Role of innate lymphoid cells in obesity and metabolic disease (Review)

Second-Generation Antipsychotics Induce Metabolic Disruption in Adipose Tissue-Derived Mesenchymal Stem Cells Through an aPKC-Dependent Pathway

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities, including visceral obesity, dyslipidemia, and insulin resistance. In this regard, visceral white adipose tissue (vWAT) plays a critical role, influencing energy metabolism, immunomodulation, and oxidative stress. Adipose-derived stem cells (ADSCs) are key players in these processes within vWAT. While second-generation antipsychotics (SGAs) have significantly improved treatments for mental health disorders, their chronic use is associated with an increased risk of MetS. In this study, we explored the impact of SGAs on ADSCs to better understand their role in MetS and identify potential therapeutic targets. Our findings reveal that olanzapine disrupts lipid droplet formation during adipogenic differentiation, impairing insulin receptor endocytosis, turnover, and signaling. SGAs also alter the endolysosomal compartment, leading to acidic vesicle accumulation and increased lysosomal biogenesis through TFEB activation. PKCζ is crucial for the SGA-induced nuclear translocation of TFEB and acidic vesicle formation. Notably, inhibiting PKCζ restored insulin receptor tyrosine phosphorylation, normalized receptor turnover, and improved downstream signaling following olanzapine treatment. This activation of PKCζ by olanzapine is driven by increased phosphatidic acid synthesis via phospholipase D (PLD), following G protein-coupled receptor (GPCR) signaling activation. Overall, olanzapine and clozapine disrupt endolysosomal homeostasis and insulin signaling in a PKCζ-dependent manner. These findings highlight SGAs as valuable tools for uncovering cellular dysfunction in vWAT during MetS and may guide the development of new therapeutic strategies to mitigate the metabolic side effects of these drugs.

Case report: Molecular characterisation of adipose-tissue derived cells from a patient with ROHHAD syndrome

There have been over 100 cases of Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) syndrome reported, but there is currently no curative treatment for children with this condition. We aimed to better characterise adipose cells from a child with ROHHAD syndrome. We isolated pre-adipocytes from a 4 year-old female patient with ROHHAD syndrome and assessed proliferation rate of these cells. We evaluated levels of DLP-Pref-1(pre-adipocyte marker) using western blotting, and concentrations of interleukin-6(IL-6) using ELISA. We performed next-generation sequencing (NGS) and bioinformatic analyses on these cells compared to tissue from an age/sex-matched control. The two most up-/down-regulated genes were validated using QPCR. We successfully isolated pre-adipocytes from a fat biopsy, by confirming the presence of Pref-1 and differentiated them to mature adipocytes. Interleukin 6, (Il-6) levels were 5.6-fold higher in ROHHAD cells compared to a control age/sex-matched biopsy. NGS revealed 25,703 differentially expressed genes (DEGs) from ROHHAD cells vs. control of which 2,237 genes were significantly altered. The 20 most significantly up/down-regulated genes were selected for discussion. This paper describes the first transcriptomic analysis of adipose cells from a child with ROHHAD vs. normal control adipose tissue as a first step in identifying targetable pathways/mechanisms underlying this condition with novel therapeutic interventions.

Adipose tissue aging is regulated by an altered immune system

Adipose tissue is a widely distributed organ that plays a critical role in age-related physiological dysfunctions as an important source of chronic sterile low-grade inflammation. Adipose tissue undergoes diverse changes during aging, including fat depot redistribution, brown and beige fat decrease, functional decline of adipose progenitor and stem cells, senescent cell accumulation, and immune cell dysregulation. Specifically, inflammaging is common in aged adipose tissue. Adipose tissue inflammaging reduces adipose plasticity and pathologically contributes to adipocyte hypertrophy, fibrosis, and ultimately, adipose tissue dysfunction. Adipose tissue inflammaging also contributes to age-related diseases, such as diabetes, cardiovascular disease and cancer. There is an increased infiltration of immune cells into adipose tissue, and these infiltrating immune cells secrete proinflammatory cytokines and chemokines. Several important molecular and signaling pathways mediate the process, including JAK/STAT, NFκB and JNK, etc. The roles of immune cells in aging adipose tissue are complex, and the underlying mechanisms remain largely unclear. In this review, we summarize the consequences and causes of inflammaging in adipose tissue. We further outline the cellular/molecular mechanisms of adipose tissue inflammaging and propose potential therapeutic targets to alleviate age-related problems.

Obesity and Adipose Tissue Dysfunction: From Pediatrics to Adults

Obesity is a growing health problem that affects both children and adults. The increasing prevalence of childhood obesity is associated with comorbidities such as cardiovascular disease, type 2 diabetes and metabolic syndrome due to chronic low-grade inflammation present at early stages of the disease. In pediatric patients suffering from obesity, the role of epigenetics, the gut microbiome and intrauterine environment have emerged as causative factors Interestingly, pediatric obesity is strongly associated with low birth weight. Accelerated weight gain oftentimes occurs in these individuals during the post-natal period, which can lead to increased risk of adiposity and metabolic disease. The pathophysiology of obesity is complex and involves biological and physiological factors compounded by societal factors such as family and community. On a cellular level, adipocytes contained within adipose tissue become dysregulated and further contribute to development of comorbidities similar to those present in adults with obesity. This review provides an overview of the current understanding of adipose tissue immune, inflammatory and metabolic adaptation of the adipose tissue in obesity. Early cellular changes as well as the role of immune cells and inflammation on the progression of disease in pivotal pediatric clinical trials, adult studies and mouse models are emphasized. Understanding the initial molecular and cellular changes that occur during obesity can facilitate new and improved treatments aimed at early intervention and subsequent prevention of adulthood comorbidities.

Metabolic Syndrome in Psoriasis Is Associated With Upregulation of CXCL16 on Monocytes and a Dysbalance in Innate Lymphoid Cells

Psoriasis is frequently associated with the metabolic syndrome and occurs more often in obese individuals. In order to understand innate immune mechanisms mediating this inflammatory pattern we investigated expression of the chemokine and lipid scavenger receptor CXCL16 in patients with psoriasis and associated comorbidities. CXCL16 expression was enhanced on all monocyte subsets in psoriatic patients compared with healthy controls and positively correlated with psoriasis activity and severity index, body mass index and the risk for cardiovascular disease indicated by PROCAM score. The intensity of CXCL16 expression on monocytes further correlated with their capability to phagocytose oxidized LDL indicating the possibility to transform into foam cells in atherosclerotic plaques. Patients with psoriasis and atherosclerosis or obesity displayed elevated numbers of innate lymphoid cells in blood with specific increase of the IFN-γ or IL-17 producing ILC1 and ILC3 subpopulations. The expression of the CXCL16 receptor, CXCR6, was increased in ILCs and co-expressed with CCR6 but not CCR7 indicating their migratory potential to psoriatic skin or adipose tissue that is characterized by strong CXCL16 and CCL20 expression. This hypothesis was supported by the finding that the percentage of CXCR6 expressing ILCs was alleviated in blood of psoriatic patients. Together these data link a strong expression of CXCL16 to metabolic syndrome in psoriasis and indicate a possible link to ILC activation and tissue distribution in obese psoriatic patients. These data contribute to the understanding of the complex interaction of innate immunity and metabolic state in psoriasis.

Fecal microbiome alterations in pediatric patients with short bowel syndrome receiving a rotating cycle of gastrointestinal prophylactic antibiotics

BACKGROUND

Pediatric patients with short bowel syndrome (SBS) are at risk of developing small intestinal bacterial overgrowth (SIBO). Prevention of SIBO using cyclic enteric antibiotics has been implemented to control the balance in microbial ecosystems, although its effectiveness has not been well studied.

PURPOSE

This study aimed to explore the change in the gut microbial composition in SBS patients during cyclic antibiotic phases and antibiotic-free period, and to compare the microbiota composition between healthy controls and SBS patients.

METHOD

SBS patients taking oral metronidazole alternating with trimethoprim-sulfamethoxazole (TMP-SMT) and antibiotic-free conditions as a '10-day cyclic protocol' were involved in fecal microbiome study using Illumina 16S sequencing.

RESULTS

When healthy control possessed the majority of Bacteroidetes spp. (54%) and Firmicutes spp. (33%), the microbial composition in SBS patients especially Firmicutes spp. and Proteobacteria spp. was prominently changed in each phase of treatment. In antibiotic-free period, SBS patients displayed 49% Firmicutes and 36% Proteobacteria. However, higher Proteobacteria than Firmicutes were detected at the commencement of metronidazole (58% versus 33%). Similarly, 56% Proteobacteria and 27% Firmicutes were found during TMP-SMT. Escherichia coli increased prominently during the antibiotic periods.

CONCLUSION

Prophylactic antibiotics change the gut microbiota composition in an unfavorable direction, especially when repeatedly used for a long period. This practice should be reconsidered.

LEVEL OF EVIDENCE

III.

Adipose-Derived Exosomes as Possible Players in the Development of Insulin Resistance

Adipose tissue (AT) is an endocrine organ involved in the management of energy metabolism via secretion of adipokines, hormones, and recently described secretory microvesicles, i.e., exosomes. Exosomes are rich in possible biologically active factors such as proteins, lipids, and RNA. The secretory function of adipose tissue is affected by pathological processes. One of the most important of these is obesity, which triggers adipose tissue inflammation and adversely affects the release of beneficial adipokines. Both processes may lead to further AT dysfunction, contributing to changes in whole-body metabolism and, subsequently, to insulin resistance. According to recent data, changes within the production, release, and content of exosomes produced by AT may be essential to understand the role of adipose tissue in the development of metabolic disorders. In this review, we summarize actual knowledge about the possible role of AT-derived exosomes in the development of insulin resistance, highlighting methodological challenges and potential gains resulting from exosome studies.

Caulerpa lentillifera (Sea Grapes) Improves Cardiovascular and Metabolic Health of Rats with Diet-Induced Metabolic Syndrome

Caulerpa lentillifera (sea grapes) is widely consumed in South-East Asia as a low-energy food with high contents of vitamins and minerals. This study investigated dried sea grapes containing 16.6% insoluble fibre commercially produced in Vietnam as an intervention. We hypothesised that insoluble fibre is the primary metabolite that will reverse diet-induced metabolic syndrome. Male Wistar rats (n = 48) were randomly allocated to four groups in a 16 week protocol. Two groups were fed either corn starch (C) or high-carbohydrate, high-fat (H) diets for the full 16 weeks. The other two groups received C and H diets for eight weeks and then received C. lentillifera added to these diets for the final eight weeks (CCL and HCL, respectively). High-carbohydrate, high-fat diet-fed rats developed obesity, hypertension, dyslipidaemia, fatty liver disease and increased left ventricular collagen deposition. C. lentillifera supplementation in HCL rats decreased body weight, systolic blood pressure, plasma concentrations of total cholesterol and non-esterified fatty acids, inflammatory cells in heart and liver, and visceral adiposity. The Firmicutes to Bacteroidetes ratio decreased in the gut microbiota of HCL rats. Therefore, C. lentillifera attenuated cardiovascular and metabolic symptoms of metabolic syndrome in rats, possibly by preventing infiltration of inflammatory cells together with modulating gut microbiota.

Absence of neurotensin attenuates intestinal dysbiosis and inflammation by maintaining Mmp7/α-defensin axis in diet-induced obese mice

We previously reported that high levels of plasma neurotensin (NT), a gut hormone released from enteroendocrine cells of the small bowel, contribute to obesity and comorbid conditions. Gut microbiota has been implicated in the obesity development. Paneth cells are critical in maintaining gut microbiota composition and homeostasis by releasing antimicrobial proteins including α-defensins. The purpose of our current study was to determine the possible role of NT in gut microbiota composition and α-defensin gene expression associated with obesity. Here we show that the ratio of Firmicutes/Bacteroidetes (F/B ratio) and intestinal proinflammatory cytokines is significantly increased in NT+/+ mice fed with a high-fat diet (HFD) which were improved in NT-deficient mice. HFD disrupted the intestinal Mmp7/α-defensin axis, which was completely prevented in NT-/- mice. In addition, NT treatment inhibited DEFA5 expression and concurrent NF-κB activity, which was blocked by a pan PKC inhibitor (Gö6983) or an inhibitor for atypical PKCs (CRT0066854). More importantly, the shRNA-mediated knockdown of atypical PKCτ reversed NT-attenuated DEFA5 expression and increased NF-κB activity. NT contributes to the HFD-induced disruption of gut microbiota composition and α-defensin expression. PKCτ/λ plays a central role in NT-mediated α-defensin gene expression which might be mediated through the inhibition of NF-κB signaling pathways in Paneth cells.

Analysis of the percentages of monocyte subsets and ILC2s, their relationships with metabolic variables and response to hypocaloric restriction in obesity

PURPOSE

Obesity results from excess energy intake over expenditure and is characterized by chronic low-grade inflammation involving circulating monocytes (Mo) and group 2 innate lymphoid cells (ILC2s) imbalance. We analyzed circulating Mo subsets and ILC2s percentages and β2-adrenergic receptor (β2AR) expression in lean and obese subjects, and the possible effect of hypocaloric restriction on these innate immune cells.

METHODS

In 139 individuals aged 45 to 57 years, classified in 74 lean individuals (>18.9kg/m2 BMI <24.9kg/m2) and 65 with obesity (n = 65), we collected fasting blood samples to detect Mo subsets, ILC2s number, and β2AR expression by flow cytometry. Lipids, insulin, leptin, and acylated-ghrelin concentrations were quantified. Resting energy expenditure (REE) was estimated by indirect calorimetry. These measurements were repeated in obese subjects after 7-weeks of hypocaloric restriction.

RESULTS

Non-classical monocytes (NCM) and β2AR expression on intermediate Mo (IM) were increased in obese individuals (p<0.001, in both cases), whereas the percent of ILC2s was decreased (p<0.0001). Stepwise regression analysis showed significantly negative associations of ILC2s with caloric intake, β2AR expression on IM with REE, but a positive relationship between NCM and HOMA-IR. Caloric restriction allowed a significant diminution of NCM and the β2AR expression on IM, as well as, an increase in the percent of classical Mo (CM), and ILC2s. ΔREE was related to ΔCD16+/CD16- ratio.

CONCLUSIONS

These findings show that in obesity occur changes in NCM, ILC2s and β2AR expression, which contribute to the low-grade inflammation linked to obesity and might revert with caloric restriction.

Immunometabolism in type 2 diabetes mellitus: tissue-specific interactions

The immune system is frequently described in the context of its protective function against infections and its role in the development of autoimmunity. For more than a decade, the interactions between the immune system and metabolic processes have been reported, in effect creating a new research field, termed immunometabolism. Accumulating evidence supports the hypothesis that the development of metabolic diseases may be linked to inflammation, and reflects, in some cases, the activation of immune responses. As such, immunometabolism is defined by 1) inflammation as a driver of disease development and/or 2) metabolic processes stimulating cellular differentiation of the immune components. In this review, the main factors capable of altering the immuno-metabolic communication leading to the development and establishment of obesity and diabetes are comprehensively presented. Tissue-specific immune responses suggested to impair metabolic processes are described, with an emphasis on the adipose tissue, gut, muscle, liver, and pancreas.

Spatial and Temporal Mapping of Human Innate Lymphoid Cells Reveals Elements of Tissue Specificity

Innate lymphoid cells (ILC) play critical roles in regulating immunity, inflammation, and tissue homeostasis in mice. However, limited access to non-diseased human tissues has hindered efforts to profile anatomically-distinct ILCs in humans. Through flow cytometric and transcriptional analyses of lymphoid, mucosal, and metabolic tissues from previously healthy human organ donors, here we have provided a map of human ILC heterogeneity across multiple anatomical sites. In contrast to mice, human ILCs are less strictly compartmentalized and tissue localization selectively impacts ILC distribution in a subset-dependent manner. Tissue-specific distinctions are particularly apparent for ILC1 populations, whose distribution was markedly altered in obesity or aging. Furthermore, the degree of ILC1 population heterogeneity differed substantially in lymphoid versus mucosal sites. Together, these analyses comprise a comprehensive characterization of the spatial and temporal dynamics regulating the anatomical distribution, subset heterogeneity, and functional potential of ILCs in non-diseased human tissues.