Thinking of exploration of the correlation between the syndrome of traditional Chinese medicine in essential hypertension and predisposing genes of rennin-angiotensin system based on the state of holistic health of body
DONG Mei 1, HUANG Li 2, ZHOU Xue-mei 2, XU Hui 2, WU Chuan-yun 2, DONG Chang-wu 2, KAN Hong-xing 3
(1. the First Hospital Affiliatied to Anhui University of Traditional Chinese Medicine, Hefei, Anhui, 230038, China
2. Clinical School of Traditional Chinese Medicine, Anhui University of Traditional Chinese Medicine, Hefei, Anhui, 230038, China
3. School of Information Engineering, Anhui University of Traditional Chinese Medicine, Hefei, Anhui, 230038, China )
Abstract: It has been shown that essential hypertension (EH) is a complicated polygenic genetic disease. Furthermore, the genesis and development of EH has been well associated with the state of holistic health of body. We select the association between three key gene polymorphism of rennin-angiotensin system (RAS) and the syndrome of traditional Chinese medicine(TCM) in EH as our enter-point, analyze the relation between interaction of polygenic locus mutations and different syndrome in EH by a new genetic statistics, correlate the exterior and interior environmental malgenic factors in patients with EH with different syndrome and carry out an association analysis from the perspective of molecular epidemiology. In that way, we may reveal part of the scientific connotation of the substantial syndrome in EH. This can not only make us have a better apprehension of the mechanisms in physiology and pathology of the genesis in EH but also bring us a guidance on early diagnosis, prophylaxis, treatment in EH. Thus, it can provide us the proof in dialectical treatment by TCM to prevent and cure EH.
key words: essential hypertension; rennin-angiotensin system; gene polymorphism; the syndrome of traditional Chinese medicine;
Funding：This work was supported by the National Nature Science Foundation of China [grant numbers 81173196].
First author：Mei Dong（1973-）Madam，Master of Medicine，associate chief physician
Corresponding author：Chang-wu Dong, E-mail address:dcw1018@aliyun.com
Essential hypertension (EH) is a major risk factor for all kinds of cardiovascular and cerebrovascular diseases, which is a most popular disease at present. In China, cardiopathy and cerebrovascular disease are the first and third cause of death in people over the age of 40 respectively. However, it is hypertension that is the first risk factor of causa mortis. Hypertensive morbidity keeps on fast ascensus and 10 million hypertensive patients increased every year, the total hypertensive patients is over two hundred million in China [1]. EH is a polygenic genetic disease caused by the interaction of heredity and environmental factors. However, the pathogenesy of hypertension whereby heredity and environment factors lead to hypertension are still not fully understood.
1. Research on the correlation between the syndrome of EH and predisposing genes from gene-gene and gene-environment interaction are consistent with the research idiea of the holistic concept in TCM.
Syndrome is the essence of the disease at the present stage. Meanwhile, the different syndrome phenotype in EH is a functional status after the response of organism with etiological factor, which not only have a relation with the character, the strong and the weak of etiological factor but also with the individual soma and environmental factor of the patient. Therefore, introducing the molecular epidemiology to association analysis the relation between gene-gene, gene-environment interaction and clinical syndrome phenotype from the perspective of the holistic health state and holistic assessing the genetic background and potential mechanisms of the syndrome in EH from micro to macro are consistent with the thinking of the holistic concept in TCM.
Environmental factor can induce gene mutation or abnormal expression of the host in EH. Thus, it can lead to the discrepancy in biological and clinical phenotype. Molecular epidemiology not only research the cause of a disease, but also research every component element of pathopoiesis risk factor from exposure to disease process. The syndrome of TCM is a pathogenetics generalization at a certain stage of disease process. It is a reactive state of association of internal cause by organism and external cause by environment. Meanwhile, it also has corresponding change follow the progress of disease process. Contemporary pathogenesis has researched the polygene regulation disorder of related gene in common disease and frequently-occurring disease instead of monogenic disease. Disease process is the result of interaction by related gene and internal and external environment, which shows polygenic complex character, dynamic evolution process and striking similarities to cognitive method of generalizing disease process by syndrome of TCM. As the syndrome is a regular pathological representation，it inevitably has a material foundation, which possibly reflect the genome level. Some investigators thought that the syndrome of TCM had specified genomics foundation and probably was a abnormal expression phenotype of gene polymorphism and multifunctional gene[2]. So, using the method of molecular epidemiology to examine the whole process of patients with EH from exposure to disease (syndrome) is bound to radically reform. This can not only make etiological theory of TCM microcosmic, objective and quantitive but also make us have a better recognition to the pathogenesis and pathological disease (syndrome). Meanwhile, it can provide better observing indexes to evaluate drug intervention, which is worth pay close attention to[3].
2. predisposing genes of RAS is a key gene to research the hereditary basis of heterogenization in EH
RAS plays a crucial role in regulating blood pressure (BP) as it can effect vascular volume, cardiovascular remodeling, salt water balance in the body through a variety of ways. The dysfunction of any one ingredient or change of quantitative expression in RAS is going to play an significant role in hypertensive pathological process. Meanwhile, intermediate phenotype of RAS can be directly described relative to other system, which has an alluring prospect as a model system in researching hypertensive genetics. This model system is suitable for the following procedures: first of all, using linkage analysis of identify candidate sites based on the intermediate phenotype, then using BP as the final phenotype to association analysis. Some investigators reported that fetal growth restriction (FGR) in embryonic period could lead to the decrease in the number of progeny nephron, disfunction of RAS, then elevate BP. So, codogenic gene of this systemic became winsome candidate gene to study the hereditary basis of EH. Thus, research on the relation of gene polymorphism between three key gene of them as angiotensinogen (AGT), angiotensin-converting enzyme(ACE) and angiotensinⅡ type l receptor (AT1R) becomes a popular topic[4-6].
There are many reports about the gene polymorphism of RAS at present. However, it is very difficult to achieve unified conclusion as the different findings of the same candidate gene are often contradictory. For instance, it has been thought that AGT gene was one of the most representative and maximum candidate gene to regulate BP and was mainly concentrated in polymorphism of M235T at present. Fejeiman et al. have shown that M235T mutation increased the risk of EH in Japanese. However, other studies did not find identical conclusion for Australia Angle-Celtic white people and Black African[7]. Other investigators found that there was no significant difference in M235T Genotypic expression between case control and normal group, which had no correlation with EH[8-9]. However, Yan liu et al. found that M235T palyed significant role in morbidity of EH in one research on Han population [10]. The correlation between I/D polymorphism of ACE gene and EH is still controversial. Some[11] but not all［8,12］studies found that it was statistically significant. Yoo et al. have shown that the relationship between DD genotype and EH was evident in man (especially old man) in the research on Korean［13］. Camcil et al. reported that the BP of children who have a family history of EH carrying DD genotype was obvious higher than those carrying other genotypes in Turkey, which was suggestive of the correlation between DD genotype, D allele and EH[14].The research on other predisposing genes polymorphism of RAS also had the similar conclusion.
Thus, at present, though it has been explored and ascertained the predisposing genes in EH in several aspects such as heredity, environment and epidemiology and so on, which gene may become the first virulence gene in EH are still not fully understood as its high genetic heterogeneity [15]. It has been shown that there were many reasons to result in this case, besides the difference in different race of people, there were intimate correlation between age, gender, life habit and pathologic state. It is the variability of these factors that lead to different even reverse conclusion by different researcher and different RAS gene polymorphism by point mutation, insertion, deletion and different number tandem duplication. It is the minute abnormality of mononucleotide polymorphism in this gene that decided great changes of biological behavior and then made all sorts of heterogeneity in hypertension.
Moreover, different geographical environment, racial dispar, ity, climatic difference, age factor and sexual disparity are the important factor to constitute different syndrome type in TCM . Thus, hypertensive predisposing genes polymorphism and the diversity of syndrome type in TCM of EH may have the same mechanisms. Searching commonness and variability of the syndrome from comparison of differential gene expression spectral of the same disease with different syndromes and different diseases with the same syndrome and setting up syndrome gene expression spectra may reveal the scientific connotation of the syndrome of TCM and provide the proof and method for objective diagnosis [16].
Therefore, using the syndrome of TCM as the classified mode of EH heterogeneity to research predisposing genes polymorphism of RAS has the higher academic value, which could be served as a new research approach.
3. Association analysis of polygenic locus is an effective way to research the correlation with syndrome and predisposing genes
It has been shown that many minor genes were involved in the morbidity of EH as a complex disease. Its genovariation has major number and higher frequency. However, the weak function and individual genovariation could not cause hypertension, which need koinonia of many genes. So, individual could not fall ill until variant association of many minor genes (adverse and protective) achieve a threshold while environmental factor participates. Thus, it is more significant to use combination with allelic variation of many candidate sites than single site mutation to research hypertensive molecular genetics.
At present, there are many exploration of the correlation between gene polymorphism of RAS and the syndrome of TCM in China. Lu et al. selected 206 cases of hypertensive patients to carry out syndrome Differentiation Classification based on its standard in TCM and compared its distribution of A1166C polymorphism of AT1R gene. They found that the distribution of AT1R genotype might have no effect on syndrome Differentiation Classification in TCM[17]. Wan et al. thought that syndrome of liver fire hyperactivity might have a background of molecular biology by analyzing the relation between M235 of AGT gene and syndrome type in TCM of EH [18]. Some one observed the distribution of gene polymorphism of ACE in 80 cases of hypertensive patients of different syndrome type in TCM by applying PCR and found that most of the patients with DD genotype of ACE gene were syndrome of liver fire hyperactivity[19]. Zou et al. reported that the effect of gene polymorphism of ACE I/D on syndrome had sex difference and DD genotype had correlation with the syndrome of TCM in hypertensive women. Syndrome type in TCM might have invariable foundation of molecular genetics. Heredity soma and development of syndrome might have potential proneness[20]. On the other hand, no significant effect of the different distribution of ACE gene on syndrome Differentiation Classification in TCM has also been reported in one study about 472 cases of patients with EH. But the frequency belong to DD genotype and D allele of Sthenia syndrome in TCM in liver fire and phlegmatic hygrosis hyperactivity were obviously lower than other Asthenia syndrome or Mixture of asthenia and sthenia[21].Our previous studies indicated that ACE gene I/D, AGT gene M235T and AT1R gene A1166C polymorphism had invariable correlation with some syndrome type of patients with EH [22-24].
The above researches all studied on the correlation between polymorphism of single site in individual RAS gene and the syndrome of TCM in EH. Rough it has been discovered that one gene polymorphism related to a few syndrome of TCM, but it is very difficult to achieve unified conclusion as the different findings and it is impossible to identify what role dose every predisposing genes play on pathogenesis of EH. There are two main reasons which lead to this result. Firstly, the relation between genotype and clinical phenotype is extremely complicated, in which genetic and environmental factor both play a role. Secondly, it has been shown that most of the genetic disease were polygenic disease which has gene-gene interaction[25].
4. Research on whole emergence of gene-gene interaction in EH by a new genetic statistics.
Because gene-gene interaction plays a crucial role in pathogenesis of complex disease, traditional analytical method such as Logistic regression analysis has evident deficiency. Follow increase in possible interaction, interactive number of variates will increase as exponential growth due to every primary effects of gene. This can lead to overparameterization and depress test efficacy.
In recent years, the research about gene-gene interaction and gene-environment interaction have increased gradually[26]. Furthermore, some new genetic statistics have been created such as multi factor dimensionality reduction (MDR), enlarged MDR (EMDR), which are an non-parametric analysis based on Logistic regression. They carry out modeling by classification in susceptivity of disease instead of depending on the preset model. All variable of investigation are classified as high and low risk factor, the data are simplified by transforming multidimensional structure to one dimensional structure, the ability to predict disease by multi factor combination of single dimension is evaluated by cross validation and permutation test. In that way, it can help researchers explore of the relation between gene-gene or gene-environment interaction and desease, which especially could be applied to the whole emergence in gene-gene interaction of complicated polygenic disease, consistent with the research idea of the multidimensional holistic concept in the syndrome of TCM. Thus, it can provide new method to research the complicated correlation between the polygenic locus mutation of predisposing genes in EH and the multiple factor that effect on the presentation of the syndrome in TCM such as soma, environment.
5. prospect
We bring out the thinking about the research on the correlation between predisposing genes polymorphism of EH and syndrome based on the hypothesis that the interaction between predisposing genes polymorphism, its specific codogenic gene product and exterior and interior environmental is one of the internal agent which form the different syndrome in EH[27]. The syndrome is the concentrated expression of overall adjustment and interaction between mental status, neurohumor factor in vivo, the immune state at that time and etiological factor, which is related to the integration of every system function in vivo instead of the alteration of one taget of some system[28].The syndrome display different symptom group in different individual probably due to the existence of different gene expression spectra or key gene polymorphism (genetic diversity) [29].Therefore, it is necessary to research the correlation with multiple sites of similar predisposing genes in EH and integrate biological phenotype of related gene and clinical phenotype of patients with EH. It is significant to wholly explore of internal relation of gene polymorphism and the syndrome of TCM from micro to macro.
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