CNS melanocortin and leptin effects on stearoyl-CoA desaturase-1 and resistin expression

The objective of this study was to determine whether centrally administered leptin decreased liver and adipose SCD1 expression or adipose resistin expression, and whether these effects were mediated by central melanocortin receptors. Male Sprague-Dawley rats were injected into the lateral cerebral ventricle (i.c.v.) once daily for 4 days with artificial cerebrospinal fluid (aCSF, 5 microl), leptin (10 microg) or MTII (0.1 nmol); two other groups were pretreated icv with the melanocortin antagonist, SHU9119 (1.0 nmol), followed by leptin or MTII. Epididymal and inguinal adipose tissue and liver were collected after rats were killed and mRNA expression of SCD1 and resistin was measured. Both leptin and MTII reduced SCD1 expression and pretreatment with SHU9119 reversed their effects. Neither leptin nor MTII affected resistin expression, but it was increased by SHU9119. These results show that CNS melanocortin receptors are likely mediators of leptin's effects on SCD1 expression in liver and adipose tissue, The findings were inconclusive concerning the effects of leptin and melanocortins on adipose resistin expression.     

Lipopolysaccharide increases resistin gene expression in vivo and in vitro

Although resistin has been thought to be an important link between obesity and diabetes, recent results do not support this hypothesis. We speculated that resistin may be involved in inflammatory processes and be induced by inflammatory stimuli. In this study, we tested whether lipopolysaccharide (LPS) induced resistin expression in rats. The results show that resistin mRNA levels in white adipose tissue and white blood cells were increased by LPS treatment. LPS also increased resistin mRNA levels in 3T3-L1 adipocytes and human peripheral blood monocytes. The results suggest that resistin is involved in insulin resistance and probably in other inflammatory responses.     

Effect of metformin on adipose tissue resistin expression in db/db mice

Resistin, a novel adipose-derived protein, has been proposed to cause insulin-resistant states in obesity. To evaluate whether an insulin-sensitizing drug, metformin, regulates adipose tissue resistin expression, murine models of obesity and diabetes, db/db mice, were treated with metformin (metformin group), insulin (insulin group), and vehicle (control group) for 4 weeks, followed by analyzing resistin protein expression in their adipose tissues. Unexpectedly, resistin protein expression was increased by 66% in the metformin group relative to the control group, while it did not differ between the insulin and control groups. Hyperinsulinemia was improved in the metformin group, while the insulin group exhibited severe hyperinsulinemia, similar to the control group. Furthermore, in comparison between obese mice (db/db mice) and age-matched lean controls, resistin protein expression was reduced by 58% in the obese mice with severe hyperinsulinemia. These data collectively suggest that resistin expression may be suppressed by hyperinsulinemia and that metformin may upregulate resistin expression via the improvement of hyperinsulinemia in obesity.     

Identification of RELMgamma,a novel resistin-like molecule with a distinct expression pattern

We have identified RELMgamma, a novel member of the resistin-like molecule/found in inflammatory zone (RELM/FIZZ) family in mice and rats. Microarray and real-time RT-PCR experiments revealed a repression of RELMgamma mRNA in nasal respiratory epithelium of cigarette smoke-exposed versus untreated rats. The analysis of the physiological tissue-specific expression revealed highest expression in hematopoietic tissues, suggesting a cytokine-like role for RELMgamma. RELMgamma is most closely related to RELMalpha/FIZZ1. Despite the high similarity, the expression properties of the two genes are clearly distinct. While RELMgamma (approved symbol retnlg) is expressed in rat white adipose tissue, minute to no expression of RELMalpha was detected in that system. Thus, previous reports analyzing RELMalpha expression in rat adipose tissue might have been influenced by cross-hybridization with RELMgamma. Finally we could demonstrate that white adipose tissue of mice shows strong RELMalpha expression but only low levels of RELMgamma, indicating a species-specific gene regulation.     

Saliva proteome profiling reveals potential salivary biomarkers for detection of oral cavity squamous cell carcinoma

Oral cavity squamous cell carcinoma (OSCC), which is frequently associated with poor prognosis and mortality, is a leading cause of cancer‐related death worldwide. Discovery of body fluid accessible biomarkers is needed to improve OSCC screening. To this end, we profiled proteomes of saliva from the healthy volunteers, the individuals with oral potentially malignant disorders (OPMD), and the OSCC patients by means of SDS‐PAGE coupled with LC‐MS/MS. In the control, the OPMD, and the OSCC groups, 958, 845, and 1030 salivary proteins were detected, respectively. With spectral counting‐based label‐free quantification, 22 overexpressed salivary proteins were identified in the OSCC group compared with the healthy controls and the OPMD individuals. Among them, resistin (RETN) was subjected to further validation with an independent cohort using ELISA. The data confirmed that the salivary RETN levels in the OSCC patients were significantly higher than that in the healthy or in the OPMD group. Moreover, the elevated levels of salivary RETN were highly correlated with late‐stage primary tumors, advanced overall stage, and lymph‐node metastasis. Our results not only reveal that profiling of saliva proteome is feasible for discovery of OSCC biomarkers, but also identify RETN as a potential salivary biomarker for OSCC detection.     

Increased resistin may suppress reactive oxygen species production and inflammasome activation in type 2 diabetic patients with pulmonary tuberculosis infection

Although it has been known for decades that patients with type 2 diabetes mellitus (DM) are more susceptible to severe tuberculosis (TB) infection, the underlying immunological mechanisms remain unclear. Resistin, a protein produced by immune cells in humans, causes insulin resistance and has been implicated in inhibiting reactive oxygen species (ROS) production in leukocytes. Recent studies suggested that IL-1β production in patients with Mycobacteria tuberculosis infection correlates with inflammasome activation which may be regulated by ROS production in the immune cells. By investigating the level of resistin in different patient groups, we found that serum resistin levels were significantly higher in severe TB and DM-only groups when compared with mild TB cases and healthy controls. Moreover, elevation of serum resistin correlated with impairment of ROS production of neutrophils in patients with both DM and TB. In human macrophages, exogenous resistin inhibits the production of ROS which are important in the mycobacterium-induced inflammasome activation. Moreover, macrophages with defective ROS production had poor IL-1β production and ineffective control of mycobacteria growth. Our results suggest that increased resistin in severe TB and DM patients may suppress the mycobacterium-induced inflammasome activation through inhibiting ROS production by leukocytes.     

Serum resistin in older patients with hip fracture: Relationship with comorbidity and biochemical determinants of bone metabolism

Objectives

To determine the relationship of serum resistin concentrations to biochemical determinants of bone metabolism, comorbidity and outcomes in patients with hip fracture (HF).

Methods

In 256 consecutive patients (mean age 81.9 ± 7.8 years; 71.1% women) serum levels of resistin (determined by ELISA), biochemical parameters of bone turnover and mineral metabolism as well as routine haematological and biochemical parameters were measured. Clinical data were recorded prospectively.

Results

In multivariate analysis cervical HF (OR = 1.81; 95% CI 1.05–3.11), diabetes (OR = 2.60; 95% CI 1.23–5.51) and history of stroke (OR = 2.67; 95% CI 1.17–6.13) were significant independent predictors of higher resistin levels (?16.26 ng/ml, median value). The independent correlates of serum resistin levels in patients with cervical HF were serum osteocalcin and magnesium (both negatively associated) and in patients with trochanteric HF, serum PTH, calcium and age (all positively associated). Resistin and glomerular filtration rate were the only independent (inverse) predictors of serum osteocalcin. Resistin levels on admission did not predict short-term outcomes.

Conclusions

In older patients with HF there is a significant association of higher resistin levels with cervical fracture, type 2 diabetes and history of stroke, which is partly influenced by the reciprocal interaction between resistin and osteocalcin. However, the design of the study does not prove causality and further prospective studies are needed to clarify these relationships.