Iron Deficiency Promotes Aortic Medial Degeneration And Its Related Mechanisms

Part Ⅰ The Correlation between Iron metabolism and Aortic Medial DegenerationSubject: To investigate the correlation between iron metabolism and aortic medial degeneration.Methods: Serum specimens and aortic medial tissues(AD group)from patients with aortic medial degenerative(aortic dissection and aortic aneurysm)from the clinical specimen library of the Cardiovascular Surgery Laboratory of Renmin Hospital of Wuhan University were selected;then serum of patients with hypertension who had aortic disease excluded(control group)by whole-aortic CTA testing was selected,and normal aortic medial tissue(control group)of brain dead organ donors was selected.Record the patient’s age,gender,body mass index,blood pressure and other basic indicators in detail;whole-genome transcriptome sequencing on aortic medial tissue were performed to analyze differentially expressed genes in pathological tissue;detecting iron metabolism status in serum and aortic medial,and statistically analyzing the correlation between iron metabolism status and aortic disease;pathological examination was used to observe the morphological changes of the aortic vessel wall.Results: A total of 200 patients with aortic disease and 60 patients with hypertension were included in this study,and serum samples were collected.At the same time,15 samples each of AMD tissue samples and normal aortic tissue samples were collected.Compared with the control group,the body mass index and the percentage of liver damage detected by ultrasound in the aortic disease group were significantly higher(p <0.05);the whole-gen transcriptome sequencing test showed that the expression of genes related to trace element metabolism in the aortic medial degeneration tissue was significantly different;the biochemical test showed that compared with the control group,the serum and aortic medial tissue of the patients with aortic disease were iron deficiency,but there was no significant difference in serum hemoglobin concentration between the groups(p> 0.05);correlation analysis showed a negative correlation between serum iron concentration and the occurrence of aortic disease(r =-0.365,p<0.0001),and Logistic regression analysis indicates that iron deficiency is an independent risk factor for aortic disease in patients with hypertension [OR 0.826,95% CI 0.752 ~ 0.907,p <0.0001];histopathological examination showed that compared with the control group,the elastic fibers in the aorta of the AD group were disintegrated and broken,and the expression of cytoskeletal protein F-actin and vascular smooth muscle cell contraction protein p-MLC were significantly reduced(p <0.05).Conclusion: Patients with aortic medial degeneration have iron deficiency in the circulation and local aortic middle layers;iron deficiency may be an important enabler for the development of aortic medial degeneration.Part Ⅱ Effect of Iron Deficiency on the Sensitivity of Aortic Medial Degeneration in Mice and Its Histological BasisSubject: To investigate the effect of iron deficiency on the susceptibility to aortic medial degeneration in mice,and to explore its histological basis.Methods: AngⅡ subcutaneous continuous pumping was used to construct a model of aortic medial degeneration in apo E-/-mice.The mice were fed with normal maintenance feed(>150 ppm iron content)and low iron feed(5 ppm iron content).48 mice were randomly divided into normal control group(NC group),AngⅡ pumping group(AngⅡ group),iron deficiency group(ID group)and iron deficiency combined with AngⅡ pumping group(ID + AngⅡ group).Take the death or feeding of mice for 4 weeks as the end point of the experiment,a survival curve was drew;each experimental group has 3 additional complex groups(6 mice / group),collect mouse serum samples every week during the experiment for biochemical detection,and dynamically observe the changes of iron metabolism status in the mouse circulation;the aortic tissues of mice were collected weekly for histopathological examination,and the changes of local iron metabolism status,histomorphological changes,and vascular smooth muscle cell function-related protein changes in the middle layer of the aorta of the mice were observed.Transferrin receptor knockout mice(TFR1-/ +)was constructed and observe the effects of iron deficiency on aortic vascular development in mice.Results: Compared with the NC group,the survival time of the mice in the AngⅡ group and ID + AngⅡ group was significantly shortened(p <0.05),of which the ID + AngⅡ group had the shortest survival time,while the survival time of the ID group mice had no significant change(p> 0.05);In the AngⅡ group,aortic aneurysms were mostly formed and the location was uncertain,while in the ID + AngⅡ group,typical aortic dissections were formed,which were widely torn;at the second week of iron deficiency feeding,the circulation and aortic tissues of the mice were observed to be partially iron deficient;Similar to the test results of clinical tissue specimens,in the model group,the elastic fibers of the aorta in the model group were disordered,disintegrated and broken,and the expression of vascular smooth muscle cytoskeleton protein F-actin and contractile function protein p-MLC decreased significantly(p <0.05),and iron deficiency could aggravate the above injuries.At the same time,the results showed that iron deficiency caused a decrease in the expression of integrin pathway node protein ITGB and filamentous pseudofoot marker Cdc42 in aortic vascular smooth muscle cells(p <0.05),and increased cell laminar pseudofoot marker Rac-1 expression(p <0.05).Transferrin receptor knockout mouse homozygotes died at embryonic day 13.5,accompanied by aortic endothelial growth factor receptor KDR and vascular smooth muscle cell marker a-SMA expression decreased(p <0.05),middle aortic elasticity The number of fibers decreased(p <0.05)and the arrangement was disordered.Conclusion: Iron deficiency can increase the susceptibility to aortic medial degeneration in mice,accelerate the process of disease and aggravate the severity of the disease.Fetal iron deficiency can cause hypoplasia of the middle layer of aorta in mice.Part Ⅲ Iron Deficiency Promotes the Aortic Medial Degeneration by Inducing the Destruction of Vascular Smooth Muscle Cytoskeleton and Contractile DysfunctionSubject: To investigate the cytological mechanism of iron deficiency-induced aortic medial degeneration.Methods: Human aortic vascular smooth muscle cells(HASMCs)were cultured.The iron in deferoxamine chelating medium was used to cultivate cells in iron-containing media with final concentrations of 20μM,50μM,and 100μM,respectively.AngⅡ was used to interfere with HASMCs.Changes in the reactivity,backbone structure,and expression of cellular functional proteins.Results: After using iron in deferoxamine chelating medium,HASMCs morphologically swelled,intercellular connections decreased,F-actin expression of cytoskeleton protein decreased(p <0.05),and the arrangement of microfilaments was disordered.And 50μM),the cell morphology changes to a normal spindle shape,the intercellular connections become tight,the arrangement of microfilaments tends to be regular,and the best is achieved when the iron concentration is 50μM;however,too high iron concentration(100μM)can also lead to swollen cell morphology and reduced cell connection.AngⅡ stimulation does not affect cell iron metabolism;increased proliferation and migration of HASMCs in iron-deficient environments(p <0.05);the expression of cellular laminar pseudopod marker protein Rac-1 increased under iron deficiency,iron supplementation could reduce its expression,AngⅡ stimulation increased the expression of this protein(p <0.05),and the cellular filamentous pseudopod marker protein Cdc42 showed a similar relationship Rac-1 protein had the opposite expression trend(p <0.05).In addition,there were no significant differences in osmotic pressure between different iron concentrations of the medium(p> 0.05).Conclusion: The balance of Iron metabolism is a necessary condition for maintaining normal morphology and function of HASMCs.Disorders of iron metabolism can induce morphology and dysfunction of HASMCs by interfering with the integrin pathway,and promote aortic medial degeneration.