Blockade of the colony-stimulating factor-1 receptor reverses bone loss in osteoporosis mouse models.

BACKGROUND: Mice lacking either colony-stimulating factor-1 (CSF-1) or its receptor, CSF-1R, display osteopetrosis. Accordingly, genetic deletion or pharmacological blockade of CSF-1 prevents the bone loss associated with estrogen deficiency. However, the role of CSF-1R in osteoporosis models of type-1 diabetes (T1D) and ovariectomy (OVX) has not been examined. Thus, we evaluated whether CSF-1R blockade would relieve the bone loss in a model of primary osteoporosis (female mice with OVX) and a model of secondary osteoporosis (female with T1D) using micro-computed tomography. METHODS: Female ICR mice at 10 weeks underwent OVX or received five daily administrations of streptozotocin (ip, 50 mg/kg) to induce T1D. Four weeks after OVX and 14 weeks after first injection of streptozotocin, mice received an anti-CSF-1R (2G2) antibody (10 mg/kg, ip; once/week for 6 weeks) or vehicle. At the last day of antibody administration, mice were sacrificed and femur and tibia were harvested for micro-computed tomography analysis. RESULTS: Mice with OVX had a significant loss of trabecular bone at the distal femoral and proximal tibial metaphysis. Chronic treatment with anti-CSF-1R significantly reversed the trabecular bone loss at these anatomical sites. Streptozotocin-induced T1D resulted in significant loss of trabecular bone at the femoral neck and cortical bone at the femoral mid-diaphysis. Chronic treatment with anti-CSF-1R antibody significantly reversed the bone loss observed in mice with T1D. CONCLUSION: Our results demonstrate that blockade of CSF-1R signaling reverses bone loss in two different mouse models of osteoporosis.

Chronic administration of Cl-amidine, a pan-peptidylarginine deiminase inhibitor, does not reverse bone loss in two different murine models of osteoporosis.

Recent in vitro studies have shown a role for the peptidyl-arginine deiminases (PADs) in bone resorption. However, it is unknown whether these enzymes are involved in bone loss in vivo. Thus, we evaluated the antiresorptive effect of a pan-PAD inhibitor in two murine models of osteoporosis: (a) primary osteoporosis induced by ovariectomy (OVX); and (b) secondary osteoporosis associated to Type-1 diabetes induced by streptozotocin (STZ, 50 mg/kg, i.p., five daily administrations). Five weeks after OVX and 15 weeks after injections of STZ, mice received daily administrations of Cl-amidine (3 or 10 mg/kg, i.p.) or vehicle for 30 consecutive days. At the end of the treatment, femur and vertebra were harvested for microCT analysis. Blood samples were collected for determination of antibodies against cyclic citrullinated peptides (anti-CCP) by enzyme-linked immunosorbent assay. Serum levels of anti-CCP antibodies from diabetic mice were not significantly different compared to control mice. However, a significant loss of both trabecular bone at the femoral neck and cortical bone at the femoral diaphysis was found in diabetic mice, and Cl-amidine did not reverse the diabetes-induced bone loss. Mice with OVX had significantly lower serum levels of anti-CCP compared to mice with sham surgery. OVX resulted in significant loss of both trabecular bone at the L5 vertebra and distal femoral metaphysis. Cl-amidine did not block the OVX-induced bone loss. Our results suggest that chronic treatment with Cl-amidine at the doses and period of time administered is not long enough to inhibit bone loss in two different murine models of osteoporosis.

Streptozocin-induced type-1 diabetes mellitus results in decreased density of CGRP sensory and TH sympathetic nerve fibers that are positively correlated with bone loss at the mouse femoral neck.

Type-1 diabetes mellitus (T1DM) results in loss of innervation in some tissues including epidermis and retina; however, the effect on bone innervation is unknown. Likewise, T1DM results in pathological bone loss and increased risk of fracture. Thus, we quantified the density of calcitonin gene-related peptide (CGRP+) sensory and tyrosine hydroxylase (TH+) sympathetic nerve fibers and determined the association between the innervation density and microarchitecture of trabecular bone at the mouse femoral neck. Ten weeks-old female mice received 5 daily administrations of streptozocin (i.p. 50mg/kg) or citrate (control group). Twenty weeks later, femurs were analyzed by microCT and processed for immunohistochemistry. Confocal microscopy analysis revealed that mice with T1DM had a significant loss of both CGRP+ and TH+ nerve fibers in the bone marrow at the femoral neck. Likewise, microCT analysis revealed a significant decrease in the trabecular bone mineral density (tBMD), bone volume/total volume ratio (BV/TB), trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular separation (Tb.Sp) in mice with T1DM as compared to control mice. Analysis of correlation revealed a positive and significant association between density of CGRP+ or TH+ nerve fibers with tBMD, BV/TV, Tb.Th and Tb.Sp, but not with trabecular number (there was a positive association only for CGRP+) and degree of anisotropy (DA). This study suggests an interaction between sensory and sympathetic nervous system and T1DM-induced bone loss. Identification of the factors involved in the loss of CGRP+ sensory and TH+ sympathetic fibers and how they regulate bone loss may result in new avenues to treat T1DM-related osteoporosis.

High-fat diet exacerbates pain-like behaviors and periarticular bone loss in mice with CFA-induced knee arthritis.

OBJECTIVE: Our aim was to quantify nociceptive spontaneous behaviors, knee edema, proinflammatory cytokines, bone density, and microarchitecture in high-fat diet (HFD)-fed mice with unilateral knee arthritis. METHODS: ICR male mice were fed either standard diet (SD) or HFD starting at 3 weeks old. At 17 weeks, HFD and SD mice received intra-articular injections either with Complete Freund's Adjuvant (CFA) or saline into the right knee joint every 7 days for 4 weeks. Spontaneous pain-like behaviors and knee edema were assessed for 26 days. At day 26 post-first CFA injection, serum levels of IL-1ß, IL-6, and RANKL were measured by ELISA, and microcomputed tomography analysis of knee joints was performed. RESULTS: HFD-fed mice injected with CFA showed greater spontaneous pain-like behaviors of the affected extremity as well as a decrease in the weight-bearing index compared to SD-fed mice injected with CFA. Knee edema was not significantly different between diets. HFD significantly exacerbated arthritis-induced bone loss at the distal femoral metaphysis but had no effect on femoral diaphyseal cortical bone. HFD did not modify serum levels of proinflammatory cytokines. CONCLUSIONS: HFD exacerbates pain-like behaviors and significantly increases the magnitude of periarticular trabecular bone loss in a murine model of unilateral arthritis.

Chronic oral or intraarticular administration of docosahexaenoic acid reduces nociception and knee edema and improves functional outcomes in a mouse model of Complete Freund's Adjuvant-induced knee arthritis.

INTRODUCTION: Clinical and preclinical studies have shown that supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs) reduce joint destruction and inflammation present in rheumatoid arthritis (RA). However, the effects of individual ω-3 PUFAs on chronic arthritic pain have not been evaluated to date. Thus, our aim in this study was to examine whether purified docosahexaenoic acid (DHA, an ω-3 PUFA) reduces spontaneous pain-related behavior and knee edema and improves functional outcomes in a mouse model of knee arthritis. METHODS: Unilateral arthritis was induced by multiple injections of Complete Freund's Adjuvant (CFA) into the right knee joints of male ICR adult mice. Mice that received CFA injections were then chronically treated from day 15 until day 25 post-initial CFA injection with oral DHA (10, 30 and 100 mg/kg daily) or intraarticular DHA (25 and 50 µg/joint twice weekly). Spontaneous flinching of the injected extremity (considered as spontaneous pain-related behavior), vertical rearing and horizontal exploratory activity (considered as functional outcomes) and knee edema were assessed. To determine whether an endogenous opioid mechanism was involved in the therapeutic effect of DHA, naloxone (NLX, an opioid receptor antagonist, 3 mg/kg subcutaneously) was administered in arthritic mice chronically treated with DHA (30 mg/kg by mouth) at day 25 post-CFA injection. RESULTS: The intraarticular CFA injections resulted in increasing spontaneous flinching and knee edema of the ipsilateral extremity as well as worsening functional outcomes as time progressed. Chronic administration of DHA, given either orally or intraarticularly, significantly improved horizontal exploratory activity and reduced flinching behavior and knee edema in a dose-dependent manner. Administration of NLX did not reverse the antinociceptive effect of DHA. CONCLUSIONS: To the best of our knowledge, this report is the first to demonstrate DHA's antinociceptive and anti-inflammatory effects as individual ω-3 PUFAs following sustained systemic and intraarticular administration in a mouse model of CFA-induced knee arthritis. The results suggest that DHA treatment may offer a new therapeutic approach to alleviate inflammation as well as a beneficial effect on pain-related functional disabilities in RA patients.

Association of a serotonin transporter gene (SLC6A4) 5-HTTLPR polymorphism with body mass index categories but not type 2 diabetes mellitus in Mexicans.

The serotonergic system has been hypothesized to contribute to the biological susceptibility to type 2 diabetes mellitus (T2DM) and body-mass index (BMI) categories. We investigate a possible association of 5-HTTLPR polymorphism (L and S alleles) in the promoter region of the serotonin transporter gene (SLC6A4) with the development of T2DM and/or higher BMI by analyzing a sample of 138 individuals diagnosed with T2DM and 172 unrelated controls from the Mexican general population. In the total sample genotypes were distributed according to Hardy-Weinberg equilibrium, and S allele frequency was 0.58. There was no statistical association between 5-HTTLPR polymorphism and the development of T2DM in this Mexican population sample (p = 0.12). Nevertheless, logistic regression analysis of the L allele and increased BMI disclosed an association, after adjusting for age, sex and T2DM (p = 0.02, OR 1.74, 95% CI: 1.079-2.808).

Clinical depressive symptoms and diabetes in a binational border population.

BACKGROUND: Depression affects more Hispanics with type 2 diabetes than other ethnic groups. This exploratory, binational study examined the prevalence and correlates of clinical depressive symptoms in Hispanics of Mexican origin with type 2 diabetes living on both sides of the Texas Mexico border. METHODS: Two binational samples, consisting of 172 adult patients of Mexican origin with type 2 diabetes in South Texas and 200 from the Northeastern region of Mexico, were compared. Logistic regression analyses were used to test personal and social correlates to clinical depressive symptoms. RESULTS: The rate of clinical depressive symptoms was similar in both South Texas and Northeastern Mexico patients (39% and 40.5%, respectively). Gender, education, emergency department visits, and burden of diabetes symptoms were predictors of clinical depressive symptoms in the South Texas sample. Among respondents in the Northeastern Mexico sample, the only statistically significant correlate to clinical depressive symptoms was the burden of diabetes symptoms. CONCLUSIONS: Diabetes and depression must be addressed as priorities in diabetes initiatives at the US Mexico border region. Further research is warranted to examine the extent and impact of involving family practice physicians from both sides of the border in depression screenings among patients with type 2 diabetes.

Prevalence of Brucella abortus antibodies in equines of a tropical region of Mexico.

A cross-sectional study was conducted to determinate the seroprevalence rate of equine brucellosis in the state of Tamaulipas, Mexico. Serum samples from 420 equines were analyzed with the Rose Bengal test at cell concentrations of 3% (RBT-3%) and 8% (RBT-8%), and positive results were confirmed with the Rivanol test (RT). Risk factors were determined with the prevalence ratio (PR) and the use of variables generated from a questionnaire administered to the animals' owners. Serum from 1 stallion had positive results with both the RBT-8% and the RT, for a seroprevalence rate of 0.238%. Drinking of water from a pond that was also used by cattle and dogs was the only associated risk factor for this animal (PR = 0.25). However, the results were considered false-positive, because the results for other horses in the same environmental conditions were negative. Although brucellosis is considered endemic in ruminants in the study area, the results obtained suggest that equines are not a reservoir of brucellosis and do not play an important role in the epidemiologic patterns of this disease in northeastern Mexico.