Medical Research: Cystic Fibrosis Is Caused by Tissue Hypoxia

New medical findings suggest that expression of the cystic fibrosis CFTR mutation gene is modulated, in a dose-dependent manner, by oxygen content in body cells. Reduced oxygen levels cause abnormalities in mucus composition leading to production of abnormally viscous and sticky mucus in various body organs. Medical studies also suggest that hyperventilation is the likely cause of cell hypoxia.

Decades of medical investigations have shown that lowered oxygen content in tissues brings about many chronic health conditions. Indeed, oxygen is fundamental for our health. People can survive for approximately a month with no exercise and no food, several days with no water, but no more than some minutes without air. It has been recognized that the lowered body oxygen content leads to cancer, diabetes, seizures, angina pain, chronic inflammation, allergies, the suppressed immune system and a number of other negative outcomes.

It is thought that cystic fibrosis is brought on by a flawed DNA - CFTR (cystic fibrosis transmembrane conductance regulator) mutation gene. This genetic factor causes the human body to manufacture unusually dense and sticky liquid, called mucus. This mucus accumulates in the respiration passages of the lungs and in the pancreas, the body organ that assists to break down food. This glutinous mucus results in dangerous lung microbial infections and serious digestive difficulties. Cystic fibrosis may also impact the sweat glands.

Novel medical findings conclude that the real story is different: the expression of the CFTR mutation gene is controlled, in a dose-dependent manner, by oxygen levels in body cells.

North American doctors from the Department of Medicine at the University of Alabama (Birmingham) screened the influence associated with cellular oxygen concentrations on CFTR in vitro (Bebök et al, 2001). The heading of their report in the American Journal of Physiology and Cell Physiology, suggests Improved oxygenation promotes CFTR maturation and trafficking in MDCK monolayers.

Another team of American researchers (from the Fleming James Cystic Fibrosis Research Center also at University of Alabama in Birmingham) investigated the effects of oxygen levels on CFTR work. They also concluded that environmental factors that induce hypoxic conditions regulate CFTR and epithelial transport of chloride ions in vitro and in vivo (Guimbellot et al, 2008).

German scientists from the Department of Gastroenterology, Hepatology, and Endocrinology (Hanover Medical School of Medicine) also confirmed the same effect. Hypoxia inducible factor-1 (HIF-1)-mediated repression of cystic fibrosis transmembrane conductance regulator (CFTR) in the intestinal epithelium. They study also clarified CFTR regulation and introduced the idea that HIF-1 (hypoxia-inducible factor -1) orchestrates responses to regulate ion and fluid movement across intestinal epithelia (Zheng et al, 2009).

Conclusions. As a result, it becomes clear now that presence of CFTR mutation gene does not guarantee development of this disease. The crucial factor that regulates the degree of abnormal ion and water transport in cystic fibrosis is oxygen availability in body cells.

The Cause of Cell Hypoxia
Furthermore, several other studies explained the cause of low oxygenation in people with CFTR mutation gene. For example, American doctors from the Department of Medicine of the University of Texas Health Science Center in Houston, Texas published a paper in the Chest magazine. The title of their article was Importance of respiratory rate as an indicator of respiratory dysfunction in patients with cystic fibrosis. They found that respiration frequency in cystic fibrosis correlated with the degree of pathological changes in the lungs. Those who breathed faster at rest had worse lung function test results.

Several more studies measured minute ventilation in groups of people with CFTR mutation gene, and all of these studies found that all tested subjects had increased ventilation rates (chronic hyperventilation). But it has been known in medicine for more than a century that hyperventilation reduces oxygen transport to cells.

As a result, while on a cell level cystic fibrosis is caused by cell hypoxia, the environmental and physiological causes of cystic fibrosis relate to heavy automatic breathing patterns.

References
Bebök Z, Tousson A, Schwiebert LM, Venglarik CJ, Improved oxygenation promotes CFTR maturation and trafficking in MDCK monolayers, Am J Physiol Cell Physiol. 2001 Jan;280(1): C135-45.
Guimbellot JS, Fortenberry JA, Siegal GP, Moore B, Wen H, Venglarik C, Chen YF, Oparil S, Sorscher EJ, Hong JS, Role of oxygen availability in CFTR expression and function, Am J Respir Cell Mol Biol. 2008 Nov;39(5): 514-21.
Zheng W, Kuhlicke J, Jäckel K, Eltzschig HK, Singh A, Sjöblom M, Riederer B, Weinhold C, Seidler U, Colgan SP, Karhausen J, Hypoxia inducible factor-1 (HIF-1)-mediated repression of cystic fibrosis transmembrane conductance regulator (CFTR) in the intestinal epithelium, FASEB J. 2009 Jan;23(1): 204-13.