Quantitative Liver Fibrosis Using Collagen Hybridizing Peptide to Predict Native Liver Survival in Biliary Atresia: A Pilot Study

In vivo monitoring of active subretinal fibrosis in mice using collagen hybridizing peptides

Subretinal fibrosis is associated with worse visual outcomes in patients with neovascular age-related macular degeneration. As there is a lack of optimal biomarkers and no method that directly detects collagen in the back of the eye, novel tools that monitor fibrosis-related changes in neovascular age-related macular degeneration are needed. Here, using two mouse models (the laser-induced choroidal neovascularization model, and the JR5558 mouse presenting with spontaneous subretinal neovascularization with fibrosis), we imaged active fibrotic lesions using fluorescently labeled collagen hybridizing peptides (CHPs), short peptides that bind to single α-chain collagen structures during collagen remodeling. JR5558 retinal pigment epithelium/choroid flat mounts showed CHP co-staining with fibrosis and epithelial mesenchymal transition-related markers; additionally, CHP histopathology staining correlated with in vivo CHP imaging. After laser-induced choroidal neovascularization, in vivo CHP binding correlated with laser intensity, histopathology CHP and fibronectin staining. Laser-induced choroidal neovascularization showed decreased CHP intensity over time in healing/regressing versus active scars in vivo, whereas increased CHP binding correlated with elevated fibrosis in JR5558 mouse eyes with age. In bispecific angiopoietin 2/vascular endothelial growth factor antibody-treated JR5558 mice, CHPs detected significantly decreased collagen remodeling versus immunoglobulin G control. These results demonstrate the first use of CHPs to directly image remodeling collagen in the eye and as a potential clinical optical biomarker of active subretinal fibrosis associated with ocular neovascularization.

Predicting Cirrhosis and Poor Outcomes of Bile Drainage Surgery for Biliary Atresia: A Multicentric Observational Study in Japan

OBJECTIVE

To identify patients with biliary atresia (BA) with extremely poor outcomes of bile drainage surgery using the infant BA liver fibrosis (iBALF) score, a liver fibrosis marker based on standard blood analysis.

BACKGROUND

Although primary liver transplantation is beginning to be considered as an alternative to bile drainage surgery in patients with BA, those most likely to benefit from this procedure have not yet been identified.

METHODS

The medical records of 380 patients with BA with bile drainage surgery between 2015 and 2019 were collected for retrospective analysis from 60 participating hospitals. To predict native liver survival at age 1 year, a receiver operating characteristic curve was drawn for the iBALF score. The cutoff value was determined as the point indicating >99% sensitivity.

RESULTS

The median age at surgery was 56 days (range: 4-183 days), and native liver survival at age 1 year was achieved in 258 (67.9%) patients. An iBALF score of 5.27 was chosen as the cutoff, and 18 patients (4.7%) were found to have an iBALF score >5.27; of these, only 2 (95% CI: 1.4%-34.7%) had native liver survival at age 1 year, indicating a significantly poorer outcome than in the other patients (95% CI: 65.7%-75.4%). Moreover, patients with an iBALF score >5.27 had significantly higher mortality and younger age at salvage liver transplantation.

CONCLUSIONS

Patients with BA having a preoperative iBALF score >5.27 had extremely poor outcomes of bile drainage surgery and may be considered candidates for primary LTx.

Collagen gene cluster expression and liver fibrogenesis in patients with biliary atresia: a preliminary study

OBJECTIVE

Biliary atresia (BA) is a progressive fibro-obliterative disease of the biliary tract, which results in end-stage liver disease. However, liver fibrosis progression may continue even after Kasai surgery. Recent evidence showed that collagen plays a pivotal role in the progression of liver fibrosis in BA. However, most studies were conducted in developed countries. We investigated the expressions of the collagen gene cluster (COL6A1, COL6A2, COL6A3, and COL1A1) in BA patients in Indonesia.

RESULTS

There was a significant down-regulated expression of COL6A1 (ΔCT 9.06 ± 2.64 vs. 5.42 ± 2.41; p = 0.0009), COL6A2 (ΔCT 8.25 ± 2.07 vs. 5.77 ± 3.51; p = 0.02), COL6A3 (ΔCT 11.2 ± 6.08 vs. 6.78 ± 3.51; p = 0.024), and COL1A1 (ΔCT 3.26 ± 1.71 vs. 0.19 ± 2.76; p = 0.0015) in BA patients compared to controls. Interestingly, the collagen gene cluster expressions were significantly associated with the presence of cirrhosis (p = 0.0085, 0.04, and 0.0283 for COL6A1, COL6A2, and COL6A3, respectively). In conclusion, our study shows the changes in the collagen gene cluster, particularly collagen type I and VI, expressions in patients with BA in a particular developing country. Our findings suggest the role of these collagen gene clusters in the liver fibrogenesis of BA.

Limited Hyperoxia-Induced Proliferative Retinopathy (LHIPR) as a Model of Retinal Fibrosis, Angiogenesis, and Inflammation

The progression to fibrosis and traction in retinopathy of prematurity (ROP) and other ischemic retinopathies remains an important clinical and surgical challenge, necessitating a comprehensive understanding of its pathogenesis. Fibrosis is an unbalanced deposition of extracellular matrix components responsible for scar tissue formation with consequent tissue and organ impairment. Together with retinal traction, it is among the main causes of retinal detachment and vision loss. We capitalize on the Limited Hyperoxia Induced Retinopathy (LHIPR) model, as it reflects the more advanced pathological phenotypes seen in ROP and other ischemic retinopathies. To model LHIPR, we exposed wild-type C57Bl/6J mouse pups to 65% oxygen from P0 to P7. Then, the pups were returned to room air to recover until later endpoints. We performed histological and molecular analysis to evaluate fibrosis progression, angiogenesis, and inflammation at several time points, from 1.5 months to 9 months. In addition, we performed in vivo retinal imaging by optical coherence tomography (OCT) or OCT Angiography (OCTA) to follow the fibrovascular progression in vivo. Although the retinal morphology was relatively preserved, we found a progressive increase in preretinal fibrogenesis over time, up to 9 months of age. We also detected blood vessels in the preretinal space as well as an active inflammatory process, altogether mimicking advanced preretinal fibrovascular disease in humans.

The Chemistry and Biology of Collagen Hybridization

Collagen provides mechanical and biological support for virtually all human tissues in the extracellular matrix (ECM). Its defining molecular structure, the triple-helix, could be damaged and denatured in disease and injuries. To probe collagen damage, the concept of collagen hybridization has been proposed, revised, and validated through a series of investigations reported as early as 1973: a collagen-mimicking peptide strand may form a hybrid triple-helix with the denatured chains of natural collagen but not the intact triple-helical collagen proteins, enabling assessment of proteolytic degradation or mechanical disruption to collagen within a tissue-of-interest. Here we describe the concept and development of collagen hybridization, summarize the decades of chemical investigations on rules underlying the collagen triple-helix folding, and discuss the growing biomedical evidence on collagen denaturation as a previously overlooked ECM signature for an array of conditions involving pathological tissue remodeling and mechanical injuries. Finally, we propose a series of emerging questions regarding the chemical and biological nature of collagen denaturation and highlight the diagnostic and therapeutic opportunities from its targeting.

Damaged collagen detected by collagen hybridizing peptide as efficient diagnosis marker for early hepatic fibrosis

Liver fibrosis is characterized by excessive synthesis and deposition of extracellular matrix (ECM) in liver tissues. However, it still has been lacking of early detection and diagnosis methods. The collagen hybridizing peptide (CHP) is a novel synthetic peptide that enables detection of collagen damage and tissue remodeling. Here, we showed that obvious CHP-positive staining could be detected in the liver while given CCl₄ for only 3 days, which was significantly enhanced while given CCl₄ for 7 days. However, H&E staining showed no significant changes in fibrous tissue, and sirius red-positive staining could only be observed while given CCl₄ for 14 days. Moreover, CHP-positive staining enhanced initially at portal area which further extended into the hepatic lobule, which was increased more significantly than sirius red-positive staining in the model of 10 and 14 days. Further proteomic analysis of CHP-positive staining revealed that pathways associated with ECM remodeling were significantly increased, while retinol metabolism was downregulated. Meanwhile, proteins enriched in cellular gene transcription and signal transduction involved in fibrogenesis were also upregulated, suggesting that fibrosis occurred in CHP-positive staining. Our study provided evidence that CHP could detect the collagen damage in liver, which might be an efficient indicator for the diagnosis of liver fibrosis at a very early stage.

Fractionated Bilirubin Among 252,892 Utah Newborns With and Without Biliary Atresia: A 15-year Historical Birth Cohort Study

OBJECTIVES

To determine whether neonatal conjugated or direct bilirubin levels were elevated in infants with biliary atresia, and to estimate the number of newborns that would have positive screens in the nursery necessitating repeat testing following discharge.

STUDY DESIGN

We used administrative data from a large integrated healthcare network in Utah to identify newborns who had a fractionated bilirubin recorded during birth admission from 2005 through 2019. Elevated conjugated bilirubin was defined as greater than 0.2 mg/dL and direct bilirubin was defined as greater than 0.5 mg/dL (>97.5^th percentile for the assays). We performed simulations to estimate the anticipated number of false positive screens.

RESULTS

There were 32 cases of biliary atresia and 468,161 live births during the study period (1/14,700). 252,892 newborns had fractionated bilirubin assessed including 26 of those subsequently confirmed to have biliary atresia. Conjugated or direct bilirubin was elevated in all 26 infants with biliary atresia and an additional 3,246 (1.3%) newborns without biliary atresia. Simulated data suggest nine to 21 per 1,000 screened newborns will have an elevated conjugated or direct bilirubin using laboratory-based thresholds for a positive screen. Screening characteristics improved with higher thresholds without increasing false negative tests.

CONCLUSIONS

This study validates the previous findings that conjugated or direct bilirubin are elevated in the newborn period in patients with biliary atresia. A higher threshold for conjugated bilirubin improved screening performance. Future studies are warranted to determine the optimal screening test for biliary atresia and to assess the effectiveness and cost-effectiveness of implementing such a program.

Peri-Operative Liver Fibrosis and Native Liver Survival in Pediatric Patients with Biliary Atresia: A Systematic Review and Meta-Analysis

No systematic review to date has examined histopathological parameters in relation to native liver survival in children who undergo the Kasai operation for biliary atresia (BA). A systematic review and meta-analysis is presented, comparing the frequency of native liver survival in peri-operative severe vs. non-severe liver fibrosis cases, in addition to other reported histopathology parameters. Records were sourced from MEDLINE, Embase, and CENTRAL databases. Studies followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and compared native liver survival frequencies in pediatric patients with evidence of severe vs. non-severe liver fibrosis, bile duct proliferation, cholestasis, lobular inflammation, portal inflammation, and giant cell transformation on peri-operative biopsies. The primary outcome was the frequency of native liver survival. A random effects meta-analysis was used. Twenty-eight observational studies were included, 1,171 pediatric patients with BA of whom 631 survived with their native liver. Lower odds of native liver survival in the severe liver fibrosis vs. non-severe liver fibrosis groups were reported (odds ratio [OR], 0.16; 95% confidence interval [CI], 0.08-0.33; I2 =46%). No difference in the odds of native liver survival in the severe bile duct destruction vs. non-severe bile duct destruction groups were reported (OR, 0.17; 95% CI, 0.00-63.63; I2 =96%). Lower odds of native liver survival were documented in the severe cholestasis vs. non-severe cholestasis (OR, 0.10; 95% CI, 0.01-0.73; I2 =80%) and severe lobular inflammation vs. non-severe lobular inflammation groups (OR, 0.02; 95% CI, 0.00-0.62; I2 =69%). There was no difference in the odds of native liver survival in the severe portal inflammation vs. non-severe portal inflammation groups (OR, 0.03; 95% CI, 0.00-3.22; I2 =86%) or between the severe giant cell transformation vs. non-severe giant cell transformation groups (OR, 0.15; 95% CI, 0.00-175.21; I2 =94%). The meta-analysis loosely suggests that the presence of severe liver fibrosis, cholestasis, and lobular inflammation are associated with lower odds of native liver survival in pediatric patients after Kasai.

Dynamic analysis of serum MMP-7 and its relationship with disease progression in biliary atresia: a multicenter prospective study

PURPOSE

We aimed to assess the dynamic changing trend of serum matrix metalloproteinase-7 (MMP-7) in biliary atresia (BA) patients from diagnosis to LTx to further elucidate its clinical value in diagnosis and prognoses and its relationship with disease progression.

METHODS

In this multicentre prospective study, 440 cholestasis patients (direct bilirubin level of > 17 μmol/L) were enrolled. Serum MMP-7 levels were measured using an enzyme-linked immunosorbent assay at diagnosis, 1 week, 2 weeks, 1 month, 6 weeks, 2 months, 3 months, 6 months and then every 6 months post-KPE. The medical record at each follow-up visit for post-Kasai portoenterostomy patient was collected and analyzed.

RESULTS

Using a cut-off value of > 26.73 ng/mL, serum MMP-7 had an AUC of 0.954 in BA neonates and 0.983 in BA infants. A genetic mutation (G137D) was associated with low MMP-7 levels in serum of BA patients. MMP-7 showed a mediation effect on the association between inflammation and liver fibrosis in BA patients. Four dynamic patterns of serum MMP-7 post-KPE were associated with prognosis. Serum MMP-7 was the only significant predictor at 6 weeks post-KPE and the most accurate predictor at 3 months post-KPE of survival with the native liver in 2 years.

CONCLUSION

As one of the critical factors associated with BA occurrence and progression, serum MMP-7 can be used for early diagnosis of BA and post-KPE MMP-7 level is the earliest prognostic biomarker so far.

Modeling oxidative injury response in human kidney organoids

Background

Hemolysis occurs in many injury settings and can trigger disease processes. In the kidney, extracellular hemoglobin can induce damage via several mechanisms. These include oxidative stress, mitochondrial dysfunction, and inflammation, which promote fibrosis and chronic kidney disease. Understanding the pathophysiology of these injury pathways offers opportunities to develop new therapeutic strategies.

Methods

To model hemolysis-induced kidney injury, human kidney organoids were treated with hemin, an iron-containing porphyrin, that generates reactive oxygen species. In addition, we developed an induced pluripotent stem cell line expressing the biosensor, CytochromeC-GFP (CytoC-GFP), which provides a real-time readout of mitochondrial morphology, health, and early apoptotic events.

Results

We found that hemin-treated kidney organoids show oxidative damage, increased expression of injury markers, impaired functionality of organic anion and cation transport and undergo fibrosis. Injury could be detected in live CytoC-GFP organoids by cytoplasmic localization of fluorescence. Finally, we show that 4-(phenylthio)butanoic acid, an HDAC inhibitor with anti-fibrotic effects in vivo, reduces hemin-induced human kidney organoid fibrosis.

Conclusion

This work establishes a hemin-induced model of kidney organoid injury. This platform provides a new tool to study the injury and repair response pathways in human kidney tissue and will assist in the development of new therapeutics.

Structurally abnormal collagen fibrils in abdominal aortic aneurysm resist platelet adhesion

BACKGROUND

Platelet adhesion to the subendothelial collagen fibrils is one of the first steps in hemostasis. Understanding how structural perturbations in the collagen fibril affect platelet adhesion can provide novel insights into disruption of hemostasis in various diseases. We have recently identified the presence of abnormal collagen fibrils with compromised D-periodic banding in the extracellular matrix remodeling present in abdominal aortic aneurysms (AAA).

OBJECTIVE

In this study, we employed multimodal microscopy approaches to characterize how collagen fibril structure impacts platelet adhesion in clinical AAA tissues.

METHODS

Ultrastructural atomic force microscopy (AFM) analysis was performed on tissue sections after staining with fluorescently labeled collagen hybridizing peptide (CHP) to recognize degraded collagen. Second harmonic generation (SHG) microscopy was used on CHP-stained sections to identify regions of intact versus degraded collagen. Finally, platelet adhesion was identified via SHG and indirect immunofluorescence on the same tissue sections.

RESULTS

Our results indicate that ultrastructural features characterizing collagen fibril abnormalities coincide with CHP staining. SHG signal was absent from CHP-positive regions. Additionally, platelet binding was primarily localized to regions with SHG signal. Abnormal collagen fibrils present in AAA (in SHG negative regions) were thus found to inhibit platelet adhesion compared to normal fibrils.

CONCLUSIONS

Our investigations reveal how the collagen fibril structure in the vessel wall can serve as another regulator of platelet-collagen adhesion. These results can be broadly applied to understand the role of collagen fibril structure in regulating thrombosis or bleeding disorders.

Adipose Stromal Cell-Secretome Counteracts Profibrotic Signals From IPF Lung Matrices

Introduction: Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease characterized by excess deposition and altered structure of extracellular matrix (ECM) in the lungs. The fibrotic ECM is paramount in directing resident cells toward a profibrotic phenotype. Collagens, an important part of the fibrotic ECM, have been shown to be structurally different in IPF. To further understand the disease to develop better treatments, the signals from the ECM that drive fibrosis need to be identified. Adipose tissue-derived stromal cell conditioned medium (ASC-CM) has demonstrated antifibrotic effects in animal studies but has not been tested in human samples yet. In this study, the collagen structural integrity in (fibrotic) lung tissue, its interactions with fibroblasts and effects of ASC-CM treatment hereon were studied. Methods: Native and decellularized lung tissue from patients with IPF and controls were stained for denatured collagen using a collagen hybridizing peptide. Primary lung fibroblasts were seeded into decellularized matrices from IPF and control subjects and cultured for 7 days in the presence or absence of ASC-CM. Reseeded matrices were fixed, stained and analyzed for total tissue deposition and specific protein expression. Results: In both native and decellularized lung tissue, more denatured collagen was observed in IPF tissue compared to control tissue. Upon recellularization with fibroblasts, the presence of denatured collagen was equalized in IPF and control matrices, whereas total ECM was higher in IPF matrices than in the control. Treatment with ASC-CM resulted in less ECM deposition, but did not alter the levels of denatured collagen. Discussion: Our data showed that ASC-CM can inhibit fibrotic ECM-induced profibrotic behavior of fibroblasts. This process was independent of collagen structural integrity. Our findings open up new avenues for ASC-CM to be explored as treatment for IPF.

Macrophage-stroma interactions in fibrosis: biochemical, biophysical, and cellular perspectives

Fibrosis results from aberrant wound healing and is characterized by an accumulation of extracellular matrix, impairing the function of an affected organ. Increased deposition of extracellular matrix proteins, disruption of matrix degradation, but also abnormal post-translational modifications alter the biochemical composition and biophysical properties of the tissue microenvironment - the stroma. Macrophages are known to play an important role in wound healing and tissue repair, but the direct influence of fibrotic stroma on macrophage behaviour is still an under-investigated element in the pathogenesis of fibrosis. In this review, the current knowledge on interactions between macrophages and (fibrotic) stroma will be discussed from biochemical, biophysical, and cellular perspectives. Furthermore, we provide future perspectives with regard to how macrophage-stroma interactions can be examined further to ultimately facilitate more specific targeting of these interactions in the treatment of fibrosis. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Intramuscular injection of Botox causes tendon atrophy by induction of senescence of tendon-derived stem cells

Background

Botulinum toxin (Botox) injection is in widespread clinical use for the treatment of muscle spasms and tendinopathy but the mechanism of action is poorly understood.

Hypothesis

We hypothesised that the reduction of patellar-tendon mechanical-loading following intra-muscular injection of Botox results in tendon atrophy that is at least in part mediated by the induction of senescence of tendon-derived stem cells (TDSCs).

Study design

Controlled laboratory study

Methods

A total of 36 mice were randomly divided into 2 groups (18 Botox-injected and 18 vehicle-only control). Mice were injected into the right vastus lateralis of quadriceps muscles either with Botox (to induce mechanical stress deprivation of the patellar tendon) or with normal saline as a control. At 2 weeks post-injection, animals were euthanized prior to tissues being harvested for either evaluation of tendon morphology or in vitro studies. TDSCs were isolated by cell-sorting prior to determination of viability, differentiation capacity or the presence of senescence markers, as well as assessing their response to mechanical loading in a bioreactor. Finally, to examine the mechanism of tendon atrophy in vitro, the PTEN/AKT-mediated cell senescence pathway was evaluated in TDSCs from both groups.

Results

Two weeks after Botox injection, patellar tendons displayed several atrophic features including tissue volume reduction, collagen fibre misalignment and increased degradation. A colony formation assay revealed a significantly reduced number of colony forming units of TDSCs in the Botox-injected group compared to controls. Multipotent differentiation capacities of TDSCs were also diminished after Botox injection. To examine if mechanically deprived TDSC are capable of forming tendon tissue, we used an isolated bioreactor system to culture tendon constructs using TDSC. These results showed that TDSCs from the Botox-treated group failed to restore tenogenic differentiation after appropriate mechanical loading. Examination of the signalling pathway revealed that injection of Botox into quadriceps muscles causes PTEN/AKT-mediated cell senescence of TDSCs.

Conclusion

Intramuscular injection of Botox interferes with tendon homeostasis by inducing tendon atrophy and senescence of TDSCs. Botox injection may have long-term adverse consequences for the treatment of tendinopathy.

Clinical relevance

Intramuscular Botox injection for tendinopathy or tendon injury could result in adverse effects in human tendons and evaluation of its long-term efficacy is warranted.