Just to clarify, complete resolution after injury can only occur if the basement membrane remains intact as this below this is where the stem cells are located. If there is damage to the basement membrane, you will have incomplete resolution and scar formation. The best example of this is skin injury.

What I was really looking for as an answer to this question was Type II pneumocytes ("stem cells" of the alveoli--> can divide into more Type I and Type II pneumocytes; also make surfactant).

"maintenance of BM integrity" seems to be the next best response, but I really had to just rule out everything else: --formation of granulation tissue --> new connective tissue formation that fills a wound; full recovery of lung tissue would require new epithelial, not connective tissue --increased angiogenesis --> I usually think about cancer or granulation tissue when I hear angiogenesis --metaplasia of mesenchymal cells to pneumocytes --> type II pneumocytes are the precursor for new pneumocytes --proliferation of fibroblasts --> this is going to give you fibrosis in the lung, which is not what you want when healing from pneumonia