Paeoniflorin ameliorates chronic colitis via the DR3 signaling pathway in group 3 innate lymphoid cells

Inhibiting the death receptor 3(DR3)signaling pathway in group 3 innate lymphoid cells(ILC3s)presents a promising approach for promoting mucosal repair in individuals with ulcerative colitis(UC).Paeoniflorin,a prominent component of Paeonia lactiflora Pall.,has demonstrated the ability to restore barrier function in UC mice,but the precise mechanism remains unclear.In this study,we aimed to delve into whether paeoniflorin may promote intestinal mucosal repair in chronic colitis by inhibiting DR3 signaling in ILC3s.C57BL/6 mice were subjected to random allocation into 7 distinct groups,namely the control group,the 2%dextran sodium sulfate(DSS)group,the paeoniflorin groups(25,50,and 100 mg/kg),the anti-tumor necrosis factor-like ligand 1A(anti-TL1A)antibody group,and the IgG group.We detected the expression of DR3 signaling pathway proteins and the proportion of ILC3s in the mouse colon using Western blot and flow cytometry,respectively.Meanwhile,DR3-overexpressing MNK-3 cells and 2%DSS-induced Rag1^(-/-)mice were used for verification.The results showed that paeoniflorin alleviated DSS-induced chronic colitis and repaired the intestinal mucosal barrier.Simultaneously,paeoniflorin inhibited the DR3 signaling pathway in ILC3s and regulated the content of cytokines(interleukin-17A,granulocyte-macrophage colony stimulating factor,and interleukin-22).Alternatively,paeoniflorin directly inhibited the DR3 signaling pathway in ILC3s to repair mucosal damage independently of the adaptive immune system.We additionally confirmed that paeoniflorin-conditioned medium(CM)restored the expression of tight junctions in Caco-2 cells via coculture.In conclusion,paeoniflorin ameliorates chronic colitis by enhancing the intestinal barrier in an ILC3-dependent manner,and its mechanism is associated with the inhibition of the DR3 signaling pathway.

Innate lymphoid cells in tissue homeostasis and diseases

Innate lymphoid cells(ILCs) are the most recently discovered family of innate immune cells. They are a part of the innate immune system, but develop from the lymphoid lineage. They lack pattern-recognition receptors and rearranged receptors, and therefore cannot directly mediate antigen specific responses. The progenitors specifically associated with the ILCs lineage have been uncovered, enabling the distinction between ILCs and natural killer cells. Based on the requirement of specific transcription factors and their patterns of cytokine production, ILCs are categorized into three subsets(ILC1, ILC2 and ILC3). First observed in mucosal surfaces, these cell populations interact with hematopoietic and non-hematopoietic cells throughout the body during homeostasis and diseases, promoting immunity, commensal microbiota tolerance, tissue repair and inflammation. Over the last 8 years, ILCs came into the spotlight as an essential cell type able to integrate diverse host immune responses. Recently, it became known that ILC subsets play a key role in immune responses at barrier surfaces, interacting with the microbiota, nutrients and metabolites. Since the liver receives the venous blood directly from the intestinal vein, the intestine and liver are essential to maintain tolerance and can rapidly respond to infections or tissue damage. Therefore, in this review, we discuss recent findings regarding ILC functions in homeostasis and disease, with a focus on the intestine and liver.

The origin and role of innate lymphoid cells in the lung

Innate lymphoid cells(ILCs),a newly identified member of the lymphoid population,play a critical role in the transition from innate to adaptive immunity in host defense.ILCs are important in mucosal barrier immunity,tissue homeostasis,and immune regulation throughout the body.Significant alterations in ILC responses in lung diseases have been observed and reported.Emerging evidence has shown that ILCs are importantly involved in the pathogenesis and development of a variety of lung diseases,i.e.,helminth infections,allergic airway inflammation,and airway hyper-responsiveness.However,as a tissue-resident cell population,the role of ILCs in the lung remains poorly characterized.In this review,we discuss the role of ILCs in lung diseases,the mechanisms underlying the ILCmediated regulation of immunity,and the therapeutic potential of modulating ILC responses.

Mahuang Xixin Fuzi decoction protects against ovalbumin-induced allergic rhinitis by inhibiting type 2 innate lymphoid cells in mice

Objective:As a traditional herbal formula,Mahuang Xixin Fuzi decoction(MXFD)has been used to treat allergic rhinitis(AR).It regulates the transcription factor GATA3 in T cells,blocks Th2 skewing and rebalances the Th1/Th2 immunity.Type 2 innate lymphoid cells(ILC2s)are closely associated with GATA3.However,it remains unknown whether ILC2s could be one mechanism through which MXFD acts.We sought to elucidate the efficacy and mechanism of action of this decoction in AR treatment.Methods:Forty C57BL/6J female mice were equally divided into control,model,loratadine-and MXFDtreated groups in random.AR was induced by ovalbumin(OVA),and then treatment with loratadine or MXFD was administered.AR scores were evaluated and compared before and after treatment.Pathological changes in the nasal mucosa and lung were observed using hematoxylin-eosin staining of tissue samples.Activation of ILC2 in nasal mucosa was assessed by immunofluorescence and quantitative polymerase chain reaction analysis.ILC2 cell count in lungs was measured by flow cytometry and levels of interleukin-(IL)4,IL-5 and IL-13 in serum were detected by ELISA.Results:The decoction alleviated the symptoms of AR in mice,improved vascular congestion and expansion,glandular hyperplasia and inflammatory cell infiltration in mouse nasal mucosa and slowly improved the interstitial pneumonia and lesions.Meanwhile,MXFD reduced the number and percentage of ILC2s in the nasal mucosa and lungs,downregulated the expression of GATA3 mRNA and RORa mRNA,and reduced the related inflammatory cytokine levels,including IL-4,IL-5 and IL-13.Conclusion:These data suggest that inhibition of ILC2s by MXFD may be an important means by which to treat AR.

AB003.Local group 2 innate lymphoid cells promote corneal regeneration after epithelial abrasion

Corneal injuries and infections are the leading cause of blindness worldwide.Thus,understanding the mechanisms that control healing of the damaged cornea is critical for the development of new therapies to promptly restore vision.Innate lymphoid cells(ILCs)are a recently identified heterogeneous cell population that has been reported to orchestrate immunity and promote tissue repair in the lungs and skin after injury.However,whether ILCs can modulate the repair process in the cornea remains poorly understood.We identified a population of cornea-resident group 2 ILCs(ILC2s)in mice that express CD127,T1/ST2,CD90,and cKit.This cell population was relatively rare in corneas at a steady state but increased after corneal epithelial abrasion.Moreover,ILC2s were maintained and expanded locally at a steady state and after wounding.Depletion of this cell population caused a delay in corneal wound healing,whereas supplementation of ILC2s through adoptive transfer partially restored the healing process.Further investigation revealed that IL-25,IL-33,and thymic stromal lymphopoietin had critical roles in corneal ILC2 responses and that CCR2-corneal macrophages were an important producer of IL-33 in the cornea.Together,these results reveal the critical role of cornea-resident ILC2s in the restoration of corneal epithelial integrity after acute injury and suggest that ILC2 responses depend on local induction of IL-25,IL-33,and thymic stromal lymphopoietin.

Ambiguous roles of innate lymphoid cells in chronic development of liver diseases

Innate lymphoid cells(ILCs) are defined as a distinct arm of innate immunity. According to their profile of secreted cytokines and lineage-specific transcriptional factors, ILCs can be categorized into the following three groups: group 1 ILCs(including natural killer(NK) cells and ILC1 s) are dependent on T-bet and can produce interferon-γ; group 2 ILCs(ILC2 s) are dependent on GATA3 and can produce type 2 cytokines, including interleukin(IL)-5 and IL-13; and, group 3 ILCs(including lymphoid tissue-like cells and ILC3 s) are dependent on RORγt and can produce IL-22 and IL-17. Collaborative with adaptive immunity, ILCs are highly reactive innate effectors that promptly orchestrate immunity, inflammation and tissue repair. Dysregulation of ILCs might result in inflammatory disorders. Evidence regarding the function of intrahepatic ILCs is emerging from longitudinal studies of inflammatory liver diseases wherein they exert both physiological and pathological functions, including immune homeostasis, defenses and surveillance. Their overall effect on the liver depends on the balance of their proinflammatory and antiinflammatory populations, specific microenvironment and stages of immune responses. Here, we review the current data about ILCs in chronic liver disease progression, to reveal their roles in different stages as well as to discuss their therapeutic potency as intervention targets.

Evaluation of the Aurora Kinase Inhibitor, ZM447439, in Canine Malignant Lymphoid Cells <i>in Vitro</i>

Aurora kinases play an important role in the cell cycle. These enzymes help establish mitotic spindles by directing centrosome duplication and separation and by regulating the spindle assembly checkpoint thereby helping control cytokinesis. An over-expression of aurora kinases has been reported in a variety of human tumors. In this study, we identified the expression of aurora-A and aurora-B kinases in canine malignant lymphoid cells. We also evaluated the effects of the aurora kinase inhibitor (ZM447439), and found that this inhibitor decreases cell viability, increases DNA content change, and leads to apoptosis in canine B- and T-cell lymphoid cell lines. The lymphotoxicity induced by ZM447439 in these canine lymphoid cell lines suggests that further in vivo evaluation of aurora kinase inhibitors as a potential treatment for canine malignant lymphoid tumors is warranted.

The protective roles of integrin α4β7 and Amphiregulin-expressing innate lymphoid cells in lupus nephritis

Type 2 innate lymphoid cells (ILC2s) have emerged as key regulators of the immune response in renal inflammatory diseases such as lupus nephritis. However, the mechanisms underlying ILC2 adhesion and migration in the kidney remain poorly understood. Here, we revealed the critical role of integrin α4β7 in mediating renal ILC2 adhesion and function. We found that integrin α4β7 enables the retention of ILC2s in the kidney by binding to VCAM-1, E-cadherin, or fibronectin on structural cells. Moreover, integrin α4β7 knockdown reduced the production of the reparative cytokine amphiregulin (Areg) by ILC2s. In lupus nephritis, TLR7/9 signaling within the kidney microenvironment downregulates integrin α4β7 expression, leading to decreased Areg production and promoting the egress of ILC2s. Notably, IL-33 treatment upregulated integrin α4β7 and Areg expression in ILC2s, thereby enhancing survival and reducing inflammation in lupus nephritis. Together, these findings highlight the potential of targeting ILC2 adhesion as a therapeutic strategy for autoimmune kidney diseases.

Guards at the gate： physiological and pathological roles of tissue-resident innate lymphoid cells in the lung

The lung Is an Important open organ and the primary site of respiration. Many life.threatening diseases develop in the lung, e.g., pneumonia, asthma, chronic obstructive pulmonary diseases （COPDs）, pulmonary fibrosis, and lung cancer. In the lung, innate Immunity serves as the frontline in both anti-irritant response and anti-tumor defense and is also critical for mucosal homeostasis; thus, it plays an important role In containing these pul- monary diseases. Innate lymphoid cells （ILCs）, charac. terized by their strict tissue residence and distinct function in the mucosa, are attracting Increased atten. tion In innate Immunity. Upon sensing the danger slg- nals from damaged epithelium, ILCs activate, proliferate, and release numerous cytoklnes with specific local functions; they also participate in mucosal immune- surveillance, Immune-regulation, and homeostasis. However, when their functions become uncontrolled, ILCs can enhance pathological states and Induce dis- eases. In this review, we discuss the physiologicel and pathological functions of ILC subsets 1 to 3 in the lung, and how the pathogenic environment affects the func- tion and plasticity of ILCs.

Type 3 innate lymphoid cell-derived lymphotoxin prevents microbiota-dependent inflammation

Splenomegaly is a well-known phenomenon typically associated with inflammation.However,the underlying cause of this phenotype has not been well characterized.Furthermore,the splenomegaly phenotype seen in lymphotoxin(LT)signaling-deficient mice is characterized by increased numbers of splenocytes and splenic neutrophils.Splenomegaly,as well as the related phenotype of increased lymphocyte counts in non-lymphoid tissues,is thought to result from the absence of secondary lymphoid tissues in LT-deficient mice.We now present evidence that mice deficient in LTα1β2 or LTβR develop splenomegaly and increased numbers of lymphocytes in non-lymphoid tissues in a microbiota-dependent manner.Antibiotic administration to LTα1β2-or LTβR-deficient mice reduces splenomegaly.Furthermore,re-derived germ-free Ltbr−/−mice do not exhibit splenomegaly or increased inflammation in non-lymphoid tissues compared to specific pathogen-free Ltbr−/−mice.By using various LTβ-and LTβR-conditional knockout mice,we demonstrate that retinoic acid-related orphan receptorγT-positive type 3 innate lymphoid cells provide the required active LT signaling to prevent the development of splenomegaly.Thus,this study demonstrates the importance of LT-mediated immune responses for the prevention of splenomegaly and systemic inflammation induced by microbiota.

The transcription factor RelB restrains group 2 innate lymphoid cells and type 2 immune pathology in vivo

The exact relationships between group 2 innate lymphoid cells(ILC2s)and Th2 cells in type 2 pathology,as well as the mechanisms that restrain the responses of these cells,remain poorly defined.Here we examined the roles of ILC2s and Th2 cells in type 2 lung pathology in vivo using germline and conditional fie/b-deficient mice.We found that mice with germline deletion of Relb^(-/-)spontaneously developed prominent type 2 pathology in the lung,which contrasted sharply with mice with T-cell-specific Relb deletion(Relb^(f/f)Cd4-Cre),which were healthy with no observed autoimmune pathology.We also found that in contrast to wild-type B6 mice,Rel6-defident mice showed markedly expanded ILC2s but not ILC1s or ILC3s.Moreover,adoptive transfer of naive CD4^(+)T cells into Rag1^(-/-)Relb^(-/-)hosts induced prominent type 2 lung pathology,which was inhibited by depletion of ILC2s.Mechanistically,we showed that Relb deletion led to enhanced expression of Bcl11b,a key transcription factor for ILC2s.We concluded that RelB plays a critical role in restraining ILC2s,primarily by suppressing Bcl11b activity,and consequently inhibits type 2 lung pathology in vivo.

Allium tuberosum alleviates pulmonary inflammation by inhibiting activation of innate lymphoid cells and modulating intestinal microbiota in asthmatic mice

Objective:This study tests whether long-term intake of Allium tuberosum(AT)can alleviate pulmonary inflammation in ovalbumin(OVA)-induced asthmatic mice and evaluates its effect on the intestinal microbiota and innate lymphoid cells(ILCs).Methods:BALB/c mice were divided into three groups:phosphate buffer saline,OVA and OVA+AT.The asthmatic murine model was established by sensitization and challenge of OVA in the OVA and OVA+AT groups.AT was given to the OVA+AT group by oral gavage from day 0 to day 27.On day 28,mice were sacrificed.Histopathological evaluation of lung tissue was performed using hematoxylin and eosin,and periodic acid-Schiff staining.The levels of IgE in serum,interleukin-5(IL-5)and IL-13 from bronchoalveolar lavage fluid(BALF)were measured by enzyme-linked immunosorbent assay.The ILCs from the lung and gut were detected by flow cytometry.16 S ribosomal DNA sequencing was used to analyze the differences in colon microbiota among treatment groups.Results:We found that long-term intake of AT decreased the number of inflammatory cells from BALF,reduced the levels of IL-5 and IL-13 in BALF,and IgE level in serum,and rescued pulmonary histopathology with less mucus secretion in asthmatic mice.16 S ribosomal DNA sequencing results showed that AT strongly affected the colonic bacteria community structure in asthmatic mice,although it had no significant effect on the abundance and diversity of the microbiota.Ruminococcaceae and Desulfovibrionaceae were identified as two biomarkers of the treatment effect of AT.Moreover,AT decreased the numbers of ILCs in both the lung and gut of asthmatic mice.Conclusion:The results indicate that AT inhibits pulmonary inflammation,possibly by impeding the activation of ILCs and adjusting the homeostasis of gut microbiota in asthmatic mice.

Transcriptional regulators dictate innate lymphoid cell fates

Research on innate lymphoid cells （ILC） has recently been a fast paced topic of immunological research. As ILCs are able to produce signature Th cytokine, ILCs have garnered considerable attention and have been described to represent the innate counterpart of the CD4＋ T helper （Th） cells. The development and function of ILCs are precisely regulated by a network of crucial tran- scription factors, which are also involved in the devel- opment or differentiation of conventional natural killer （cNK） cells and T cells. In this review, we will summarize the key transcriptional regulators and their functions through each phases of ILC development. With the phase of ILC lineage commitment, we will focus in particular on the roles of the transcription regulators Id2 and GATA-3, which in collaboration with other transcriptional factors, are critically involved in the generation of ILC fate determined progenitors. Once an ILC lineage has been established, several other transcription factors are required for the specification and functional regulation of distinct mature ILC subsets. Thus, a comprehensive understanding of the interactions and regulatory mech- anisms mediated by these transcription factors will help us to further understand how ILCs exert their helper-like functions and bridge the innate and adaptive immunity.

Sensing of physiological regulators by innate lymphoid cells

Maintenance of homeostasis and immune protection rely on the coordinated action of different physiological systems.Bidirectional communication between the immune system and physiological systems is required to sense and restore any disruption of equilibrium.Recent transcriptomic analyses of innate lymphoid cells(ILCs)from different tissues have revealed that ILCs express a large array of receptors involved in the recognition of neuropeptides,hormones and metabolic signals.ILCs rapidly secrete effector cytokines that are central in the development and activation of early immune responses,but they also constitutively secrete mediators that are important for tissue homeostasis.To achieve these functions effectively,ILCs integrate intrinsic and extrinsic signals that modulate their constitutive and induced activity.Disruption of the regulation of ILCs by physiological regulators leads to altered immune responses with harmful consequences for the organism.An understanding of these complex interactions between the immune system and physiological mediators is crucial to decipher the events leading to the protective versus pathological effects of these cells.

NKR-P1B expression in gut-associated innate lymphoid cells is required for the control of gastrointestinal tract infections

Helper-type innate lymphoid cells(ILC)play an important role in intestinal homeostasis.Members of the NKR-P1 gene family are expressed in various innate immune cells,including natural killer(NK)cells,and their cognate Clr ligand family members are expressed in various specialized tissues,including the intestinal epithelium,where they may play an important role in mucosalassociated innate immune responses.In this study,we show that the inhibitory NKR-P1B receptor,but not the Ly49 receptor,is expressed in gut-resident NK cells,ILC,and a subset ofγδT cells in a tissue-specific manner.ILC3 cells constitute the predominant cell subset expressing NKR-P1B in the gut lamina propria.The known NKR-P1B ligand Clr-b is broadly expressed in gut-associated cells of hematopoietic origin.The genetic deletion of NKR-P1B results in a higher frequency and number of ILC3 andγδT cells in the gut lamina propria.However,the function of gut-resident ILC3,NK,andγδT cells in NKR-P1B-deficient mice is impaired during gastrointestinal tract infection by Citrobacter rodentium or Salmonella typhimurium,resulting in increased systemic bacterial dissemination in NKR-P1B-deficient mice.Our findings highlight the role of the NKR-P1B:Clr-b recognition system in the modulation of intestinal innate immune cell functions.

Establishment and function of tissue-residenl nnate lymphoid cells in the skin

Innate lymphoid cells （ILCs） are a newly classified family of immune cells of the lymphoid lineage. While they could be found in both lymphoid organs and non-lym-phoid tissues, ILCs are preferentially enriched in barrier tissues such as the skin, intestine, and lung where they could play important roles in maintenance of tissue integrity and function and protection against assaults of foreign agents. On the other hand, dysregulated activation of ILCs could contribute to tissue inflammatory diseases. In spite of recent progress towards understanding roles of ILCs in the health and disease, mech-anisms regulating specific establishment, activation, and function of ILCs in barrier tissues are still poorly understood. We herein review the up-to-date understanding of tissue-specific relevance of ILCs. Particularly we will focus on resident ILCs of the skin, the outmost barrier tissue critical in protection against various foreign hazardous agents and maintenance of thermal and water balance. In addition, we will discuss remaining outstanding questions yet to be addressed.

Reciprocal costimulatory molecules control the activation of mucosal type 3 innate lymphoid cells during engagement with B cells

Innate lymphoid cells(ILCs)are the counterpart of T helper cells in the innate immune system and share multiple phenotypes with T helper cells.Inducible T-cell costimulator(ICOS)is recognized on T cells and participates in T-cell activation and T and B-cell engagement in lymphoid tissues.However,the role of ICOS in ILC3s and ILC3-involved interactions with the immune microenvironment remains unclear.Here,we found that ICOS expression on human ILC3s was correlated with the activated state of ILC3s.ICOS costimulation enhanced the survival,proliferation,and capacity of ILC3s to produce cytokines(IL-22,IL-17A,IFN-γ,TNF,and GM-CSF).Via synergistic effects of ICOS and CD40 signaling,B cells promoted ILC3 functions,and ILC3-induced T-cellindependent B-cell IgA and IgM secretion primarily required CD40 signaling.Hence,ICOS is essential for the nonredundant role of ILC3s and their interaction with adjacent B cells.

Innate lymphoid cells and gastrointestinal disease

Innate lymphoid cells(ILCs)are a group of innate immune cells,which constitute the first line of defense in the immune system,together with skin and mucous membrane.ILCs also play an important role in maintaining the homeostasis of the body,particularly in the complex and diverse environment of the intestine.ILCs respond to different microenvironments,maintaining homeostasis directly or indirectly through cytokines.As a result,ILCs,with complex and pleiotropic characteristics,are associated with many gastrointestinal diseases.Their ability of transition among those subgroups makes them function as both promoting and inhibiting cells,thus affecting homeostasis and disease progressing to either alleviation or deterioration.With these special characteristics,ILCs theoretically can be used in the new generation of immunotherapy as an alternative and supplement to current tumor therapy.Our review summarizes the characteristics of ILCs with respect to category,function,and the relationship with intestinal homeostasis and gastrointestinal diseases.In addition,potential tumor immunotherapies involving ILCs are also discussed to shed light on the perspectives of immunotherapy.

Innate Lymphoid Cells in Normal Pregnancy and Pregnancy-Related Diseases

Innate lymphoid cells(ILCs)are a group of lymphocytes without diversified antigen receptors encoded by gene rearrangement on T and B cells.ILCs,which are tissue-resident innate immune cells,expressed particularly in the mucosa or the barrier surface,contribute to the formation of lymphoid organs,the maintenance of tissue homeostasis,and the regulation of antimicrobial defenses.It has been recently reported that ILCs were enriched at the maternal-fetal interface.During a successful pregnancy,the maternal immune system must tolerate a fetus as an allograft.With the new defined of ILCs,a number of studies have shown that three types of ILCs are involved in embryonic development and pregnancy maintenance as well as the occurrence and development of pregnancy-related complications.This article reviews the types and roles of ILCs in normal pregnancy and pregnancy-related diseases.

ASSAYS AND LIGHT MICROSCOPIC MORPHOLOGY FOR ERRFC AND ANAE POSITIVE CELLS OF LYMPHOID CELLS DURING YOLK-SAC HEMOPOIESIS IN CHICK EMBRYO

I.INTRODUCTION The theory about 3 stages of embryonic hemopoiesis has been accepted by most investigators. Yolk sac is the first hemopoietic organ at the early stage of embryonic.