CHICAGO--(BUSINESS WIRE)--Fitch Ratings has upgraded one class, downgraded one class and affirmed 15 classes of J.P. Morgan Chase Commercial Mortgage Securities Corp., series 2005-CIBC12. A detailed list of rating actions follows at the end of this press release. KEY RATING DRIVERS The affirmations and upgrade reflect Fitch's expectation for the successful repayment of the majority of loans with upcoming maturity dates. 23 non-specially serviced loans, representing 57.9% of the current pool bal