Background: Anemia is the most frequent extraintestinal manifestation of inflammatory bowel disease (IBD) and is associated with the risk of Crohn’s disease. Anemia significantly impairs quality of life, increases hospitalization rates, and increases medical care costs of IBD patients. Iron deficiency is the most frequent cause of anemia in IBD; however, the mechanisms involved are still poorly understood. Here, we investigated the role of the IBD risk gene, protein tyrosine phosphatase non-receptor type 2 ( PTPN2), in regulating iron homeostasis. Methods: Constitutive Ptpn2 wild type (WT), heterozygous (Het), and knockout (KO) 3-week-old mice were analyzed for serum iron content, complete blood count parameters, and intestinal and extraintestinal non-heme iron. Protein and RNA from duodenal epithelial cells (DECs) were assayed by western blotting and qPCR. Localization of the brush border ferrous iron transporter, DMT1, and the ferrous iron absorption driver, NHE3, in duodenal tissue was determined by immunohistochemistry (IHC). Results: Ptpn2-KO mice had reduced i) serum iron ( p=0.0007; n=10); ii) serum iron carrier transferrin saturation ( p=0.0077; n=8); iii) hemoglobin ( p=0.0002; n=5); iv) hematocrit ( p=0.0023; n=5); v) intestinal non-heme iron: duodenum ( p=0.0128; n=10) and jejunum ( p=0.0006; n=8); and vi) extraintestinal tissue non-heme iron: liver ( p=0.0014; n=10), spleen ( p=0.04; n=10), kidney ( p=0.0004; n=7), and gastrocnemius muscle ( p=0.0436; n=9) vs. Ptpn2-WT and Het mice. This indicated that loss of Ptpn2 causes characteristics of anemia including decreased serum iron and tissue iron storage and impaired intestinal iron homeostasis. DEC gene expression of the intracellular iron storage molecule ferritin ( Fth1) was reduced ( p=0.048; n=4) while the basolateral cellular iron importer transferrin receptor 1 ( Tfrc1) was significantly increased ( p=0.0048; n=5) in Ptpn2-KO mice. Reduced FTH1 protein expression ( p=0.007; n=12) and increased TFRC1 protein expression ( p=0.0021; n=8) in DECs of Ptpn2-KO mice was confirmed by western blot, indicating cellular iron deficiency. DMT1 (n=6) and NHE3 (n=8) protein expression in DECs was unaltered, whereas IHC showed reduced apical membrane DMT1 and NHE3 in the duodenal epithelium of Ptpn2-KO mice (n=6), suggesting a possible mechanism of impaired intestinal non-heme iron uptake. Conclusions: Loss of Ptpn2 in mice causes features of anemia including iron deficiency associated with mislocalization of DMT1 and reduced apical membrane expression of NHE3. These findings identify a critical role for PTPN2 in regulating systemic iron homeostasis. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.