Human leptin enhances activation and proliferation of human circulating T lymphocytes

The Interplay between Obesity and Inflammation

Obesity is an important condition affecting the quality of life of numerous patients and increasing their associated risk for multiple diseases, including tumors and immune-mediated disorders. Inflammation appears to play a major role in the development of obesity and represents a central point for the activity of cellular and humoral components in the adipose tissue. Macrophages play a key role as the main cellular component of the adipose tissue regulating the chronic inflammation and modulating the secretion and differentiation of various pro- and anti-inflammatory cytokines. Inflammation also involves a series of signaling pathways that might represent the focus for new therapies and interventions. Weight loss is essential in decreasing cardiometabolic risks and the degree of associated inflammation; however, the latter can persist for long after the excess weight is lost, and can involve changes in macrophage phenotypes that can ensure the metabolic adjustment. A clear understanding of the pathophysiological processes in the adipose tissue and the interplay between obesity and chronic inflammation can lead to a better understanding of the development of comorbidities and may ensure future targets for the treatment of obesity.

Women With a History of Preeclampsia Exhibit Accelerated Aging and Unfavorable Profiles of Senescence Markers

BACKGROUND

Senescence, a mechanism of cellular aging, which is characterized by irreversible proliferation arrest and a proinflammatory secretory phenotype, has been documented in women with preeclampsia. As cellular senescence can persist and progress, we postulated that it is associated with accelerated aging phenotype and accumulation of comorbidities in women with a history of preeclampsia.

METHODS

We included a cohort of women with a history of preeclampsia (n=40) age- and parity-matched to a group of referent women with normotensive pregnancies (n=40). Women with prior major cardiovascular events, neurological, or autoimmune conditions were excluded. We collected urine and blood samples to study markers of aging, data on multimorbidity at the time of enrollment, and prospectively followed them for events over the course of 6 years, on average.

RESULTS

Women with a history of preeclampsia exhibited unfavorable aging profiles compared with referent women, including decreased urinary α-Klotho (P=0.018); increased leptin (P=0.016) and leptin/adiponectin ratio (P=0.027), and increased extracellular vesicles positive for tissue factor (P=0.025). Women with a history of preeclampsia likewise had a higher rate of comorbidities at the time of enrollment (P=0.003) and had a 4× higher risk of developing major cardiovascular events compared with referent women (P=0.003).

CONCLUSIONS

Our data suggest that a history of preeclampsia is associated with accelerated aging as indicated by senescence marker differences and the accumulation of multimorbidity later in life. Targeting cellular senescence may offer novel, mechanism-based approaches for the diagnosis and treatment of adverse health outcomes in women with a history of preeclampsia.

Calorie restriction-induced leptin reduction and T-lymphocyte activation in blood and adipose tissue in men with overweight and obesity

BACKGROUND

T-Lymphocyte activation is modulated by the adipokine leptin and serum concentrations of this hormone can be reduced with short-term calorie restriction. The aim of this study was to understand whether leptin per se is important in determining levels of T-lymphocyte activation in humans, by investigating whether the reduction in leptin concentration following calorie restriction is associated with a decrease in T-Lymphocyte activation in blood and adipose tissue.

METHODS

Twelve men with overweight and obesity (age 35-55 years, waist circumference 95-115 cm) reduced their calorie intake by 50% for 3 consecutive days. Blood and subcutaneous adipose tissue were obtained for isolation of immune cells and cytokine analysis. CD4+ and CD8 + T-Lymphocytes were identified and characterised according to their expression of activation markers CD25 and CD69 by flow cytometry.

RESULTS

Serum leptin was reduced by (mean ± SEM) 31 ± 16% (p < 0.001) following calorie restriction. The percentage of blood CD4 + CD25 + T-lymphocytes and level of CD25 expression on these lymphocytes were significantly reduced by 8 ± 10% (p = 0.016) and 8 ± 4% (p = 0.058), respectively. After calorie restriction, ex vivo leptin secretion from abdominal subcutaneous adipose tissue explants was not changed, and this corresponded with a lack of change in adipose tissue resident T-Lymphocyte activation.

CONCLUSIONS

Serum leptin was reduced after calorie restriction and this was temporally associated with a reduction in activation of blood CD4 + CD25 + T-Lymphocytes. In abdominal subcutaneous adipose tissue, however, leptin secretion was unaltered, and there were no observed changes in adipose resident T-Lymphocyte activation.

The effect of leptin gene polymorphisms (LEP rs7799039 and LEPR rs1137101) on febrile neutropenia

Background and aim

Leptin is mainly produced in adipose tissue and released into systemic circulation. Leptin and its receptor LEPR activate the Janus kinase/signal transducers and activators of transcription signaling cascade and increase cytokine discharge. In our study, we aimed to examine the role of leptin gene (LEP) rs7799039 and LEPR rs1137101 polymorphisms on the susceptibility for febrile neutropenia (FEN) attacks and their relationship with clinical findings during the course of FEN.

Methods

This study included pediatric patients with a diagnosis of malignancy who applied to the pediatric emergency department between December 2019 and June 2022 and healthy controls. The genotypes of the LEP rs7799039 and LEPR rs1137101 genes were statistically compared between patients and healthy controls. In addition, the relationship between the genotype distribution of LEP rs7799039 and LEPR rs1137101 polymorphisms and clinical features during the course of FEN was investigated.

Results

In the statistical analysis in terms of LEP rs7799039 and LEPR rs1137101 genotype distributions between the patient and healthy groups, there was no significant difference. Patients with the AA genotype of LEPR rs1137101 polymorphism had significantly more commonly a body mass index (BMI) value of <25, and all the patients with the AG/GG genotype had a BMI value of 25 and above. LEP rs7799039 and LEPR rs1137101 genotype distributions were not statistically significant with other clinical features.

Conclusions

It was revealed that leptin gene polymorphisms did not have a significant effect during the course of FEN.

Putative Molecular Mechanisms Underpinning the Inverse Roles of Mitochondrial Respiration and Heme Function in Lung Cancer and Alzheimer's Disease

Mitochondria are the powerhouse of the cell. Mitochondria serve as the major source of oxidative stress. Impaired mitochondria produce less adenosine triphosphate (ATP) but generate more reactive oxygen species (ROS), which could be a major factor in the oxidative imbalance observed in Alzheimer's disease (AD). Well-balanced mitochondrial respiration is important for the proper functioning of cells and human health. Indeed, recent research has shown that elevated mitochondrial respiration underlies the development and therapy resistance of many types of cancer, whereas diminished mitochondrial respiration is linked to the pathogenesis of AD. Mitochondria govern several activities that are known to be changed in lung cancer, the largest cause of cancer-related mortality worldwide. Because of the significant dependence of lung cancer cells on mitochondrial respiration, numerous studies demonstrated that blocking mitochondrial activity is a potent strategy to treat lung cancer. Heme is a central factor in mitochondrial respiration/oxidative phosphorylation (OXPHOS), and its association with cancer is the subject of increased research in recent years. In neural cells, heme is a key component in mitochondrial respiration and the production of ATP. Here, we review the role of impaired heme metabolism in the etiology of AD. We discuss the numerous mitochondrial effects that may contribute to AD and cancer. In addition to emphasizing the significance of heme in the development of both AD and cancer, this review also identifies some possible biological connections between the development of the two diseases. This review explores shared biological mechanisms (Pin1, Wnt, and p53 signaling) in cancer and AD. In cancer, these mechanisms drive cell proliferation and tumorigenic functions, while in AD, they lead to cell death. Understanding these mechanisms may help advance treatments for both conditions. This review discusses precise information regarding common risk factors, such as aging, obesity, diabetes, and tobacco usage.

Emerging mechanisms of obesity-associated immune dysfunction

Obesity is associated with a wide range of complications, including type 2 diabetes mellitus, cardiovascular disease, hypertension and nonalcoholic fatty liver disease. Obesity also increases the incidence and progression of cancers, autoimmunity and infections, as well as lowering vaccine responsiveness. A unifying concept across these differing diseases is dysregulated immunity, particularly inflammation, in response to metabolic overload. Herein, we review emerging mechanisms by which obesity drives inflammation and autoimmunity, as well as impairing tumour immunosurveillance and the response to infections. Among these mechanisms are obesity-associated changes in the hormones that regulate immune cell metabolism and function and drive inflammation. The cargo of extracellular vesicles derived from adipose tissue, which controls cytokine secretion from immune cells, is also dysregulated in obesity, in addition to impairments in fatty acid metabolism related to inflammation. Furthermore, an imbalance exists in obesity in the biosynthesis and levels of polyunsaturated fatty acid-derived oxylipins, which control a range of outcomes related to inflammation, such as immune cell chemotaxis and cytokine production. Finally, there is a need to investigate how obesity influences immunity using innovative model systems that account for the heterogeneous nature of obesity in the human population.

Leptin haploinsufficiency exerts sex-dependent partial protection in SOD1G93A mice by reducing inflammatory pathways in the adipose tissue

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by significant metabolic disruptions, including weight loss and hypermetabolism in both patients and animal models. Leptin, an adipose-derived hormone, displays altered levels in ALS. Genetically reducing leptin levels (Lepob/+) to maintain body weight improved motor performance and extended survival in female SOD1G93A mice, although the exact molecular mechanisms behind these effects remain elusive. Here, we corroborated the sexual dimorphism in circulating leptin levels in ALS patients and in SOD1G93A mice. We reproduced a previous strategy to generate a genetically deficient leptin SOD1G93A mice (SOD1G93ALepob/+) and studied the transcriptomic profile in the subcutaneous adipose tissue and the spinal cord. We found that leptin deficiency reduced the inflammation pathways activated by the SOD1G93A mutation in the adipose tissue, but not in the spinal cord. These findings emphasize the importance of considering sex-specific approaches in metabolic therapies and highlight the role of leptin in the systemic modulation of ALS by regulating immune responses outside the central nervous system.

The complex relationship between obesity and neurodegenerative diseases: an updated review

Obesity is a global epidemic, affecting roughly 30% of the world's population and predicted to rise. This disease results from genetic, behavioral, societal, and environmental factors, leading to excessive fat accumulation, due to insufficient energy expenditure. The adipose tissue, once seen as a simple storage depot, is now recognized as a complex organ with various functions, including hormone regulation and modulation of metabolism, inflammation, and homeostasis. Obesity is associated with a low-grade inflammatory state and has been linked to neurodegenerative diseases like multiple sclerosis (MS), Alzheimer's (AD), and Parkinson's (PD). Mechanistically, reduced adipose expandability leads to hypertrophic adipocytes, triggering inflammation, insulin and leptin resistance, blood-brain barrier disruption, altered brain metabolism, neuronal inflammation, brain atrophy, and cognitive decline. Obesity impacts neurodegenerative disorders through shared underlying mechanisms, underscoring its potential as a modifiable risk factor for these diseases. Nevertheless, further research is needed to fully grasp the intricate connections between obesity and neurodegeneration. Collaborative efforts in this field hold promise for innovative strategies to address this complex relationship and develop effective prevention and treatment methods, which also includes specific diets and physical activities, ultimately improving quality of life and health.

Body mass index-dependent immunological profile changes after left ventricular assist device implantation

Purpose

Infection is a common complication following left ventricular assist device (LVAD) implantation. Patients with obesity are particularly at risk due to their high percentage of adipose tissue and the resulting chronic inflammatory state and resulting immunological changes. This study investigated changes of immunological parameters in relation to body mass index (BMI) during the first year after LVAD implantation.

Methods

Blood samples were obtained prior to LVAD implantation and at 3 (1st FU), 6 (2nd FU) and 12 mo (3rd FU) after LVAD implantation. Patients were divided into three groups (normal weight: BMI of 18.5-24.9 kg/m2; n=12; pre-obesity: 25.0-29.9 kg/m2; n=15; obesity: ≥ 30.0 kg/m2; n=17) based on their BMI at the time of LVAD implantation. Flow cytometric analyses for CD4+ and CD8+ T cells, regulatory T cells (Tregs), B cells as well as dendritic cells (DCs) were performed.

Results

After LVAD implantation, obese patients (0.51 ± 0.20%) showed a higher proportion of overall DCs than normal-weight (0.28 ± 0.10%) and pre-obese patients (0.32 ± 0.11%, p<0.01) at 3rd FU. The proportion of BDCA3+ myeloid DCs was lower in obese patients (64.3 ± 26.5%) compared to normal-weight patients (82.7 ± 10.0%, pnormal-weight vs. obesity=0.05) at 2nd FU after LVAD implantation. The analysis of BDCA4+ plasmacytoid DCs revealed a reduced proportion in pre-obese (21.1 ± 9.8%, pnormal-weight vs. pre-obesity=0.01) and obese patients (23.7 ± 10.6%, pnormal-weight vs. obesity=0.05) compared to normal-weight patients (33.1 ± 8.2%) in the 1st FU. T cell analysis showed that CD4+ T cells of obese patients (62.4 ± 9.0%) significantly increased in comparison to pre-obese patients (52.7 ± 10.0%, ppre-obesity vs. obesity=0.05) and CD8+ T cells were lower in obese patients (31.8 ± 8.5%) than in normal-weight patients (42.4 ± 14.2%; pnormal-weight vs. obesity=0.04) at the 3rd FU. Furthermore, we observed significantly reduced proportions of Tregs in pre-obese patients compared to normal-weight and obese patients at 2nd FU (p=0.02) and 3rd FU (p=0.01) after LVAD implantation.

Conclusion

This study reported changes of the innate and adaptive immune system of pre-obese and obese compared to normal-weight patients one year after LVAD implantation. DCs and their subsets, CD8+ T cells and Tregs were affected immune cell populations that indicate immunological changes which might increase the incidence of postoperative infection.

Role of leptin in the pathophysiology of preeclampsia

Preeclampsia (PE) is a severe pregnancy complication. The exact pathogenesis of PE remains unclear, but it is related to immune, inflammatory, circulatory, and oxidative stress factors. Leptin is a protein involved in these processes and is essential for maintaining a normal pregnancy and healthy fetal growth. Abnormal increases in leptin levels have been observed in the peripheral blood and placenta of patients with PE. Disturbances in leptin can affect the proliferation and hypertrophy of vascular smooth muscle cells, which are important for placentation. Leptin also regulates arterial tension and trophoblast function in pregnant women. In addition, consistently high levels of leptin are linked to hyperactive inflammation and oxidative stress reactions in both patients with PE and animal models. This review focuses on the role of leptin in the pathophysiology of PE and elucidates its potential mechanisms.

Relationship between leptin and white blood cells: a potential role in infection susceptibility and severity-the Olivetti Heart Study

A number of evidence showed an emerging role of leptin on immune system, involving inflammation, and innate and adaptive immunity. Few observational studies have evaluated the relationship between leptin and immunity, albeit with low statistical power and methodological differences. Therefore, the aim of this study was to evaluate the potential role of leptin on the immunity, expressed as white blood cells (WBC)-and its subpopulations, by comprehensive multivariate models in a sample of adult men. A cross-sectional evaluation of a general population comprised 939 subjects participating in the Olivetti Heart Study, with available leptin levels and WBC-and its subpopulations. WBC were significantly and positively associated with leptin, C-reactive protein and HOMA index (p < 0.05), but not with age and anthropometric indices (p > 0.05). The multivariate analysis confirmed the association between leptin and WBC, after accounting for main confounders (p < 0.05). Additional analysis on WBC subpopulations showed a positive and significant correlation between leptin and lymphocytes, monocytes and eosinophils (p < 0.05), but not with neutrophils and basophils (p > 0.05). After stratification by body weight, the positive and significant association between leptin and WBC-and its subpopulations-was found in excess body weight participants. The results of this study indicate a direct relationship between leptin levels and WBC-and its subpopulations-in excess body weight participants. These results support the hypothesis that leptin has modulatory functions on immunity and role in the pathophysiology of immune-related diseases, in particular in those associated with excess body weight.

Ghrelin and Leptin Concentrations in Patients after SARS-CoV2 Infection

SARS-CoV2 infection can lead to severe cytokine storm especially in obese patients. Ghrelin acts not only as an appetite regulator but can also play a key role in the immune reaction. Leptin, secreted mainly by the white adipose tissue, can act as a pro-inflammatory cytokine. The crucial question is whether or not the cytokine storm in COVID-19 patients with obesity is linked to adipokine dysregulation. The aim of this study was to assess ghrelin and leptin concentrations in patients 6 months after SARS-CoV2 infection in comparison to a control group considering the influence of sex. The study group included 53 patients with a history of COVID-19 and 87 healthy subjects in the control group. Leptin and ghrelin concentrations as well as hormonal and biochemical parameters were measured. A significantly higher ghrelin concentration was observed in the COVID-19 group in comparison to the control group, with a statistically significant impact of sex on the relationship between COVID-19 and ghrelin concentration, which was lower in the males. No statistically significant differences in leptin concentration were observed between the groups. A significant negative correlation was observed between ghrelin and testosterone and morning cortisol levels in the COVID-19 group. The current study showed that ghrelin levels were significantly higher in patients 6 months after a mild course of SARS-CoV2 infection. To confirm the hypothetical protective role of ghrelin in the inflammatory process, it would be necessary to compare serum ghrelin levels between patients after mild and severe courses of COVID-19. Due to the small sample size and the lack of patients with a severe course of COVID-19, these observations need further investigation. There were no differences in leptin concentrations between the COVID-19 patients and the control group.

Implications of obesity and adiposopathy on respiratory infections; focus on emerging challenges

Obesity is characterized by excessive adipose tissue accumulation, which impacts physiological, metabolic, and immune functions. Several respiratory infections, including bacterial pneumonia, influenza, and coronavirus disease 2019, appear to be linked to unfavorable results in individuals with obesity. These may be attributed to the direct mechanical/physiological effects of excess body fat on the lungs’ function. Notably, adipose tissue dysfunction is associated with a low-grade chronic inflammatory status and hyperleptinemia, among other characteristics. These have all been linked to immune system dysfunction and weakened immune responses to these infections. A better understanding and clinical awareness of these risk factors are necessary for better disease outcomes.

Leptin regulates thymic plasmacytoid dendritic cell ability to influence the thymocyte distribution in vitro

Leptin, the adipocyte-derived hormone, involved in regulating food intake and body weight, plays an important role in immunity and reproduction. Leptin signals via the specific membrane receptors expressed in most types of immune cells including dendritic cells (DCs) and thymocytes. Leptin enhances thymopoiesis and modulates T-cell-mediated immunity. Thymic plasmacytoid DCs (pDCs) are predominated in the thymus. They play an important role in thymocyte differentiation. We have analyzed whether leptin mediates its effects on human thymocytes by influencing on pDCs. We used leptin at concentration corresponding to its level during II-III trimesters of physiological pregnancy. We cultivated leptin-primed pDCs with autologous thymocytes and estimated the main thymocyte subsets expressing αβ chains of the T-cell receptor (αβTCR), natural regulatory T-cells (tTreg), natural T-helpers producing interleukin-17 (nTh17) and invariant natural killer T-cells (iNKT) in vitro. We have shown that leptin augmented CD86, CD276 expressions and depressed IL-10 productions by pDCs. Leptin-primed pDCs decreased the percentage of CD4⁺CD8⁺αβTCR⁺ thymocytes, increased CD4^hiCD8^-/loαβTCR⁺ cells. pDCs cultivated with leptin decreased the number of iNKT precursors, and did not change the number of tTreg and nTh17 precursors. Thus, leptin's important role in regulation of thymic pDC abilities to influence on the thymocyte distribution was indicated in vitro.

Leptin, Adiponectin, and Melatonin Modulate Colostrum Lymphocytes in Mothers with Obesity

Pregnancy complicated by obesity is associated with adverse triggered gestational and neonatal outcomes, with reductions in the subtypes of CD4+ T-lymphocytes representing the modulators of inflammation. It needs to be better established how maternal nutritional statuses impact the neuroendocrine-immune system's action and affect the immunological mechanisms of the maternal-infant relationship via breastfeeding. This study examined the effects of maternal obesity on human colostrum lymphocytes and the intracellular mechanisms of lymphocyte modulation in the presence of leptin, adiponectin, and melatonin via cell proliferation; the release of intracellular calcium; and apoptosis induction. This cross-sectional study analyzed colostrum samples from 52 puerperal splits and divided them into overweight and eutrophic groups. Colostrum lymphocytes underwent immunophenotyping and cell proliferation by flow cytometry and intracellular calcium release and apoptosis assays by immunofluorescence in the presence or absence of hormones. Significant differences were considered when p < 0.05 by the chi-square or t-test. Maternal obesity reduced the population of T-lymphocytes and TCD4+ in human colostrum and proliferative activities (p < 0.05). These hormones restore lymphocyte proliferation to a level similar to the eutrophic group (p < 0.05). Leptin, adiponectin, melatonin hormones, and biological actions consolidated in the scientific literature also represent maternal and infant protection mechanisms via colostrum and the modulation of human colostrum lymphocytes.

Leptin-producing monocytes in the airway submucosa may contribute to asthma pathogenesis

BACKGROUND

Obesity leads to an increase in the incidence and severity of asthma. Adipokines, such as leptin, secreted by adipocytes induce systemic inflammation, causing airway inflammation. We previously reported that leptin activates both inflammatory and structural cells, including lung fibroblasts. However, little is known about the differential leptin expression and responsiveness to leptin in asthmatic individuals and healthy controls (HC). In this study, we investigated the expression and origin of leptin in asthmatic airways. We also compared the effect of leptin on asthmatic and HC fibroblasts.

METHODS

Lung specimens from asthmatic and non-asthmatic patients were analyzed by immunohistochemical staining using anti-leptin and anti-CD163 antibodies. Leptin mRNA and protein levels in human monocytes were detected by real-time PCR and western blotting and ELISA, respectively. We used flow cytometry to analyze asthmatic and HC lung fibroblasts for leptin receptor (Ob-R) expression. Further, we determined cytokine levels using cytometric bead array and ELISA and intracellular phosphorylation of specific signaling molecules using western blotting.

RESULTS

Asthma specimens displayed accumulation of leptin-positive inflammatory cells, which were also positive for CD163, a high-affinity scavenger receptor expressed by monocytes and macrophages. Leptin expression was observed at both transcript and protein levels in human blood-derived monocytes. No significant differences were observed between asthmatic and HC lung fibroblasts in Ob-R expression, cytokine production, and intracellular phosphorylation of p38 mitogen-activated protein kinase.

CONCLUSIONS

Our findings reveal similar responsiveness of control and asthmatic fibroblasts to leptin. However, the accumulation of inflammatory leptin-producing monocytes in the airway may contribute to the pathogenesis of asthma.

Leptin deficiency in CD8+ T cells ameliorates non-segmental vitiligo by reducing interferon-γ and Granzyme B

Background

Vitiligo is an autoimmune skin disease mainly mediated by CD8⁺ T cells, which affects about 0.1%-2% population of the world. Leptin plays a critical role in regulating the activation of CD8⁺ T cells. However, the effect of Leptin on vitiligo remains unclear.

Objectives

To explore the effect of leptin on CD8⁺ T cells and its influence on vitiligo.

Methods

RNA sequencing and Quantitative Real-time PCR (RT-qPCR) were used to explore the differentially expressed genes. Immunofluorescence staining was performed on skin lesions. Leptin in serum was detected by enzyme linked immunosorbent assay (ELISA). The peripheral blood mononuclear cells were detected by flow cytometry after leptin stimulation for 72 hours. A vitiligo model was established by monobenzone on Leptin KO mice.

Results

557 differentially expressed genes were found, including 154 up-regulated and 403 down-regulated genes. Lipid metabolism pathways showed a close relationship to the pathogenesis of vitiligo, especially the PPAR signaling pathway. RT-qPCR (p = 0.013) and immunofluorescence staining (p = 0.0053) verified that LEPR expressed significantly higher in vitiligo. The serum leptin level of vitiligo patients was significantly lower than that of healthy controls (p = 0.0245). The interferon-γ subset of CD8⁺LEPR⁺ T cells from vitiligo patients was significantly higher (p = 0.0189). The protein level of interferon-γ was significantly increased after leptin stimulation in vitro (p = 0.0217). In mice, Leptin deficiency resulted in less severe hair depigmentation. Leptin deficiency also resulted in significantly lower expressed vitiligo-related genes, such as Cxcl9 (p = 0.0497), Gzmb (p < 0.001), Ifng (p = 0.0159), and Mx1 (p < 0.001) after modeling.

Conclusion

Leptin could promote the progression of vitiligo by enhancing the cytotoxic function of CD8⁺ T cells. Leptin may become a new target for vitiligo treatment.

High baseline body mass index predicts recovery of CD4+ T lymphocytes for HIV/AIDS patients receiving long-term antiviral therapy

The relationship between baseline BMI and CD4+ T cells during follow-up in HIV patients in China requires further evaluation. We conducted a retrospective cohort study based on adult AIDS patients who underwent or received antiretroviral therapy from 2003 to 2019 in Guangxi, China. BMI was divided into categories and compared, and after adjusting for BMI being related to the change in CD4 lymphocyte count, with normal weight as the reference group, the BMI before treatment was positively correlated with the changes in CD4+ T cells at different time periods. Among them, obese patients had significant CD4+ cell gain. In patients with pretreatment CD4+ T lymphocyte counts <200 cells/μL, a higher BMI was associated with an increased likelihood of achieving immunologic reconstitution [≥350 cells/μL: AHR: 1.02(1.01, 1.04), P = 0.004; ≥500 cells/μL: AHR: 1.03 (1.01, 1.05), P = 0.004]. Underweight in HIV patients was a risk factor for poor viral suppression [AHR: 1.24 (1.04, 1.48), P = 0.016]. Our study demonstrated that HIV/AIDS patients receiving ART with higher baseline BMI had better immune reconstitution and that baseline BMI could be an important predictor of immune reconstitution in patients receiving ART. Baseline BMI was not associated with virological failure, but a lower baseline BMI indicated poor viral suppression during follow-up.

Role of Leptin as a Link between Asthma and Obesity: A Systematic Review and Meta-Analysis

Asthma and obesity are considered as highly prevalent diseases with a great impact on public health. Obesity has been demonstrated to be an aggravating factor in the pathogenesis of asthma. Adipose tissue secretes proinflammatory cytokines and mediators, including leptin, which may promote the development and severity of asthma in obese patients. This study is a systematic review and a meta-analysis based on the relationship between leptin and asthma during obesity. MEDLINE, Cochrane, EMBASE and CINAHL databases were used. Data heterogeneity was analyzed using Cochran’s Q and treatment effect with the DerSimonian and Laird method. Random effect analyses were carried out to test data sensitivity. Asymmetry was estimated using Begg’s and Egger’s tests. All studies showed significant differences in leptin levels. The effect of the measures (p < 0.001), data sensitivity (p < 0.05) and data asymmetry were statistically significant, as well as tBegg’s test (p = 0.010) and Egge’s test (p < 0.001). Despite the existing limiting factors, the results of this study support the relevant role of leptin in the pathophysiology of asthma in obese subjects. Nevertheless, further studies are needed to obtain better insight in the relationship between leptin and asthma in obesity.

Bioinformatics insights into the genes and pathways on severe COVID-19 pathology in patients with comorbidities

Background: Coronavirus disease (COVID-19) infection is known for its severe clinical pathogenesis among individuals with pre-existing comorbidities. However, the molecular basis of this observation remains elusive. Thus, this study aimed to map key genes and pathway alterations in patients with COVID-19 and comorbidities using robust systems biology approaches. Methods: The publicly available genome-wide transcriptomic datasets from 120 COVID-19 patients, 281 patients suffering from different comorbidities (like cardiovascular diseases, atherosclerosis, diabetes, and obesity), and 252 patients with different infectious diseases of the lung (respiratory syncytial virus, influenza, and MERS) were studied using a range of systems biology approaches like differential gene expression, gene ontology (GO), pathway enrichment, functional similarity, mouse phenotypic analysis and drug target identification. Results: By cross-mapping the differentially expressed genes (DEGs) across different datasets, we mapped 274 shared genes to severe symptoms of COVID-19 patients or with comorbidities alone. GO terms and functional pathway analysis highlighted genes in dysregulated pathways of immune response, interleukin signaling, FCGR activation, regulation of cytokines, chemokines secretion, and leukocyte migration. Using network topology parameters, phenotype associations, and functional similarity analysis with ACE2 and TMPRSS2-two key receptors for this virus-we identified 17 genes with high connectivity (CXCL10, IDO1, LEPR, MME, PTAFR, PTGS2, MAOB, PDE4B, PLA2G2A, COL5A1, ICAM1, SERPINE1, ABCB1, IL1R1, ITGAL, NCAM1 and PRKD1) potentially contributing to the clinical severity of COVID-19 infection in patients with comorbidities. These genes are predicted to be tractable and/or with many existing approved inhibitors, modulators, and enzymes as drugs. Conclusion: By systemic implementation of computational methods, this study identified potential candidate genes and pathways likely to confer disease severity in COVID-19 patients with pre-existing comorbidities. Our findings pave the way to develop targeted repurposed therapies in COVID-19 patients.

Early prediction and longitudinal modeling of preeclampsia from multiomics

Preeclampsia is a complex disease of pregnancy whose physiopathology remains unclear. We developed machine-learning models for early prediction of preeclampsia (first 16 weeks of pregnancy) and over gestation by analyzing six omics datasets from a longitudinal cohort of pregnant women. For early pregnancy, a prediction model using nine urine metabolites had the highest accuracy and was validated on an independent cohort (area under the receiver-operating characteristic curve [AUC] = 0.88, 95% confidence interval [CI] [0.76, 0.99] cross-validated; AUC = 0.83, 95% CI [0.62,1] validated). Univariate analysis demonstrated statistical significance of identified metabolites. An integrated multiomics model further improved accuracy (AUC = 0.94). Several biological pathways were identified including tryptophan, caffeine, and arachidonic acid metabolisms. Integration with immune cytometry data suggested novel associations between immune and proteomic dynamics. While further validation in a larger population is necessary, these encouraging results can serve as a basis for a simple, early diagnostic test for preeclampsia.

Leptin and Asthma: What Are the Interactive Correlations?

Leptin is an adipokine directly correlated with the proinflammatory obese-associated phenotype. Leptin has been demonstrated to inhibit adipogenesis, promote fat demarcation, promote a chronic inflammatory state, increase insulin sensitivity, and promote angiogenesis. Leptin, a regulator of the immune response, is implicated in the pathology of asthma. Studies involved in the key cell reaction and animal models of asthma have provided vital insights into the proinflammatory role of leptin in asthma. Many studies described the immune cell and related cellular pathways activated by leptin, which are beneficial in asthma development and increasing exacerbations. Subsequent studies relating to animal models support the role of leptin in increasing inflammatory cell infiltration, airway hyperresponsiveness, and inflammatory responses. However, the conclusive effects of leptin in asthma are not well elaborated. In the present study, we explored the general functions and the clinical cohort study supporting the association between leptin and asthma. The main objective of our review is to address the knowns and unknowns of leptin on asthma. In this perspective, the arguments about the different faces of leptin in asthma are provided to picture the potential directions, thus yielding a better understanding of asthma development.

Ellagic Acid from Terminalia arjuna Fruits Protects Against Chromium and Cobalt Toxicity in Primary Human Lymphocytes

Increased accumulation of heavy metal ions such as Cr⁶⁺ and Co²⁺ due to release from prostheses and metallic implants has been reported. These metal ions have been shown to affect both resting and activated lymphocytes. Natural remedies towards mitigating the cytotoxic effects of metal ions are clearly warranted. Polyphenolic compounds which are part of hydrolysable tannins from natural plant sources are considered effective in cheating heavy metal ions in a biological system. We have isolated and characterized a polyphenolic compound (ellagic acid) from Terminalia arjuna fruits that has been tested for its ability to attenuate the metal ion toxicity in primary human lymphocytes in culture. Cr⁶⁺ and Co²⁺ (100 μM) decreased lymphocyte viability and proliferation and increased apoptosis of resting as well as CD3 and/or CD28-stimulated lymphocytes. Metal ions markedly diminished the cytokine (interleukin-2 and interferon-γ) secretion from activated lymphocytes. Pretreatment with ellagic acid at 25, 50, and 100 μM concentrations effectively improved viability and proliferative responses of both resting and activated lymphocytes, while attenuating the apoptotic index. Ellagic acid also tended to normalize the cytokine secretion from the activated lymphocytes even in the presence of metal ions, suggesting broad effects on the adaptive immune system.

Influence of Nutritional Status and Physical Exercise on Immune Response in Metabolic Syndrome

Metabolic Syndrome (MetS) is a cluster of metabolic alterations mostly related to visceral adiposity, which in turn promotes glucose intolerance and a chronic systemic inflammatory state, characterized by immune cell infiltration. Such immune system activation increases the risk of severe disease subsequent to viral infections. Strong correlations between elevated body mass index (BMI), type-2-diabetes and increased risk of hospitalization after pandemic influenza H1N1 infection have been described. Similarly, a correlation between elevated blood glucose level and SARS-CoV-2 infection severity and mortality has been described, indicating MetS as an important predictor of clinical outcomes in patients with COVID-19. Adipose secretome, including two of the most abundant and well-studied adipokines, leptin and interleukin-6, is involved in the regulation of energy metabolism and obesity-related low-grade inflammation. Similarly, skeletal muscle hormones—called myokines—released in response to physical exercise affect both metabolic homeostasis and immune system function. Of note, several circulating hormones originate from both adipose tissue and skeletal muscle and display different functions, depending on the metabolic context. This review aims to summarize recent data in the field of exercise immunology, investigating the acute and chronic effects of exercise on myokines release and immune system function.

The Head-to-Toe Hormone: Leptin as an Extensive Modulator of Physiologic Systems

Leptin is a well-known hunger-sensing peptide hormone. The role of leptin in weight gain and metabolic homeostasis has been explored for the past two decades. In this review, we have tried to shed light upon the impact of leptin signaling on health and diseases. At low or moderate levels, this peptide hormone supports physiological roles, but at chronically higher doses exhibits detrimental effects on various systems. The untoward effects we observe with chronically higher levels of leptin are due to their receptor-mediated effect or due to leptin resistance and are not well studied. This review will help us in understanding the non-anorexic roles of leptin, including their contribution to the metabolism of various systems and inflammation. We will be able to get an alternative perspective regarding the physiological and pathological roles of this mysterious peptide hormone.

Obesity as a Risk Factor for Dementia and Alzheimer's Disease: The Role of Leptin

Obesity is a growing worldwide health problem, affecting many people due to excessive saturated fat consumption, lack of exercise, or a sedentary lifestyle. Leptin is an adipokine secreted by adipose tissue that increases in obesity and has central actions not only at the hypothalamic level but also in other regions and nuclei of the central nervous system (CNS) such as the cerebral cortex and hippocampus. These regions express the long form of leptin receptor LepRb, which is the unique leptin receptor capable of transmitting complete leptin signaling, and are the first regions to be affected by chronic neurocognitive deficits, such as mild cognitive impairment (MCI) and Alzheimer's Disease (AD). In this review, we discuss different leptin resistance mechanisms that could be implicated in increasing the risk of developing AD, as leptin resistance is frequently associated with obesity, which is a chronic low-grade inflammatory state, and obesity is considered a risk factor for AD. Key players of leptin resistance are SOCS3, PTP1B, and TCPTP whose signalling is related to inflammation and could be worsened in AD. However, some data are controversial, and it is necessary to further investigate the underlying mechanisms of the AD-causing pathological processes and how altered leptin signalling affects such processes.

Does weight loss lead to improvement of dermatological conditions: What is the evidence?

Obese and overweight individuals may have a wide gamut of cutaneous features and can have more severe manifestations of multiple dermatological conditions. There have been multiple expert opinions on the favorable effects of weight reduction in improving skin conditions. Over the past decade, there have been few studies evaluating the response of exercise and other modes of weight loss on various dermatoses such as psoriasis, acne, hidradenitis suppurativa, acanthosis nigricans. In this review, we have attempted to provide a summary of the benefits of reduction of body weight on various skin aliments.

Could very low-calorie ketogenic diets turn off low grade inflammation in obesity? Emerging evidence

Obesity is an emerging non-communicable disease associated with chronic low-grade inflammation and oxidative stress, compounded by the development of many obesity-related diseases, such as cardiovascular disease, type 2 diabetes mellitus, and a range of cancers. Originally developed for the treatment of epilepsy in drug non-responder children, the ketogenic diet (KD) is being increasingly used in the treatment of many diseases, including obesity and obesity-related conditions. The KD is a dietary pattern characterized by high fat intake, moderate to low protein consumption, and very low carbohydrate intake (<50 g) that has proved to be an effective and weight-loss tool. In addition, it also appears to be a dietary intervention capable of improving the inflammatory state and oxidative stress in individuals with obesity by means of several mechanisms. The main activity of the KD has been linked to improving mitochondrial function and decreasing oxidative stress. β-hydroxybutyrate, the most studied ketone body, has been shown to reduce the production of reactive oxygen species, improving mitochondrial respiration. In addition, KDs exert anti-inflammatory activity through several mechanisms, e.g., by inhibiting activation of the nuclear factor kappa-light-chain-enhancer of activated B cells, and the inflammatory nucleotide-binding, leucine-rich-containing family, pyrin domain-containing-3, and inhibiting histone deacetylases. Given the rising interest in the topic, this review looks at the underlying anti-inflammatory and antioxidant mechanisms of KDs and their possible recruitment in the treatment of obesity and obesity-related disorders.

Adipokines, Weight Gain and Metabolic and Inflammatory Markers After Antiretroviral Therapy Initiation: AIDS Clinical Trials Group (ACTG) A5260s

BACKGROUND

The adipokines leptin and adiponectin, produced primarily by adipose tissue, have diverse endocrine and immunologic effects, and circulating levels reflect adipocyte lipid content, local inflammation, and tissue composition. We assessed relationships between changes in regional fat depots, leptin and adiponectin levels, and metabolic and inflammatory markers over 96 weeks in the AIDS Clinical Trials Group (ACTG) A5260s metabolic substudy of the A5257 randomized trial of tenofovir disoproxil fumarate/emtricitabine plus atazanavir/ritonavir, darunavir/ritonavir, or raltegravir among treatment-naive persons with human immunodeficiency virus (PWH).

METHODS

Fat depots were measured using dual-energy absorptiometry and abdominal computed tomographic imaging at treatment initiation and 96 weeks later. Serum leptin and adiponectin, homeostatic model assessment of insulin resistance (HOMA-IR), and high-sensitivity C-reactive protein (hsCRP) were measured at the same timepoints. Multivariable regression models assessed relationships between fat depots, adipokines, HOMA-IR, and hsCRP at week 96.

RESULTS

Two hundred thirty-four participants maintained viral suppression through 96 weeks (90% male, 29% black, median age 36 years). Serum leptin increased over 96 weeks (mean change 22%) while adiponectin did not (mean change 1%), which did not differ by study arm. Greater trunk, limb, and abdominal subcutaneous and visceral fat were associated with higher HOMA-IR and hsCRP at 96 weeks, but serum leptin level was a stronger determinant of these endpoints using a mediation model approach. A similar mediating effect was not observed for adiponectin.

CONCLUSIONS

Higher circulating leptin is associated with greater HOMA-IR and hsCRP independent of fat depot size, suggesting that greater adipocyte lipid content may contribute to impaired glucose tolerance and systemic inflammation among PWH starting antiretroviral therapy.

Prognostic impact of body mass index (BMI) in HER2+ breast cancer treated with anti-HER2 therapies: from preclinical rationale to clinical implications

Human Epidermal growth factor Receptor 2 (HER2) overexpression or HER2 gene amplification defines a subset of breast cancers (BCs) characterized by higher biological and clinical aggressiveness. The introduction of anti-HER2 drugs has remarkably improved clinical outcomes in patients with both early-stage and advanced HER2+ BC. However, some HER2+ BC patients still have unfavorable outcomes despite optimal anti-HER2 therapies. Retrospective clinical analyses indicate that overweight and obesity can negatively affect the prognosis of patients with early-stage HER2+ BC. This association could be mediated by the interplay between overweight/obesity, alterations in systemic glucose and lipid metabolism, increased systemic inflammatory status, and the stimulation of proliferation pathways resulting in the stimulation of HER2+ BC cell growth and resistance to anti-HER2 therapies. By contrast, in the context of advanced disease, a few high-quality studies, which were included in a meta-analysis, showed an association between high body mass index (BMI) and better clinical outcomes, possibly reflecting the negative prognostic role of malnourishment and cachexia in this setting. Of note, overweight and obesity are modifiable factors. Therefore, uncovering their prognostic role in patients with early-stage or advanced HER2+ BC could have clinical relevance in terms of defining subsets of patients requiring more or less aggressive pharmacological treatments, as well as of designing clinical trials to investigate the therapeutic impact of lifestyle interventions aimed at modifying body weight and composition. In this review, we summarize and discuss the available preclinical evidence supporting the role of adiposity in modulating HER2+ BC aggressiveness and resistance to therapies, as well as clinical studies reporting on the prognostic role of BMI in patients with early-stage or advanced HER2+ BC.

The ambiguous role of obesity in oncology by promoting cancer but boosting antitumor immunotherapy

Obesity is nowadays considered a pandemic which prevalence's has been steadily increasingly in western countries. It is a dynamic, complex, and multifactorial disease which propitiates the development of several metabolic and cardiovascular diseases, as well as cancer. Excessive adipose tissue has been causally related to cancer progression and is a preventable risk factor for overall and cancer-specific survival, associated with poor prognosis in cancer patients. The onset of obesity features a state of chronic low-grade inflammation and secretion of a diversity of adipocyte-derived molecules (adipokines, cytokines, hormones), responsible for altering the metabolic, inflammatory, and immune landscape. The crosstalk between adipocytes and tumor cells fuels the tumor microenvironment with pro-inflammatory factors, promoting tissue injury, mutagenesis, invasion, and metastasis. Although classically established as a risk factor for cancer and treatment toxicity, recent evidence suggests mild obesity is related to better outcomes, with obese cancer patients showing better responses to treatment when compared to lean cancer patients. This phenomenon is termed obesity paradox and has been reported in different types and stages of cancer. The mechanisms underlying this paradoxical relationship between obesity and cancer are still not fully described but point to systemic alterations in metabolic fitness and modulation of the tumor microenvironment by obesity-associated molecules. Obesity impacts the response to cancer treatments, such as chemotherapy and immunotherapy, and has been reported as having a positive association with immune checkpoint therapy. In this review, we discuss obesity's association to inflammation and cancer, also highlighting potential physiological and biological mechanisms underlying this association, hoping to clarify the existence and impact of obesity paradox in cancer development and treatment.

Leptin in Dental Pulp and Periapical Tissues: A Narrative Review

Leptin is a non-glycosylated 16 kDa protein synthesized mainly in adipose cells. The main function of leptin is to regulate energy homeostasis and weight control in a central manner. There is increasing evidence that leptin also has systemic effects, acting as a link between innate and acquired immune responses. The expression of leptin and its receptor in human dental pulp and periradicular tissues have already been described, as well as several stimulatory effects of leptin protein expression in dental and periodontal tissues. The aim of this paper was to review and to compile the reported scientific literature on the role and effects of leptin in the dental pulp and periapical tissues. Twelve articles accomplished the inclusion criteria, and a comprehensive narrative review was carried out. Review of the available scientific literature concluded that leptin has the following effects on pulpal and periapical physiology: 1) Stimulates odontogenic differentiation of dental pulp stem cells (DPSCs), 2) Increases the expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1), odontoblastic proteins involved in odontoblastic differentiation and dentin mineralization, 3) Stimulates vascular endothelial growth factor (VEGF) expression in human dental pulp tissue and primary cultured cells of human dental pulp (hDPCs), 4) Stimulates angiogenesis in rat dental pulp cells, and 5) Induces the expression of interleucinas 6 and 8 in human periodontal ligament cells (hPDLCs). There is evidence which suggests that leptin is implicated in the dentin mineralization process and in pulpal and periapical inflammatory and reparative responses.

High-throughput segmentation of unmyelinated axons by deep learning

Axonal characterizations of connectomes in healthy and disease phenotypes are surprisingly incomplete and biased because unmyelinated axons, the most prevalent type of fibers in the nervous system, have largely been ignored as their quantitative assessment quickly becomes unmanageable as the number of axons increases. Herein, we introduce the first prototype of a high-throughput processing pipeline for automated segmentation of unmyelinated fibers. Our team has used transmission electron microscopy images of vagus and pelvic nerves in rats. All unmyelinated axons in these images are individually annotated and used as labeled data to train and validate a deep instance segmentation network. We investigate the effect of different training strategies on the overall segmentation accuracy of the network. We extensively validate the segmentation algorithm as a stand-alone segmentation tool as well as in an expert-in-the-loop hybrid segmentation setting with preliminary, albeit remarkably encouraging results. Our algorithm achieves an instance-level [Formula: see text] score of between 0.7 and 0.9 on various test images in the stand-alone mode and reduces expert annotation labor by 80% in the hybrid setting. We hope that this new high-throughput segmentation pipeline will enable quick and accurate characterization of unmyelinated fibers at scale and become instrumental in significantly advancing our understanding of connectomes in both the peripheral and the central nervous systems.

Leptin Promotes Greater Ki67 Expression in CD4+ T Cells From Obese Compared to Lean Persons Living With HIV

While antiretroviral therapy (ART) has proven effective in suppressing viremia and disease progression among people living with human immunodeficiency virus (HIV; PLWH), suboptimal CD4+ T cell reconstitution remains a major obstacle in nearly 30% of ART-treated individuals. Epidemiological studies demonstrate that obesity, or a body mass index (BMI) ≥ 30 kg/m2, is positively correlated with greater CD4+ T cell recovery in PLWH on ART. Leptin is a known immunomodulator that is produced in proportion to fat mass and is increased in obese individuals, including PLWH. We hypothesized that CD4+ T cells from obese PLWH have increased cell proliferation and cytokine production compared to cells from lean PLWH, potentially modulated by differential effects of leptin signaling. To test this hypothesis, peripheral blood mononuclear cells from obese and lean PLWH with long-term virologic suppression on the same ART regimen were pretreated with recombinant leptin and then stimulated with anti-CD3/CD28 or PMA/ionomycin to measure Ki67 expression, leptin receptor (LepR) surface expression and cytokine production. In the absence of leptin, Ki67 expression and IL-17A production were significantly higher in CD4+ T cells from obese compared to lean PLWH. However, LepR expression was significantly lower on CD4+ T cells from obese compared to lean PLWH. After leptin treatment, Ki67 expression was significantly increased in CD4+ T cells from obese PLWH compared to the lean participants. Leptin also increased IL-17A production in CD4+ T cells from obese healthy controls. In contrast, leptin decreased IL-17A production in CD4+ T cells from both obese and lean PLWH. Combined, these results demonstrate that obesity is associated with greater CD4+ T cell proliferation among PLWH, and that higher circulating leptin levels in obesity may contribute to improved CD4+ T reconstitution in PLWH initiating ART.

Targeting memory T cell metabolism to improve immunity

Vaccination affords protection from disease by activating pathogen-specific immune cells and facilitating the development of persistent immunologic memory toward the vaccine-specific pathogen. Current vaccine regimens are often based on the efficiency of the acute immune response, and not necessarily on the generation of memory cells, in part because the mechanisms underlying the development of efficient immune memory remain incompletely understood. This Review describes recent advances in defining memory T cell metabolism and how metabolism of these cells might be altered in patients affected by mitochondrial diseases or metabolic syndrome, who show higher susceptibility to recurrent infections and higher rates of vaccine failure. It discusses how this new understanding could add to the way we think about immunologic memory, vaccine development, and cancer immunotherapy.

Umbilical Cord Blood Leptin and IL-6 in the Presence of Maternal Diabetes or Chorioamnionitis

Diabetes during pregnancy is associated with elevated maternal insulin, leptin and IL-6. Within the placenta, IL-6 can further stimulate leptin production. Despite structural similarities and shared roles in inflammation, leptin and IL-6 have contrasting effects on neurodevelopment, and the relative importance of maternal diabetes or chorioamnionitis on fetal hormone exposure has not been defined. We hypothesized that there would be a positive correlation between IL-6 and leptin with progressively increased levels in pregnancies complicated by maternal diabetes and chorioamnionitis. To test this hypothesis, cord blood samples were obtained from 104 term infants, including 47 exposed to maternal diabetes. Leptin, insulin, and IL-6 were quantified by multiplex assay. Factors independently associated with hormone levels were identified by univariate and multivariate linear regression. Unlike IL-6, leptin and insulin were significantly increased by maternal diabetes. Maternal BMI and birth weight were independent predictors of leptin and insulin with birth weight the strongest predictor of leptin. Clinically diagnosed chorioamnionitis and neonatal sepsis were associated with increased IL-6 but not leptin. Among appropriate for gestational age infants without sepsis, IL-6 and leptin were strongly correlated (R=0.6, P<0.001). In summary, maternal diabetes and birth weight are associated with leptin while chorioamnionitis is associated with IL-6. The constraint of the positive association between leptin and IL-6 to infants without sepsis suggests that the term infant and placenta may have a limited capacity to increase cord blood levels of the neuroprotective hormone leptin in the presence of increased cord blood levels of the potential neurotoxin IL-6.

The Leptin Axis and Its Association With the Adaptive Immune System in Breast Cancer

Adipose tissue secretes various peptides, including leptin. This hormone acts through the leptin receptor (Ob-R), which is expressed ubiquitously on the surface of various cells, including breast cancer cells and immune cells. Increasing evidence points to an interaction between the tumor microenvironment, tumor cells, and the immune system. Leptin plays an important role in breast cancer tumorigenesis and may be implicated in activation of the immune system. While breast cancer cannot be considered an immunogenic cancer, the triple-negative subtype is an exception. Specific immune cells - tumor infiltrating lymphocytes - are involved in the immune response and act as predictive and prognostic factors in certain breast cancer subtypes. The aim of this article is to review the interaction between adipose tissue, through the expression of leptin and its receptor, and the adaptive immune system in breast cancer.

Reduced Th1 response is associated with lower glycolytic activity in activated peripheral blood mononuclear cells after metabolic and bariatric surgery

BACKGROUND

Obesity promotes cellular immunometabolism changes that trigger the activation of macrophages and lymphocytes, leading to systemic inflammation. Activated leukocytes undergo metabolic reprogramming, increasing glycolytic activity.

OBJECTIVE

To examine whether the reduction in the inflammatory state associated with bariatric surgery is associated with decreased glycolytic activity in leukocytes. Setting Single-center, prospective observational study.

METHODS

This study involved 18 patients with obesity undergoing bariatric surgery. All measurements were performed preoperatively and six months postoperatively. Peripheral blood mononuclear cells and plasma were obtained to determine the glycolytic rate and mitochondrial membrane potential as surrogates of the metabolic switching and high-sensitivity C-reactive protein, adipokines, and CD69 expression as inflammatory and activation markers.

RESULTS

Glycolytic activity engaged by CD3/CD28 activation was reduced six months after bariatric surgery, associated with decreased levels of T helper (Th) 1 and Th17 signature cytokines. An overall reduction in inflammatory markers was observed, which correlated with a higher adiponectin/leptin ratio.

CONCLUSIONS

Metabolic and bariatric surgery-induced weight loss leads to reprogramming in T cells' metabolic machinery, resulting in reduced stimulation of glycolysis after activation, which may explain the decrease in systemic inflammation mediated by cytokines such as interferon-γ and interleukin-17A.

Emerging Biomarkers and Targeted Therapies in Feline Mammary Carcinoma

Feline mammary carcinoma (FMC) is a common aggressive malignancy with a low survival rate that lacks viable therapeutic options beyond mastectomy. Recently, increasing efforts have been made to understand the molecular mechanisms underlying FMC development, using the knowledge gained from studies on human breast cancer to discover new diagnostic and prognostic biomarkers, thus reinforcing the utility of the cat as a cancer model. In this article, we review the current knowledge on FMC pathogenesis, biomarkers, and prognosis factors and offer new insights into novel therapeutic options for HER2-positive and triple-negative FMC subtypes.

Emerging role of leptin in joint inflammation and destruction

Rheumatoid arthritis (RA) is an autoimmune disease characterized by tumor-like hyperplasia and inflammation of the synovium, which causes synovial cell invasion into the bone and cartilage. In RA pathogenesis, various molecules in effector cells (i.e., immune cells and mesenchymal cells) are dysregulated by genetic and environmental factors. Consistent with the early stages of RA, these pathogenic cells cooperate and activate each other directly by cell-to-cell contact or indirectly via humoral factors. Recently, growing evidence has revealed essential role of adipokines, which are multifunctional signal transduction molecules, in the immune system. In this review, we summarize the current understanding of the cross-talk between leptin, one of the most well-known and best-characterized adipokines, and osteoimmunology. Furthermore, we discuss the contribution of leptin to the pathogenesis of RA and its potential mechanisms.

Leptin, Both Bad and Good Actor in Cancer

Leptin is an important regulator of basal metabolism and food intake, with a pivotal role in obesity. Leptin exerts many different actions on various tissues and systems, including cancer, and is considered as a linkage between metabolism and the immune system. During the last decades, obesity and leptin have been associated with the initiation, proliferation and progression of many types of cancer. Obesity is also linked with complications and mortality, irrespective of the therapy used, affecting clinical outcomes. However, some evidence has suggested its beneficial role, called the "obesity paradox", and the possible antitumoral role of leptin. Recent data regarding the immunotherapy of cancer have revealed that overweight leads to a more effective response and leptin may probably be involved in this beneficial process. Since leptin is a positive modulator of both the innate and the adaptive immune system, it may contribute to the increased immune response stimulated by immunotherapy in cancer patients and may be proposed as a good actor in cancer. Our purpose is to review this dual role of leptin in cancer, as well as trying to clarify the future perspectives of this adipokine, which further highlights its importance as a cornerstone of the immunometabolism in oncology.

The Postnatal Leptin Surge Supports Immune Cell Function in Rats

Background: Leptin plays an important role in the regulation of the immune response. There is a physiological surge of leptin in rodents during the neonatal period, which has mainly been studied in the context of brain development. However, little is known about the effects of this neonatal leptin surge on immunity. Therefore, we investigated whether blocking this leptin surge could affect several immune functions.Methods: Male and female rats were injected subcutaneously with 5 mg/Kg/day of rat pegylated super leptin antagonist during the neonatal period (PND5-9). On the peripubertal period, relevant functions as well as cytokine release by spleen leukocytes were studied in these animals.Results: The results showed that the animals significantly display an impaired anti-tumor NK activity and chemotactic and proliferation capacity of lymphocytes in response to mitogens. In addition, several cytokine concentrations, released under mitogen-stimulated conditions, were also altered.Conclusion: In conclusion, the neonatal leptin surge seems to be involved in the establishment of an adequate immune response and cytokine profile, which are crucial for the maintenance of a healthy life.

The impact of obesity on immune response to infection: Plausible mechanisms and outcomes

Emerging data suggest an association between obesity and infectious diseases. Although the mechanisms underlying this link are not well established, a number of potential factors may be involved. Indeed, the obesity-related vulnerability to infectious diseases could be due to chronic low-grade inflammation, hyperglycemia, hyperinsulinemia, and hyperleptinemia, which lead to a weakening of both the innate and adaptive immune responses. In addition, obesity results in anatomical-functional changes by the mechanical obstacle of excessive adipose tissue that blunt the respiratory mechanisms and predisposing to respiratory infections. Subjects with obesity are also at risk of skin folds and sweat more profusely due to the thick layers of subcutaneous fat, favoring the proliferation of microorganisms and slowing the repair of wounds down. All these factors make subjects with obesity more prone to develop nosocomial infections, surgical site, skin and soft tissue infections, bacteremia, urinary tract infections, and mycosis. Furthermore, infections in subjects with obesity have a worse prognosis, frequently prolonging hospitalization time as demonstrated for several flu viruses and recently for COVID-19. Thus, the aim of this manuscript is to provide an overview of the current clinical evidence on the associations between obesity and infectious diseases highlighting physio pathological insights involved in this link.

Less airway inflammation and goblet cell metaplasia in an IL-33-induced asthma model of leptin-deficient obese mice

BACKGROUND

Obesity-associated asthma is a phenotype of severe asthma. Late-onset, non-eosinophilic and female-dominant phenotype is highly symptomatic and difficult to treat. Leptin, an adipokine, exerts an immunomodulatory effect. IL-33 associated with innate immunity induces type 2 inflammation and is present in adipose tissue. The purpose of this study was to elucidate the pathogenesis of obesity-associated asthma by focusing on the interaction between leptin and IL-33.

METHODS

In leptin-deficient obese (ob/ob) and wild-type mice, IL-33 was instilled intranasally on three consecutive days. In part of the mice, leptin was injected intraperitoneally prior to IL-33 treatment. The mice were challenged with methacholine, and airway hyperresponsiveness (AHR) was assessed by resistance (Rrs) and elastance (Ers) of the respiratory system using the forced oscillation technique. Cell differentiation, IL-5, IL-13, eotaxin, keratinocyte-derived chemokine (KC) in bronchoalveolar lavage fluid (BALF) and histology of the lung were analyzed. For the in vitro study, NCI-H292 cells were stimulated with IL-33 in the presence or absence of leptin. Mucin-5AC (MUC5AC) levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

Ob/ob mice showed greater Rrs and Ers than wild-type mice. IL-33 with leptin, but not IL-33 alone, enhanced Ers rather than Rrs challenged with methacholine in ob/ob mice, whereas it enhanced Rrs alone in wild-type mice. IL-33-induced eosinophil numbers, cytokine levels in BALF, eosinophilic infiltration around the bronchi, and goblet cell metaplasia were less in ob/ob mice than in wild-type mice. However, leptin pretreatment attenuated these changes in ob/ob mice. MUC5AC levels were increased by co-stimulation with IL-33 and leptin in vitro.

CONCLUSIONS

Ob/ob mice show innate AHR. IL-33 with leptin, but not IL-33 alone, induces airway inflammation and goblet cell metaplasia and enhances AHR involving peripheral airway closure. This is presumably accelerated by mucus in ob/ob mice. These results may explain some aspects of the pathogenesis of obesity-associated asthma.

The Adjuvants Polyphosphazene (PCEP) and a Combination of Curdlan Plus Leptin Promote a Th17-Type Immune Response to an Intramuscular Vaccine in Mice

Our aim was to determine whether polyphosphazene (PCEP), Curdlan (β-glucan, a dectin-1 agonist), and Leptin could act as adjuvants to promote a Th17-type adaptive immune response in mice. Mice were vaccinated via the intramuscular route then boosted three weeks later with Ovalbumin plus: PCEP, Leptin, Curdlan, PCEP+Curdlan, Curdlan+Leptin, or saline. Mice vaccinated with OVA+PCEP and OVA+Curdlan+Leptin showed significantly higher frequency of antigen-specific CD4+ T cells secreting IL-17 relative to OVA-vaccinated mice. No formulation increased the frequency of CD4+ T cells secreting IL-4 or IFNγ. Since activation of innate immunity precedes the development of adaptive immunity, we wished to establish whether induction of Th17-type immunity could be predicted from in vitro experiments and/or from the local cytokine environment after immunization with adjuvants alone. Elevated IL-6 and TGFβ with reduced secretion of IL-12 is a cytokine milieu known to promote differentiation of Th17-type immunity. We injected the immunostimulants or saline buffer into murine thigh muscles and measured acute local cytokine production. PCEP induced significant production of IL-6 and reduced IL-12 production in muscle but it did not lead to elevated TGFβ production. Curdlan+Leptin injected into muscle induced significant production of TGFβ and IL-17 but not IL-6 or IL-12. We also stimulated splenocytes with media or PCEP, Leptin, Curdlan, PCEP+Curdlan, Curdlan+Leptin, PCEP+Leptin, and PCEP+Curdlan+Leptin and measured cytokine production. PCEP stimulation of splenocytes failed to induce significant production of IL-6, IL-12, TGFβ, or IL-17 and therefore ex vivo splenocyte stimulation failed to predict the increased frequency of Th17-type T cells in response to the vaccine. Curdlan-stimulated splenocytes produced Th1-type, inducing cytokine, IL-12. Curdlan+/-PCEP stimulated TGF-β production and Curdlan+Leptin+/- PCEP induced secretion of IL-17. We conclude that PCEP as well as Curdlan+Leptin are Th17-type vaccine adjuvants in mice but that cytokines produced in response to these adjuvants in muscle after injection or in ex vivo cultured splenocytes did not predict their role as a Th17-type adjuvant. Together, these data suggest that the cytokine environments induced by these immunostimulants did not predict induction of an antigen-specific Th17-type adaptive immune response. This is the first report of these adjuvants inducing a Th17-type adaptive immune response.

Serum leptin level as a diagnostic and prognostic marker in infectious diseases and sepsis: A comprehensive literature review

BACKGROUND

Infections and sepsis are common causes of morbidity and mortality, with an increasing incidence worldwide. Leptin is involved in the inflammatory process and may modulate the cytokine production, immune cell proliferation and endothelial function. There are conflicting results regarding alterations of leptin levels in infectious diseases and the outcome from sepsis.The aim of the current article is to provide an overview of the medical literature on the correlations between variations of leptin levels and infectious diseases and sepsis.

METHODS

We performed an extensive literature search in PubMed and Google Scholar databases, using keywords to identify articles related to leptin in infectious diseases and sepsis. Searches were referenced using medical subject headings that included "leptin," "adipokines," "sepsis," "infectious diseases," "leptin deficiency," "leptin resistance" or "hyperleptinemia." The language of publication, journal, or country were not included as limitation criteria.Articles or abstracts containing adequate information, such as age, sex, anthropometric indices, clinical presentation, comorbidities, and management were included in the study, whereas articles with insufficient clinical and demographic data were excluded. We assessed the quality of the studies selected.The final review of all databases was conducted on June 18, 2020.

RESULTS

We find the results from the current review to be of great importance due to the possible therapeutic role of leptin analogs in states of leptin deficiency associated with infectious diseases or sepsis.In hyperleptinemia, a therapeutic plan for obtaining leptin neutralization also needs further investigations. This could lead to the reduction of proinflammatory responses.There is a need for further studies to demonstrate the specificity and sensitivity of leptin in the early diagnosis of sepsis and the need to measure serum leptin levels in routine evaluation of the critical patient.

CONCLUSION

The multiple effects of leptin are of growing interest, but further studies are needed to elucidate the role of leptin signalling in infectious diseases and sepsis. Because very few human studies are reported, we recommend the need for further research.Better understanding of the pathophysiology of sepsis and the implication of circulating total leptin in this process could help physicians in managing this life-threatening condition.

The role of immune dysfunction in obesity-associated cancer risk, progression, and metastasis

Obesity has been linked to an increased risk of and a worse prognosis for several types of cancer. A number of interrelated mediators contribute to obesity's pro-tumor effects, including chronic adipose inflammation and other perturbations of immune cell development and function. Here, we review studies examining the impact of obesity-induced immune dysfunction on cancer risk and progression. While the role of adipose tissue inflammation in obesity-associated cancer risk has been well characterized, the effects of obesity on immune cell infiltration and activity within the tumor microenvironment are not well studied. In this review, we aim to highlight the impact of both adipose-mediated inflammatory signaling and intratumoral immunosuppressive signaling in obesity-induced cancer risk, progression, and metastasis.