Overhydroxylation of Lysine of Collagen Increases Uterine Fibroids Proliferation: Roles of Lysyl Hydroxylases, Lysyl Oxidases, and Matrix Metalloproteinases

Hypoxia in uterine fibroids: role in pathobiology and therapeutic opportunities

Uterine fibroids are the most common tumors in females affecting up to 70% of women world-wide, yet targeted therapeutic options are limited. Oxidative stress has recently surfaced as a key driver of fibroid pathogenesis and provides insights into hypoxia-induced cell transformation, extracellular matrix pathophysiology, hypoxic cell signaling cascades, and uterine biology. Hypoxia drives fibroid tumorigenesis through (1) promoting myometrial stem cell proliferation, (2) causing DNA damage propelling transformation of stem cells to tumor initiating cells, and (3) driving excess extracellular matrix (ECM) production. Common fibroid-associated DNA mutations include MED12 mutations, HMGA2 overexpression, and Fumarate hydratase loss of function. Evidence suggests an interaction between hypoxia signaling and these mutations. Fibroid development and growth are promoted by hypoxia-triggered cell signaling via various pathways including HIF-1, TGFβ, and Wnt/β-catenin. Fibroid-associated hypoxia persists due to antioxidant imbalance, ECM accumulation, and growth beyond adequate vascular supply. Current clinically available fibroid treatments do not take advantage of hypoxia-targeting therapies. Growing pre-clinical and clinical studies identify ROS inhibitors, anti-HIF-1 agents, Wnt/β-catenin inhibition, and TGFβ cascade inhibitors as agents that may reduce fibroid development and growth through targeting hypoxia.

Uterine Collagen Cross-Linking: Biology, Role in Disorders, and Therapeutic Implications

Collagen is an essential constituent of the uterine extracellular matrix that provides biomechanical strength, resilience, structural integrity, and the tensile properties necessary for the normal functioning of the uterus. Cross-linking is a fundamental step in collagen biosynthesis and is critical for its normal biophysical properties. This step occurs enzymatically via lysyl oxidase (LOX) or non-enzymatically with the production of advanced glycation end-products (AGEs). Cross-links found in uterine tissue include the reducible dehydro-dihydroxylysinonorleucine (deH-DHLNL), dehydro-hydroxylysinonorleucine (deH-HLNL), and histidinohydroxymerodesmosine (HHMD); and the non-reducible pyridinoline (PYD), deoxy-pyridinoline (DPD); and a trace of pentosidine (PEN). Collagen cross-links are instrumental for uterine tissue integrity and the continuation of a healthy pregnancy. Decreased cervical cross-link density is observed in preterm birth, whereas increased tissue stiffness caused by increased cross-link density is a pathogenic feature of uterine fibroids. AGEs disrupt embryo development, decidualization, implantation, and trophoblast invasion. Uterine collagen cross-linking regulators include steroid hormones, such as progesterone and estrogen, prostaglandins, proteoglycans, metalloproteinases, lysyl oxidases, nitric oxide, nicotine, and vitamin D. Thus, uterine collagen cross-linking presents an opportunity to design therapeutic targets and warrants further investigation in common uterine disorders, such as uterine fibroids, cervical insufficiency, preterm birth, dystocia, endometriosis, and adenomyosis.

Histological assessment and gene expression analysis of intra-oral soft tissue graft donor sites

AIM

To determine the structural and gene expression features of different intra-oral soft tissue donor sites (i.e., anterior palate, posterior palate, maxillary tuberosity and retromolar pad).

MATERIALS AND METHODS

Standardized mucosal tissue punch biopsies were collected from at least one donor site per subject. Histological processing was performed to determine tissue morphometry and quantify collagen composition. Site-specific gene distribution was mapped using targeted gene expression analysis and validated using real time polymerase chain reaction (qPCR).

RESULTS

A total of 50 samples from 37 subjects were harvested. Epithelial thickness did not differ between sites. However, lamina propria was thicker in the maxillary tuberosity (2.55 ± 0.92 mm) and retromolar pad (1.98 ± 0.71 mm) than in the lateral palate. Type I collagen was the predominant structural protein in the lamina propria (75.06%-80.21%). Genes involving collagen maturation and extracellular matrix regulation were highly expressed in the maxillary tuberosity and retromolar pad, while lipogenesis-associated genes were markedly expressed in the lateral palate. The retromolar pad showed the most distinct gene expression profile, and the anterior and posterior palate displayed similar transcription profiles.

CONCLUSIONS

Tissue samples harvested from the anterior and posterior palate differed morphologically from those from the maxillary tuberosity and retromolar pad. Each intra-oral site showed a unique gene expression profile, which might impact their biological behaviour and outcomes of soft tissue augmentation procedures.

Update on the Role and Regulatory Mechanism of Extracellular Matrix in the Pathogenesis of Uterine Fibroids

Uterine fibroids (UFs), also known as leiomyomas, are benign tumors of the myometrium affecting over 70% of women worldwide, particularly women of color. Although benign, UFs are associated with significant morbidity; they are the primary indication for hysterectomy and a major source of gynecologic and reproductive dysfunction, ranging from menorrhagia and pelvic pain to infertility, recurrent miscarriage, and preterm labor. So far, the molecular mechanisms underlying the pathogenesis of UFs are still quite limited. A knowledge gap needs to be filled to help develop novel strategies that will ultimately facilitate the development of therapies and improve UF patient outcomes. Excessive ECM accumulation and aberrant remodeling are crucial for fibrotic diseases and excessive ECM deposition is the central characteristics of UFs. This review summarizes the recent progress of ascertaining the biological functions and regulatory mechanisms in UFs, from the perspective of factors regulating ECM production, ECM-mediated signaling, and pharmacological drugs targeting ECM accumulation. In addition, we provide the current state of knowledge by discussing the molecular mechanisms underlying the regulation and emerging role of the extracellular matrix in the pathogenesis of UFs and in applications. Comprehensive and deeper insights into ECM-mediated alterations and interactions in cellular events will help develop novel strategies to treat patients with this common tumor.

Targeting Lysyl Oxidase as a Potential Therapeutic Approach to Reducing Fibrotic Scars Post-operatively: Its Biological Role in Post-Surgical Scar Development

Abdominal and pelvic surgery, or any surgical injury of the peritoneum, often leads to chronic abdominal adhesions that may lead to bowel obstruction, infertility, and pain. Current therapeutic strategies are usually ineffective, and the pathological mechanisms of the disease are unclear. Excess collagen cross-linking is a key mediator for extra-cellular matrix deposition and fibrogenesis. Lysyl oxidase is a key enzyme that catalyzes the formation of stabilizing cross-links in collagen. Dysregulation of Lysyl oxidase (Lox) expressing upregulates collagen cross-linking, leading ECM deposition. Tissue hypoxia during surgery induces molecular mechanisms and active transcription factors to promote the expression of several genes related to inflammation, oxidative stress, and fibrosis, such as transforming growth factor beta, and Lox. Studies have shown that targeting Lox improves clinical outcomes and fibrotic parameters in liver, lung, and myocardial fibrosis, therefore, Lox may be a potential drug target in the prevention of postsurgical adhesion.

Perspectives on pediatric congenital aortic valve stenosis: Extracellular matrix proteins, post translational modifications, and proteomic strategies

In heart valve biology, organization of the extracellular matrix structure is directly correlated to valve function. This is especially true in cases of pediatric congenital aortic valve stenosis (pCAVS), in which extracellular matrix (ECM) dysregulation is a hallmark of the disease, eventually leading to left ventricular hypertrophy and heart failure. Therapeutic strategies are limited, especially in pediatric cases in which mechanical and tissue engineered valve replacements may not be a suitable option. By identifying mechanisms of translational and post-translational dysregulation of ECM in CAVS, potential drug targets can be identified, and better bioengineered solutions can be developed. In this review, we summarize current knowledge regarding ECM proteins and their post translational modifications (PTMs) during aortic valve development and disease and contributing factors to ECM dysregulation in CAVS. Additionally, we aim to draw parallels between other fibrotic disease and contributions to ECM post-translational modifications. Finally, we explore the current treatment options in pediatrics and identify how the field of proteomics has advanced in recent years, highlighting novel characterization methods of ECM and PTMs that may be used to identify potential therapeutic strategies relevant to pCAVS.

Importance of Fibrosis in the Pathogenesis of Uterine Leiomyoma and the Promising Anti-fibrotic Effects of Dipeptidyl Peptidase-4 and Fibroblast Activation Protein Inhibitors in the Treatment of Uterine Leiomyoma

Uterine fibroid or leiomyoma is the most common benign uterus tumor. The tumor is primarily composed of smooth muscle (fibroid) cells, myofibroblast, and a significant amount of extracellular matrix components. It mainly affects women of reproductive age. They are uncommon before menarche and usually disappear after menopause. The fibroids have excessive extracellular matrix components secreted by activated fibroblast cells (myofibroblast). Myofibroblast has the characteristics of fibroblast and smooth muscle cells. These cells possess contractile capability due to the expression of contractile proteins which are normally found only in muscle tissues. The rigid nature of the tumor is responsible for many side effects associated with uterine fibroids. The current drug treatment strategies are primarily hormone-driven and not anti-fibrotic. This paper emphasizes the fibrotic background of uterine fibroids and the mechanisms behind the deposition of excessive extracellular matrix components. The transforming growth factor-β, hippo, and focal adhesion kinase-mediated signaling pathways activate the fibroblast cells and deposit excessive extracellular matrix materials. We also exemplify how dipeptidyl peptidase-4 and fibroblast activation protein inhibitors could be beneficial in reducing the fibrotic process in leiomyoma. Dipeptidyl peptidase-4 and fibroblast activation protein inhibitors prevent the fibrotic process in organs such as the kidneys, lungs, liver, and heart. These inhibitors are proven to inhibit the signaling pathways mentioned above at various stages of their activation. Based on literature evidence, we constructed a narrative review on the mechanisms that support the beneficial effects of dipeptidyl peptidase-4 and fibroblast activation protein inhibitors for treating uterine fibroids.

Transcriptome Analysis of mRNA in Uterine Leiomyoma Using Next-generation RNA Sequencing

Background:

Uterine leiomyoma is a benign smooth muscle tumor of monoclonal nature in the female reproductive tract and is one of the major health problems. More than 70% of the female population suffers from uterine leiomyoma in their lifetime and in the advanced condition, it is associated with pregnancy complications and infertility.

Objective:

Characterization and relative expression of mRNA transcripts through transcriptome profiling in uterine leiomyoma and adjacent normal myometrium.

Methods:

Uterine leiomyoma tissue of an Indian female, age 32 years, with a family history of leiomyoma (evident from mother’s hysterectomy for the same pathology) was used. Patient showed 9 multiple large lesions appearing heterogeneously, deforming the uterine contour and causing distortion and splaying of the endometrial cavity showing disease aggressiveness was taken for Next-generation sequencing (NGS) to develop whole transcriptome profile along with the adjacent normal myometrium as control. The validation of the relative expression of the selective transcripts was done using Real-Time PCR.

Results:

The transcriptome profile indicated 128 genes up-regulated and 98 down-regulated, with the Log2 fold change ≥ 2 and P ≤ 0.05, highlighting the molecular network closely associated with focal adhesion, hyaluronan and MAPK-signaling pathways. The mean relative fold change obtained from quantitative PCR as well as the P-values of 10 selected transcripts evaluated from student’s t-test were as follows: BCAN: 7.93 fold (p-value =0.0013); AAK1: 2.2 fold (p-value =0.0036); PCBP3: 3.4 fold (p-value =0.0197); MOV10L1: 3.4 fold (p-value =0.0062); TWISTNB: 1.8 fold (p-value =0.006); TMSB15A: 2.1 fold (p-value =0.0023); SMAD1: 0.8 fold (p-value =0.0112); ANXA1: 0.6 fold (p-value =0.0012); FOS: 0.6 fold (p-value =0.0191); SLFN11: 0.56 fold (p-value =0.0001).

Conclusion:

The present study provides a roadmap, towards the analysis of genes and their roles in corresponding pathways throwing light on their possible involvement in the pathology of the disease.

Collagen cross-linking mediated by lysyl hydroxylase 2: an enzymatic battlefield to combat fibrosis

The hallmark of fibrosis is an excessive accumulation of collagen, ultimately leading to organ failure. It has become evident that the deposited collagen also exhibits qualitative modifications. A marked modification is the increased cross-linking, leading to a stabilization of the collagen network and limiting fibrosis reversibility. Not only the level of cross-linking is increased, but also the composition of cross-linking is altered: an increase is seen in hydroxyallysine-derived cross-links at the expense of allysine cross-links. This results in irreversible fibrosis, as collagen cross-linked by hydroxyallysine is more difficult to degrade. Hydroxyallysine is derived from a hydroxylysine in the telopeptides of collagen. The expression of lysyl hydroxylase (LH) 2 (LH2), the enzyme responsible for the formation of telopeptidyl hydroxylysine, is universally up-regulated in fibrosis. It is expected that inhibition of this enzyme will lead to reversible fibrosis without interfering with the normal repair process. In this review, we discuss the molecular basis of collagen modifications and cross-linking, with an emphasis on LH2-mediated hydroxyallysine cross-links, and their implications for the pathogenesis and treatment of fibrosis.

Evidence of biomechanical and collagen heterogeneity in uterine fibroids

Objective

Uterine fibroids (leiomyomas) are common benign tumors of the myometrium but their molecular pathobiology remains elusive. These stiff and often large tumors contain abundant extracellular matrix (ECM), including large amounts of collagen, and can lead to significant morbidities. After observing structural multiformities of uterine fibroids, we aimed to explore this heterogeneity by focusing on collagen and tissue stiffness.

Methods

For 19 fibroids, ranging in size from 3 to 11 centimeters, from eight women we documented gross appearance and evaluated collagen content by Masson trichrome staining. Collagen types were determined in additional samples by serial extraction and gel electrophoresis. Biomechanical stiffness was evaluated by rheometry.

Results

Fibroid slices displayed different gross morphology and some fibroids had characteristics of two or more patterns: classical whorled (n = 8); nodular (n = 9); interweaving trabecular (n = 9); other (n = 1). All examined fibroids contained at least 37% collagen. Tested samples included type I, III, and V collagen of different proportions. Fibroid stiffness was not correlated with the overall collagen content (correlation coefficient 0.22). Neither stiffness nor collagen content was correlated with fibroid size. Stiffness among fibroids ranged from 3028 to 14180 Pa (CV 36.7%; p<0.001, one-way ANOVA). Stiffness within individual fibroids was also not uniform and variability ranged from CV 1.6 to 42.9%.

Conclusions

The observed heterogeneity in structure, collagen content, and stiffness highlights that fibroid regions differ in architectural status. These differences might be associated with variations in local pressure, biomechanical signaling, and altered growth. We conclude the design of all fibroid studies should account for such heterogeneity because samples from different regions have different characteristics. Our understanding of fibroid pathophysiology will greatly increase through the investigation of the complexity of the chemical and biochemical signaling in fibroid development, the correlation of collagen content and mechanical properties in uterine fibroids, and the mechanical forces involved in fibroid development as affected by the various components of the ECM.

The lysyl oxidase like 2/3 enzymatic inhibitor, PXS-5153A, reduces crosslinks and ameliorates fibrosis

Fibrosis is characterized by the excessive deposition of extracellular matrix and crosslinked proteins, in particular collagen and elastin, leading to tissue stiffening and disrupted organ function. Lysyl oxidases are key players during this process, as they initiate collagen crosslinking through the oxidation of the ε-amino group of lysine or hydroxylysine on collagen side-chains, which subsequently dimerize to form immature, or trimerize to form mature, collagen crosslinks. The role of LOXL2 in fibrosis and cancer is well documented, however the specific enzymatic function of LOXL2 and LOXL3 during disease is less clear. Herein, we describe the development of PXS-5153A, a novel mechanism based, fast-acting, dual LOXL2/LOXL3 inhibitor, which was used to interrogate the role of these enzymes in models of collagen crosslinking and fibrosis. PXS-5153A dose-dependently reduced LOXL2-mediated collagen oxidation and collagen crosslinking in vitro. In two liver fibrosis models, carbon tetrachloride or streptozotocin/high fat diet-induced, PXS-5153A reduced disease severity and improved liver function by diminishing collagen content and collagen crosslinks. In myocardial infarction, PXS-5153A improved cardiac output. Taken together these results demonstrate that, due to their crucial role in collagen crosslinking, inhibition of the enzymatic activities of LOXL2/LOXL3 represents an innovative therapeutic approach for the treatment of fibrosis.

The Role of Tumor Necrosis Factor α in the Biology of Uterine Fibroids and the Related Symptoms

Uterine fibroids (UFs) are the most common benign tumors of the female genital tract. The incidence of UFs has been estimated at 25⁻80% depending on selected population. The pathophysiology of UFs remains poorly understood. The transformation of smooth muscle cells of the uterus into abnormal, immortal cells, capable of clonal division, is the main component of all pathways leading to UF tumor formation and tumor necrosis factor α (TNF-α) is believed to be one of the key factors in this field. TNF-α is a cell signaling protein involved in systemic inflammation and is one of the cytokines responsible for the acute phase reaction. This publication presents current data about the role of tumor necrosis factor α in the biology of UFs and the related symptoms. TNF-α is an extremely important cytokine associated with the biology of UFs, UF-related symptoms and complaints. Its concentration has been proven to be elevated in women with clinically symptomatic UFs. The presented data suggest the presence of an "inflammation-like" state in women with UFs where TNF-α is a potent inflammation inducer. The origin of numerous symptoms reported by women with UFs can be traced back to the TNF-α influence. Nevertheless, our knowledge on this subject remains limited and TNF-α dependent pathways in UF pathophysiology should be investigated further.

Matrix Metalloproteinase Activity Correlates With Uterine Myoma Volume Reduction After Ulipristal Acetate Treatment

CONTEXT

Ulipristal acetate (UPA), a selective progesterone receptor modulator, clinically reduces uterine myoma size in 80% of cases. However, the molecular mechanism of action is still poorly understood, as is the reason why 20% of myomas do not respond to treatment.

OBJECTIVE

To elucidate whether matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are associated with myoma volume shrinkage after UPA therapy.

DESIGN

Prospective study.

SETTING

Academic research unit of a university hospital.

PATIENTS

Uterine biopsies were obtained from 59 patients with symptomatic myomas undergoing myomectomy, 45 of whom were treated preoperatively with either one or greater than or equal to two, 3-month courses of UPA and 14 not given any hormone therapy to serve as controls. Myoma volume was individually monitored during UPA therapy to determine any substantial clinical response (defined as a reduction in volume of >25%). Three groups were established based on the response to treatment: responsive (R) after one course (n = 12); R after two to four courses (n = 15); and nonresponsive (NR; n = 18).

INTERVENTIONS

UPA treatment given as preoperative management for symptomatic myomas.

MAIN OUTCOME MEASURES

MMP and TIMP expression assessed by zymography and immunohistochemistry.

RESULTS

Compared with controls and NR myomas, responders showed significantly higher expression levels for MMP-1 (P < 0.0001) and MMP-2 (P = 0.009) and significantly lower expression levels for TIMP-1 (P = 0.040).

CONCLUSIONS

The correlation found between MMP expression and volume fold change supports the notion that MMPs play a key role in UPA-induced myoma shrinkage.