Could inflammation be a key component in the progression of benign prostatic hyperplasia?

Purpose of review This review covers recent developments in the role of chronic inflammation in the pathogenesis and progression of benign prostatic hyperplasia (BPH). Recent findings A paper on the subanalysis of the Medical Therapy of Prostate Symptoms study highlighted the role of chronic inflammation in the progression of BPH as determined by the pathological tissue obtained in the 4.5-year study. It shows patients with inflammation had significantly larger prostates, higher serum prostate specific antigen and a greater risk of urinary retention. This follows several other in-situ studies which demonstrated that elevated expression of pro-inflammatory cytokines in BPH. IL-6, IL-8 and IL-17 may perpetuate chronic immune response in BPH and induce fibromuscular growth by an autocrine or paracrine loop or via induction of COX-2 expression. Immune reaction may be activated via Toll-like receptor signalling and mediated by macrophages and T cells. Conversely, anti-inflammatory factors such as macrophage inhibitory cytokine-1 decreased in symptomatic BPH tissues. Animal models provided evidence for the presence of unique T-cell subsets which may suppress autoimmunity in healthy Sprague-Dawley rats resistant to chronic nonbacterial prostatitis. Summary The pathogenesis of BPH is still unresolved, although chronic inflammation may play a significant role in disease progression. Further research is required to determine the putative (auto)antigen, the influence of infiltrating inflammatory cells on the stromal/epithelial cell crosstalk and a new classification of BPH quantifying local and systemic inflammatory/immune reactions in relation to clinical relevance. New treatments for BPH investigating these specific inflammatory pathways may arise as we learn more about the way they work.