Mechanistic insight into lysyl oxidase in vascular remodeling and angiogenesis

Vascular remodeling and angiogenesis are two key processes in the maintenance of vascular homeostasis and involved in a wide array of vascular pathologies. Following these processes, extracellular matrix (ECM) provides the mechanical foundation for vascular walls. Lysyl oxidase (LOX), the key matrix-modifying enzyme, has been demonstrated to significantly affect structural abnormality and dysfunction in the blood vessels. The role of LOX in vascular remodeling and angiogenesis has always been the subject in the current medical research. Therefore, we presently make a summarization of the biosynthesis of LOX and the mechanisms involved in vascular remodeling and angiogenesis, as well as the role of LOX in diseases associated with vascular abnormalities and the therapeutic potential via targeting LOX. In particular, we give a proposal that LOX likely reshapes matrisome-associated genes expressions in the regulation of vascular remodeling and angiogenesis, which serves as a mechanistic insight into the critical role of LOX in these two aspects. Additionally, LOX has also dual effects on the vascular dysfunction, namely, inhibition of LOX for improving hypertension, restenosis and malignant tumor while activation of LOX for curing arterial aneurysm and dissection. LOX-targeted therapy may provide a promising therapeutic strategy for the treatment of various vascular pathologies associated with vascular remodeling and angiogenesis.

Lysyl oxidase promotes bleomycin-induced lung fibrosis through modulating inflammation

Enzymes involved in collagen biosynthesis, including lysyl oxidase （LOX）, have been proposed as potential therapeutic targets for idio- pathic pulmonary fibrosis. LOX expression is significantly upregulated in bleomycin （BLM）-induced lung fibrosis, and knockdown of LOX expression or inhibition of LOX activity alleviates the lung fibrosis. Unexpectedly, treatment of the mice with LOX inhibitor at the inflammatory stage, but not the fibrogenic stage, efficiently reduces collagen deposition and normalizes lung architecture. Inhibition of LOX impairs inflammatory ceU infiltration, TGF-β signaling, and myofibroblast accumulation. Furthermore, ectopic expres- sion of LOX sensitizes the fibrosis-resistant Balb/c mice to BLM-induced inflammation and lung fibrosis. These results suggest that LOX is indispensable for the progression of BLM-induced experimental lung fibrosis by aggravating the inflammatory response and subse- quent fibrosis process after lung injury.

Critical involvement of lysyl oxidase in seizure-induced neuronal damage through ERK-Alox5-dependent ferroptosis and its therapeutic implications

Recent insights collectively suggest the important roles of lysyl oxidase(LysOX)in the pathological processes of several acute and chronic neurological diseases,but the molecular regulatory mechanisms remain elusive.Herein,we explore the regulatory role of LysOX in the seizure-induced ferroptotic cell death of neurons.Mechanistically,LysOX promotes ferroptosis-associated lipid peroxidation in neurons via activating extracellular regulated protein kinase(ERK)-dependent 5-lipoxygenase(Alox5)signaling.In addition,overexpression of LysOX via adeno-associated viral vector(AAV)-based gene transfer enhances ferroptosis sensitivity and aggravates seizure-induced hippocampal damage.Our studies show that pharmacological inhibition of LysOX withβ-aminopropionitrile(BAPN)significantly blocks seizure-induced ferroptosis and thereby alleviates neuronal damage,while the BAPN-associated cardiotoxicity and neurotoxicity could further be reduced through encapsulation with bioresponsive amorphous calcium carbonate-based nanocarriers.These findings unveil a previously unrecognized LysOX-ERK-Alox5 pathway for ferroptosis regulation during seizure-induced neuronal damage.Suppressing this pathway may yield therapeutic implications for restoring seizure-induced neuronal injury.

Estradiol plays a role in regulating the expression of lysyl oxidase family genes in mouse urogenital tissues and human Ishikawa cells

The lysyl oxidase （LOX） family encodes the copper-dependent amine oxidases that play a key role in determining the tensile strength and structural integrity of connective tissues by catalyzing the crosslinking of elastin or collagen. Estrogen may upregulate the expression of LOXand lysyl oxidase-like 1 （LOXL1） in the vagina. The objec- tive of this study was to determine the effect of estrogen on the expression of all LOX family genes in the urogenital tissues of accelerated ovarian aging mice and human Ishikawa cells. Mice and Ishikawa cells treated with estradiol （E2） showed increased expression of LOXfamily genes and transforming growth factor IB1 （TGF-β1）. Ishikawa cells treated with TGF-β1 also showed increased expression of LOXfamily genes. The Ishikawa cells were then treated with either E2 plus the TGF-β receptor （TGFBR） inhibitor SB431542 or E2 alone. The expression of LOXfamily genes induced by E2 was reduced in the Ishikawa cells treated with TGFBR inhibitor. Our results showed that E2 increased the ex- prassion of the LOXfamily genes, and suggest that this induction may be mediated by the TGF-β signal pathway. E2 may play a role in regulating the expression of LOXfamily genes.

Lysyl oxidase inhibition enhances browning of white adipose tissue and adaptive thermogenesis

Accumulating evidence from both animal and human studies suggests that activation of beige fat increases cellular energy expenditure,ultimately reducing adiposity.Here,we report the central role of adipocyte-derived lysyl oxidase(Lox)in the formation of thermogenic beige fat.Mice exposed to cold or aβ3 agonist showed drastically lower Lox expression in thermogenically activated beige fat.Importantly,inhibition of Lox activity with BAPN stimulated biogenesis of beige fat in inguinal white adipose tissue(iWAT)under housing conditions and potentiated cold-induced adaptive thermogenesis and beiging in both iWAT and epididymal white adipose tissue(eWAT).Notably,white adipocytes with Lox repression undergo transdifferentiation into beige adipocytes which can be suppressed by tumor necrosis factor-α(TNFα)via ERK activation.This work provides new insight into the molecular control to expand beige fat by Lox inhibition and suggest the potential for utilizing inhibitor of Lox to treat the emerging epidemics of obesity and diabetes.

Progression and Regression of Abdominal Aortic Aneurysms in Mice

Objective:Abdominal aortic aneurysm(AAA)is a significant medical problem with a high mortality rate.Nevertheless,the underlying mechanism for the progression and regression of AAA is unknown.Methods:Experimental model of AAA was first created by porcine pancreatic elastase incubation around the infrarenal aorta of C57BL/6 mice.Then,AAA progression and regression were evaluated based on the diameter and volume of AAA.The aortas were harvested for hematoxylin-eosin staining(HE),orcein staining,sirius red staining,immunofluorescence analysis and peris’prussian blue staining at the indicated time point.Finally,P-aminopropionitrile monofumarate(BAPN)was used to explore the underlying mechanism of the regression of AAA.Results:When we extended the observation period to 100 days,we not only observed an increase in the AAA diameter and volume in the early stage,but also a decrease in the late stage.Consistent with AAA diameter and volume,the aortic thickness showed the same tendency based on HE staining.The elastin and collagen content first degraded and then regenerated,which corresponds to the early deterioration and late regression of AAA.Then,endogenous up-regulation of lysyl oxidase(LOX)was detected,accompanying the regression of AAA,as detected by an immunofluorescent assay.BAPN and LOX inhibitor considerably inhibited the regression of AAA,paralleling the degradation of elastin lamella and collagen.Conclusion:Taken together,we tentatively conclude that endogenous re-generation of LOX played an influential role in the regression of AAA.Therefore,regulatory factors on the generation of LOX exhibit promising therapeutic potential against AAA.

A multifunctional scaffold that promotes the scaffold-tissue interface integration and rescues the ROS microenvironment for repair of annulus fibrosus defects

Due to the limited self-repair ability of the annulus fibrosus (AF), current tissue engineering strategies tend to use structurally biomimetic scaffolds for AF defect repair. However, the poor integration between implanted scaffolds and tissue severely affects their therapeutic effects. To solve this issue, we prepared a multifunctional scaffold containing loaded lysyl oxidase (LOX) plasmid DNA exosomes and manganese dioxide nanoparticles (MnO2 NPs). LOX facilitates extracellular matrix (ECM) cross-linking, while MnO2 NPs inhibit excessive reactive oxygen species (ROS)-induced ECM degradation at the injury site, enhancing the crosslinking effect of LOX. Our results revealed that this multifunctional scaffold significantly facilitated the integration between the scaffold and AF tissue. Cells were able to migrate into the scaffold, indicating that the scaffold was not encapsulated as a foreign body by fibrous tissue. The functional scaffold was closely integrated with the tissue, effectively enhancing the mechanical properties, and preventing vascular invasion, which emphasized the importance of scaffold-tissue integration in AF repair.

LOX upregulates FAK phosphorylation to promote metastasis in osteosarcoma

Osteosarcoma is a malignant bone tumor that commonly occurs in the pediatric population.Despite the use of chemotherapy and surgery,metastasis remains to be the leading cause of death in patients with osteosarcoma.We have previously reported that cytoplasmic mislocalization of p27 is associated with a poor outcome in osteosarcoma.In this study,we further show that lysyl oxidase(LOx)expression was associated with p27 mislocalization.Lox is an enigmatic molecule that acts as a tumor suppressor or a metastatic promoter;however,its role in osteosarcoma is still unclear.Hence,we performed both in vitro and in vivo analyses to dissect the role of Lox in osteosarcoma.The result of our survival analysis indicated that Lox expression significantly correlated with a poor outcome in osteosarcoma with or without controlling for the initial metastasis status(P<0.05).Functionally,we found that higher LoX expression promoted osteosarcoma cell proliferation,migration,and invasiveness in vitro and produced a higher number of mice with pulmonary metastases in an orthotopic xenograft mouse model.Mechanistically,phospho-FAK was increased in osteosarcoma cells with high LOX expression.Our results further showed that FAK inhibition significantly reduced tumor cell proliferation and migration in vitro as well as LoX-mediated metastasis in mice.Together,our findings suggest that there is a novel link between p27 mislocalization and LOX expression.LOX plays a pivotal role in osteosarcoma metastasis by upregulating FAK phosphorylation.FAK inhibition may constitute a promising therapeutic strategy to reduce the development of metastasis in osteosarcoma with Lox overexpression.

Proteins:Neglected active ingredients in edible bird’s nest

Edible bird’s nest(EBN)is a kind of natural invigorant with a long history of consumption in Asia,especially in China.EBN is formed by mixing the saliva of swiftlets(Aerodramus)with feathers and other components during the breeding season.Proteins are the most important nutrient in EBN.By studying proteins in EBN,we can not only elucidate their components at the molecular level,but also study their bioactivities.Therefore,it is of great significance to study the proteins in EBN.Previous research on the proteins in EBN was preliminary and cursory,and no one has summarized and analyzed the proteins in EBN and correlated the bioactivities of these proteins with the biological functions of EBN.This article focused on the proteins in EBN,listed the proteins identified in different proteomic studies,and introduced the sources,structures and bioactivities of the most frequently identified proteins,including acidic mammalian chitinase,lysyl oxidase homolog 3,mucin-5AC,ovoinhibitor,nucleobindin-2,calciumbinding protein(MW:4.5×10~4)and glucose-regulated protein(MW:7.8×10~4).The properties of these proteins are closely related to the bioactivities of EBN.Therefore,this article can provide inspiration for further research on the efficacy of EBN.

Three-dimensional decellularized tumor extracellular matrices with different stiffness as bioengineered tumor scaffolds

In the three-dimensional(3D)tumor microenvironment,matrix stiffness is associated with the regulation of tumor cells behaviors.In vitro tumor models with appropriate matrix stiffness are urgently desired.Herein,we prepare 3D decellularized extracellular matrix(DECM)scaffolds with different stiffness to mimic the microenvironment of human breast tumor tissue,especially the matrix stiffness,components and structure of ECM.Furthermore,the effects of matrix stiffness on the drug resistance of human breast cancer cells are explored with these developed scaffolds as case studies.Our results confirm that DECM scaffolds with diverse stiffness can be generated by tumor cells with different lysyl oxidase(LOX)expression levels,while the barely intact structure and major components of the ECM are maintained without cells.This versatile 3D tumor model with suitable stiffness can be used as a bioengineered tumor scaffold to investigate the role of the microenvironment in tumor progression and to screen drugs prior to clinical use to a certain extent.