Helicobacter pylori Infection Induces Anemia, Depletes Serum Iron Storage, and Alters Local Iron-Related and Adult Brain Gene Expression in Male INS-GAS Mice

Abstract

Iron deficiency anemia (IDA) affects > 500 million people worldwide, and is linked to impaired cognitive development and function in children. Helicobacter pylori, a class 1 carcinogen, infects about half of the world’s population, thus creating a high likelihood of overlapping risk. This study determined the effect of H. pylori infection on iron homeostasis in INS-GAS mice. Two replicates of INS-GAS/FVB male mice (n = 9-12/group) were dosed with H. pylori (Hp) strain SS1 or sham dosed at 6–9 weeks of age, and were necropsied at 27–29 weeks of age. Hematologic and serum iron parameters were evaluated, as was gene expression in gastric and brain tissues. Serum ferritin was lower in Hp SS1-infected mice than uninfected mice (p < 0.0001). Infected mice had a lower red blood cell count (p<0.0001), hematocrit (p < 0.001), and hemoglobin concentration (p <0.0001) than uninfected mice. Relative expression of gastric hepcidin antimicrobial peptide (Hamp) was downregulated in mice infected with Hp SS1 compared to sham-dosed controls (p<0.001). Expression of bone morphogenic protein 4 (Bmp4), a growth factor upstream of hepcidin, was downregulated in gastric tissue of Hp SS1-infected mice (p<0.001). Hp SS1-infected mice had downregulated brain expression of tyrosine hydroxylase (Th) (p = 0.02). Expression of iron-responsive genes involved in myelination (myelin basic protein (Mbp) and proteolipid protein 2 (Plp2)) was downregulated in infected mice (p = 0.001 and p = 0.02). Expression of synaptic plasticity markers (brain derived neurotrophic factor 3 (Bdnf3), Psd95 (a membrane associated guanylate kinase), and insulin-like growth factor 1 (Igf1)) was also downregulated in Hp SS1-infected mice (p = 0.09, p = 0.04, p = 0.02 respectively). Infection of male INS-GAS mice with Hp SS1, without concurrent dietary iron deficiency, depleted serum ferritin, deregulated gastric and hepatic expression of iron regulatory genes, and altered iron-dependent neural processes. The use of Hp SS1-infected INS-GAS mice will be an appropriate animal model for further study of the effects of concurrent H. pylori infection and anemia on iron homeostasis and adult iron-dependent brain gene expression.

Dietary Composition Influences Incidence of Helicobacter pylori-Induced Iron Deficiency Anemia and Gastric Ulceration

“…Previous studies in rodent models have reached inconsistent conclusions about the capacity of H. pylori to cause anemia (19)(20)(21)(22). The inconsistent conclusions might reflect the use of different H. pylori strains, differences in animal models, differences in diets, or differences in the time points selected for analysis.…”

“…In one study, H. pylori-infected male INS-GAS mice (which overexpress gastrin) exhibited reductions in both hemoglobin and serum ferritin levels compared to uninfected animals; however, the mean corpuscular volume (MCV; a measure of the average size of erythrocytes) was elevated in the infected cohort (21), a finding that differs from the reduced MCV typically observed in patients with IDA. Infection of INS-GAS mice with the related organism H. felis also resulted in anemia (19).…”

“…Animal studies examining a potential link between H. pylori infection and anemia have also yielded conflicting results (19)(20)(21)(22). In one study, H. pylori-infected male INS-GAS mice (which overexpress gastrin) exhibited reductions in both hemoglobin and serum ferritin levels compared to uninfected animals; however, the mean corpuscular volume (MCV; a measure of the average size of erythrocytes) was elevated in the infected cohort (21), a finding that differs from the reduced MCV typically observed in patients with IDA.…”

Helicobacter pylori infection and low dietary iron alter behavior, induce iron deficiency anemia, and modulate hippocampal gene expression in female C57BL/6 mice

“…Other stomach sections were used for DNA and RNA extraction to evaluate mRNA expression and H . pylori colonization level, as previously described [25]. Stomach tissue samples (linear strips from the squamo-columnar junction through the proximal duodenum) and liver tissue samples collected for DNA and RNA extraction were flash-frozen in liquid nitrogen and stored at -80°C.…”

“…Molecular analysis of whole brain tissue revealed that chronic H . pylori infection of INS-GAS mice resulted in reduced expression of genes involved in dopamine metabolism, myelination, and maintenance of synaptic plasticity; all changes characteristic of brain iron deficiency [25]. These findings prompted the current study in C57BL/6 mice, a strain commonly used as a background strain for behavioral studies.…”