Increased Tenascin-C expression contributes to cardiac dysfunction and fibrosis in Duchenne muscular dystrophy

Introduction and aims

Cardiac fibrosis is characterized by the net accumulation of extracellular matrix (ECM) proteins in the cardiac interstitium and contributes to cardiac contractile dysfunction. In Duchenne muscular dystrophy (DMD), cardiomyopathy develops as a result of a dystrophin deficiency causing fibrofatty replacement of the myocardium, however the underlying mechanisms are not fully understood. There is a growing collection of evidence that ECM proteins, including Tenascin C (TN-C), plays a maladaptive role in left ventricular (LV) remodelling and cardiac fibrosis in ischemic heart disease. The aims of our study were 1) to assess TN-C levels, fibrosis and cardiac dysfunction in DMD patients, and 2) to clarify the role of TN-C in cardiovascular dysfunction and fibrosis using male mdx (n=10) and mdx TN-C KO mice (n=8).

Results

In male patients with DMD (n=18) and age matched controls (n=12) undergoing cardiac MRI, we detected greater myocardial fibrosis than in control hearts. In addition, we observed an elevation of TN-C plasma levels [median concentration (3.55); interquartile range (0.61–7.43) ng/mL] in DMD patients, and its expression negatively correlated to LV ejection fraction (EF) [median LVEF (45); interquartile range (37.5–51.5) %]. Male wt, mdx and mdx TN-C KO age-matched (10 months) mice were used. Transthoracic echocardiography was performed and fibrosis was assessed on cardiac tissue sections. Wire myography was used to assess vascular endothelial function. To explore the signalling pathways contributing to cardiac fibrosis, human cardiac fibroblasts (hCFs) were treated with recombinant human TN-C or TGF-β and gene expression and epigenetic regulation of NF-kB/p65 were assessed. Mdx mice showed significantly increased cardiac fibrosis which was accompanied with markedly elevated TN-C level in cardiac tissue and plasma compared to wt animals (p<0.05, respectively). Moreover, TN-C level in plasma correlated positively with the degree of cardiac dilation in dystrophic mice. In addition, vascular endothelial function was notably impaired in mdx mice. In contrast, we observed preserved vascular function in mdx- TN-C KO mice, this was accompanied by a significant reduction in cardiac fibrosis in compared to age-matched mdx mice (p<0.05, respectively). hCFs treated with TN-C or TGF-β showed increased collagen and α-SMA expressions which could be prevented by application of siRNA against TN-C. In addition, both TN-C and TGF-β caused p65/NF-κB promoter demethylation and subsequently triggered pro-inflammatory and pro-fibrotic signalling, which could be reversed by applying p38 MAPK inhibitor in hCFs.

Conclusion

TN-C is a critical component of cardiac fibrosis and cardiac dysfunction in DMD. The activation of NF-κB p65 signalling pathway may play a role in TN-C induced fibrosis. Thus, TN-C may be a mediator and potential target for therapy in DMD-associated cardiovascular complications.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Österreichische MuskelforschungFWF - Austrian Science Found P 35878

Ivabradine rescues vascular abnormalities in a mouse model of duchenne muscular dystrophy

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fonds zur Förderung der wissenschaftlichen Forschung

Ivabradine rescues vascular abnormalities in a mouse model of muscular dystrophy

Background

Duchenne muscular dystrophy (DMD) is a rare genetic disorder that primarily affects boys, initiated by the absence of dystrophin and is mainly differentiated by skeletal muscle degeneration and cardiac dysfunction. However, recent studies have underlined the importance of vascular abnormalities such as augmented arterial stiffness and endothelial dysfunction in the progression of cardiac complications in DMD. Several pleiotropic effects of ivabradine have been identified, including the reduction of vascular complications in coronary artery and ischemic heart disease patients. Nevertheless, whether chronic ivabradine treatment could improve the vascular complications in DMD is largely unknown.

Methods

In this study, vascular abnormalities in both dystrophin and utrophin deficient (mdx-utr KO) mice were examined, a severe and progressive animal model of DMD. Mice (4-6 weeks old) were subjected to ivabradine (10 mg/kg/day in drinking water) or vehicle treatments for 3 to 4 weeks. At the end of the treatment, aorta and lung tissue were collected to assess the vascular reactivity by wire myograph and the activity of angiotensin-converting enzyme (ACE) activity was measured in lung tissue respectively.

Results

Comparable with DMD patients, mdx-utr KO mice also exhibit vascular abnormalities and cardiac fibrosis. Ivabradine-treated mice showed a significantly improved endothelium-dependent vasodilation (p<0.05) and decreased vascular stiffness compared to vehicle-treated animals (p<0.01). In addition, lung ACE activity was significantly reduced in the treated mice in comparison to the control group (p<0.01) indicating less activation in the renin-angiotensin-aldosterone system, which causative plays role in the progression of vascular and cardiac dysfunction.

Conclusions

In conclusion, our study shows for the first time the beneficial effects of chronic ivabradine treatment on the progression of cardiac vascular complications in DMD and this may present a novel therapeutic approach. Further studies are needed to clarify the underling signalling mechanisms.

Dissecting the progression of cardiac dysfunction in tumor-bearing mice

Funding Acknowledgements

Type of funding sources: None.

Background

Cancer patients undergoing heart-related complications result in high incidences of mortality. Nevertheless, it is still not fully understood whether localized tumors affect heart function prior to the onset of cachexia, hence, making the heart more vulnerable for functional abnormalities in later stages of the disease. In addition to analyse heart function, we focus on the expression BCL-2–associated athanogene 3 (BAG3), a co-chaperone protein and Hsp70, which are highly expressed in tumor but decrease in cardiomyocytes (CM) in heart failure (HF).

Methods

Colon-26 adenocarcinoma cells (C26; n=22) with/without shIL-6 (C26 shIL-6; n=22) were injected subcutaneously into the right flank of 10-11 weeks old BALB/c male mice. Control mice were injected with vehicle (PBS; n=8). Cardiac function was assessed by echocardiography and invasive hemodynamic measurements 10 (early) and 20 (late) days after the injection, respectively. In addition, the expression of BAG3 and Hsp70 were determined by Western blot as well as the extend of cardiac fibrosis was determined by Masson-Goldner's trichrome staining.

Results

The tumor size was comparable between the two injected groups. However, only C26 group showed a significant loss of subcutaneous fat and skeletal muscle (p<0.05, respectively), suggesting cachexia. Heart weight normalized to tibia length was not changed in the injected groups as compared to controls (day 20). However, left ventricular ejection fraction (LVEF) showed a tendency to decline in the early phase (p~0.08) in both injected group and it reached significance at late stage (p<0.05). Invasive hemodynamic assessment also confirmed the contractile dysfunction, resulting in a decrease in LV systolic pressure and increase of LV end-diastolic pressure (p<0.05, respectively). Importantly, these functional changes in the heart in tumor-bearing mice were associated with a marked reduction in both BAG3 and Hsp70 in the myocardium. Furthermore,  there was no sign of cardiac fibrosis in the injected groups.

Discussion

Our study shows for the first time that tumor rather than cancer cachexia plays a significant maladaptive role in the progression of cardiac dysfunction in a mouse model of C26 injection-induced cachexia. The progression of cardiac contractile dysfunction was associated with a decline in BAG3 and Hsp70 in tumor-bearing mice, suggesting changes of BAG3/Hsp 70 signalling may be a critical component as well as target.

Tenascin-C provokes cardiac fibrosis and endothelial impairment in Duchenne Muscular Dystrophy

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): FWF Austrian Science Fund

Cardiac fibrosis and dilated cardiomyopathy are major contributors to mortality in Duchenne muscular dystrophy (DMD) patients. There is a growing collection of evidence that Tenascin C (TN-C) plays a maladaptive role in cardiac remodelling and fibrosis.

Our aims were to 1) assess the vascular dysfunction and cardiac fibrosis and its link to TN-C in a mouse model of DMD and 2) explore the effect of knocking out TN-C in dystrophic mice.

Male wt, mdx and mdx TN-C KO age-matched mice were used. Cardiac fibrosis was assessed on tissue sections. Wire myography was used to test the vascular reactivity and endothelial cells (ECs) were isolated from mouse lung tissues to characterize the oxidative stress and inflammatory marker expression. To study the signalling pathways contributing to cardiac fibrosis, human cardiac fibroblasts (hCFs) were treated with TN-C or TGF-β and gene expression and epigenetic regulation of p65 were assessed.

Cardiac fibrosis was markedly increased in mdx mice which was accompanied with elevated TN-C level in cardiac tissue and plasma compared to wt animals. In addition, endothelial cells isolated from mdx mice also showed a marked upregulation of oxidative stress and inflammatory markers and in line with that vascular endothelial function was impaired in mdx mice. Interestingly, mdx- TN-C KO mice showed preserved vascular function as well as reduced cardiac fibrosis compared to age-matched mdx mice. hCFs treated with TN-C or TGF-β showed increased collagen and α-SMA expressions which could be reduced by TN-C siRNA. In addition, both TN-C and TGF-β promote p65/NF-κB promoter demethylation and subsequently stimulate pro-inflammatory and pro-fibrotic signalling, which could be reversed by applying p38 MAPK inhibitor in hCFs.

TN-C promotes oxidative stress and inflammation in ECs and fibroblasts, contributing to severe endothelial dysfunction and cardiac fibrosis. In addition, activation of NF-κB p65 signalling pathway may play a role in TN-C induced fibrosis. Thus, TN-C may be a critical mediator and potential target for therapy in DMD.

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.

AB0151 PRELIMINARY RESULTS SHOW AN INCREASED EXPRESSION OF COINHIBITORY RECEPTORS IN SYSTEMIC SCLEROSIS

Background:

Recent studies suggest dysregulation in T cell activation in systemic sclerosis (SSc). Co-inhibitory-receptors (Co-IRs) such as TIM-3, PD-1 and LAG-3 play a crucial role in controlling excessive T cell activation and in maintaining immune homeostasis. Engagement of these receptors by their ligand’s limits cytokine production in response to TCR or activating NK receptor stimulation and hence limit tissue damage from excessive immune activation. However, chronically increased expression of multiple Co-IRs is a hallmark of immune exhaustion. We evaluate the role of these soluble Co-IRs in diffuse SSc (dcSSc).

Objectives:

Establish the role of CiR and their ligands in diffuse systemic sclerosis.

Understand how immune regulatory mechanisms influence the development of fibrosis.

Provide a better understanding of the disease and fibrosis in general.

Methods:

PBMC’s(Peripheral blood mononuclear cells) and dermal fibroblasts from SSc patients were isolated and investigated for markers of T cell inhibition. These cells were analysed using flow cytometry in a 10 colour panel. Cells were stained for PD1, TIM3, TIGIT, LAG3, CD3, CD8, CD4 and CD19 along with a Live/dead marker. Co-cultures of fibroblasts and PBMCs will be setup, and treated with various drugs that act on the Co-IRs.

Results:

The proportion of CD4+ T cells expressing PD1 were markedly increased in SSc patients compared to healthy volunteers and Rheumatoid Arthritis patients.

There was increased expression of both TIGIT and TIM3 in the CD4+ T cells. (Figure 1)

Similarly, the co-expression of these receptors on the CD4+ T cell population was elevated compared to healthy volunteers. (figure 2)

Conclusion:

Soluble co-inhibitors are differentially expressed in early dcSSc compared to healthy volunteers and other autoimmune diseases. Our preliminary data indicates that these co inhibitors could play an important role in unravelling the pathogenesis of systemic sclerosis. Inhibition or activation of these receptors through different treatment modalities can be utilized as a novel patient centric treatment strategy.

References:

[1]Fukasawa, T., Yoshizaki, A., Ebata, S., Nakamura, K., Saigusa, R., Miura, S., … Sato, S. (2017). Contribution of Soluble Forms of Programmed Death 1 and Programmed Death Ligand 2 to Disease Severity and Progression in Systemic Sclerosis.Arthritis & Rheumatology,69(9), 1879–1890.

[2]Greisen S, Rasmussen T, Stengaard-Pedersen K, Hetland M, Hørslev-Petersen K, Hvid M, et al. Increased soluble programmed death-1 (sPD-1) is associated with disease activity and radiographic progression in early rheumatoid arthritis. Scand J Rheumatol 2014; 43:101-8.

[3]de Paoli, F., Nielsen, B., Rasmussen, F., Deleuran, B., & Søndergaard, K. (2014). Abatacept induces clinical improvement in patients with severe systemic sclerosis.Scandinavian Journal of Rheumatology,43(4), 342–345.

[4]Kwon, B. (2010). Intervention with costimulatory pathways as a therapeutic approach for graft-versus-host disease.Experimental and Molecular Medicine. Nature Publishing Group.

Acknowledgments:

FOREUM: Foundation of Research in Rheumatology

Disclosure of Interests:

None declared

OP0254 CHROMATIN CONFORMATION SIGNATURE ANALYSIS IN EARLY VS LATE SCLERODERMA PHENOTYPES

Background:

Systemic sclerosis (scleroderma, SSc) is a heterogeneous disease in which clinical outcomes vary widely. Predicting outcomes on an individual basis remains challenging despite progress made through autoantibody analysis and gene expression profiling. Effective targeted therapies are evolving and accurately predicting outcomes is important to enable patient stratification for therapy.

Chromatin Conformation Signature (CCS) profiling of peripheral blood for systemic epigenetic deregulations could be used for such a purpose. The EpiSwitch platform offering high throughput and resolution chromosome conformation (3C) capture detects significant regulatory changes in 3D genome architecture and maps long range interaction between distant genomic locations. This then reveals the spatial disposition and physical properties of the chromosome, such as chromatin loops and inter-chromosomal connections, which have a role in network organization and genetic epistasis controlling gene expression. EpiSwitch automated platform has been successfully utilised in patient stratification in RA, MS and other indications.

This methodology could be applied to patients with SSc to identify CCS associated with different phenotypes and may ultimately be used to stratify and identify patients into pathogenic subtypes.

Objectives:

We aimed to determine significant CCSs associated with early and late phenotypes of SSc.

Methods:

The EpiSwitch-based chromosome conformation capture (3C) method was applied to blood samples from early phenotype, and late phenotype SSc patients. Intact nuclei were isolated from peripheral blood mononuclear cells and subjected to formaldehyde fixation resulting in crosslinking between physically touching segments of the genome via contacts between their DNA bound proteins. For quantification of cross-linking frequencies, the cross linked DNA was digested and then subjected to ligation. Cross-linking was then reversed and individual ligation products detected and quantified by EpiSwitch custom oligo array annotated across the whole genome to the anchoring sites of 3D genome architecture.

Results:

7 significant CCSs were found over the HLA-C, HLA-B and TNF regions on Chromosome 6 in the early phenotype. The top 8 pathways for genetic locations associated to the CCSs are shown in Table 1.

Table 1.

Top 8 pathways for genetic locations associated to significant CCS for the early phenotype.

GeneSet1Natural Killer cell mediated cytotoxicity2Immunoregulatory interations between a lymphoid cell and a non-lymphoid cell3Antigen Processing & presentation4Phagosome5Graft versus host disease6Type 1 diabetes mellitus7Osteoclast differentiation8Class 1 MHC mediated antigen processing & presentation

2 significant CCSs were found centred around the IFNG region of chromosome 12 in the late phenotype. The top 8 pathways for genetic locations associated to significant CCSs are shown in Table 2.

Table 2.

Top 8 pathways for genetic locations associated to significant CCS for the late phenotype.

GeneSet1Surfactant metabolism2IL12 signalling mediated by STAT43Protein digestion & absorption4Calcineruin regulated NFAT dependent transcription in lymphocytes5Transcriptional misregulation in cancer6Kaposi’s sarcoma associated herpes virus infection7IL2 mediated signalling events8Inflammatory bowel disease

Conclusion:

Significant CCSs, as part of 3D genomic regulatory control, and their associated pathways for the genetic locations, were identified in both late and early phenotypes. There were distinct CCSs in the early phenotype compared to the late suggesting the CCSs change as the disease progresses and varies between phenotypes. If CCSs could be linked to each clinically defined subgroup across a SSc cohort they could be used as a biomarker tool to predict outcome and progression in patients.

Disclosure of Interests:

Megan Galloway: None declared, Ewan Hunter: None declared, Alexandre Akoulitchev: None declared, Shivanee Vigneswaran: None declared, Bahja Abdi: None declared, Christopher Denton Grant/research support from: GlaxoSmithKline, Inventiva, CSF Behring, Consultant of: Roche-Genentech, Actelion, GlaxoSmithKline, Sanofi Aventis, Inventiva, CSL Behring, Boehringer Ingelheim, Bayer, David Abraham: None declared, Richard Stratton: None declared

P6011NKX2-5 contributes to EndoMT and endothelial dysfunction in pulmonary arterial hypertension

Background

The onset of inflammation, hypoxia or shear stress within blood vessels can result in endothelial-to-mesenchymal transition (EndoMT), a disease-associated process where endothelial cells (ECs) downregulate endothelial markers and acquire mesenchymal features. EndoMT is observed in patients with scleroderma-associated pulmonary hypertension (SSc-PAH), which have the highest mortality amongst all the scleroderma patient subgroups. The homeobox transcriptional factor NKX2-5 is fundamental for cardiovascular development. However, NKX2-5 expression has not been reported yet in ECs of adult pulmonary blood vessels.

Purpose

To investigate the role of NKX2-5 in the pulmonary endothelium of SSc-PAH.

Methods

Human pulmonary artery endothelial cells (HPAECs) were treated with a cocktail of TGF-β (5 ng/mL), TNF-α (5 ng/mL), and IL-1β (0.1 ng/mL) for 5 days. Immunofluorescence was used to detect NKX2-5 and other markers in ECs. Western blotting and qPCR evaluated, respectively, protein and gene expression. Lentiviral transduction forced NKX2-5 expression in the cells. Transendothelial electrical resistance (TEER) measurements evaluated endothelial barrier function. Pharmacological inhibition was performed to determine the pathways that lead to NKX2-5 activation. Casein kinase 2 (CK2)-inhibition (CX4945) of a chronic hypoxia mouse model of PAH was used to assess right ventricular systolic pressure (RVSP).

Results

Immunofluorescence showed a strong expression of NKX2-5 in the endothelium of SSc-PAH human lungs (p<0.0001). Western blot analysis demonstrated a 5.3-fold downregulation of CD31 (p<0.001), and an increased production of NKX2-5 (5.6-fold, p<0.0001) and of Procollagen I (12-fold, p=0.0009) after 5 days of cytokine stimulation on HPAECs. Relative mRNA expression has shown a 3-fold gene downregulation of CD31 (p=0.0002) and a reduction of VE-Cadherin (2.3-fold, p=0.0008) and of vWF (10.4-fold, p=0.003) in EndoMT, whereas gene expression of COL1α2 (8.5-fold, p<0.0001) and of NKX2-5 (1.5-fold, p=0.003) were upregulated. Immunofluorescence of cells has revealed a decreased VE-Cadherin expression concomitant with upregulation of NKX2-5 in EndoMT cells. Forced expression of NKX2-5 downregulated endothelial markers and endothelial barrier function was impaired whereas proliferation rate of cells was increased. Inhibition of PI3K, ERK5, ALK5 and CK2 reduced NKX2-5 protein expression within cells. CK2-inhibited mice under hypoxia conditions resembled the normoxia mice group by normalising RVSP.

Conclusion

HPAECs undergoing EndoMT express NKX2-5 in vitro and in vivo, via mediation of CK2, TGF-β, ERK5 and PI3K signalling. NKX2-5 downregulates key adherence junctional proteins, disrupting endothelial barrier function. This study highlights the involvement of NKX2-5 in EndoMT and in endothelial dysfunction, leading to vascular disease progression in SSc-PAH.

Acknowledgement/Funding

British Heart Foundation, Arthritis Research UK, Scleroderma Research UK and Royal Free Hospital Charity

Can New Ultrasound Signs Help in Identifying Follicular Variant of Papillary Carcinoma of Thyroid? - A Pilot Study

AIM

To describe two new ultrasound signs for thyroid nodules - "nodule in nodule" and "hypoechoic internal septae" and assess their usefulness in differentiating follicular variant of papillary thyroid carcinoma (FVPTC) from benign thyroid nodules (BTN).

METHODOLOGY

Ultrasound findings of 210 patients with histopathologically proven FVPTC (68 nodules, M:F=13:47 with mean age of 39.5±11.9 years) and BTN (165 nodules, (M:F=41:109 with mean age of 44±11.3 years) were retrospectively reviewed from PACS by a single radiologist blinded to the final diagnosis. Logistic regression analysis was performed to identify the best predictors of FVPTC and their diagnostic performance was assessed.

RESULTS

The "nodule in nodule" sign was seen in 80.9% of FVPTC and only 12.1% of BTN. The "hypoechoic internal septae" sign was seen in 44.1% of FVPTC and 17% of BTN. Younger patients, heterogeneous echotexture, nodule in nodule sign, thick incomplete non-uniform halo and presence of significant nodes were the best predictors of FVPTC (p<0.05). The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and relative risk for FVPTC given as odds ratio (95% CI) for heterogeneous echotexture and nodule in nodule sign which were the best 2 predictors of FVPTC were 91.2%, 81.8%, 67.3%, 95.7%, 84.5%, 46.5 (18.5-117.4) and 80.9%, 87.7%, 74.3%, 91.2%, 86.2%, 32.5 (15.04-70.2), respectively. There was improvement in the specificity (91.5%) and accuracy (86.6%) when a combined criterion of heterogeneous echotexture and nodule in nodule sign was applied to predict FVPTC.

CONCLUSION

The "nodule in nodule" sign is common in FVPTC and when combined with heterogeneous echotexture can differentiate FVPTC and BTN with high specificity.

The innate immune system, toll-like receptors and dermal wound healing: A review

Wound healing is a complex physiological process comprised of discrete but inter-related and overlapping stages, requiring exact timing and regulation to successfully progress, yet occurs spontaneously in response to injury. It is characterised by four phases, coagulation, inflammation, proliferation and remodelling. Each phase is predominated by particular cell types, cytokines and chemokines. The innate immune system represents the first line of defence against invading microorganisms. It is entirely encoded with the genome, and comprised of a cellular response with specificity provided by pattern recognition receptors (PRRs) such as toll-like receptors (TLRs). TLRs are activated by exogenous microbial pathogen associated molecular patterns (PAMPs), initiating an immune response through the production of pro-inflammatory cytokines and further specialist immune cell recruitment. TLRs are also activated by endogenous molecular patterns termed damage associated molecular patterns (DAMPs). These ligands, usually shielded from the immune system, act as alarm signals alerting the immune system to damage and facilitate the normal wound healing process. TLRs are expressed by cells essential to wound healing such as keratinocytes and fibroblasts, however the specific role of TLRs in this process remains controversial. This article reviews the current knowledge on the potential role of TLRs in dermal wound healing where inflammation arising from pathogenic activation of these receptors appears to play a role in chronic ulceration associated with diabetes, scar hypertrophy and skin fibrosis.

Notizen: Silydianin und Silychristin, zwei isomere Silymarine aus Silybum marianum L. Gaertn. (Mariendistel) / Silydianin and Silychristin, two Isomeric Silymarins from Silybum marianum L. Gaertn. (milk thistle)

Two isomeric flavonolignans (Silymarins) have been isolated from the fruits of Silybum marianum L. Gaertn. and structurally elucidated mainly by means of NMR/mass spectroscopy and X-ray analysis respectively.

Characterization of virus-like particles in GARDASIL® by cryo transmission electron microscopy

Cryo-transmission electron microscopy (cryoTEM) is a powerful characterization method for assessing the structural properties of biopharmaceutical nanoparticles, including Virus Like Particle-based vaccines. We demonstrate the method using the Human Papilloma Virus (HPV) VLPs in GARDASIL®. CryoTEM, coupled to automated data collection and analysis, was used to acquire images of the particles in their hydrated state, determine their morphological characteristics, and confirm the integrity of the particles when absorbed to aluminum adjuvant. In addition, we determined the three-dimensional structure of the VLPs, both alone and when interacting with neutralizing antibodies. Two modes of binding of two different neutralizing antibodies were apparent; for HPV type 11 saturated with H11.B2, 72 potential Fab binding sites were observed at the center of each capsomer, whereas for HPV 16 interacting with H16.V5, it appears that 60 pentamers (each neighboring 6 other pentamers) bind five Fabs per pentamer, for the total of 300 potential Fab binding sites per VLP.

Disassembly and reassembly of human papillomavirus virus-like particles produces more virion-like antibody reactivity

Background

Human papillomavirus (HPV) vaccines based on major capsid protein L1 are licensed in over 100 countries to prevent HPV infections. The yeast-derived recombinant quadrivalent HPV L1 vaccine, GARDASIL(R), has played an important role in reducing cancer and genital warts since its introduction in 2006. The L1 proteins self-assemble into virus-like particles (VLPs).

Results

VLPs were subjected to post-purification disassembly and reassembly (D/R) treatment during bioprocessing to improve VLP immunoreactivity and stability. The post-D/R HPV16 VLPs and their complex with H16.V5 neutralizing antibody Fab fragments were visualized by cryo electron microscopy, showing VLPs densely decorated with antibody. Along with structural improvements, post-D/R VLPs showed markedly higher antigenicity to conformational and neutralizing monoclonal antibodies (mAbs) H16.V5, H16.E70 and H263.A2, whereas binding to mAbs recognizing linear epitopes (H16.J4, H16.O7, and H16.H5) was greatly reduced.

Strikingly, post-D/R VLPs showed no detectable binding to H16.H5, indicating that the H16.H5 epitope is not accessible in fully assembled VLPs. An atomic homology model of the entire

HPV16 VLP was generated based on previously determined high-resolution structures of bovine papillomavirus and HPV16 L1 pentameric capsomeres.

Conclusions

D/R treatment of HPV16 L1 VLPs produces more homogeneous VLPs with more virion-like antibody reactivity. These effects can be attributed to a combination of more complete and regular assembly of the VLPs, better folding of L1, reduced non-specific disulfide-mediated aggregation and increased stability of the VLPs. Markedly different antigenicity of HPV16 VLPs was observed upon D/R treatment with a panel of monoclonal antibodies targeting neutralization sensitive epitopes. Multiple epitope-specific assays with a panel of mAbs with different properties and epitopes are required to gain a better understanding of the immunochemical properties of VLPs and to correlate the observed changes at the molecular level. Mapping of known antibody epitopes to the homology model explains the changes in antibody reactivity upon D/R. In particular, the H16.H5 epitope is partially occluded by intercapsomeric interactions involving the L1 C-terminal arm. The homology model allows a more precise mapping of antibody epitopes. This work provides a better understanding of VLPs in current vaccines and could guide the design of improved vaccines or therapeutics.

In-depth process understanding of RECOMBIVAX HB® maturation and potential epitope improvements with redox treatment: multifaceted biochemical and immunochemical characterization

Recombinant Hepatitis B surface antigen virus-like particles (VLPs) produced in yeast undergo spontaneous maturation during the vaccine production process, and the biophysical characteristics of the particles with respect to maturation were described in Zhao et al. (2006) [13]. Here we report additional biochemical and immunochemical characterization by various techniques, including the use of a panel of monoclonal antibodies (mAbs) that differ in their selectivity and conformation-sensitivity, for probing surface epitope structures. Crosslinking via interchain disulfide formation and binding of conformational specific antibodies in the mature particles were shown to be progressively enhanced. We show that redox-mediated VLP maturation is superior to heat-induced maturation in terms of generating VLPs which exhibit more complete crosslinking (>95%) and 2- to 3-fold higher antigenicity as defined by conformational antibodies. Therefore, the resulting VLPs from redox treatment resemble more closely their plasma-derived counterparts. The value of using multiple mAbs for probing surface epitopes was clearly demonstrated as different mAbs showed different degrees of sensitivity to the structural changes during HBsAg VLP maturation. The rapid, label-free technology of surface plasmon resonance performed at a single antigen concentration was shown to correlate well with a sandwich ELISA using parallel line analysis, currently implemented for product release and stability testing of RECOMBIVAX HB(®). Surface plasmon resonance offers both convenience and flexibility; multiple mAbs can be tested one at a time in the same set of experiments, providing a means to assess changes to individual epitopes. Taken together, these quantitative analytical tools enable more rapid, in-depth, and comprehensive process monitoring, process optimization, and assessment of product consistency and stability.

IL-4(-/-) mice with lethal Mesocestoides corti infections--reduced Th2 cytokines and alternatively activated macrophages

Protection against Mesocestoides corti, a cestode that invades vital organs, is dependent on the production of IL-4, as IL-4(-/-) mice were found to have higher parasite burdens when compared with wild-type mice. The goal of this study was to investigate the role of IL-4 in immunity to M. corti, focusing on the immunological profile and on potential mediators of pathology. IL-4(-/-) mice infected with M. corti showed 100% mortality by 32 days, whereas wild-type mice survived for approximately 1 year. Parasite burdens were significantly increased in the liver, peritoneal, and thoracic cavities of IL-4(-/-) mice, associated with impaired recruitment of inflammatory cells and a reduction in monocytes and macrophages. IL-5 production by splenocytes and expression in liver tissue was decreased in infected IL-4(-/-) mice compared with wild-type mice. In contrast, IL-4(-/-) mice produced increased amounts of IFNgamma and TNFalpha. Alternatively activated macrophages were a major feature of liver granulomas in wild-type mice evidenced by Arginase I expression, while livers from infected IL-4(-/-) mice showed impaired alternative macrophage activation without increased classical macrophage activation. Thus, lethality during M. corti infection of IL-4(-/-) mice is associated with decreased Th2 cytokines, increased Th1 cytokines and impairment of alternatively activated macrophages.

Abstract B190: Efficacy of the specific ETA receptor antagonist zibotentan (ZD4054) in cancer cells and fibroblasts from colorectal cancer

Endothelin-1 (ET-1) contributes to growth and progression of solid cancers, mainly through endothelin receptor A (ETAR). Therefore endothelin receptor antagonism is emerging as a potential treatment for neoplasms. We evaluated the efficacy of the specific ETAR antagonist zibotentan (ZD4054) in blocking ET-driven cellular effects in colorectal cancer (CRC). CRC cell lines (HT29, SW620) and primary normal fibroblast strains isolated from human colorectal tissues (CF36, CF56, CF65, CF75) were incubated in ET-1 with/without BQ123, zibotentan (ETAR antagonists), BQ788 (ETBR antagonist). Resultant cell growth was measured by the colourimetric methylene blue assay; migration by a modified monolayer scratch assay; contraction in collagen gels; downstream effectors by western blotting. ET-1 driven growth (18%–45% above control) was significantly inhibited (p&lt;0.01) by ETAR (not ETBR) antagonism (BQ123=zibotentan CRC; fibroblasts). ET-1 driven fibroblast migration and contraction were blocked by ETAR and ETBR antagonism (zibotentan=BQ123). CRC cells did not migrate or contract. ET-1-stimulated expression of downstream effectors was driven by ETAR or ETBR, eg: (1) connective tissue growth factor (CTGF) was blocked by ETAR antagonism (zibotentan&gt;BQ123; CRC and fibroblasts); (2) collagen XI was blocked by ETAR&gt;ETBR antagonism (zibotentan&gt;BQ123; fibroblasts). The specific ETAR antagonist zibotentan is at least as efficacious as BQ123 in blocking ET-1 driven growth, migration and contraction both in CRC cells and colorectal fibroblasts, which form the supporting tumor stroma. Zibotentan is a strong candidate for adjuvant treatment in CRC.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B190.

Bilateral testicular enlargement and seminoma in a patient with acromegaly

Growth hormone (GH) excess has been associated with soft tissue changes and an increase in the incidence of colonic polyps and gastrointestinal cancer. We describe a patient with endogenous GH excess caused by a pituitary tumour, resulting in acromegaly. The patient had bilateral testicular enlargement, with tumour of the right testicle. Pituitary MRI revealed a macroadenoma. After resection of the pituitary tumour, GH levels fell below 0.5 ng/ml, with acromegaly resolution. Testicular resection revealed seminoma. Following acromegaly resolution, the enlarged remaining testicle decreased in size. The implications of the testicular enlargement and seminoma in the presence of a GH-secreting tumour are discussed.

Significance of serum colony-stimulating factor-1 as a breast cancer marker

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Background: A specific and sensitive biomarker that indicates the presence of breast cancer is highly desirable, yet available markers are of limited value. Colony-stimulating factor-1 (CSF-1) is involved in mammary gland development and mediates breast cancer progression. Earlier work indicated correlation of serum CSF-1 with breast cancer staging, and a recent report suggests that CSF-1 is a potential breast cancer marker, however the data reported so far await validation. Methods: In a prospective study in 799 women with no history of malignant disease undergoing surgery, serum CSF-1 levels were measured by a commercially available ELISA. In this cohort, 312 patients had breast cancer and 487 age-matched women had benign tumors. The tumor size, nodal and metastasis status, histological tumor type, hormone and human epidermal growth factor receptor 2 (HER2) and menopausal status were evaluated. Mean CSF-1 serum concentrations were compared between the patient groups by non-parametric Wilcoxon two-sample and Kruskal-Wallis test. The area under the receiver operating characteristic curve was calculated by logistic regression. Results: Mean serum CSF-1 concentrations were significantly higher in all patients with malignant tumors (502±429 pg/mL) as compared to those with benign tumors (382±344 pg/mL) (p<0.0001, Wilcoxon). Increased CSF-1 concentrations were significantly related to malignant versus non-malignant disease in logistic regression and receiver operating characteristic analysis (p<0.0001, AUC=0.6). Increased CSF-1 levels in patients with malignant tumors were associated with postmenopausal (p=0.0038) but not premenopausal (p=0.94) status (Wilcoxon). Serum CSF-1 concentrations did not correlate significantly with tumor size, nodal and metastasis status, hormone receptor and HER2 status of patients (Kruskal-Wallis). Conclusions: Our data suggest that serum CSF-1 could serve as a breast cancer marker in postmenopausal women. While its serum levels are not related to breast cancer stage at diagnosis, they might be useful for breast cancer screening in postmenopausal women.

No significant financial relationships to disclose.

Endothelin--role in vascular disease

It is now two decades since it was demonstrated that ET-1 is one of the most powerful vasoconstrictors in biology. ET-1 mediates its effects through two membrane G-protein coupled receptors, ET(A) and ET(B), which exhibit a wide tissue distribution including the endothelial cells, vascular smooth muscle cells and adventitial fibroblasts. In recent years, ET-1 has been identified as a key player of endothelial dysfunction in various cardiovascular, autoimmune and CTDs. Endothelial dysfunction results from endothelial cell injury subsequently leading to the generation of an inflammatory process and endothelial cell activation. Thus, beyond its known 'classical' vasoactive effects, ET-1 is additionally considered to be an important mediator in vessel remodelling ultimately leading to major changes in cellular and tissue architecture; it also appears to function in conjunction with other growth factors and cytokines. Consequently, ET-1 receptor antagonists may be useful in ameliorating progression of vascular dysfunction and vascular disease due to their ability to negatively modulate vasoconstrictor pathways, cytokines and inflammatory markers production, and growth factor effects. This review briefly summarizes the current knowledge on the role of ETs in vascular dysfunction and vascular disease, with a particular emphasis on ET-1 in CTDs.

Connective tissue growth factor: growth factor, matricellular organizer, fibrotic biomarker or molecular target for anti-fibrotic therapy in SSc?

SSc is characterized by enhanced extracellular matrix (ECM) production resulting in excessive scarring and replacement fibrosis affecting the interstitial and vascular compartments of multiple organs. Although the precise molecular mechanisms driving fibrosis remain elusive, TGF-beta and connective tissue growth factor (CTGF), are considered key mediators. CTGF is over-expressed in lesional tissue and enhanced levels in the circulation are an indicator of disease extent and severity. Rapidly induced by TGF-beta and ET-1, CTGF activates several signal transduction pathways via surface receptors that modulate the functional activities of fibroblasts, endothelial and smooth muscle cells. In vivo, over-expression of CTGF causes ECM accumulation and promotes tissue fibrosis. In animal models of SSc, neutralization of CTGF with antibody blockade or siRNA, suppresses fibrogenesis. This article examines the role of CTGF as an integrator of extracellular signals, fibrotic biomarker and discusses the potential value of CTGF antagonism as a therapeutic strategy in SSc.