In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Acute tubulo - interstitial nephritis ( ATIN ) is an important cause of acute renal failure resulting from a variety of insults , including immune complex - mediated tubulo - interstitial injury , but drugs such as non - steroidal anti - inflammatory drugs ( NSAIDs ) are a far more frequent cause .
### Output Text:
Acute tubulo - interstitial nephritis ( ATIN ) is an important cause of acute renal failure resulting from a variety of insults , including immune complex - mediated tubulo - interstitial injury , but drugs such as non - steroidal anti - inflammatory drugs ( NSAIDs ) are a far more frequent cause . 