Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Gastritis ?
    ### Response:
    Common causes of gastritis include
                
- Helicobacter pylori (H. pylori) infection  - damage to the stomach lining, which leads to reactive gastritis  - an autoimmune response
                
H. pylori infection. H. pylori is a type of bacteriaorganisms that may cause an infection.
    