A Single Meal Containing Raw, Crushed Garlic Influences Expression of Immunity- and Cancer-Related Genes in Whole Blood of Humans

Abstract

Background: Preclinical and epidemiologic studies suggest that garlic intake is inversely associated with the progression of cancer and cardiovascular disease.

Objective: We designed a study to probe the mechanisms of garlic action in humans.

Methods: We conducted a randomized crossover feeding trial in which 17 volunteers consumed a garlic-containing meal (100 g white bread, 15 g butter, and 5 g raw, crushed garlic) or a garlic-free control meal (100 g white bread and 15 g butter) after 10 d of consuming a controlled, garlic-free diet. Blood was collected before and 3 h after test meal consumption for gene expression analysis in whole blood. Illumina BeadArray was used to screen for genes of interest, followed by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) on selected genes. To augment human study findings, Mono Mac 6 cells were treated with a purified garlic extract (0.5 μL/mL), and mRNA was measured by qRT-PCR at 0, 3, 6, and 24 h.

Results: The following 7 genes were found to be upregulated by garlic intake: aryl hydrocarbon receptor (AHR), aryl hydrocarbon receptor nuclear translocator (ARNT), hypoxia-inducible factor 1α (HIF1A), proto-oncogene c-Jun (JUN), nuclear factor of activated T cells (NFAT) activating protein with immunoreceptor tyrosine-based activation motif 1 (NFAM1), oncostatin M (OSM), and V-rel avian reticuloendotheliosis viral oncogene homolog (REL). Fold-increases in mRNA transcripts ranged from 1.6 (HIF1A) to 3.0 (NFAM1) (P < 0.05). The mRNA levels of 5 of the 7 genes that were upregulated in the human trial were also upregulated in cell culture at 3 and 6 h: AHR, HIF1A, JUN, OSM, and REL. Fold-increases in mRNA transcripts in cell culture ranged from 1.7 (HIF1A) to 12.1 (JUN) (P < 0.01). OSM protein was measured by ELISA and was significantly higher than the control at 3, 6, and 24 h (24 h: 19.5 ± 1.4 and 74.8 ± 1.4 pg/mL for control and garlic, respectively). OSM is a pleiotropic cytokine that inhibits several tumor cell lines in culture.

Conclusion: These data indicate that the bioactivity of garlic is multifaceted and includes activation of genes related to immunity, apoptosis, and xenobiotic metabolism in humans and Mono Mac 6 cells. This trial is registered at clinicaltrials.gov as NCT01293591.

Keywords: Mono Mac 6; cancer; garlic; gene expression; immunity.

Conflict of interest statement

Author disclosures: CS Charron, HD Dawson, GP Albaugh, PM Solverson, BT Vinyard, GI Solano-Aguilar, A Molokin, and JA Novotny, no conflicts of interest.

© 2015 American Society for Nutrition.

Figures

FIGURE 1

Expression of AHR (A), ARNT (B), HIF1A (C), JUN (D), OSM (E), NFAM1 (F), and REL (G) in Mono Mac 6 cells in response to garlic extract (0.5 μL/mL). Values are least squares means ± SEs; n = 3. *Different from control at that time, P < 0.01 (Fisher’s protected least significant different test). The Ct data were normalized to RPL32 and are subtracted from 45 (total number of PCR cycles), so that increasing levels of mRNA are represented by increasing values on the y-axis. AHR, aryl hydrocarbon receptor; ARNT, aryl hydrocarbon receptor nuclear translocator; Ct, threshold cycle; HIF1A, hypoxia-inducible factor 1α JUN, proto-oncogene c-Jun; RPL32, ribosomal protein L32.

FIGURE 2

Concentration of oncostatin M protein produced by Mono Mac 6 cells treated with garlic extract (0.5 μL/mL). Values are least squares means ± SEs; n = 3. *Different from control at that time, P < 0.01.