Recent studies have identified distinct subsets of innate lymphocytes, collectively called innate lymphoid cells (ILCs), which lack antigen receptor expression but produce various effector cytokines. ...Group 2 ILCs (ILC2s) respond to epithelial cell-derived cytokines such as interleukin (IL)-25, IL-33 and thymic stromal lymphopoietin (TSLP), produce large amounts of type 2 cytokines, and have a key role in anti-helminth innate immunity and in the pathophysiology of allergic inflammation. The reported phenotypic characteristics of mouse ILC2s vary, depending on the tissue source and preparation method. This protocol describes improved methods for tissue-specific isolation and analysis of mouse ILC2s of high purity and yield from fat tissue, lung, bronchoalveolar lavage fluid (BALF) and small intestine. These improved methods are the result of our thorough investigation of enzymes used for tissue digestion, methods for the elimination of undesired cells, and a combination of antibodies for the detection and isolation of ILC2s. In addition, this new protocol now enables the isolation of ILC2s of high yield, even from inflamed tissues. Depending on the tissue being analyzed, it takes ∼2-4 h for isolation and flow cytometric analysis of ILC2s from the various tissues of a single mouse and ∼4-8 h to sort purified ILC2s from pooled tissues of multiple mice.
Summary
Asthma is a complex heterogeneous disease of the airways characterized by lung inflammation, airway hyperreactivity (AHR), mucus overproduction, and remodeling of the airways. Group 2 innate ...lymphoid cells (ILC2s) play a crucial role in the initiation and propagation of type 2 inflammatory programs in allergic asthma models, independent of adaptive immunity. In response to allergen, helminths or viral infection, damaged airway epithelial cells secrete IL‐33, IL‐25, and thymic stromal lymphopoietin (TSLP), which activate ILC2s to produce type 2 cytokines such as IL‐5, IL‐13, and IL‐9. Furthermore, ILC2s coordinate a network of cellular responses and interact with numerous cell types to propagate the inflammatory response and repair lung damage. ILC2s display functional plasticity in distinct asthma phenotypes, enabling them to respond to very different immune microenvironments. Thus, in the context of non‐allergic asthma, triggered by exposure to environmental factors, ILC2s transdifferentiate to ILC1‐like cells and activate type 1 inflammatory programs in the lung. In this review, we summarize accumulating evidence on the heterogeneity, plasticity, regulatory mechanisms, and pleiotropic roles of ILC2s in allergic inflammation as well as mechanisms for their suppression in the airways.
Obesity is strongly and independently associated with an increased risk of severe illness and death from coronavirus disease 2019 (COVID-19). The pathophysiological changes that result from elevated ...body weight lead to metabolic dysfunction, chronic inflammation, impaired immunological responses, and multisystem disorders, which increase vulnerability to severe illness from COVID-19. While vaccination strategies are under way across the world, the second and third waves of the pandemic, along with the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains, continue to threaten the stability of medical systems worldwide. Furthermore, evidence from previous pandemics suggests that vaccines are less effective in obese individuals than in their healthy-weight counterparts over the long term. Therefore, a consideration of lifestyle changes that can boost metabolic health and immunity is critical to reduce the risk of complications and severe illness from viral infection. In this review, we discuss the potential mechanisms linking excess body weight with COVID-19 morbidity. We also present evidence that intermittent fasting (IF), a dietary program that has gained popularity in recent years, may be an effective strategy to improve metabolic health and immunity and thus reduce the impact of obesity on COVID-19 morbidity and mortality.
Obesity is a strong risk factor for severe illness and mortality from coronavirus disease 2019 (COVID-19) infection. Mechanisms linking obesity with severe COVID-19 include diabetes-associated hyperglycemia, inflammation, weakened immune function, and metabolic dysfunction.Obese populations have a known history of poor response to vaccination and it is unknown whether this will also affect their vaccine-induced immunity to COVID-19. Therefore, it is important to implement dietary and lifestyle changes that potentially boost metabolic and immune health to mitigate the impacts of COVID-19.Intermittent fasting (IF) is associated with weight loss, improved glucose homeostasis, metabolic health restoration, and strengthened immune responses.Amid COVID-19 lockdowns, which are associated with more-sedentary lifestyles, the incorporation of IF may be a practical way to curb unhealthy eating habits, maximize healthy lifestyles, and improve mood and emotional well-being.
Group 2 innate lymphoid cells (ILC2s) are abundant in non-lymphoid tissues and increase following infectious and inflammatory insults. In solid tumors, however, ILC2s constitute a relatively small ...proportion of immune cells. Here, we show, using melanoma as a model, that while the IL-33/IL C2/eosinophil axis suppresses tumor growth, tumor-derived lactate attenuates the function and survival of ILC2s. Melanomas with reduced lactate production (LDHAlow) are growth delayed and typified by an increased number of ILC2s compared with control tumors. Upon IL-33 stimulation, ILC2s accompanied by eosinophils more effectively restrain the growth of LDHAlow tumors than control melanomas. Furthermore, database analysis reveals a negative correlation between the expression of LDHA and markers associated with ILC2s and the association of high expression of IL33 and an eosinophil marker SIGLEC8 with better overall survival in human cutaneous melanoma patients. This work demonstrates that the balance between the IL-33/ILC2/eosinophil axis and lactate production by tumor cells regulates melanoma growth.
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•ILC2s are involved in eosinophil-associated antitumor responses in melanoma•Lactic acid inhibits function and decreases survival of ILC2s•Tumors with decreased lactic acid production exhibit increased infiltration of ILC2s
Wagner et al. demonstrate, using melanoma as a model, that group 2 innate lymphoid cells (ILC2s) activated by IL-33 potentiate the eosinophil-associated antitumor response. In contrast, lactate production by melanoma cells impairs function and survival of ILC2s, leading to an enhanced tumor growth.
Innate lymphoid cells (ILCs) are composed of three main subsets. In this issue of Immunity, Simoni et al. (2017) show using mass-cytometry that human ILCs are highly heterogeneous between individuals ...and tissues and lack a previously proposed helper-type ILC1 population.
Innate lymphoid cells (ILCs) are composed of three main subsets. Simoni et al. (2017) show using mass-cytometry that human ILCs are highly heterogeneous between individuals and tissues and lack a previously proposed helper-type ILC1 population.
Abstract
Group 2 innate lymphoid cells (ILC2s) are type 2 cytokine-producing cells that have important roles in helminth infection and allergic inflammation. ILC2s are tissue-resident cells, and ...their phenotypes and roles are regulated by tissue-specific environmental factors. While the role of ILC2s in the lung, intestine and bone marrow has been elucidated in many studies, their role in adipose tissues is still unclear. Here, we report on the role of ILC2-derived bone morphogenetic protein 7 (BMP7) in adipocyte differentiation and lipid accumulation. Co-culture of fat-derived ILC2s with pluripotent mesenchymal C3H10T1/2 cells and committed white preadipocyte 3T3-L1 cells resulted in their differentiation to adipocytes and induced lipid accumulation. Co-culture experiments using BMP7-deficient ILC2s revealed that BMP7, produced by ILC2s, induces differentiation into brown adipocytes. Our results demonstrate that BMP7, produced by ILC2s, affects adipocyte differentiation, particularly in brown adipocytes.
ILC2-derived BMP7 regulates adipogenesis
Obesity is associated with increased bone mineral density (BMD) but the mechanism for this is unclear. Serum levels of the adipokine adiponectin are inversely correlated with obesity, but results ...from studies on its relationship to bone mass are conflicting. The objective of this study was to compare bone mineral content (BMC), BMD and biomechanical strength properties of femur and lumbar vertebrae in 8- and 16-week old adiponectin transgenic mice (AdTg). These mice exhibit significantly elevated circulating adiponectin but have similar body weights compared to wild-type (WT) littermates that were used as controls. Female AdTg mice displayed significantly lower femur BMC at 8 and 16 weeks of age and femur neck peak load was significantly lower in 8-week old AdTg mice of both genders compared to controls. The peak load from compression testing of an individual lumbar vertebra was significantly lower in female AdTg mice compared to WT at 8 weeks, and this difference persisted at 16 weeks of age. In addition, lumbar vertebrae BMC was significantly lower in 16-week old male AdTg mice compared to WT although vertebra peak load was not different. Serum adiponectin levels were inversely correlated with femur BMC. In summary, elevated circulating adiponectin inhibits the acquisition of bone mass in growing mice and results in decreased biomechanical measures of functional strength that are surrogate measures of susceptibility to fractures. These results support a role for circulating adiponectin as a metabolic link that can explain, at least in part, the positive relationship between obesity and both bone mass and reduced susceptibility to fractures.
The increased prevalence of obesity and metabolic diseases has heightened interest in adipose tissue biology and its potential as a therapeutic target. To better understand cellular heterogeneity and ...complexity of white adipose tissue (WAT), we employed cytometry by time-of-flight (CyTOF) to characterize immune and stromal cells in visceral and subcutaneous WAT depots under normal and high-fat diet feeding, by quantifying the expression levels of 32 surface marker proteins. We observed comparable proportions of immune cells in two WAT depots under steady state, but depot-distinct subtypes of adipose precursor cells (APC), suggesting differences in their adipogenic and fibrogenic potential. Furthermore, in addition to pro-inflammatory immune cell shifts, significant pro-fibrotic changes were observed in APCs under high-fat diet, suggesting that APCs are early responders to dietary challenges. We propose CyTOF as a complementary and alternative tool to current high-throughput single-cell transcriptomic analyses to better understand the function and plasticity of adipose tissue.
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•Application of CyTOF for cellular characterization in two adipose depots•Adipose depot-distinct APC subpopulations•APCs are early responders under obesogenic conditions to regulate WAT fibrosis
Immunology; Cell biology; Specialized functions of cells
The aging of white adipose tissue (WAT) involves senescence of adipose stem and progenitor cells (ASPCs) and dysregulation of immune cell populations, serving as a major driver of age-associated ...adipose dysfunction and metabolic diseases. Conversely, the elimination of senescent ASPCs is associated with improvements in overall health. Intermittent fasting (IF), a dietary intervention that incorporates periodic cycles of fasting and refeeding, has been reported to promote weight loss and fat mass reduction and improve glucose and insulin homeostasis in both murine and human studies. While previous studies have assessed the effects of IF on obesity-associated metabolic dysfunction, few studies have examined the aging-specific changes to ASPCs and immune cell populations in WAT. Here, we show that IF in 18–20-month-old mice reduced senescent phenotypes of ASPCs and restored their adipogenic potential. Intriguingly, IF-treated mice exhibited an increase in adipose eosinophils, which has been reported to be associated with improved WAT homeostasis and immunological fitness in aged mice. The observed cellular and metabolic changes suggest that IF may be a feasible lifestyle regimen to reduce cellular senescence which could result in attenuation of downstream aging-induced WAT dysfunction and metabolic diseases.
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