Assessing strategies to enhance microbial-derived aromatic amino acid metabolites in fermented foods to mitigate obesity-associated metabolic and immune perturbations

Fermented food consumption is linked to reduced inflammation and improved metabolic health, yet the specific bioactive components responsible for these benefits remain unclear. Related to their immunomodulatory potential, there is rising interest in a class of aromatic amino acid (ArAA) microbial-derived metabolites: phenyllactic acid (PLA), 4-hydroxyphenyllactic acid (4HPLA), and indole-3-lactic acid (ILA), termed herein as aryl-lactates. Phenylalanine, tyrosine, and tryptophan are metabolized to PLA, 4HPLA, and ILA, respectively via enzymatic activity in select lactic acid bacteria (LAB) found in fermented foods and the gut microbiome. This dissertation aimed to establish methods for maximizing microbial ArAA metabolism in whole fermented food matrices to promote aryl hydrocarbon receptor (AhR) bioactivity, investigate metabolic and inflammatory impacts of aryl-lactate consumption in the context of a high-fat diet (HFD)-induced obesity mouse model, and determine whether aryl-lactates enhance clearance of apoptotic cells by macrophages in an in vitro setting. Using targeted metabolomics, the presence of aryl-lactates was first established within commercially available fermented foods. After pinpointing fermented food-associated LAB able to produce high levels of aryl-lactates (i.e., Lactiplantibacillus plantarum), fermentation conditions were leveraged to increase aryl-lactate production in food matrices (yogurt, sauerkraut) up to 5x103 fold vs. standard fermentation conditions. Utilizing ex vivo reporter assays, food matrix conditions to optimize aryl-lactate concentrations were found to enhance AhR activity compared to standard conditions and commercial products. With reduced AhR activity as a hallmark of many chronic inflammatory diseases, including obesity, we next sought to investigate the impact of aryl-lactate consumption on a HFD-induced obesity mouse model. Aryl-lactates (PLA, 4HPLA, or ILA) were given in drinking water (0.25 mg/mL) in concentrations similar to that of 1 serving of aryl-lactate optimized fermented foods. After a 2d lead in of aryl-lactates, mice (n=4-8/group) were given a HFD (45% fat) or control diet (CD; 10% fat) for 10 weeks (aryl-lactates given individually) or 16 weeks (aryl-lactates combined). Select aryl-lactates mitigated HFD-induced alterations, including weight gain (4HPLA), impaired body composition (ILA, 4HPLA), glucose tolerance (4HPLA), food intake (ILA), compromised barrier integrity (4HPLA), and dysregulated expression of metabolic and inflammatory genes (i.e., Cd36, Lpl, Ccl4, Cxcl10). When given all three aryl-lactates (PLA+4HPLA+ILA) for 16wks, similar decreased body weight gain and improved body composition was observed compared to HFD alone. Further, circulating AhR activity was significantly higher in aryl-lactate consuming mice compared to HFD alone (p=0.0218). Liver analysis revealed significantly lower lipid accumulation in aryl-lactate treated mice compared to HFD alone, and hepatic RNA sequencing revealed 1,323 HFD-induced differentially expressed genes (DEGs), which was lowered to only 68 DEGs when HFD mice were given aryl-lactates. These data indicate that aryl-lactates consumed in concentrations similar to those found in fermented foods with optimized ArAA metabolism improve HFD-induced metabolic and immune perturbations. Next, we investigated an imperative process to maintain tissue homeostasis that is known to be dysregulated in liver disease—efferocytosis. Using THP-1 monocyte-derived macrophages and apoptotic Jurkat T (bait) cells, efferocytosis was assessed via flow cytometry. Both 4HPLA and ILA enhanced efferocytosis, resulting in a 22-26% relative increase in apoptotic cell clearance. Therefore, a possible mechanism for which aryl-lactate consumption mediates HFD-induced hepatic lipid accumulation is via enhancing macrophage efferocytosis. Future work will continue to divulge the mechanisms behind aryl-lactate—mediated improvements in HFD-induced obesity, focusing on leveraging fermented foods as a source of aryl-lactates with potential to improve human health.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nutritional Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Kasperek, Mikaela C.

Contributors dc:contributor

• Allen, Jacob M.
• Miller, Michael J.
• Khan, Naiman A
• Loman, Brett R
• Hernandez-Saavedra, Diego

• Fermented Foods
• Aromatic Amino Acids
• Metabolites
• Aryl-lactates
• Phenyllactic Acid
• 4-hydroxyphenyllactic Acid
• Indole-3-lactic Acid
• Obesity

Statement dc:rights

• Copyright 2025 Mikaela C Kasperek

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129876

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129876