Have you ever noticed a skin care product advertised as “microbiome friendly” and wondered what that meant? The microbiome is the collection of all the microbes—including bacteria, viruses, and fungi—that live in a specific environment, such as on the skin or in the digestive tract.

It’s a common misconception that all microbes are harmful—in truth, much of the human microbiome is made up of microbes that form beneficial symbiotic relationships with us. Microbiome-friendly skin care products don’t have antimicrobial properties that could harm the beneficial bacteria that live on our skin.

Your Microbiome and You

Throughout our immunology miniseries, we introduced the immune system and its many functions and components. Additionally, we highlighted how vaccines train your immune system, how the system can go awry, and how NIGMS-supported researchers are studying immunology and infectious diseases. Put your knowledge about the immune system to the test by taking the quiz below.

It's common knowledge that too much cholesterol and other fats can lead to disease and that a healthy diet involves watching how much fatty food we eat. However, our bodies need a certain amount of fat to function—and we can't make it from scratch.

Triglycerides, cholesterol, and other essential fatty acids—the fats our bodies can't make on their own—store energy, insulate us, and protect our vital organs. They act as messengers, helping proteins do their jobs. They also start chemical reactions that help control growth, immune function, reproduction, and other aspects of basic metabolism. Fats also help the body stockpile certain nutrients. Vitamins A, D, E, and K, for example, are stored in the liver and in fatty tissues.

The cycle of making, breaking, storing, and using fats is at the core of how all animals, including humans, regulate their energy. An imbalance in any step can result in disease. For instance, having too many triglycerides in our bloodstream raises our risk of clogged arteries, which can lead to heart attack and stroke.

The immune system is designed to closely monitor the body for signs of intruders that may cause infection. But what happens if it malfunctions? Overactive and underactive immune systems can both have negative effects on your health.

What do antibodies, mucus, and stomach acid have in common? They’re all parts of the immune system!

The immune system is a trained army of cells, tissues, and organs that work together to block, detect, and eliminate harmful insults to your body. It can protect you from invaders like bacteria, viruses, fungi, and parasites.

Innate and Adaptive

The immune system is often thought of as two separate platoons: the innate immune system and the adaptive immune system. Although these two platoons have different jobs and are made up of soldiers with different specialties, they work together to prevent infections.

Bacteria can cause many common illnesses, including strep throat and ear infections. If you’ve ever gone to the doctor for one of these infections, they likely prescribed an antibiotic—a medicine designed to fight bacteria. Because bacteria can also cause life-threatening infections, antibiotics have saved many lives. However, the widespread use of antibiotics has fueled a growing problem: antibiotic resistance.

Antibiotic-resistant bacteria can survive some or even all antibiotics. Other microorganisms, including fungi, can similarly become resistant to the medicines that are used to treat them. Infections from these microorganisms affect many people and are difficult to treat. According to the Centers for Disease Control and Prevention, in the U.S. alone, resistant bacteria and fungi infect 2.8 million people each year, and more than 35,000 die as a result.

Pharmacologists research how the body acts on medicines (e.g., absorption, excretion) and how medicines act in the body, as well as how these effects vary from person to person. NIGMS-funded pharmacology researchers are:

• Conducting research to design medicines with fewer side effects
• Exploring how genes cause people to respond differently to medicines
• Developing new methods and molecular targets for drug discovery
• Discovering medicines based on natural products
• Understanding how medicines act using computers
• Monitoring brain function under anesthesia to develop safer anesthetic medicines that reduce side effects
• Creating artificial tissue to heal muscles after traumatic injuries
• Investigating how to treat patients with sepsis
• Measuring tissue damage from burns to help improve treatment options

You might know that tiny individual units called cells make up your body. But did you know some of your cells die every day as a part of their normal life cycle? These deaths are balanced by other cells splitting into two identical cells, a process called mitosis.

What we put into our bodies can affect how they function and what they do. For example, a sugary snack will probably make you feel differently than a high-protein meal. Similarly, different medicines elicit different responses in your body, and pharmacologists try to fine-tune each medicine to balance the desired (on-target) with the undesired (off-target) effects—a branch of pharmacology called pharmacodynamics.

Most medicines work by binding to a molecular target, usually proteins like receptors or enzymes, and either blocking or supporting its activity, which results in their therapeutic effects.

Have you ever wondered what happens inside your body when you take a medicine? An area of pharmacology called pharmacokinetics is the study of precisely that. Here, we follow a medicine as it enters the body, finds its therapeutic target (also called the active site), and then eventually leaves the body.

To begin, a person takes or is given a dose of medicine by a particular route of administration, such as by mouth (oral); through the skin (topical), mucous membranes
(nasal), or lungs (inhaled); or through a needle into a muscle (intramuscular) or into a vein (intravenous). Sometimes medicines can be administered right where they’re needed, like a topical antibiotic ointment on a scrape, but most medicines need to enter the blood to reach their therapeutic target and be effective. Those are the ones we’ll continue following, using the common pharmacokinetic acronym ADME: