MetLife Inc. and Prudential Financial Inc. are cutting Wall Street’s middlemen out of the resurgent market for loans backed by some of the nation’s most-prized commercial properties, Bloomberg News reported yesterday. Banks from Deutsche Bank AG to JPMorgan Chase & Co. — which originate loans and then sell them off as securities — risk losing out as rising borrowing costs prompt them to charge more to make money. Insurers are offering cheaper real estate loans because they don’t need to quickly sell the debt at a profit, pushing Wall Street firms to lower their standards just to get deals done. As a result, sales of commercial-mortgage backed bonds are falling short of predictions for the best year since 2007: Issuance slumped to $14.6 billion from $20 billion in the same period last year, according to data compiled by Bloomberg. Bank of America Corp. cut its forecast last week for deals tied to single loans, typically backed by the higher-quality properties that insurers target, as sales plunged 66 percent from last year’s record $9.1 billion.