Bronchial epithelial transcriptomics and experimental validation reveal asthma severity-related neutrophilc signatures and potential treatments

Airway epithelial transcriptome analysis of asthma patients with different severity was used to disentangle the immune infiltration mechanisms affecting asthma exacerbation, which may be advantageous to asthma treatment. Here we introduce various bioinformatics methods and develop two models: an OVA/CFA-induced neutrophil asthma mouse model and an LPS-induced human bronchial epithelial cell damage model. Our objective is to investigate the molecular mechanisms, potential targets, and therapeutic strategies associated with asthma severity. Multiple bioinformatics methods identify meaningful differences in the degree of neutrophil infiltration in asthma patients with different severity. Then, PTPRC, TLR2, MMP9, FCGR3B, TYROBP, CXCR1, S100A12, FPR1, CCR1 and CXCR2 are identified as the hub genes. Furthermore, the mRNA expression of 10 hub genes is determined in vivo and in vitro models. Reperixin is identified as a pivotal drug targeting CXCR1, CXCR2 and MMP9. We further test the potential efficiency of Reperixin in 16HBE cells, and conclude that Reperixin can attenuate LPS-induced cellular damage and inhibit the expression of them. In this study, we successfully identify and validate several neutrophilic signatures and targets associated with asthma severity. Notably, Reperixin displays the ability to target CXCR1, CXCR2, and MMP9, suggesting its potential therapeutic value for managing deteriorating asthma.

Themis2 regulates natural killer cell memory function and formation

Immunological memory is a hallmark of the adaptive immune system. Although natural killer (NK) cells are innate immune cells important for the immediate host defence, they can differentiate into memory NK cells. The molecular mechanisms controlling this differentiation are yet to be fully elucidated. Here we identify the scaffold protein Themis2 as a critical regulator of memory NK cell differentiation and function. Themis2-deficient NK cells expressing Ly49H, an activating NK receptor for the mouse cytomegalovirus (MCMV) antigen m157, show enhanced differentiation into memory NK cells and augment host protection against MCMV infection. Themis2 inhibits the effector function of NK cells after stimulation of Ly49H and multiple activating NK receptors, though not specific to memory NK cells. Mechanistically, Themis2 suppresses Ly49H signalling by attenuating ZAP70/Syk phosphorylation, and it also translocates to the nucleus, where it promotes Zfp740-mediated repression to regulate the persistence of memory NK cells. Zfp740 deficiency increases the number of memory NK cells and enhances the effector function of memory NK cells, which further supports the relevance of the Themis2-Zfp740 pathway. In conclusion, our study shows that Themis2 quantitatively and qualitatively regulates NK cell memory formation.

CD95L/FasL and TRAIL in tumour surveillance and cancer therapy

The membrane-bound death ligands CD95L/FasL and TRAIL, which activate the corresponding death receptors CD95/Fas, TRAILR1 and TRAILR2, induce apoptosis in many tumour cells, but can also elicit an inflammatory response. This chapter focuses on the relevance of CD95L/FasL and TRAIL for the tumour surveillance function of natural killer cells and cytotoxic T-cells and discuss current concepts of utilizing these ligands in tumour therapy.

Evolution of effectors and receptors of innate immunity

The bony fishes are derived from one of the earliest divergent vertebrate lineages to have both innate and acquired immune systems. They are considered by some to be an ideal model to study the underpinnings of immune systems precisely because of their phylogenetic position and the fact that their adaptive immune systems have not been elaborated to the extent seen in mammals. By the same token, examination of innate immune systems in invertebrates and early chordates can provide insight into how homologous systems operate in fish and higher vertebrates. Herein, we provide an overview of the molecular evidence that we hope helps clarify the evolutionary relationships of innate immune molecules identified in bony fishes. The innate immune systems being considered include select chemokines (CC and CXC chemokines and their receptors), cytokines (IL-1, IL-8, interferons, TGF-beta, TNF-alpha), acute phase proteins (SAA, SAP, CRP, alpha2M, and the complement components--C3-C9, MASP, MBL, Bf), NK cell receptors, and molecules upstream and downstream of the Toll signaling pathways.

Altered Donor and Recipient Ly49+ NK Cell Subsets in Allogeneic H-2d → H-2b and H-2b → H-2d Bone Marrow Chimeras

NK cells reject non-self hematopoietic bone marrow (BM) grafts via Ly49 receptor-mediated MHC class I-specific recognition and calibration of receptor expression levels. In this paper we investigated how Ly49+ subset frequencies were regulated dependent on MHC class I expression. The development of donor and host Ly49A+ (recognizes H-2Dd and H-2Dk ligands) and Ly49C/I+ (Ly49CBALB/c recognizes H-2Kb, H-2Kd, and H-2Dd, and Ly49CB6 recognizes only H-2Kb) NK cell frequencies were monitored for 120 days in murine-mixed allogeneic BM chimeras. C57BL/6 (H-2b) BM was transplanted into BALB/c (H-2d) mice and vice versa. Peripheral NK cell populations were examined every 5 days. Chimerism was found to be stable with 80–90% donor NK cells. In contrast to syngeneic controls reexpressing pretransplant patterns, donor and host NK cells revealed new and mainly reduced subset frequencies 55 days after allogeneic transplantation. Recipient NK cells acquired these later than donor NK cells. In H-2d → H-2b chimeras Ly49A+, Ly49C/I+, and Ly49A+/Ly49C/I+ proportions were mainly diminished upon interaction with cognate ligands. Also in H-2b → H-2d chimeras, Ly49A+ and Ly49A+/Ly49C/I+ subsets were reduced, but there was a transient normalization of Ly49C/I+ proportions in the noncognate host. After 120 days all subsets were reduced. Therefore, down-regulation of developing Ly49A+ and Ly49C/I+ chimeric NK cell frequencies by cognate ligands within 7–8 wk after BM transplantation may be important for successful engraftment.

Tolerance and Alloreactivity of the Ly49D Subset of Murine NK Cells

Class I-specific stimulatory and inhibitory receptors expressed by NK cell subsets contribute to the alloreactive potential of the self-tolerant murine NK cell repertoire. In this report, we have studied potential mechanisms of tolerance to the function of the positive signaling Ly49D receptor in mice that express one of its ligands, H2-Dd. Our results demonstrate that H2-Dd-expressing mice possess a large Ly49D+ subset of NK cells that is functionally capable of rejecting bone marrow cell (BMC) allografts in vivo and lysing allogeneic Con A lymphoblasts in vitro. Also, we show that the Ly49D receptor is responsible for the ability of H2b/d F1 hybrid mice to reject H2d/d parental BMC (hybrid resistance). Thus, deletion or anergy of Ly49D+ cells in H2-Dd+ hosts cannot explain self tolerance. Our functional studies revealed that coexpression of the Dd-specific Ly49A or Ly49G2 inhibitory receptors by Ly49D+ cells resulted in tolerance to Dd+ targets, while coexpression of Kb-specific inhibitory receptors Ly49C/I resulted in tolerance to Kb+ targets. Only in H2d/d cells did Ly49C/I dominantly inhibit Ly49D-Dd stimulation. This correlated with an increased mean fluorescence intensity of Ly49C expression, as well as an increased percentage of Ly49C+ cells in the Ly49D+A/G2− compartment. Therefore, we conclude that self tolerance of the Ly49D subset can be achieved through coexpression of a sufficient level of self-specific inhibitory receptors.

Diversity of NK Cell Receptor Repertoire in Adult and Neonatal Mice

Murine NK cytotoxicity is regulated by two families of MHC class I-specific receptors, namely Ly49 and CD94/NKG2. We developed a single-cell RT-PCR method to analyze expression of all known Ly49 and NKG2A genes in individual NK cells and determined the receptor repertoires of NK cells from adult and neonatal (1-wk-old) C57BL/6 mice. In adult mouse NK cells, up to six different receptors were coexpressed in random combinations. Of 62 NK cells examined, 42 different patterns of receptor expression were observed. Most of them expressed at least one Ly49, whereas NKG2A was detected in 32% of the cells. Over 75% of them expressed Ly49C, I, or NKG2A, which are thought to recognize self-class I MHC (H-2b). Coexpression of multiple Ly49 receptors and NKG2A was stochastic. In contrast, very few neonatal NK cells expressed any Ly49, but almost 60% of them expressed NKG2A. These results demonstrate that adult NK cells are quite heterogeneous and have diverse receptor repertoires. They also suggest that the expression of NKG2A precedes Ly49 expression in NK cell ontogeny, and NKG2A is a major inhibitory receptor in neonatal NK cells.

Mouse NKR-P1B, a Novel NK1.1 Antigen with Inhibitory Function

The mouse NK1.1 Ag originally defined as NK cell receptor (NKR)-P1C (CD161) mediates NK cell activation. Here, we show that another member of the mouse CD161 family, NKR-P1B, represents a novel NK1.1 Ag. In contrast to NKR-P1C, which functions as an activating receptor, NKR-P1B inhibits NK cell activation. Association of NKR-P1B with Src homology 2-containing protein tyrosine phosphatase-1 provides a molecular mechanism for this inhibition. The existence of these two NK1.1 Ags with opposite functions suggests a potential role for NKR-P1 molecules, such as those of the Ly-49 gene family, in regulating NK cell function.

Engagement of Natural Cytotoxicity Programs Regulates AP-1 Expression in the NKL Human NK Cell Line

NK cell cytotoxicity is a fast and efficient mechanism of target cell lysis. Using transcription analysis, such as multiplex messenger assays, we show here that natural cytotoxicity exerted by the human NKL cell line correlates with mRNA accumulation of very early activator protein (AP)-1 transcription factor genes such as JunB, FosB and c-Fos. In addition, DNA-binding activities of Jun-Fos heterodimers were observed by electrophoretic mobility shift assays during the course of natural cytotoxicity. Interaction between immunoglobulin-like transcript-2/leukocyte Ig-like receptor 1 on NKL cells and HLA-B27 on target cells leads to an impairment of NKL natural cytotoxicity, which correlates with an absence of JunB, FosB, and c-Fos transcription, as well as an absence of their DNA-binding activity. Our studies thus indicate that, despite the rapidity of NK cell-mediated lysis, AP-1 transcription factor is activated during the early stage of NK cell cytolytic programs and that engagement of NK cell inhibitory receptors for MHC class I molecules impairs the very early activation of AP-1.