Patients with Crohn's disease (CD) have higher risk for osteoporosis following decreased level of osteocalcin. We hypothesize that active inflammation following Mycobacterium avium subsp. paratuberculosis (MAP) infection results in elevation of undercarboxylated osteocalcin (ucOC) and downregulation of active osteocalcin in CD patients and cow-disease model (Johne's disease). In this study, we measured ucOC, active osteocalcin, and calcium levels in sera from 42 cattle (21 infected with MAP and 21 healthy cattle), 18 CD patients, and 20 controls. The level of ucOC in MAP bovine samples was higher than that in MAP controls (318 ± 57.2 nmol/mL vs. 289 ± 95.8 nmol/mL, P > 0.05). Consequently, mean calcium level in bovine MAP was significantly higher than that in bovine-MAP samples (9.98 ± 0.998 mg/dL vs. 7.65 ± 2.12 mg/dL, P < 0.05). Also, the level of ucOC was higher in CD-MAP than in CD-MAP (561 ± 23.7 nmol/mL vs. 285 ± 19.6 nmol/mL, P < 0.05). Interestingly, the mean osteocalcin level in MAP bovine was lower than that in MAP bovine (797 ± 162 pg/mL vs. 1190 ± 43 pg/mL) and it was lower in CD-MAP than in CD-MAP infection (1.89 ± 0.184 ng/mL vs. 2.19 ± 0.763 ng/mL) (P < 0.05). The correlation between MAP infection and elevation of sera ucOC, reduction of active osteocalcin and increased calcium supports MAP infection role in CD and complications with osteoporosis.

We previously discovered that single nucleotide polymorphisms (SNPs) in PTPN2/22 (T-cell negative-regulators) occur in 78% of rheumatoid arthritis (RA), along with Mycobacterium avium paratuberculosis (MAP) infection in 33% of patients. In Crohn’s disease, we reported that SNPs in TNFα and receptors (TNFRSF1A/TNFRSF1B) benefited intracellular MAP-survival, increased infection, and elevated inflammatory response mimicking the poor response to anti-TNFα treatment in some patients. Here, we studied the frequency and effects of SNPs in TNFα/TNFRSF1A/TNFRSF1B in RA including gene expression, MAP infection, and osteoporosis marker levels in blood (54 RA and 48 healthy controls). TNFα:rs1800629 (GA) was detected in 19/48 (40%) RA and 8/54 (15%) controls (p-value < 0.05, odds ratio (OR) = 3.6, 95% CI: 1.37–9.54). TNFRS1B:rs3397 (CT) was detected in 21/48 (44%) RA and 10/54 (19%) controls (p-value < 0.05, OR = 4.43, 95% CI: 1.73–11.33). In RA, rs3397 downregulated TNFRSF1B expression (CC > CT (0.34 ± 0.14) and CC > TT (0.27 ± 0.12)), compared to wildtype CC (0.51 ± 0.17), p-value < 0.05. MAP DNA was detected significantly in 17/48 (35.4%) RA compared to 11/54 (20.4%) controls (p-value < 0.05, OR = 2.14, 95% CI: 1.12–5.20). The average osteocalcin level was significantly lower (p-value < 0.05) in RA (2.70 ± 0.87 ng/mL), RA + MAP (0.60 ± 0.31 ng/mL), RA + TNFRSF1B:rs3397 (TT) (0.67 ± 0.35 ng/mL), compared to the healthy control (5.31 ± 1.39 ng/mL), and MAP-free RA (3.85 ± 1.31 ng/mL). Overall, rs3397 appears to downregulate TNFRSF1B, increase MAP infection, worsen inflammation, and cause osteocalcin deficiency and possibly osteoporosis in RA.

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Epithelial cells are polarized with defined apical tight junctions (TJs), lateral adherens junctions (AJs), and basal integrin–matrix interactions. However, it is increasingly recognized that resident cell junction proteins can be found in varying locations and with previously unrecognized functions. Our study here presents the nanoarchitecture and nanocolocalization of cell junction proteins in culture and tissue by stochastic optical reconstruction microscopy (STORM). The Z‐axial view of noncancerous MDCK‐II and PZ‐HPV‐7 cell–cell junctions resolved β‐catenin and p120ctn localizations to TJs and AJs, with p120ctn apical to β‐catenin and colocalizing with TJ protein claudin‐7. More basally, p120ctn and β‐catenin become colocalized. This topography was lost in isogenic Ras‐transformed MDCK cells and cancerous PC3 cells, where p120ctn becomes basally localized in relation to β‐catenin. Claudin‐7 gene conditional knockout (cKO) in mice also have altered polarity of p120ctn relative to β‐catenin, like that seen in normal‐to‐cancer cell phenotypic transformation. Additionally, claudin‐7 cKO resulted in redistribution and relocalization of other cell junction proteins, including claudin‐1, zonula occludens‐1, integrin α2, epithelial cell adhesion molecule, and focal adhesion kinase (FAK); specifically, integrin α2 and FAK were observed at the apical–lateral compartment. Our data show that STORM reveals regional cellular junction nanoarchitecture previously uncharacterized, providing new insight into potential trans‐compartmental modulation of protein functions.