Quantifying the association of radiographic osteoarthritis in knee or hip joints with other knees or hips: the Johnston County Osteoarthritis Project.

OBJECTIVE: To quantify the association of radiographic osteoarthritis (ROA) in one knee or hip joint with other knee or hip joints. METHODS: We analyzed baseline data from the Johnston County Osteoarthritis Project (n = 3068). We fit 4 models for left/right knee/hip. The Kellgren-Lawrence (KL) radiographic grade severity scale was KL 0/1 (no/questionable ROA), 2 (mild ROA), or 3/4 (moderate/severe ROA). We estimated associations between KL grade in contralateral joints and other joint sites (e.g., worst hip in knee models), adjusting for sex, race/ethnicity (African American/white), age, and measured body mass index, using cumulative odds logistic regression models. Interactions were investigated: race/ethnicity by sex; race/ethnicity and sex by the 2 explanatory variables. RESULTS: Contralateral joint KL grade was strongly associated with KL grade, with OR ranging from 9.2 (95% CI 7.1, 11.9) to 225.0 (95% CI 83.6, 605.7). In the left knee model, the contralateral joint association was stronger among African Americans than whites, but for the other models the associations by race/ethnicity were identical. Models examining other joint sites showed weaker but mostly statistically significant associations (OR 1.4 to 1.8). CONCLUSION: We found a strong multivariable-adjusted association between KL grades in contralateral knees and hips, and a modest association with the other joint site (e.g., knees vs hips). These results suggest that diagnosis of ROA in 1 large joint may be a marker for risk of multijoint ROA, and warrant interventions to reduce the incidence or severity of ROA at these other joints.

Induction of follistatin precedes gastric transformation in gastrin deficient mice.

We previously showed that antral gastric tumors develop in gastrin-deficient (Gas(-/-)) mice. Therefore Gas(-/-) mice were studied sequentially over 12 months to identify molecular mechanisms underlying gastric transformation. Fundic atrophy developed by 9 months in Gas(-/-) mice. Antral mucosal hyperplasia developed coincident with the focal loss of TFF1 and Muc5AC. Microarray analysis of 12 month Gas(-/-) tumors revealed an increase in follistatin, an activin/BMP antagonist. We found that elevated follistatin expression occurred in the proliferative neck zone of hyperplastic antrums, in antral tumors of Gas(-/-) mice, and also in human gastric cancers. Follistatin induced cyclin D1 and the trefoil factors TFF1 and TFF2 in a gastric cancer cell line. We concluded that antral hyperplasia in Gas(-/-) mice involves amplification of mucous cell lineages due to follistatin, suggesting its role in the development of antral gastric tumors.

Induction of DMBT1 expression by reduced ERK activity during a gastric mucosa differentiation-like process and its association with human gastric cancer.

Abnormalities in the expression of DMBT1 (deleted in malignant brain tumors 1) have been implicated in the development of esophageal, gastric and colorectal cancers of the alimentary tract, but the underlying mechanism remains unclear. In the present study, using the gastric cell line AGS, we identified two intracellular signaling molecules protein kinase C (PKC) and extracellular signal-related kinase (ERK). They mediated both the phorbol myristate acetate (PMA) downregulation of DMBT1 expression and the initiation of cell differentiation, which was measured by cell cycle withdrawal and the induction of the tissue-specific marker trefoil factor 1 (TFF1). A time-course study showed that following the PMA activation of ERK kinase, the induction of TFF1 and the reduction of DMBT1 were detected at the same time point. We then demonstrated a minimal level of DMBT1 in proliferating AGS cells seeded at low density, where ERK activity was high. Reduction of ERK activity, either by an ERK inhibitor PD98059 or by high-density seeding, significantly reduced AGS cell growth judged by CFSE labeling. This cellular effect was elicited by cyclin D/p21 (Cip/Waf1) and G(0)/G(1) arrest, and was accompanied by a marked increase in DMBT1-expressing cells. Finally, we showed that siRNA directed against DMBT1 had no effect on the induction of a cell growth arrest marker, gut-enriched Kruppel-like factor (GKLF), but reduced the PMA induction of TFF1. Along with its upregulation coinciding with G(0)/G(1) arrest, and its attenuation in differentiated cells, these results suggest that the transient induction of DMBT1 is apparently specific at an early stage of gastric epithelial differentiation-like process, when it may play a role in cell fate decision. Consistent with such a potential function, we detected frequent abnormalities of the DMBT1 expression in the specimens of human gastric adenocarcinoma.

Interferon gamma induction of gastric mucous neck cell hypertrophy.

Chronic inflammation of the gastric epithelium is believed to induce mucosal changes that can eventually develop into gastric cancer. In gastrin-deficient (G-/-) mice exhibiting chronic inflammation in the hypochlorhydric stomach, we documented a prominent fundic mucous cell lineage sharing morphological similarity with preneoplastic changes reported in Helicobacter-infected mice. To study the identity and origin of this cell lineage, we screened for different gastric mucosal cell markers. The clusters of large, foamy cells stained for trefoil factor 2 (TFF2/SP), MUC6 and the lectin Griffonia Simplicifolia II (GSII), but not for the intestine-specific transcription factor Cdx2, suggested that they arise from gastric mucous neck cells. Ki67-labeled GSII-positive neck cells in Helicobacter felis-infected, but not G-/- stomachs, suggested that mucous neck cell proliferation accounted for expansion of this compartment in the H. felis model of gastritis, but not the G-/- model. Using RNase protection assays and quantitative PCR, we found that interferon gamma (IFNgamma) was the most abundant proinflammatory cytokine in the G-/- stomach. We also found that this Th1 cytokine can increase the abundance of mucous neck cells, since its infusion into mice recapitulated the appearance of these cells as observed in both G-/- and H. felis-infected mice. Using the human gastric cell line NCI-N87, we showed that IFNgamma induces the secretion of mucus and expression of MUC6, TFF2 and pepsinogen II, but not of pepsinogen I and intrinsic factor. In conclusion, our results demonstrate that inflammation, specifically the proinflammatory cytokine IFNgamma, induced expansion of the fundic mucous neck cell compartment, which likely represents both increased mucus production and cell number.

Chronic gastritis in the hypochlorhydric gastrin-deficient mouse progresses to adenocarcinoma.

The current study tests the hypothesis that chronic atrophic gastritis from hypochlorhydria in the gastrin-deficient mouse predisposes the stomach to gastric cancer. Gross morphology and histology of 12-month-old wild-type (WT), gastrin-deficient (G-/-) and somatostatin-deficient (SOM-/-) mice were examined. Parietal and G cells, Ki67, TUNEL, villin and MUC2 expression were analysed by immunohistochemistry. RUNX3 and STAT3 expression was analysed by Western blot. Anchorage-independent growth was determined by cell cluster formation in soft agar. Compared to the WT and SOM-/- mice, hypochlorhydric G-/- mice developed parietal cell atrophy, significant antral inflammation and intestinal metaplasia. Areas of metaplasia within the G-/- mouse stomach showed decreased RUNX3 expression with elevated MUC2 and villin expression. Cells isolated from the tumor grew in soft agar. However, the cells isolated from WT, nontransformed G-/- and SOM-/- gastric tissue did not form colonies in soft agar. Consistent with elevated antral proliferation, tumor tissue isolated from the G-/- mice showed elevated phosphorylated STAT3 expression. We then examined the mechanism by which STAT3 was constitutively expressed in the tumor tissue of the G-/- mice. We found that IFNgamma expression was also significantly higher in the tumor tissue of G-/- mice compared to WT and SOM-/- animals. To determine whether STAT3 was regulated by IFNgamma, MKN45 cells were cocultured with IFNgamma or gastrin. IFNgamma significantly stimulated phosphorylation of STAT3 in the MKN45 cell line, but not gastrin. Therefore, we show here that in the hypochlorhydric mouse stomach, the chronic gastritis, atrophy, metaplasia, dysplasia paradigm can be recapitulated in mice. Moreover, neoplastic transformation of the antral gastric mucosa does not require gastrin.

DMBT1, a regulator of mucosal homeostasis through the linking of mucosal defense and regeneration?

DMBT1 (deleted in malignant brain tumor 1), which encodes a large scavenger receptor cysteine rich (SRCR) B protein, has been proposed to be a tumor suppressor gene, due to the high frequency of its homozygous deletion and the lack of expression in a variety of cancers. However, studies on its physiological functions and its relationship with tumorigenesis are still at an initial stage. Two mucosal defense-related molecules, gp-340 and salivary agglutinin, have been identified to be alternatively spliced products of DMBT1, which suggests that DMBT1 is a pattern recognition receptor in innate immunity. Meanwhile, results from immunohistochemical staining and studies at the cellular level, began to associate DMBT1 with a proliferation to differentiation switching process in gastrointestinal epithelial cells. Together with its up-regulation in inflammation, these findings suggest that DMBT1 might be a local regulator of homeostasis, possibly through linking mucosal inflammation to the modulation of epithelial regeneration, and whose abnormality is a frequent cause of malignancy.