Can sle be treated?

Yes. Sle is thought to be caused by an immune reaction that erroneously attacks the body. There are many different "disease-modifying agents " that can help turn off these reactions. Rheumatologists are the medical specialists that treat these types of diseases.
Yes. All people with systemic lupus should take Plaquenil (hydroxychloroquine) unless allergic. It helps control flares & prevent organ damage. Also nsaids help pain. Immune suppression drugs may be needed. Preventing infection (vaccines, hand-washing, etc.) and preventing heart disease are important. A rheumatologist is helpful.