Did you know that Indian soldiers are at risk from altitude induced hypoxia?

School of Biosciences, Apeejay Stya University organized a webinar on “Role of Immune Cells in Hypoxia-Induced Pulmonary Hypertension”. The guest speaker was Dr. Rahul Kumar, Assistant Professor in the Department of Medicine at the University of California, San Francisco, USA. His lab is trying to understand the role of inflammatory immune cells in causing hypoxia-induced pulmonary vascular diseases. He has published more than 50 publications so far in top-rated journals including Nature Communications, Circulation, Cardiovascular Research, American Journal of Critical Care and Medicine and JCI.

Dr. Rahul said Hypoxia refers to very low oxygen levels in the blood. Pulmonary hypertension is considered present when the mean pulmonary artery pressure is greater than 25 mm Hg at rest. Its common symptoms are shortness of breath (dyspnea) and right heart failure. 

Talking about the difference between Pulmonary Hypertension and Systemic Hypertension, D. Rahul said in the former the blood pressure in the lungs (pulmonary artery system) is higher than normal, while in the latter there is high blood pressure in the systemic arteries – the vessels that carry blood from the heart to the body’s tissues (other than the lungs).

He said Right heart catheterization (RHC) is the “gold standard” in the diagnosis and differentiation of pulmonary hypertension. 

He said World Health Organization (WHO) has divided pulmonary hypertension into five broad groups: Pulmonary arterial hypertension, Left Heart Disease, Chronic Hypoxia Lung Disease, Chronic Thromboembolic and Unclear Multifactorial Mechanisms. Earlier, patients with pulmonary hypertension used to survive for maximum of 3-4 years, but now with medical advancement the patients can live up to 15-20 years. 

Dr. Rahul explained in detail about Chronic Hypoxia. One of the factors contributing to this ailment is high altitude exposure. All over the world more than 14 million people reside at high altitude and up to 1 million people in the US live 10,000 feet or more above the sea level. He said in developing world there are 15-30 million cases of pulmonary hypertension and out of which 5-7 million are due to high altitude exposure.

“In India, more than 5 lakh people live in high altitude and every year around 70,000 pilgrims go to higher regions and many die due to low oxygen. We also have a large deployment of army at high altitude regions,” Dr. Rahul remarked. 

He said high altitude can cause illness for people whose bodies aren’t used to working on so little oxygen. He said that it’s important to acclimatize yourself to altitude changes, otherwise you are prone to life-threatening illness such as High-altitude pulmonary edema (HAPE) and High-altitude cerebral edema (HACE).  The former causes your lungs to swell with fluid while the latter causes your brain to swell with fluid. He explained through his research that prolonged stay at high altitude remodels your lungs.  He said under hypoxic conditions, bone marrow derived circulatory Ly6c+ monocytes are recruited to become pathologic interstitial. 

In conclusion, he said, “In hypoxia, there’s a recruitment of interstitial macrophages (IMs) and IMs produces Thrombospondin-1 which in turn activates Transforming growth factor beta-1 (TGF-β1) which is involved in Vasoconstriction and Vascular remodeling. So, if you go to high altitude for 2-3 days your vessels will get constricted, but if you will stay for longer there will be remodeling and ultimately you will get Pulmonary Hypertension. So, blocking Thrombospondin-1 could be an important factor to stop Pulmonary Hypertension.”

In India, more than 5 lakh people live in high altitude and every year around 70,000 pilgrims go to higher regions and many die due to low oxygen. We also have a large deployment of army at high altitude regions.

-Dr. Rahul Kumar, Assistant Professor in the Department of Medicine at the University of California, San Francisco, USA