Pirin polypeptide and immune modulation

A method of preventing infection by one or more bacteria or reducing a level of the one or more bacteria in a tissue or an organ in a subject, comprising administering to the subject a pharmaceutical composition that comprises:

• (i) a pirin-related polypeptide of Bacteroides thetaiotaomicron, wherein the pirin-related polypeptide comprises an amino acid sequence having at least 90% identity to SEQ ID NO:
• 2, as determined by a sequence alignment performed using a Basic Local Alignment Search Tool algorithm with a gap open penalty of 0, a gap extension penalty of 0, and a Blocks Substitution Matrix of 62;
• and
• (ii) a pharmaceutically acceptable excipient, diluent, or carrier.

A method of regulating the expression of one or more pro-inflammatory genes or barrier integrity genes in a cell or cells of a subject, comprising administering to the subject a pharmaceutical composition that comprises:

• (i) a pirin-related polypeptide of Bacteroides thetaiotaomicron, wherein the pirin-related polypeptide comprises an amino acid sequence having at least 90% identity to SEQ ID NO:
• 2, as determined by a sequence alignment performed using a Basic Local Alignment Search Tool algorithm with a gap open penalty of 0, a gap extension penalty of 0, and a Blocks Substitution Matrix of 62;
• and
• (ii) a pharmaceutically acceptable excipient, diluent, or carrier.