Systemic lupus erythematosus (SLE) - causes, symptoms, diagnosis & pathology

Alright, “systemic lupus erythematosus,” k we totally got this.

“Systemic” is easy, and refers to affecting multiple organs in the body.

“Erythematosus” means reddening of the skin, alright alright.

“Lupus” is latin for “wolf”.

So affects multiple organs wolf...reddening of the skin?

Not exactly, the modern use of lupus usually refers to a variety of diseases that affect

the skin...which was possibly originally used since these diseases resemble a wolf bite

on the patients’ skin.

Is that true?

Who knows.

At any rate, systemic lupus erythematosus, or SLE, sometimes just lupus, is a disease

that’s systemic, and affects a wide variety of organs, but notably often causes red lesions

on the skin.

But how does lupus affect all these organs?

Well usually the immune system protects the body’s tissues from invaders, but lupus

is an autoimmune disease, which means that immune cells start attacking the very tissues

their supposed to protect.

With lupus, essentially any tissue or organ can be targeted.

And just like a ton of other autoimmune diseases though, it’s not completely clear why it

develops, and like most diseases it’s the result of both genetics and the environment.

Alright so let’s go over a specific scenario to show how this plays out.

Let’s say this guy has susceptibility genes—genes that make him susceptible to getting lupus,

and he’s exposed to UV radiation in sunlight, which we know is an environmental risk factor

for lupus.

Well, given enough UV rays, think like sunburn, the cell’s DNA can become so badly damaged,

that the cell undergoes programmed cell death, or apoptosis, and it dies.

This produces all these little apoptotic bodies, and exposes the insides of the cell, including

parts of the nucleus, like DNA, histones, and other proteins, to the rest of the body.

Well those susceptibility genes specifically have an effect on this person’s immune system