Midkine proteins in cardio-vascular disease. Where do we come from and where are we heading to?

Dahuang Zhechong pill attenuates hepatic sinusoidal capillarization in liver cirrhosis and hepatocellular carcinoma rat model via the MK/integrin signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Dahuang Zhechong pill (DHZCP), a traditional Chinese medicine, was derived from the famous book Unk "Synopsis of Prescriptions of the Golden Chamber" during the Han dynasty. Owing to its ability to invigorate the circulation of blood in Chinese medicine, DHZCP is usually used for treating liver cirrhosis (LC) and hepatocellular carcinoma (HCC). Clinical application have shown that DHZCP exhibits satisfactory therapeutic effects in HCC adjuvant therapy; however, little is known about its underlying mechanisms.

AIM OF THE STUDY

We aimed to clarify the mechanism of DHZCP against hepatic sinusoidal capillarization in rats with LC and HCC by inhibiting the MK/integrin signaling pathway of liver sinusoidal endothelial cells (LSECs).

MATERIALS AND METHODS

The contents of 29 characteristic components in DHZCP were determined by ultraperformance liquid chromatography-tandem mass spectrometry. DEN (Diethylnitrosamine)-induced LC and HCC rat models were constructed, and DHZCP was administered when the disease entered the LC stage. After 4 or 12 weeks of administration, hematoxylin and eosin staining, Masson staining, Metavir score, and SSCP (Single strand conformation polymorphism) gene mutation detection were used to confirm tissue fibrosis and cancer. The levels of NO, ET-1 and TXA2, which can regulate vasomotor functions and activate the MK/Itgα6/Src signaling pathway were evaluated by using immunohistochemistry, chemiluminescence, immunofluorescence, Western blot analysis, and enzyme-linked immunosorbent assay (ELISA). Similar methods were also used to evaluate the levels of VEGF, VEGFR, Ang-2 and Tie, which can promote pathological angiogenesis and activate the MK/Itgα4/NF-κB signaling pathway. In vitro cell experiments were performed using potential pharmacodynamic molecules targeting integrins in DHZCP were selected by molecular docking, and the effects of these molecules on the function of LSECs were studied by Itgα4+ and Itgα6+ cell models.

RESULTS

At the stage of LC, the animal experiments demonstrated that DHZCP mainly inhibited the MK/Itgα6 signaling pathway to increase the number and size of hepatic sinus fenestration, reversed the ET-1/NO and TXA2/NO ratios, regulated hepatic sinus relaxation and contraction balance, reduced the portal vein pressure, and inhibited cirrhotic carcinogenesis. At the HCC stage, DHZCP could also significantly inhibit the MK/Itgα4 signaling pathway, reduce pathological angiogenesis, and alleviate disease progression. The results of the cell experiments showed that Rhein, Naringenin, Liquiritin and Emodin-8-O-β-D-glucoside (PMEG) were involved in vascular regulation by affecting the MK/integrin signaling pathway. Liquiritin and PMEG mainly blocked the MK/α6 signal, which is important in regulating the vasomotor function of the liver sinus. Naringenin and Rhein mainly acted by blocked the signaling of MK/α4 action signal, which are potent molecules that inhibit pathological angiogenesis.

CONCLUSIONS

DHZCP could improve the hepatic sinusoidal capillarization of LC and HCC by inhibiting the MK/Itgα signaling pathway and inhibited disease progression. Rhein, Naringenin, Liquiritin and PMEG were the main active molecules that affected the MK/Itgα signaling pathway.

Proteomic profiling of serum identifies a molecular signature that correlates with clinical outcomes in COPD

OBJECTIVE

Novel biomarkers related to main clinical hallmarks of Chronic obstructive pulmonary disease (COPD), a heterogeneous disorder with pulmonary and extra-pulmonary manifestations, were investigated by profiling the serum levels of 1305 proteins using Slow Off-rate Modified Aptamers (SOMA)scan technology.

METHODS

Serum samples were collected from 241 COPD subjects in the multicenter French Cohort of Bronchial obstruction and Asthma to measure the expression of 1305 proteins using SOMAscan proteomic platform. Clustering of the proteomics was applied to identify disease subtypes and their functional annotation and association with key clinical parameters were examined. Cluster findings were revalidated during a follow-up visit, and compared to those obtained in a group of 47 COPD patients included in the Melbourne Longitudinal COPD Cohort.

RESULTS

Unsupervised clustering identified two clusters within COPD subjects at inclusion. Cluster 1 showed elevated levels of factors contributing to tissue injury, whereas Cluster 2 had higher expression of proteins associated with enhanced immunity and host defense, cell fate, remodeling and repair and altered metabolism/mitochondrial functions. Patients in Cluster 2 had a lower incidence of exacerbations, unscheduled medical visits and prevalence of emphysema and diabetes. These protein expression patterns were conserved during a follow-up second visit, and substanciated, by a large part, in a limited series of COPD patients. Further analyses identified a signature of 15 proteins that accurately differentiated the two COPD clusters at the 2 visits.

CONCLUSIONS

This study provides insights into COPD heterogeneity and suggests that overexpression of factors involved in lung immunity/host defense, cell fate/repair/ remodelling and mitochondrial/metabolic activities contribute to better clinical outcomes. Hence, high throughput proteomic assay offers a powerful tool for identifying COPD endotypes and facilitating targeted therapies.

Midkine mediates dysfunction of liver sinusoidal endothelial cells through integrin α4 and α6

Midkine (MK)² is an important regulatory molecule that promotes pathological angiogenesis of hepatocellular carcinoma (HCC). Although some studies have shown that its expression is increased in chronic liver disease, its effect on sinusoidal vasculopathy are still unclear. In this study, we demonstrated that MK was mainly secreted by liver sinus endothelial cells (LSECs) during the stage of precancerous lesions. Increased expression of its receptor integrin was an important mechanism by which MK participated in sinusoidal vasculopathy through autocrine and positive feedback effects. LSECs with high expression of integrin α6 (Itgα6⁺) and integrin α4 (Itgα4⁺) were used to study the mechanism of MK, and it was found that the effect of MK on LSECs was closely related to the integrin subtypes. The activation of MK /integrin α6/Src/Shc signaling pathway promoted the expression of ET-1, TXA2 and reduced the production of NO, and then induced the capillary vascularization of liver sinusoids, while the activation of MK/integrin α4/NF-κB pathway mainly induced angiogenesis by promoting the production of VEGF and Ang2. In the three-dimensional co-culture system of hepatocytes (BRL-3A) and LSECs, MK significantly increased the production of reactive oxygen species (ROS) in the co-culture system of highly expressed integrin LSECs and decreased the expression of tumor suppressor gene P53 in hepatocytes. These results suggested that MK /integrin signaling pathway, especially MK /integrin α6, was an important mechanism leaded to persistent sinusoidal hepatic vasculopathy in chronic liver disease and induced HCC，while MK/integrin α 4 activation was more involved in pathological angiogenesis.

Pulmonary midkine inhibition ameliorates sepsis induced lung injury

Background

Midkine is a multi-functional molecule participating in a various key pathological process. We aimed to evaluate the change of midkine in sepsis and its association with angiotensin-converting enzyme (ACE) system, as well as the mechanism by which midkine induced in sepsis and lung injury.

Methods

The peripheral blood sample of septic patients on admission was obtained and measured for midkine, ACE and angiotensin II. Cecal ligation and puncture (CLP) mouse model was used, and adeno-associated virus (AAV) was stilled trans-trachea for regional targeting midkine expression, comparing the severity of lung injury. Furthermore, we studied the in vitro mechanism of midkine activates ACE system by using inhibitors targeting candidate receptors of midkine, and its effects on the vascular endothelial cells.

Results

Plasma midkine was significantly elevated in sepsis, and was closely associated with ACE system. Both circulating and lung midkine was increased in CLP mouse, and was related to severe lung injury. Regional interfering midkine expression in lung tissue by AAV could alleviate acute lung injury in CLP model. In vitro study elucidated that Notch 2 participated in the activation of ACE system and angiotensin II release, induced by midkine and triggered vascular endothelial injury by angiotensin II induced reactive oxygen species production.

Conclusions

Midkine inhibition ameliorates sepsis induced lung injury, which might via ACE/Ang II pathway and the participation of Notch 2 in the stimulation of ACE.

Trial registration

Clinicaltrials.gov NCT02605681. Registered 12 November 2015

Multiple pathophysiological roles of midkine in human disease

Midkine (MK) is a low molecular-weight protein that was first identified as the product of a retinoic acid-responsive gene involved in embryonic development. Recent studies have indicated that MK levels are related to various diseases, including cardiovascular disease (CVD), renal disease and autoimmune disease. MK is a growth factor involved in multiple pathophysiological processes, such as inflammation, the repair of damaged tissues and cancer. The pathophysiological roles of MK are diverse. MK enhances the recruitment and migration of inflammatory cells upon inflammation directly and also through induction of chemokines, and contributes to tissue damage. In lung endothelial cells, oxidative stress increased the expression of MK, which induced angiotensin-converting enzyme (ACE) expression and the consequent conversion from Ang I to Ang II, leading to further oxidative stress. MK inhibited cholesterol efflux from macrophages by reducing ATP-binding cassette transporter A1 (ABCA1) expression, which is involved in lipid metabolism, suggesting that MK is an important positive factor involved in inflammation, oxidative stress and lipid metabolism. Furthermore, MK can regulate the expansion, differentiation and activation of T cells as well as B-cell survival; mediate angiogenic and antibacterial activity; and possess anti-apoptotic activity. In this paper, we summarize the pathophysiological roles of MK in human disease.

Midkine Is Elevated After Multiple Trauma and Acts Directly on Human Cardiomyocytes by Altering Their Functionality and Metabolism

Background and Purpose: Post-traumatic cardiac dysfunction often occurs in multiply injured patients (ISS ≥ 16). Next to direct cardiac injury, post-traumatic cardiac dysfunction is mostly induced by the release of inflammatory biomarkers. One of these is the heparin-binding factor Midkine, which is elevated in humans after fracture, burn injury and traumatic spinal cord injury. Midkine is associated with cardiac pathologies but the exact role of Midkine in the development of those diseases is ambiguous. The systemic profile of Midkine after multiple trauma, its effects on cardiomyocytes and the association with post-traumatic cardiac dysfunction, remain unknown.

Experimental Approach: Midkine levels were investigated in blood plasma of multiply injured humans and pigs. Furthermore, human cardiomyocytes (iPS) were cultured in presence/absence of Midkine and analyzed regarding viability, apoptosis, calcium handling, metabolic alterations, and oxidative stress. Finally, the Midkine filtration capacity of the therapeutic blood absorption column CytoSorb ®300 was tested with recombinant Midkine or plasma from multiply injured patients.

Key Results: Midkine levels were significantly increased in blood plasma of multiply injured humans and pigs. Midkine acts on human cardiomyocytes, altering their mitochondrial respiration and calcium handling in vitro. CytoSorb®300 filtration reduced Midkine concentration ex vivo and in vitro depending on the dosage.

Conclusion and Implications: Midkine is elevated in human and porcine plasma after multiple trauma, affecting the functionality and metabolism of human cardiomyocytes in vitro. Further examinations are required to determine whether the application of CytoSorb®300 filtration in patients after multiple trauma is a promising therapeutic approach to prevent post-traumatic cardiac disfunction.

Ciliary neurotrophic factor stimulates cardioprotection and the proliferative activity in the adult zebrafish heart

Unlike mammals, adult zebrafish can regenerate their hearts after injury via proliferation of cardiomyocytes. The cell-cycle entry of zebrafish cardiac cells can also be stimulated through preconditioning by thoracotomy, a chest incision without myocardial damage. To identify effector genes of heart preconditioning, we performed transcriptome analysis of ventricles from thoracotomized zebrafish. This intervention led to enrichment of cardioprotective factors, epithelial-to-mesenchymal transition genes, matrix proteins and components of LIFR/gp130 signaling. We identified that inhibition of the downstream signal transducer of the LIFR/gp130 pathway through treatment with Ruxolitinib, a specific JAK1/2 antagonist, suppressed the cellular effects of preconditioning. Activation of LIFR/gp130 signaling by a single injection of the ligand Cilliary Neurotrophic Factor, CNTF, was sufficient to trigger cardiomyocyte proliferation in the intact heart. In addition, CNTF induced other pro-regenerative processes, including expression of cardioprotective genes, activation of the epicardium, enhanced intramyocardial Collagen XII deposition and leucocyte recruitment. These effects were abrogated by the concomitant inhibition of the JAK/STAT activity. Mutation of the cntf gene suppressed the proliferative response of cardiomyocytes after thoracotomy. In the regenerating zebrafish heart, CNTF injection prior to ventricular cryoinjury improved the initiation of regeneration via reduced cell apoptosis and boosted cardiomyocyte proliferation. Our findings reveal the molecular effectors of preconditioning and demonstrate that exogenous CNTF exerts beneficial regenerative effects by rendering the heart more resilient to injury and efficient in activation of the proliferative programs.

Midkine Controls Arteriogenesis by Regulating the Bioavailability of Vascular Endothelial Growth Factor A and the Expression of Nitric Oxide Synthase 1 and 3

Midkine is a pleiotropic factor, which is involved in angiogenesis. However, its mode of action in this process is still ill defined. The function of midkine in arteriogenesis, the growth of natural bypasses from pre-existing collateral arteries, compensating for the loss of an occluded artery has never been investigated. Arteriogenesis is an inflammatory process, which relies on the proliferation of endothelial cells and smooth muscle cells. We show that midkine deficiency strikingly interferes with the proliferation of endothelial cells in arteriogenesis, thereby interfering with the process of collateral artery growth. We identified midkine to be responsible for increased plasma levels of vascular endothelial growth factor A (VEGFA), necessary and sufficient to promote endothelial cell proliferation in growing collaterals. Mechanistically, we demonstrate that leukocyte domiciled midkine mediates increased plasma levels of VEGFA relevant for upregulation of endothelial nitric oxide synthase 1 and 3, necessary for proper endothelial cell proliferation, and that non-leukocyte domiciled midkine additionally improves vasodilation.

The data provided on the role of midkine in endothelial proliferation are likely to be relevant for both, the process of arteriogenesis and angiogenesis. Moreover, our data might help to estimate the therapeutic effect of clinically applied VEGFA in patients with vascular occlusive diseases.

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Leukocyte domiciled midkine is decisive for collateral endothelial cell proliferation in arteriogenesis.

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Midkine controls the bioavailability of VEGFA mediating endothelial Nos1 and Nos3 expression.

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Nos1 and Nos3, relevant for endothelial cell proliferation, can substitute for each other.

Arteriogenesis is a life and tissue saving process as it compensates for the loss of an occluded artery. Decoding the underlying molecular mechanisms is a prerequisite for the development of novel therapeutic options to treat patients with vascular occlusive diseases. Lautz et al. identified midkine to be responsible for the increased bioavailability of VEGFA during arteriogenesis, necessary and sufficient to promote endothelial cell proliferation. These data might help to estimate the therapeutic effect of clinically applied VEGFA. As the identified mechanisms might also apply for angiogenesis, they are likely to be of broader relevance, e.g. in terms of tumor treatment.

Midkine's Role in Cardiac Pathology

Midkine (MDK) is a heparin-binding growth factor that is normally expressed in mid-gestational development mediating mesenchymal and epithelial interactions. As organisms age, expression of MDK diminishes; however, in adults, MDK expression is associated with acute and chronic pathologic conditions such as myocardial infarction and heart failure (HF). The role of MDK is not clear in cardiovascular disease and currently there is no consensus if it plays a beneficial or detrimental role in HF. The lack of clarity in the literature is exacerbated by differing roles that circulating and myocardial MDK play in signaling pathways in cardiomyocytes (some of which have yet to be elucidated). Of particular interest, serum MDK is elevated in adults with chronic heart failure and higher circulating MDK is associated with worse cardiac function. In addition, pediatric HF patients have higher levels of myocardial MDK. This review focuses on what is known about the effect of exogenous versus myocardial MDK in various cardiac disease models in an effort to better clarify the role of midkine in HF.