**Core Concept**
The primary goal of glucocorticoid treatment in rheumatoid arthritis is to modulate the immune response and reduce inflammation. Glucocorticoids exert their anti-inflammatory effects by inhibiting the expression of pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha).

**Why the Correct Answer is Right**
Glucocorticoids act by binding to the glucocorticoid receptor, which then translocates to the nucleus and binds to DNA, inhibiting the transcription of pro-inflammatory genes. This leads to a decrease in the production of pro-inflammatory cytokines, which are responsible for the inflammation and joint damage seen in rheumatoid arthritis. Additionally, glucocorticoids have anti-angiogenic properties, which inhibit the formation of new blood vessels that supply the inflamed tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while glucocorticoids do have some immunosuppressive effects, their primary goal in rheumatoid arthritis is not to suppress the immune system, but to reduce inflammation.
**Option B:** This option is incorrect because glucocorticoids do not directly affect the underlying joint damage caused by rheumatoid arthritis, but rather aim to reduce the inflammation and symptoms associated with the disease.
**Option C:** This option is incorrect because while glucocorticoids can have some effects on bone metabolism, their primary goal in rheumatoid arthritis is not to affect bone health, but to reduce inflammation.

**Clinical Pearl / High-Yield Fact**
Glucocorticoids should be used judiciously in rheumatoid arthritis, as long-term use can lead to side effects such as osteoporosis, glaucoma, and cataracts. However, they remain a crucial component of treatment for many patients, particularly in the short-term management of acute flares.

**Correct Answer: D. Reduction of inflammation.**