Tokyo's benchmark Nikkei index closed lower on Wednesday as investors locked in profits ahead of the US Federal Reserve's meeting. The Nikkei 225 index slid 0.51 percent or 150.29 points to end at 29,291.01, while the broader Topix index was flat, ending up 0.02 percent or 0.38 points to 1,975.86. nf/kaf/reb