Effect of the Leptin Receptor Q223R Polymorphism on the Host Transcriptome following Infection with Entamoeba histolytica

Abstract

dResistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues were analyzed for changes in gene expression. By 72 h postchallenge, all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. Thirty-seven genes were differentially expressed in response to infection at 72 h, including proinflammatory genes (CXCL2, S100A8/9, PLA2G7, ITBG2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h postchallenge of infected Q223 versus R223 mice identified a subset of differentially expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide into this previously uncharacterized mechanism of mucosal immunity.T he association of leptin signaling with infectious diseases has long been suspected; however, only recently was the significant association between leptin and human disease described (1-4). It was determined that a common genetic mutation of the leptin receptor (LEPR), Q223R, was associated with an approximately 4-fold increase in likelihood of infection with Entamoeba histolytica in a Bangladeshi cohort of children (4). The murine model of amebiasis recapitulated the human findings, demonstrating that 223R (homozygous for arginine) mice were significantly more susceptible to infection with E. histolytica than Q223 (homozygous for glutamine) mice. In addition, both ob/ob (leptin Ϫ/Ϫ ) and db/db (LEPR Ϫ/Ϫ ) mice had increased rates of E. histolytica infection and worse tissue destruction and mortality. Finally, the use of tissue-specific LEPR knockouts demonstrated that the site of action for LEPR was located within the intestinal epithelial cell (IEC) population (5).LEPR belongs to the gp130 family of cytokine receptors. Upon leptin binding to the homodimeric LEPR, Janus kinase 2 (JAK2) is activated, leading to the phosphorylation of tyrosines 985, 1077, and 1138 on LEPR, which in turn are recognized by Src homology 2 domain-containing tyrosine phosphatase (SHP2) and suppressor of cytokine signaling 3 (SOCS3), STAT5a/b, and STAT3 (respectively) (6)(7)(8). Murine studies demonstrated that signal...

Leptin Receptor Mutation Results in Defective Neutrophil Recruitment to the Colon during Entamoeba histolytica Infection

“…The mouse model of an E. histolytica cecal infection was used to determine the differences between Q223 and R223 mice early during an infection. Previous work had shown that by 12 h after infection a difference could be observed in infection rates between Q223 and R223 mice, with complete eradication in Q223 but not R223 mice by 72 h ( 11 ). This 12-h time point was therefore chosen to investigate the very early host processes that could account for the differences in phenotypes.…”

“…The rapid divergence of infection phenotypes observed, with full eradication of infection by 72 h in mice with the ancestral Q223 leptin receptor allele ( 11 ), suggested that the innate immune system was responsible for the differences in infection clearance. R223 mice were observed to have a reduced neutrophil population in the lamina propria compared to Q223 mice 12 h after infection.…”

Immunobiotic Lactobacillus administered post-exposure averts the lethal sequelae of respiratory virus infection

“…Samples (total 24, 6 mice per group) from mice that received two inoculations of L. plantarum or two inoculations of pbs/bsa diluent prior to virus or vehicle only challenge and harvested on day 19 were processed further for DNA microarray analysis. RNA extraction and target preparation were performed as described (Mackey-Lawrence et al, 2013) for all samples except RNA was extracted using RNeasy 96 well kit (Qiagen, Valencia, CA). Hybridization, fluidics and scanning were performed according to standard Affymetrix protocols (http://www.affymetrix.com) with the whole mouse genome 430 2.0 chip within the Genomics Unit of the Research Technologies Section (NIAID).…”

TSLP Expression: Analysis with a ZsGreen TSLP Reporter Mouse

“…RNA quality was determined using 2100 Bioanalyzer (Agilent Technologies, Santa Clara, CA) and the Agilent RNA 6000 Pico kit. RNA was quantitated by RT-QPCR as described in Mackey-Lawrence et al, 2013 (21). The lowest RNA yield of 0.9 ng was from 654 cells.…”