Network Medicine is a network based approach to decode complex diseases.
A car mechanic needs 4 important things to fix a car - 1. replace/spare parts, 2. diagnostic tools to analyse the problem and know what part is the problem and what part is healthy, 3. blueprint of the car representing various parts of the car and how they are connected together, and finally 4. the parts list. Similarly, a doctor requires various data to treat a patient. As of today, we have 1. metabolomics, proteomics and transcriptomics,etc to study the chemical processes involving proteins, metabolites, DNA and RNA molecules; 2. genomics to give the list of genes and 3. gene therapy being, one way to replace the genes/components. But, what is missing in the puzzle are the diagnostic tools to analyse the ailment of the patient at DNA level. This is where Network Medicine comes into picture. Albert Làszló Barabàsi, a physicist, more well known in the field of network theory talks about this concept and how we can use it to understand the diseases better. He says, "The emerging tools of network medicine offer a platform to explore systematically not only the molecular complexity of a particular disease, leading to the identification of disease modules and pathways".
Cells contain lot of information - information not just about proteins and genes but also data related to nature of interactions among them. The paper describes how cellular network within our cells form a network representation, where nodes are genes and proteins, and links are physical interactions among them. Understanding this wiring diagram is the key to understanding the human disease. Then, we can solve the disease in three steps: 1. Get the map, 2. Find the disease module, 3. Drug it.
.
As of now, we do not have a map for the cells. Scientists, until now, could map upto 5% of these links. As a result, the nodes(genes) of the disease seam to be dispersed in the network. Dana-Farber Cancer Institute (DFCI) research group systematically mapped protein interactions in the cell related to Asthma disease. The 100 or more genes associated with Asthma are shown in the diagram below(Shown as Purple Nodes). From this dig., we can understand both disease mechanism and disease pathway. Network science can help us to identify candidate disease genes, those that could hold the module together ie., exploit the colective intelligence of the network to identify the Asthma Module. Using the same tools, Chronic Obstructive Pulmonory Disease (COPD), a lung disease that makes it difficult to breathe, are constructed in the map(shown as Yellow Nodes). We can see clearly that both share same type of genes in the Cellular network map.
Such a mapping tool, is immensely helpful to understand the relation between all diseases and evaluate the network of diseases, where each disease can be represented as a node. If two diseases are connected to each other, they have a shared gene, and very likely their disease module overlaps, and we can infer that they must be in the same region of the network. This helps us to classify the diseases better. Surprisingly, the network depicts links between completely unrelated diseases sometimes. Today, if a person gets two different diseases, he/she might go to different doctors in different hospitals. But, if the map shows that the two diseases are connected and rooted in the same neighbourhood, they might have the same cause and the patient might have to see "Networkologist" instead of a cardiologist, neurologist or a cancer specialist to get the diseases properly diagnosed and get a single comprehensive medication for both the ailments. This would be a significant breakthrough in medical history.
References :
1. http://www.barabasilab.com/pubs/CCNR-ALB_Publications/201012-18_NatureRev-NetMedicine/201012-18_NatureRev-NetMedicine.pdf
