Human body evolves to fight illness

Wayne Smith was standing next to the window, looking outside. Years ago, he was a captain on a ferry sailing between Port Jefferson, New York and Bridgeport, Conn. I could tell from the look in his eyes, dark green and curious, that he was still searching for a new horizon to conquer.

And on that day, one could easily imagine him sailing toward the horizon: The skies were bright blue, the leaves on the trees were turning red, yellow and rust, and from the window on the ninth floor of the medical tower, Wayne could see the shores of New York and the narrow sliver of the Atlantic Ocean separating Long Island from the coast of Connecticut.

Wayne was standing there, half-holding, half-leaning on an IV pole on which an antibiotic solution was hanging in a piggyback. Capt. Wayne was sailing nowhere. Instead, he was fighting for his life. He was fighting a severe bacterial infection in his lungs: pneumococcal pneumonia.

Pneumococci (plural for pneumococcus) cells can live alone, but they prefer not to. They typically live in pairs. It is likely that several billions years ago two separate pneumococcal cells living alone in the universe conjoined. They might have found each other serendipitously, or were forced upon each other by a radical change in their environment, but they clung to each other and stuck together. This new configuration must have conferred some survival benefit, for even today, billions of years later, looking under an electron microscope, you can see these pneumococci, round and plump, glued to each other like two sumo wrestlers frozen in an eternal embrace.

To find a pneumococcus near you, look no further than within thyself! For pneumococci reside, in very large numbers, in the nasopharynx (a cavity behind the nose and the mouth) of healthy, asymptomatic individuals. They are part of a much larger community of microorganisms called microbiome, which literally share our body space. These microbial cells “pneumococci are just a small part of this community” live in us (about a thousand species of bacteria reside in the human gut, for example) and on our skin. Microbial cells are smaller and weigh much less than our own human cells, but they outnumber our own cells by far, only 10 percent of our cells are human, the other 90 percent are microbial.

Pneumococci like most of the other bacteria living with us lead a peaceful life. Inside our body, in a stable environment, steady temperature, and constant supply of nutrients, they hide from the elements. With us they move to a safer place, they meet and mingle with other bacteria and they have a chance to spread. For them, every sneeze is an opportunity: a cloud of minute droplets is formed, within which pneumococci can move up in life, to another human being, a different environment, the nasopharynx of a different host.

But at times, this peaceful, stable co-existence is disturbed. It happens most often in susceptible individuals: a child, a person whose immune system is compromised, or an elderly patient like Capt. Wayne. It is then that this dynamic duo of cells, the pneumococci, moves into new unknown territory: the membranes that surround the brain and the spinal cord, the inner ear, and the lungs, causing meningitis, otitis media and pneumonia. It is there that its virulence can become deadly.

As I watched Capt. Wayne, I saw a highly pixelated picture. He is an organism made of billions of cells that holds many more billions of bacteria. He is a multicellular organism whose cells are at war with each other. Could Wayne survive this attack of the bacteria within? Could his immune system effectively fight back? Will the antibiotics flowing into his veins control the bacteria that had gone rogue?

Wayne’s chance of surviving his pneumococcal infection might have been determined billions of years before I met him in a Long Island hospital:?Contact was made between two individual pneumococcal cells. Whether serendipitously or forced by a change in the environment, a union was created. A common cell wall was formed allowing the most primitive of sexual acts, the exchange of genetic material, in the form of DNA, between two cells.

At that moment, the genes enabling on-demand adaptation and powerful resistance to even the most powerful of antibiotics could have been composed, and a unified, potent, and at times lethal bacterium was created.

To fight these and other virulent microorganisms, and to withstand other challenges, the human body engaged in a different, more sophisticated act of genetic exchange: The game of love, lust, and sex. But my time is up, so I promise to return in a fortnight with the full story of why sex was born.

Editor’s note: Dr. Shahar Madjar is a urologist at Bell Hospital in Ishpeming. Read and comment on prior columns by Dr. Madjar at DrMadjar.com.