Identification of the nasal mucosa as a new target for leptin action

Evaluating the Association of Obesity and Chronic Rhinosinusitis: A Systematic Review and Meta-analysis

OBJECTIVE

The aim of this Meta-analysis and systematic review was to perform a comprehensive assessment of the association of chronic rhinosinusitis (CRS) with overweight/obesity, leptin hormone, and its associated metabolic dysregulation.

DATA SOURCES

Ovid MEDLINE, Embase, Web of Science, and Cochrane Central Register of Controlled Trials, were searched for studies from 1946 to October 2022, using predefined syntax.

REVIEW METHODS

Outcome data for the meta-analysis were extracted on odds ratios (OR) of CRS prevalence based on the presence of overweight/obesity and mean serum leptin levels. A Meta-analysis was performed using the DerSimonian-Laird estimator to pool extracted data by the generalized inverse variance approach. Random effect models were utilized due to the small sample size. A qualitative synthesis was performed on articles that did not meet the inclusion criteria for the Meta-analysis.

RESULTS

Thirty-six studies met the systematic review inclusion criteria out of 1113 articles screened. A total of 6 studies were included in the pooled Meta-analysis of the various outcome variables. Our pooled meta-analysis observed a positive association between overweight/obesity and the prevalence of CRS (OR = 1.33, 95% confidence interval [CI]: 1.17-1.51). The pooled ratio of the means analysis of the mean serum leptin levels between CRS with nasal polyposis and control patients was 2.21 (95% CI: 1.45; 3.36).

CONCLUSION

Our pooled Meta-analysis indicates a positive association between overweight/obesity and CRS. Future prospective studies are needed to explore the association between CRS and obesity with an understanding of potential confounding comorbidities, including studies focused on assessing the underlying immunologic mechanism of this association.

Nose-to-brain delivery of nanotherapeutics: Transport mechanisms and applications

The blood-brain barrier presents a key limitation to the administration of therapeutic molecules for the treatment of brain disease. While drugs administered orally or intravenously must cross this barrier to reach brain targets, the unique anatomical structure of the olfactory system provides a route to deliver drugs directly to the brain. Entering the brain via receptor, carrier, and adsorption-mediated transcytosis in the nasal olfactory and trigeminal regions has the potential to increase drug delivery. In this review, we introduce the physiological and anatomical structures of the nasal cavity, and summarize the possible modes of transport and the relevant receptors and carriers in the nose-to-brain pathway. Additionally, we provide examples of nanotherapeutics developed for intranasal drug delivery to the brain. Further development of nanoparticles that can be applied to intranasal delivery systems promises to improve drug efficacy and reduce drug resistance and adverse effects by increasing molecular access to the brain. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Notch-1 decreased expression contributes to leptin receptor downregulation in nasal epithelium from allergic turbinates

BACKGROUND

Allergic rhinitis is characterized by a remodeling of nasal epithelium. Since the Notch and TGF-β signaling pathways are known to be involved in cell differentiation and remodeling processes and leptin adipokine has already been identified as a marker for homeostasis in human bronchial and nasal epithelial cells of asthmatics, roles played by these pathways have been investigated for chronic allergic rhinitis.

METHODS

The leptin/leptin receptor expression has been investigated in a study with 40 biopsies from allergic (AR, n = 18) and non-allergic (C, n = 22) inferior turbinates, using immunohistochemistry, immunofluorescence staining and RT-PCR. In addition, extracts from in vitro samples prepared from primary cells of inferior turbinates as well as in vitro cultured human nasal epithelial RPMI 2650 cells (ATCC-CCL-30) were also tested for leptin expression and activation of the Notch-1 pathway.

RESULTS

With regards to AR, in vivo expression levels of both leptin and its receptor significantly decreased in comparison to C. Furthermore, leptin receptor mRNA was significantly reduced in AR as compared to C. Immunofluorescence showed an apparent co-expression of leptin receptor with Notch-1, which was not seen with TGF-β. In vitro, in primary turbinate epithelial cells, the expression of leptin receptor and Notch-1 significantly decreased in AR as compared to C. Moreover, in RPMI 2650 cells, leptin receptor expression was shown to be induced by Notch-1 ligand signaling.

CONCLUSION

Thus, both the leptin and Notch-1 pathways appear to represent markers for epithelial homeostasis in allergic rhinitis.

Intranasal delivery of N-terminal modified leptin-pluronic conjugate for treatment of obesity

Leptin is an adipocyte-secreted hormone that is delivered via a specific transport system across the blood-brain barrier (BBB) to the brain where it acts on the hypothalamus receptors to control appetite and thermogenesis. Peripheral resistance to leptin due to its impaired brain delivery prevents therapeutic use of leptin in overweight and moderately obese patients. To address this problem, we modified the N-terminal amine of leptin with Pluronic P85 (LepNP85) and administered this conjugate intranasally using the nose-to-brain (INB) route to bypass the BBB. We compared this conjugate with the native leptin, the N-terminal leptin conjugate with poly(ethylene glycol) (LepNPEG5K), and two conjugates of leptin with Pluronic P85 attached randomly to the lysine amino groups of the hormone. Compared to the random conjugates of leptin with P85, LepNP85 has shown higher affinity upon binding with the leptin receptor, and similarly to native hormone activated hypothalamus receptors after direct injection into brain. After INB delivery, LepNP85 conjugate was transported to the brain and accumulated in the hypothalamus and hippocampus to a greater extent than the native leptin and LepNPEG5K and activated leptin receptors in hypothalamus at lower dose than native leptin. Our work suggests that LepNP85 can access the brain directly after INB delivery and confirms our hypothesis that the improvement in brain accumulation of this conjugate is due to its enhanced brain absorption. In conclusion, the LepNP85 with optimized conjugation chemistry is a promising candidate for treatment of obesity.

Fluticasone furoate maintains epithelial homeostasis via leptin/leptin receptor pathway in nasal cells

Leptin is involved in the lung epithelial homeostasis. Its role in the nasal tract is largely unknown. Allergic rhinitis (AR) is induced by the allergen exposure leading to consequential structural abnormalities in the nasal epithelium. Topical corticosteroids are recommended as first-line therapy in AR. Parietaria pollen is one of the most important allergenic sources in the southern Europe. In vitro, in human nasal epithelial cell line RPMI 2650, we aimed to determine whether allergen stimulation acts on leptin/leptin receptor pathway and how fluticasone furoate (FF) influences this pathway. The effects of the major allergen recombinant Par j 1 (rPar j 1), of FF, of leptin, and of TGF-β1 on cell proliferation, on leptin/leptin receptor expression and modulation (by clonogenic test, by RT-q-RT-PCR, by immunocytochemistry and by flow-cytometry), and on STAT-3 activation (assessing nuclear translocation by western blot analysis) were assessed. We found that rPar j 1 and TGF-β1 significantly decreased cell proliferation and down-regulated the leptin/leptin receptor pathway, whereas FF and leptin reverted them, both alone and in combination. Furthermore, rPar j 1 reduced, while leptin and FF increased STAT-3 activation. In conclusion, FF and leptin itself are able to preserve nasal epithelial homeostasis restoring the leptin/leptin receptor pathway altered by rPar j 1 exposure.