathobiology of SSc.

Table 1.

Table of the most significantly differentially expressed genes with highest fold change and adjusted p-value (FDR) between the migratory and resident SSc fibroblast population

Significantly upregulated genes in SSc migratory fibroblastsSignificantly upregulated genes in SSc resident fibroblastsFold changeAdjusted p valueFold changeAdjusted p valueGPR15.990.01CCL238.66<0.0001PPME14.860.011CXCL824.360.0001KIF20A4.340.015ICAM115.38<0.0001CENPF4.310.018EGR115.190.0002STC24.180.01EGR212.770.0002ASPM3.880.02IFI44L11.50.002TRIB33.600.011CXCL611.43<0.0001HAPLN13.360.039PDGF-D10.140.0003CCNB23.290.025OAS38.940.0009KIF143.240.027IFIT18.580.004

Disclosure of Interests

Kristina Clark: None declared, Alice Cole: None declared, Xu Shiwen: None declared, Voon Ong: None declared, Christopher D Buckley Employee of: founder of Mestag Therapeutics https://mestagtherapeutics.com/, Christopher P Denton: None declared.

AB0557 CO-EXISTENCE OF SYSTEMIC SCLEROSIS HALLMARK AUTOANTIBODIES ASSOCIATES WITH DISTINCT CLINICAL PHENOTYPE

Background:

Systemic sclerosis (SSc) is typically manifests with distinct SSc-specific antibodies (SSc-Abs): anti-topoisomerase I (ATA), anti-centromere (ACA), anti-RNA polymerase III (ARA), anti-U3RNP (u3RNP), anti-U1RNP (U1RNP), anti-PmScl (PmScl), anti-Ku (Ku) and anti-Th/T0 (Th/T0), each being characterised by different clinical features and prognosis. The presence of >1 SSc-Abs is rare with minimum data about these patients’ clinical phenotype.

Objectives:

To describe and compare the clinical features of SSc patients with >1 SSc-Ab

Methods:

The autoantibody profiles of 2799 SSc patients from February 2001 to June 2017 were retrospectively reviewed. Patients with >1 SSc-Abs were identified. Clinical features were collected and compared to historical cohorts of SSc patients with single SSc-Ab positivity. Patients were excluded if treated prior to their immunology test with rituximab, iv immunoglobulins or stem cell transplantation. Statistical analysis was performed using Fisher exact test.

Results:

72 patients (2.6%) with >1 SSc-Ab were identified. Full clinical data were available for 63 patients. 60 patients (2.1%) had double Ab positivity and 3 patients had triple Ab positivity (0.1%). 13 Ab combinations were present. U1RNP and ATA was the most frequent combination (35%), patients were significantly younger (51.38 years) than both U1RNP (58.64 years, p=0.050) and ATA (62.03 years, p=0.002) patients and more commonly of diffuse subset (dcSSc) (p=0.001 and p=0.041 respectively). Compared to ATA patients overlap features were more frequent (43% vs 15%, p=0.004) including inflammatory arthritis (p=0.025) and myositis (p=0.013) (Table 1). U1RNP and ACA had a significantly higher prevalence of pulmonary arterial hypertension compared to U1RNP (p=0.039) and ACA (p=0.022) patients, and compared to ACA patients they were younger (57.88 vs 68.75, p=0.015) with a higher incidence of myositis (p=0.001). U1RNP and ARA patients were more frequently dcSSc subtype compared to U1RNP patients (75% vs 21%, p=0.040). U1RNP and PmScl patients had a higher prevalence of myositis compared to U1RNP patients (p=0.006). ATA and ACA patients behaved similarly to ATA patients with a significantly higher prevalence of lung fibrosis (p=0.006) and myositis (p=0.041) compared to ACA. ACA and PmScl (7%) had higher prevalence of myositis compared to ACA patients (p=0.04).

Table 1. Frequency of clinical features in some of the double antibody group combinations, compared to our cohort of patients with only one of the SSc specific antibody. Significant p values (<0.05) highlighted in bold. ILD (interstitial lung disease), PAH (pulmonary arterial hypertension), SRC (scleroderma renal crisis).

Conclusion:

Coexistence of hallmark autoantibodies is exceedingly rare in SSc patients. When combined, both SSc-Abs have the potential to synergistically interact and modify the clinical phenotype.

Disclosure of Interests:

Corrado Campochiaro Speakers bureau: Novartis, Pfizer, Roche, GSK, SOBI, Kristina Clark: None declared, Lauren Host: None declared, Alper Sari: None declared, Svetlana Nihtyanova: None declared, Christopher Denton Grant/research support from: GlaxoSmithKline, CSL Behring, and Inventiva, Consultant of: Medscape, Roche-Genentech, Actelion, GlaxoSmithKline, Sanofi Aventis, Inventiva, CSL Behring, Boehringer Ingelheim, Corbus Pharmaceuticals, Acceleron, Curzion and Bayer, Voon Ong: None declared

The myth of pulmonary Raynaud's phenomenon: the contribution of pulmonary arterial vasospasm in patients with systemic sclerosis related pulmonary arterial hypertension

OBJECTIVE

To investigate the contribution of cold induced pulmonary vasospasm by peripheral and central cold stimulus in exacerbating pulmonary arterial hypertension (PAH) in patients with systemic sclerosis undergoing cardiac catheterisation.

METHODS

In a prospective pilot study, 21 patients with systemic sclerosis and catheter proven PAH had mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), and cardiac output (CO) measured before and after peripheral (hand immersion into cold water at 10-15 degrees C for two minutes if tolerated) and central (direct cold water at 4 degrees C injected into the right atrium) cold pressor challenge. Markers of endothelial activation, platelet function, and nitric oxide degradation were measured in blood sampled from the pulmonary artery.

RESULTS

19 of the patients (mean (SD) age, 56 (4) years; baseline mPAP, 34 (8) mm Hg; PVR, 420 (87) dyne.s.cm(-5); CO, 6.4 (1.8) l/min) tolerated cold hand immersion for the maximum two minute duration. All 21 tolerated central cold pressor challenge (three to five injections of 10 ml saline boluses at 4 degrees C). There was no significant change in haemodynamics after cold challenge by either route of provocation. Levels of endothelin-1, von Willebrand factor, fibrinogen, and 3-nitrotyrosine were raised compared with control values in patients with systemic sclerosis but without PAH, but did not change significantly after peripheral cold challenge.

CONCLUSIONS

Pulmonary vasospasm in response to peripheral and centrally administered cold pressor challenge is unlikely to contribute to persistence of pulmonary arterial hypertension in patients with systemic sclerosis.

Molecular basis of androgen receptor diseases

androgens act through a single intracellular androgen receptor (AR) which is encoded by a single-copy gene in the X chromosome. Disruption of the AR by genetic mutation results in complete androgen insensitivity syndrome (CAIS) and the female phenotype in otherwise healthy 46XY individuals. Although CAIS is the best known phenotype, recent studies from our laboratory and elsewhere show that malfunction of the AR is associated with many androgen-regulated diseases or conditions that cross traditional clinical disciplines ranging from paediatrics (ambiguous genitalia), gynaecology (primary amenorrhoea), urology (prostate cancer), neurology (spinal bulbar muscular atrophy), reproductive medicine (male infertility), orthopedics (rheumatoid arthritis), oncology (breast cancer) and dermatology (hirsutism, baldness and acne). Of particular interest are the roles that polymorphic CAG trinucleotide repeat tracts and subtle mutations in the AR ligand-binding domain have in the aetiology of male infertility and prostate cancer, two conditions affecting large numbers of patients. Novel mechanisms of pathogenesis have been uncovered in these cases, and they involve defective protein-protein interactions with coregulator molecules such as TIF2 (transcriptional intermediary factor 2). Knowledge of the critical role that the AR plays in the pathogenesis of these diverse conditions has led to improved diagnostic methods and successful therapy.

Children's readiness for learning front crawl swimming

This study attempted to establish whether an optimal age could be identified at which children were ready to learn the front crawl swimming stroke. The variables examined were: the number of lessons, the age of commencing lessons and the time duration for learning to swim 10m front crawl (Level 3). Longitudinal records of 326 children, aged between 2 and 8 years, were analysed using General Linear Model two-way (Age x Sex) analysis of variance procedures. The main effect for age was significant (p < 0.001) for all three variables. Post hoc analysis revealed that the children who started at 5 years of age received significantly fewer number of lessons and took shorter duration compared to those who commenced learning to swim at an earlier age. Whether pupils started lessons at 2, 3 or 4 years of age, they achieved Level 3 at approximately the same mean age of 5 1/2 years. The optimal readiness period was identified in this study to be between 5 and 6 years of age. There was little evidence of gender differences for all three variables.