Soy-tomato enriched diet reduces inflammation and disease severity in a pre-clinical model of chronic pancreatitis

Chronic pancreatitis (CP) is a fibro-inflammatory syndrome of the pancreas in individuals with genetic, environmental, and/or other risk factors who develop persistent pathological responses to parenchymal injury or stress. CP patients experience recurrent abdominal pain, nausea, and maldigestion, with complications including exocrine insufficiency, fat-soluble vitamin deficiency, metabolic bone disease, and diabetes mellitus. There is no clinical therapy to reverse inflammatory damage in CP; current management focuses on symptom palliation and treatment of complications. Therefore, new therapeutic or dietary strategies to lessen inflammation could markedly improve quality of life in CP patients. Complex foods such as soy and tomatoes contain bioactive metabolites with anti-inflammatory properties. The gut microbiota metabolizes soy into isoflavones (e.g., genistein, daidzein) with reported inhibitory effects on immunity and inflammation. Prior work from the authors’ group shows a soy-enriched diet reduces pro-inflammatory cytokines and suppressive immune populations in prostate cancer patients, and soy isoflavones reduce immune cell activation in vitro. Tomatoes and their constituents (carotenoids like lycopene, flavonoids such as naringenin and quercetin) have been associated with decreased systemic inflammation and reduced risk of chronic diseases, and can directly modulate inflammation. The team developed a novel soy-tomato juice evaluated in healthy individuals for compliance, bioavailability, and sensory acceptability. Research question/hypothesis: Administration of a soy-tomato enriched diet can reduce inflammation and severity of chronic pancreatitis.

The authors review evidence that: (1) Soy-derived isoflavones (genistein, daidzein) and their metabolites can inhibit immune activation and inflammation; previous clinical work by the group demonstrated reduced pro-inflammatory cytokines and immunosuppressive cells in men consuming soy-enriched foods. (2) Tomato consumption is linked with reduced systemic inflammation and lower risk of inflammation-related diseases, including certain cancers; bioactives such as lycopene, naringenin, and quercetin can modulate inflammatory pathways, including COX and PGE2. (3) A novel soy-tomato juice was previously shown to have good bioavailability and acceptability in humans. These data support testing a combined soy-tomato dietary intervention for anti-inflammatory effects in CP.

Study design: Pre-clinical, controlled mouse study using a caerulein-induced chronic pancreatitis (CP) model. Animals: 8-week-old male C57BL/6 mice (Jackson Laboratories) randomized to groups. CP induction: Intraperitoneal injections of caerulein at 50 µg/kg, administered hourly for 7 hours, twice weekly. Mice received injections for 6 weeks total. Baseline (no CP) mice received PBS injections. Dietary intervention: All mice were on control diet initially. After 4 weeks of caerulein injections (CP established), one CP cohort received a soy-tomato enriched diet for the final 2 weeks; a CP control cohort continued the control diet. A no-CP group remained on control diet. Diet composition: Soy-tomato diet based on AIN-93G with 10% (w/w) tomato powder (from high-lycopene hybrids OH2461 and FG99-218) and 0.7246 g per 100 g diet of a 40% (w/w) soy isoflavone extract (Solgen 40, Tradichem). Control diet was AIN-93G with 7% corn oil (in lieu of soybean oil). Carotenoids (lycopene, beta-carotene) and isoflavones (daidzin, glycitin, genistin, daidzein, glycitein, genistein) in diets were quantified by UHPLC/HPLC-PDA using authentic standards. Outcomes and assays: - Disease severity: Pancreata collected at endpoint, fixed, paraffin-embedded, and stained with H&E and Masson’s Trichrome (MT). A modified chronic pancreatitis index (CPI; score 0–15) summed loss of acini, mononuclear inflammation, stromal fibrosis, polymorphonuclear cells (PMNs), and acinar necrosis. Loss of acini and inflammation were assessed in 10 random high-power fields; fibrosis across entire MT-stained sections. - Serum enzymes: Amylase and lipase measured by Alfa Wassermann VetAce analyzer. - Systemic cytokines/chemokines: Sera analyzed using Meso Scale Discovery multiplex for TNF-α, IL-1β, IL-5, IL-6, IL-4, CXCL1. - Pancreatic gene expression: qRT-PCR on pancreatic RNA (TRIZOL extraction; cDNA via high-capacity kit). TaqMan assays for Il6, Il1b, Tnfa, Tgfb, Ly6g, Cd68; normalized to 18S rRNA and then to no-CP controls. - Immune cell profiling: Flow cytometry on splenocytes for CD11b, Ly6G, Ly6C (g-MDSC, m-MDSC), F4/80 (macrophages), NK1.1 (NK cells), CD3, CD4, CD8 (T cells). - T cell infiltration in pancreas: CD3 immunohistochemistry (Abcam SP7) with quantification over defined fields. - Activity monitoring: Infrared photobeam-based system (IR Actimeter) measured spontaneous activity over 6 hours, four days before endpoint; metrics included stereotyped and locomotor movements, total activity, percent resting, distance traveled, mean velocity. Sample sizes: Typically N=10 mice/group for CPI and serum cytokines; N=5 mice/group for serum enzymes and pancreatic qRT-PCR; N=4 mice/group for activity monitoring; CD3 IHC quantification n=10 fields with one outlier removed for analysis as specified. Statistics: Two-sample t-tests for CPI and CD3 infiltration between CP diet groups; exact Wilcoxon rank-sum for pancreatic gene expression; Kruskal–Wallis with Dwass–Steel–Critchlow–Fligner for activity parameters across three groups; one-way ANOVA with Tukey’s post-hoc for other three-group outcomes (log-transformations as needed). Ethics: Approved by The Ohio State University IACUC; procedures followed institutional and PHS policies.

- Disease severity: CP mice fed the soy-tomato diet had significantly reduced chronic pancreatitis index compared to CP mice on control diet (p=0.032), with less acinar loss and reduced interstitial/replacement fibrosis. - Serum enzymes: CP control mice showed decreased serum lipase (p=0.007) and amylase (p=0.018) versus no-CP mice; CP mice on soy-tomato diet had higher lipase (p=0.012) and amylase (p<0.001), similar to no-CP controls, suggesting preserved acinar function. - Activity/health: CP control mice had reduced stereotyped movement, locomotor movement, and total activity, with increased time at rest. Soy-tomato diet reversed these changes, yielding elevated activity and reduced resting (overall activity improvements p<0.05; reduced time at rest p=0.053; total activity improvements comparable to no-CP, p=0.055). Distance traveled and mean velocity improved in soy-tomato-fed CP mice. - Systemic inflammation: Soy-tomato diet significantly reduced serum TNF-α, IL-1β, and IL-5 in CP mice compared to CP control (p<0.05). IL-6, IL-4, and CXCL1 changes were not reported as significant. - Pancreatic gene expression: Trends toward lower Il6 and Il1b and lower Ly6g and Cd68 in pancreatic tissue of soy-tomato-fed CP mice; higher Tnfa; no change in Tgfb. These local tissue differences were not statistically significant in this study. - Pancreatic T cell infiltration: Significantly fewer CD3+ T cells in pancreata of soy-tomato-fed CP mice vs CP control (p=0.007). - Immune cell populations (spleen): CP increased g-MDSC (p=0.003), total MDSC (p=0.008), and NK cells (p=0.024) vs no-CP. Soy-tomato diet reduced g-MDSC (p=0.029) and total MDSC (p=0.036) vs CP control, with no significant changes in monocytic-MDSC, macrophages, or NK cells. A trend toward increased circulating CD3+ and CD8+ T cells was observed with soy-tomato diet.

The study tested the hypothesis that a soy-tomato enriched diet mitigates inflammation and disease severity in chronic pancreatitis. In a murine caerulein-induced CP model, the diet reduced histopathologic severity (acinar loss and fibrosis), preserved acinar function (normalized serum amylase/lipase), lowered systemic inflammatory cytokines (TNF-α, IL-1β, IL-5), decreased pancreatic CD3+ T cell infiltration, and diminished circulating MDSC, especially granulocytic MDSC. These biological improvements coincided with enhanced spontaneous activity and reduced resting behavior, indicating improved overall health and potentially reduced pain-like behavior in CP mice. The findings align with prior clinical and preclinical reports showing anti-inflammatory effects of soy isoflavones and tomato bioactives. The reduction in IL-5 may reflect modulation of eosinophil-related pathways implicated in CP tissue remodeling and fibrosis. The observed reduction in MDSC suggests a mechanism whereby the diet may limit immunosuppression and inflammatory cytokine production; tomato/soy flavonoids and carotenoids can inhibit COX2/PGE2 pathways, which promote MDSC differentiation, providing a plausible mechanistic link. While pancreatic gene expression changes trended favorably, they were not statistically significant, possibly due to sample size or intervention duration; nevertheless, systemic changes were robust. Overall, the results support dietary modulation as a non-pharmacologic approach to reduce inflammation and improve function in CP.

A soy-tomato enriched diet reduced disease severity, systemic inflammatory cytokines, pancreatic T cell infiltration, and circulating MDSC, while preserving exocrine function and improving activity/health in a murine CP model. These pre-clinical data support soy-tomato dietary interventions as a potential, safe, non-pharmacologic approach to mitigate inflammation and symptoms in chronic pancreatitis. Future research should: (1) identify and quantify the bioactive metabolites mediating effects (metabolomics in serum and pancreas); (2) elucidate mechanisms, including roles of MDSC, COX2/PGE2 signaling, ROS, and specific T cell subsets; (3) extend intervention duration and increase cohort sizes to detect local tissue changes; (4) directly assess nociception and compare with pharmacologic anti-inflammatories/analgesics; and (5) translate findings to human CP trials leveraging existing safety and bioavailability data for the soy-tomato formulation.

- Sample sizes for some endpoints were small (e.g., activity monitoring N=4/group; serum enzymes and qRT-PCR N=5/group), limiting power, particularly for pancreatic gene expression where trends were not statistically significant. - Duration of dietary intervention was relatively short (2 weeks after CP establishment), which may have limited detection of local tissue changes. - Only male mice were used; sex differences were not assessed. - No healthy (no-CP) cohort on soy-tomato diet was included, consistent with many dietary studies, but precluding assessment of diet effects in healthy animals. - Pain/nociception was inferred from activity measures rather than directly quantified with nociception assays. - Concentrations of soy/tomato metabolites in pancreatic tissue were not measured; relationships between tissue levels and effects remain unknown.