Do you ever wonder how the body fights off the many microscopic bugs, or microbes, you encounter daily?
You are exposed to millions of microbes every day by breathing them in, by ingesting them in food or drink, or through wounds in your skin, yet you rarely get sick. When you do get sick, the symptoms can last a few hours to several months. So, why are there differences in your body’s response?
Luckily, your body possesses numerous specialized cells and proteins that make up the immune system. These immune cells are always on the lookout for different microbes. Using specialized machinery, these cells recognize most microbes and kill them without you feeling any disease symptoms.
Sometimes we encounter a microbe that our immune cells cannot immediately eliminate. With time, our immune system can usually get rid of them, but meanwhile you will feel sick because of the side effects of your immune system’s extra efforts to kill these microbes.
Once in awhile, your immune system just cannot control the infection, even though it mounts a perfectly good immune response. Such is the case with Lyme disease, caused by a spiral-shaped bacterium known as Borrelia burgdorferi.
Lyme disease was first reported in Old Lyme, Conn., hence its name. It took several years to figure out that the disease was spread by the bite of ticks infected with Borrelia burgdorferi.
Most infected people develop a bull’s-eye shaped rash at the site of the tick bite, which can grow quite large over time. Otherwise, people develop cold-like symptoms for a few days and then recover, so they often do not go to see a physician.
Unfortunately in these cases, Borrelia burgdorferi has not been removed by your immune system, but instead goes into hiding throughout your body. If the infection is identified and treated with antibiotics at this early stage, then it is cleared from your body. But if not treated early, Borrelia burgdorferi can cause disease weeks or months later in almost any part of your body.
Symptoms may include arthritis, heart irregularities, nerve pain, foggy memory, chronic fatigue, and many other symptoms which you do not normally associate with the slight cold that you had suffered weeks to months earlier.
Thus, a correct diagnosis of Lyme disease may not be made until your body has suffered extensive damage, which may not improve even with an eventual correct diagnosis and antibiotic treatment that kills the bacteria.
So, why is our immune responses not controlling this infection? Because Borrelia burgdorferi has several tricks up its sleeve to outsmart our immune cells.
To begin with, these spiral-shaped bacteria use a corkscrew-like motility to bore through our skin and deeper tissues much faster than our immune cells; they are just too fast to catch.
Another trick is that Borrelia burgdorferi can constantly change the types of molecules they put on their surface. By the time our immune cells learn to recognize this microbe, it has already changed its appearance. Imagine if a person keeps wearing a different mask and costume each time you meet him; you would never know his real identity. Borrelia burgdorferi fools our immune system in a similar fashion.
At the University of Toledo College of Medicine and Life Sciences, formerly the Medical College of Ohio, I work in the laboratory of R. Mark Wooten, where we study the different mechanisms Borrelia burgdorferi uses to trick our immune cells.
To better understand Borrelia burgdorferi tricks, we have developed a mutant strain which produces a strong green color that we are able to see while this microbe is inside the skin of infected mice by using an advanced microscopy technique. By this method we can see what this bacterium is doing inside its natural environment and how it evades the immune system.
What have we learned? We know that the immune cells rapidly recognize the bacteria and start to eat them. However, within one day the immune cells no longer recognize the bacteria and just quit chasing them: It is as if they have turned invisible to the immune cells.
We also know that the immune cells also quickly produce a protein called interlukin-10 (IL-10) that is normally only produced after a microbe has been cleared from the body. This IL-10 notifies the immune cells to stop responding since their job is complete.
Putting these facts together, we realized that Borrelia burgdorferi are playing another trick on our immune cells by causing them to believe that their job is complete before they clear Borrelia burgdorferi by somehow triggering this early IL-10 production.
I am trying to identify the source of this early IL-10 response and to determine its negative effect on the different types of immune cells in our body. We are looking for new targets for better treatment of Lyme disease. To do this, we need to better understand this mechanism of evading our immune system.
If we can prevent Borrelia burgdorferi from concealing itself, our immune cells will be able to recognize and eliminate this bacteria efficiently, allowing better management of the disease.
Muhammed Saad Moledina is a student earning his doctor of philosophy in the University of Toledo College of Medicine and Life Sciences Biomedical Science Program. Mr. Moledina is doing his research in the laboratory of R. Mark Wooten in the department of medical microbiology and immunology. For more information, contact MuhammedSaad.Moledina@utoledo.edu or go to utoledo.edu/med/grad/biomedical.
First Published June 5, 2017, 4:00 a.m.