What Causes Horizontal Lines In Nails That Grows Into Bumps?

My fingernails (thumbs, index and the midles) have horizontal lines as the nail grows it developes little bumps it is not painful. I have the same in my toenails. But my tonails are worst no bumps just the transversal lines and these lines are deep. I have had this for years. I am 42 years old I would like to know if I can do something to make them look better or if is possible to cure.