ILC2 Diversity, Location, and Function in Pulmonary Disease

Regulation of the human cathelicidin antimicrobial peptide gene by 1α,25-dihydroxyvitamin D3 in primary immune cells

Heat-killed Lactobacillus casei strain lactic acid bacteria DK128 was investigated as potential probiotics to determine its antiviral effects on influenza virus. Intranasal pretreatment of mice with heat-killed DK128 resulted in the recruitment of various innate immune cells into the airways, conferring broad protection against lethal infection with H1, H3, and H5 subtype influenza viruses, preventing body weight loss, and lowering lung viral loads. The protection against lethal infection as a result of killed-DK128 pretreatment was correlated with significantly reduced infiltrates of natural killer cells, neutrophils, and monocytes as well as with increased alveolar macrophage populations. Mice with killed-DK128-mediated protection against H3N2 primary infection effectively developed heterosubtypic adaptive immunity to H1N1 pandemic virus. Further mechanistic studies using various knockout mouse models discovered that B cells but not CD4 and CD8 T cells were absolutely required for heat-killed DK128-mediated protection. Therefore, this study provides evidence that heat-killed DK128 can be developed as beneficial probiotics and that the cross-talk between innate and adaptive immune cells is playing an essential role in conferring influenza antiviral immunity.

Who am I? (re-)Defining fibroblast identity and immunological function in the age of bioinformatics.

Hyper-IgE syndrome (HIES) is a very rare primary immune deficiency characterized by elevated serum IgE levels, recurrent bacterial infections, chronic dermatitis, and connective tissue abnormalities. Autosomal dominant (AD) HIES involves a mutation in signal transducer and activator of transcription 3 (STAT3) that leads to an impaired TH17 response. STAT3 signaling is also involved in the function of RORγt+ type 3 innate lymphoid cells (ILC3s) and RORγt+TH17 cells. The aim of this study was to investigate the role of innate immune cells such as innate lymphoid cells (ILCs), granulocytes, and monocytes in a patient with HIES. Peripheral blood mononuclear cells (PBMCs) from a patient with HIES and three age-matched healthy controls were obtained for the analysis of the innate and adaptive immune cells. The frequencies of ILCs in PBMCs were lower in the patient with HIES than in the controls. Moreover, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-17A produced by ILC3s in PBMCs were lower in the patient with HIES than the controls. Compared with the controls, classical monocytes (CD14+CD16low), which have a high antimicrobial capability, were also lower in the patient with HIES, while non-classical monocytes (CD14lowCD16+) as well as intermediate monocytes (CD14+CD16intermediate) were higher. Taken together, these results indicate that the impaired immune defense against pathogenic microbes in the patient with HIES might be partially explained by functional defects in ILC3s and inflammatory monocytes.

Recent studies have highlighted an emerging role for neuro-immune interactions in mediating allergic diseases. Allergies are caused by an overactive immune response to a foreign antigen. The peripheral sensory and autonomic nervous system densely innervates mucosal barrier tissues including the skin, respiratory tract and gastrointestinal (GI) tract that are exposed to allergens. It is increasingly clear that neurons actively communicate with and regulate the function of mast cells, dendritic cells, eosinophils, Th2 cells and type 2 innate lymphoid cells in allergic inflammation. Several mechanisms of cross-talk between the two systems have been uncovered, with potential anatomical specificity. Immune cells release inflammatory mediators including histamine, cytokines or neurotrophins that directly activate sensory neurons to mediate itch in the skin, cough/sneezing and bronchoconstriction in the respiratory tract and motility in the GI tract. Upon activation, these peripheral neurons release neurotransmitters and neuropeptides that directly act on immune cells to modulate their function. Somatosensory and visceral afferent neurons release neuropeptides including calcitonin gene-related peptide, substance P and vasoactive intestinal peptide, which can act on type 2 immune cells to drive allergic inflammation. Autonomic neurons release neurotransmitters including acetylcholine and noradrenaline that signal to both innate and adaptive immune cells. Neuro-immune signaling may play a central role in the physiopathology of allergic diseases including atopic dermatitis, asthma and food allergies. Therefore, getting a better understanding of these cellular and molecular neuro-immune interactions could lead to novel therapeutic approaches to treat allergic diseases.

Introduction.Considering the development of technologies and techniques, it is highly relevant today to continue studying the features of interaction of drugs developed and introduced into clinical practice in the 1960s and 1980s with the elements of the immune system located in the mucosa, since many of these drugs have local dosage forms. One such drug is benzidamine hydrochloride, registered as a nonsteroidal anti-inflammatory drug with extended pharmacodynamic properties.Objective. To evaluate the effect of benzidamine hydrochloride preparation on the cells of innate and acquired immunity located in the mucosa in an in vitro model.Materials and Methods. Cell fractions of neutrophils isolated from patients with infectious inflammation were used in the study. Sterile isolated neutrophils from the venous blood of patients were transferred into RPMI-1640 medium, where the investigated pharmacological drug was added, and incubation with cells was performed. Fluorescence microscopy was used to detect and count neutrophil extracellular traps. Cell fractions of lymphocytes isolated from patients with infectious inflammation were also used in the study. A commercial drug containing benzidamine hydrochloride, Tantum Verde (Angelini Pharma S.p.a., Italy), was used in the study.Results and discussion. Benzidamine causes significant inhibition of neutrophil extracellular trap formation. This suggests that at the beginning of application the drug enhances the antimicrobial response of the body, and then as the concentration decreases it demonstrates classic anti-inflammatory properties. The drug also enhances the neutrophil extracellular trap structure. The total number of B-lymphocytes tends to normalize under the effect of benzidamine. These data allow us to conclude about the ability of the drug to attenuate the severity of the inflammatory process, apparently by inhibiting the action of inflammatory cytokines.Conclusion.In the course of the in vitro study it was shown that benzidamine hydrochloride (Tantum Verde) has immunomodulatory properties against innate immunity cells – neutrophils, and its anti-inflammatory properties against adaptive immunity cells – lymphocytes – were confirmed.

Population ageing is accelerating worldwide. As per the WHO, the world's population over 60 years will double by 2050 with 80% living in low and middle income countries. The elderly are highly susceptible to complex age-related-diseases, which represent more economic burden on the medical care systems. Thus, the UN has announced (2020)(2021)(2022)(2023)(2024)(2025)(2026)(2027)(2028)(2029)(2030) as the decade of healthy aging in alignment with the last ten years of the SDGs. Despite the presence of different therapeutic strategies, many diseases are spreading in the elderly and are accompanied by therapy resistance. As the age progresses, the immune system losses its proper functional balance, protection against pathogens and homeostatic properties in a condition called inflammaging. The Inflammaging is characterized by chronic low-grade inflammation and tissue damage development, which leads to immunesenescence defined as the decline in immune cell function. Moreover, there is an ongoing wave of research supporting the therapeutic role of lifestyle and pharmacological interventions in rejuvenating aged immune system to promote healthy ageing. In this Research Topic, we have compiled research articles contributing to our understanding of disruption of immune system related to immunesenescence and associated diseases.features related to neurocryptococcosis infection. Cryptococcus neoformans (C. Neoformans andC. gattii) infectious disease of central nervous system (CNS) increases in older adults. The authors demonstrated the immunesenscence as the putative cause of the increased susceptibility to infections in older people. This increase incidence of infection was attributed to the enhanced pro-inflammatory activity of macrophage M1 cells, increased production of Th2 cells and their cytokines, impaired inflammatory response of neutrophils and increased IFN-I mediated neuroinflammatory status related to inflammaging. Dissecting these underlying molecular mechanisms of immunesenescence impact on neurocryptococcosis infection improves understanding of new approaches for prevention and recognition of neurocryptococcosis in older adults.Immune exhaustion shares overlapping features with immunesenescence; Surendar et al. showed a unique signature of the immune exhaustion in osteomyelitis (OMS). By the detailed enumeration of innate and adaptive immune cells, and their markers, they found increased anti-inflammatory pattern. This pattern was evidenced by increased immune exhaustion phenotype and immune regulatory cells, in addition to decreased immune activation markers along with pronounced involvement of the Tfh memory B cell axis. Together, the study suggested immune modulating therapy as a promising alternative against the OMS infection to dampen the microbial evasion mechanisms in the current era of increased antibiotic resistance.Other diseases associated with immune features that are common in immunesenescence are also addressed in this topic such as, non-alcoholic fatty liver disease (NAFLD) and Aspergillus fumigatus keratitis. The elderly usually suffer from the NAFLD complications more than the young people. Guo et al. reviewed the advances of the cutting-edge technologies such as, single-cell RNA sequencing (scRNA seq) and time-of-flight mass spectrometry flow cytometry, etc … in identification of the innate and adaptive immunological mechanisms involved in the NAFLD pathology. They improved the understanding of the accumulation and activation molecular mechanisms of immune cells in NAFLD. Senescent microenvironment is characterized by accumulation of innate immune cells, especially macrophage. Guibo et al. studied the molecular mechanisms driving the polarization of macrophages in Aspergillus fumigatus infection. The study presented the Dectin-1 as an indispensable player in inflammatory macrophage polarization in the antifungal innate immunity through the MAPK signaling pathway in fungal keratitis.Highlighting the mechanisms involved in immunesenescence will improve the understanding of the development, interpretation, diagnosis or manipulation of its associated diseases. The four articles published in this research topic have contributed to address the updates and recent advances in immunesenescence microenvironment. We believe the outcomes of these research groups also suggested potential markers and therapeutic targets combatting immunesenscence.

Chapter 8 - Innate lymphoid cells in autoimmune diseases

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative disorders of the central nervous system (CNS). Increasing evidence supports the view that dysfunction of innate immune cells initiated by accumulated and misfolded proteins plays essential roles in the pathogenesis and progression of these diseases. The TLR family was found to be involved in the regulation of microglial function in the pathogenesis and progression of AD or PD, making it as double-edged sword in these diseases. Altered function of peripheral innate immune cells was found in AD and PD and thus contributed to the development and progression of AD and PD. Alteration of different subsets of T cells was found in the peripheral blood and CNS in AD and PD. The CNS-infiltrating T cells can exert both neuroprotective and neurotoxic effects in the pathogenesis and progression. Here, we review recent evidences for the roles of innate and adaptive immune cells in the pathogenesis and progression of AD and PD.

The vertebrate immune system comprises both adaptive and innate immune cells with distinct functions during the resolution of inflammation and wound healing after tissue injury. Recent evidence implicates a requirement for innate immune cells from the myeloid lineage during the early stages of limb regeneration in the Mexican axolotl. Understanding the functions of innate and adaptive immune cells in the axolotl has been hampered by a lack of approaches to isolate and analyze these cells. Here we describe a protocol to isolate myeloid cells from the regenerating axolotl limb that incorporates intravenous delivery of physiological labels. In addition we provide a protocol to enrich for leukocytes in the peripheral blood. These protocols produce single-cell suspensions that can be analyzed using flow cytometry or sorted into specific subsets using fluorescent-activated cell sorting (FACS). FACS is a routine approach to sort cells based on their physical characteristics as well as their cell surface antigen repertoire. Isolated cell populations can then be analyzed in a wide range of downstream assays to facilitate a greater understanding of leukocyte biology in the axolotl.

Osteoporosis or porous bone disorder is the result of an imbalance in an otherwise highly balanced physiological process known as ‘bone remodeling’. The immune system is intricately involved in bone physiology as well as pathologies. Inflammatory diseases are often correlated with osteoporosis. Inflammatory mediators such as reactive oxygen species (ROS), and pro-inflammatory cytokines and chemokines directly or indirectly act on the bone cells and play a role in the pathogenesis of osteoporosis. Recently, Srivastava et al. (Srivastava RK, Dar HY, Mishra PK. Immunoporosis: Immunology of Osteoporosis-Role of T Cells. Frontiers in immunology. 2018;9:657) have coined the term “immunoporosis” to emphasize the role of immune cells in the pathology of osteoporosis. Accumulated pieces of evidence suggest both innate and adaptive immune cells contribute to osteoporosis. However, innate cells are the major effectors of inflammation. They sense various triggers to inflammation such as pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), cellular stress, etc., thus producing pro-inflammatory mediators that play a critical role in the pathogenesis of osteoporosis. In this review, we have discussed the role of the innate immune cells in great detail and divided these cells into different sections in a systemic manner. In the beginning, we talked about cells of the myeloid lineage, including macrophages, monocytes, and dendritic cells. This group of cells explicitly influences the skeletal system by the action of production of pro-inflammatory cytokines and can transdifferentiate into osteoclast. Other cells of the myeloid lineage, such as neutrophils, eosinophils, and mast cells, largely impact osteoporosis via the production of pro-inflammatory cytokines. Further, we talked about the cells of the lymphoid lineage, including natural killer cells and innate lymphoid cells, which share innate-like properties and play a role in osteoporosis. In addition to various innate immune cells, we also discussed the impact of classical pro-inflammatory cytokines on osteoporosis. We also highlighted the studies regarding the impact of physiological and metabolic changes in the body, which results in chronic inflammatory conditions such as ageing, ultimately triggering osteoporosis.

Type 2 immune responses are critical for host defense, mediate allergy and Th2-high asthma. The transcription factor, promyelocytic leukemia zinc finger (PLZF), has emerged as a significant regulator of type 2 inflammation in the lung; however, its exact mechanism remains unclear. In this review, we summarized recent findings regarding the ability of PLZF to control the development and function of innate lymphoid cells (ILCs), iNKT cells, memory T cells, basophils, and other immune cells that drive type 2 responses. We discussed the important role of PLZF in the pathogenesis of Th2-high asthma. Collectively, prior studies have revealed the critical role of PLZF in the regulation of innate and adaptive immune cells involved in type 2 inflammation in the lung. Therefore, targeting PLZF signaling represents a promising therapeutic approach to suppress Th2-high asthma.

Immune cell activation is a stringently regulated process, as exaggerated innate and adaptive immune responses can lead to autoinflammatory and autoimmune diseases. Perhaps the best-characterized molecular pathway promoting cell activation is the nuclear factor-κB (NF-κB) signaling pathway. Stimulation of this pathway leads to transcription of numerous pro-inflammatory and cell-survival genes. Several mechanisms tightly control NF-κB activity, including the key regulatory zinc finger (de)ubiquitinating enzyme A20/tumor necrosis factor α-induced protein 3 (TNFAIP3). Single nucleotide polymorphisms (SNPs) in the vicinity of the TNFAIP3 gene are associated with a spectrum of chronic systemic inflammatory diseases, indicative of its clinical relevance. Mice harboring targeted cell-specific deletions of the Tnfaip3 gene in innate immune cells such as macrophages spontaneously develop autoinflammatory disease. When immune cells involved in the adaptive immune response, such as dendritic cells or B-cells, are targeted for A20/TNFAIP3 deletion, mice develop spontaneous inflammation that resembles human autoimmune disease. Therefore, more knowledge on A20/TNFAIP3 function in cells of the immune system is beneficial in our understanding of autoinflammation and autoimmunity. Using the aforementioned mouse models, novel A20/TNFAIP3 functions have recently been described including control of necroptosis and inflammasome activity. In this review, we discuss the function of the A20/TNFAIP3 enzyme and its critical role in various innate and adaptive immune cells. Finally, we discuss the latest findings on TNFAIP3 SNPs in human autoinflammatory and autoimmune diseases and address that genotyping of TNFAIP3 SNPs may guide treatment decisions.

Innate Immune System for Diagnostics and Therapy: Progress in Fundamental Knowledge and Clinical Application

Clinical tools that measure changes in immune cell metabolism would improve the diagnosis and treatment of immune dysfunction. PET, utilizing probes for specific metabolic processes, detects regions of immune activation in vivo. In this study we investigated the immune cell specificity of PET probes for two different metabolic pathways: [18F]-2-fluorodeoxyglucose ([18F]-FDG) for glycolysis and [18F]-2-fluoro-D-(arabinofuranosyl)cytosine ([18F]-FAC) for deoxycytidine salvage. We isolated innate and adaptive immune cells from tissues of mice challenged with a retrovirus-induced sarcoma and measured their ability to accumulate FDG and FAC. We determined that the two probes had distinct patterns of accumulation: FDG accumulated to the highest levels in innate immune cells, while FAC accumulated predominantly in CD8+ T cells in a manner that correlated with cellular proliferation. This study demonstrates that innate and adaptive cell types differ in glycolytic and deoxycytidine salvage demands during an immune response and that these differential metabolic requirements can be detected with specific PET probes. Our findings have implications for the interpretation of clinical PET scans that use [18F]-FDG or [18F]-FAC to assess immune function in vivo and suggest potential applications of metabolic PET to monitor the effects of targeted immune modulation.