Genetic mutations in the innate immune receptor nucleotide-binding oligomerization domain-containing 2 (Nod2) have demonstrated increased susceptibility to Crohn’s disease, an inflammatory bowel disease which is hypothesized to be accompanied by changes in the gut microbiota. Nod2 responds to the presence of bacteria, specifically a fragment of the bacterial cell wall, muramyl dipeptide (MDP). The proposed site of this interaction is the leucine-rich repeat (LRR) domain. Surface plasmon resonance and molecular modeling were used to investigate the interaction of the LRR domain with MDP. A functional and pure LRR domain was obtained from E. coli expression in high yield. The LRR domain binds to MDP with high affinity, with a KD of 212 ± 24 nM. Critical portions of the receptor were determined by alanine scanning mutagenesis of putative binding residues. Fragment analysis of MDP revealed that both the peptide and carbohydrate portion contribute to the binding interaction.

Recent advancements toward the treatment of Crohn’s disease (CD) indicate great promise for long-term remission. CD patients suffer from a complex host of dysregulated interactions between their innate immune system and microbiome. The most predominant link to the onset of CD is a genetic mutation in the innate immune receptor nucleotide-binding oligomerization domain-containing 2 (NOD2). NOD2 responds to the presence of bacteria and stimulates the immune response. Mutations to NOD2 promote low diversity and dysbiosis in the microbiome, leading to impaired mucosal barrier function. Current treatments suppress the immune response rather than enhancing the function of this critical protein. New progress towards stabilizing NOD2 signaling through its interactions with chaperone proteins holds potential in the development of novel CD therapeutics.

Directed enzyme evolution has led to significant application of biocatalysis for improved chemical transformations throughout the scientific and industrial communities. Biocatalytic reactions utilizing evolved enzymes immobilized within microporous supports have...

Bacterial peptidoglycan (PG) is recognized by the human innate immune system to generate an appropriate response. To gain an appreciation of how this essential polymer is sensed, a surface plasmon resonance (SPR) assay using varied PG surface presentation was developed. PG derivatives were synthesized and immobilized on the surface at different positions on the molecule to assess effects of ligand orientation on the binding affinities of NOD-like receptors (NLRs). NLRP1 and NOD2 are cytosolic innate immune proteins known to generate an immune response to PG. Both possess conserved leucine rich repeat domains (LRR) as proposed sites of molecular recognition, though limited biochemical evidence exists regarding the mechanisms of PG recognition. Here direct biochemical evidence for the association of PG fragments to NOD2 and NLRP1 with nanomolar affinity is shown. The orientations in which the fragments were presented on the SPR surface influenced the strength of PG recognition by both NLRs. This assay displays fundamental differences in binding preferences for PG by innate immune receptors and reveals unique recognition mechanisms between the LRRs. Each receptor uses specific ligand structural features to achieve optimal binding, which will be critical information to manipulate these responses and combat diseases.

Process analytical technology was used to monitor formation of a stable emulsion product, with results providing improved understanding of emulsion-based vaccine adjuvant formation processes.