Rheumatoid arthritis occurs when the immune system attacks cells within joints

Visualizing a joint under attack from rheumatoid arthritis

A particularly difficult arthritis subtype is rheumatoid arthritis, a painful condition provoking a vicious cycle of joint inflammation, destruction, and dysfunction. It begins with a misfiring of the patient’s own immune system—for unknown reasons, it identifies joint and cartilage cells as foreign, initiating an attack to eliminate the supposed "invaders."

Rheumatoid arthritis affects about 1% of the population

Rheumatoid arthritis is an autoimmune condition leading to breakdown and inflammation of multiple joints throughout the body. This academic article provides an updated deep dive into our current cellular understanding of rheumatoid arthritis, how it is diagnosed, and the variety of medications available for treating this painful condition.

Arthritis is an umbrella term for various conditions that cause joint pain

Arthritis isn’t one single disease, but rather a range of conditions that all lead back to the same outcome—joint pain. This American Academy of Orthopaedic Surgeons primer is a go-to resource for understanding what arthritis is, the most common types, and various treatment options depending on the underlying cause.

Research links the gut microbiome and rheumatoid arthritis

Arthritis is a potentially disabling joint condition that currently affects nearly one in five adults across the globe. Doctors still don't know what causes rheumatoid arthritis, but the answer may be partly determined by chemicals produced by bacteria in the gut.

How autoimmune diseases, which attack your own tissues and cells, work in the body

These diseases remain some of medicine's thorniest problems because the immune system can mistakenly attack almost any tissue in the body, resulting in myriad diseases, including lupus (numerous tissues affected), Hashimoto's (thyroid), and MS (the nervous system).

Autoimmunity is when the body attacks itself, causing inflammation

Inflammation is the body's way of healing itself, and acute inflammation saves our lives when we have injuries or infections. It increases blood flow to the affected areas to bring immune cells to fight off invaders. This often results in short-term swelling, redness, and pain.

The most common type of arthritis is osteoarthritis, or age-related cartilage loss

The most common form of arthritis is osteoarthritis. It's caused by cartilage loss within our joints as we age. This article is formatted specifically for patients. It provides easily digestible information on our most evidence-based understanding of osteoarthritis causes, symptoms, and treatments.

There is no cure for the general condition of arthritis

While there are innumerable conditions ultimately leading to the joint pain we collectively term "arthritis," one common pathway is progressive inflammation and joint damage many years after an injury.

Chronic inflammation can cause cellular damage and could lead to cancer

Over time, this cellular defense system can inadvertently damage cells and tissues when it's in this heightened alarm mode over a prolonged period. This occurs because, when immune cells are sent somewhere without a true target, they may attack healthy cells and tissues.

Anatomy of a healthy knee joint

To understand arthritis, study a normal joint. Where two bones come together, each is lined by a cartilage cap. These bones are linked together by strong ligaments. The inner juncture is lined by a joint capsule (synovial membrane) containing lubricating joint fluid between the two surfaces, allowing for near-frictionless motion.

Why CAR-T therapy has become one of the main focus areas for autoimmune diseases

The therapy, originally targeting cancer, involves taking a patient's own T cells, genetically reprogramming them to recognize and attack a specific target and then infusing them back into patients. For autoimmune diseases, the therapy instead programs them to target immune cells that are causing problems, restoring immune system tolerance.

Type 1 diabetes is an inherent autoimmune disorder inhibiting insulin production

Diabetes causes the body to attack insulin-producing cells in the pancreas, causing a shortage or lack of insulin. This prevents the body from accessing and storing blood sugar—the brain and muscles' primary energy source. It's unclear what causes Type 1 diabetes, an incurable yet manageable chronic condition as of 2024.

Scleroderma, which causes skin to harden and scar, has no FDA-approved treatment

It's an autoimmune disease that disproportionately causes worse complications in African American people for unknown reasons. It causes the body to overproduce collagen after the immune system attacks the body's own connective tissue, leading to excess collagen deposits and restricted blood circulation as small blood vessels are damaged. It can damage various organs, including the lungs.

Measles attacks the body’s immune system, leaving it vulnerable to secondary complications

A measles infection begins in the lungs, where it hijacks cells known as macrophages and begins to replicate itself. It then uses a Trojan horse method to enter the lymph nodes, where it attacks vulnerable T and B cells. Symptoms include fever and rashes.

An interactive explanation of blood transfusion

The antigens and Rh factors of blood cells (which determines your blood type) must be compatible with your immune system—which is why blood transfusions between patients must have matching types. In a mismatch, the immune system will attack and destroy donor blood cells, triggering a potentially fatal reaction.

Inflammation appears to cause specific symptoms of depression

A large analysis of existing studies published in 2021 found that systemic inflammation is associated with fatigue, appetite changes, and sleep disruption, rather than some of depression's broader symptoms including hopelessness about the future, or feeling fearful. This may suggest that inflammation influences specific symptoms of the condition, rather than the disease as a whole.

Necrosis is the unplanned death of cells and the tissue they comprise

If cells die prematurely due to a lack of blood flow, injury, or disease, they and their organelles can swell, leading to rupture of the surrounding cell membrane. This releases the cell's contents into the surrounding tissue, causing inflammation and damage to neighboring cells.

Cancer is runaway growth of abnormal, mutated cells

Cancer cells have mutations in their DNA that allow uncontrolled growth and division, dodge usual mechanisms of cell death, and can often spread throughout the body. This is, in part, why the disease is so difficult to treat, with a wide variety of mechanisms and types that poses unique challenges.

As deposits build up under the eye, the retina bends with macular degeneration

The retina bends due to the accumulation of proteins and other materials beneath it. That's considered the milder "dry" form of macular degeneration. Another form, called "wet" macular degeneration, is caused by abnormal blood vessels leaking fluid into the eye, which can rapidly affect central vision.

Poison ivy's characteristic rash is caused by an allergic response to an oily compound in the plant called urushiol.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

Pollen and other allergens that are inhaled rarely cause anaphylaxis

Food allergies, insect stings, medications, and latex exposure are the main causes of the life-threatening allergic response called anaphylaxis. To reverse this severe reaction, a patient must typically receive an injection of epinephrine, otherwise known as adrenaline, a hormone that can relax some of the body’s muscles and increase heart rate, among other effects. Pollen allergies typically fuel a more localized reaction that isn’t as severe.

What is cardiovascular disease?

Cardiovascular diseases are a range of related health conditions that develop in the heart and blood vessels. This article and related infographics detail cardiovascular disease types and treatments.

An individual retirement account is a type of tax-advantaged investment account

An IRA lets individuals at most income levels invest either pre- or post-tax money for retirement. IRAs are often good solutions for people who don’t have the option to invest in a 401(k) plan—or for those who want to put even more money aside for retirement.

Tattoos remain visible on your skin thanks to immune cells called macrophages

The neuroscience of REM atonia disorders, where patients act out dreams

What prevents the typical person from acting out their dreams? Temporary paralysis of skeletal muscles, usually leading up to, and during, REM sleep. This academic article and related graphics explore what happens when this process doesn't go as planned, leading to REM sleep behavior disorder.

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted and led to authorities' suspicions he was conspiring with the Russians

The 1794 incident involved André-Ignace-Joseph Dufresnoy, a French army physician researching the plants' potential medicinal properties. Rhus radicans is a scientific name for the plant, though it's commonly called Toxicodendron radicans.

Ringworm is caused by a fungus, not a worm

Ringworm, formally known as tinea and known for its red circular rash, is responsible for about 325 million infections at any given time—comprising roughly half the world’s fungal skin infection burden. It’s caused by a type of fungus called a dermatophyte, which also causes athlete’s foot and jock itch. Doctors typically prescribe antifungal tablets or powders to stamp out these fungal invaders.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

Firework or sparkler burns, even if they cover a relatively small area of skin, can significantly affect our range of motion.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

Legendary architect Frank Lloyd Wright designed the SC Johnson headquarters in Wisconsin, aiming to make a cathedral-like workplace

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

American dance legend Martha Graham, sometimes called 'the Picasso of dance,' refused to perform at the 1936 Olympics in Berlin and conceived the piece 'Chronicle' in response to the experience.

The rivalry between Alexander Hamilton and Thomas Jefferson centered on federalism—the question of how much power the federal government should hold relative to the states.

US consumers collectively owe more than $1T to credit card companies—almost as much as they owe in auto loans.