by Folabomi Oladosu, PhD
Post-doctoral researcher specializing in pain and women’s health at NorthShore University HealthSystem
At the start of your doctor’s visit, as the nurse checks your pulse and blood pressure, you probably take slow deep breaths, trying to convince your doctor and yourself that you’re cool, calm, and collected. (No? Is that just me?)
Your blood pressure can tell your doctor a lot about you—including your risk for peripheral arterial disease, or PAD. In PAD, arteries that carry blood throughout the body are narrowed by deposits of fat and cholesterol. The disease is common, with more than three million new cases surfacing every year. PAD puts people at increased risk of both heart attack and stroke, so it’s important to treat it quickly and effectively.
When diet, physical activity, or medications are not enough, surgery is the next step to open up the narrowed arteries. Options include an angioplasty, where a tiny balloon is inserted into the blocked artery. The balloon is inflated to crush the plaque deposits and then removed to restore blood flow.
Following surgery, these once clogged arteries should carry red blood cells throughout the body like an amusement park water slide. To your dismay, you find this water park attraction might need more repairs three to 12 months later because of restenosis, the abnormal re-narrowing of arteries following surgery (Get it? Re-stenosis). Restenosis occurs in about 40 percent of patients after angioplasty and is usually treated with yet another surgery.
What causes this re-narrowing? Inserting the balloon and compressing the plaque may cause a mild arterial injury. The immune system responds, sending in white blood cells and platelets to repair the artery. But sometimes the immune system goes overboard and causes scarring instead. This means that the same arteries that were first narrowed by fatty deposits are narrowed yet again because of scarring caused by the immune system.
Why does the immune system to go into hyper-drive following surgery? One contributing factor may be—amazingly—the bacteria living in our gut. Drs. Eugene Chang and Betty Theriault of the University of Chicago collaborated with Dr. Karen Ho of Northwestern University to investigate the role of the gut microbiome on arterial healing following surgery.
Using their extensive knowledge and technical expertise, the team developed a method to study arterial healing in germ-free mice, mice with no gut bacteria. Their work revealed that germ-free mice developed much less arterial scarring following surgery compared to normal mice. Their research also showed that the immune system of germ-free mice was different than normal mice, using different white blood cells less likely to encourage swelling and scarring at the injury site.
All of us have been surrounded by germs since the day we were born. So if we need an angioplasty, we’d be like those normal mice, more likely to have arterial scarring after surgery.
Is there anything we can do to prevent restenosis? Related work by Drs. Ho and Chang suggests yes. A month-long treatment of the antibiotic vancomycin paired with sodium butyrate (a compound that slows cell growth) reduced arterial scarring in rats following an angioplasty. Legumes like beans and peanuts, when digested by gut bacteria, are a common source of sodium butyrate. This suggests that the dietary changes prior to angioplasty may help reduce arterial scarring and restenosis.
This “basic science” research by Drs. Chang, Theriault, and Ho provides great insights for better health. It shows that, despite their microscopic size, gut bacteria can greatly influence how we heal from common surgeries. The humble legume–cheap, tasty, easily stored, and environmentally friendly to grow—may help to keep our internal water slides open for service long after initial repairs.