Identifying changes in immune cells and constructing prognostic models using immune-related genes in post-burn immunosuppression

Background Burn patients are prone to infection as well as immunosuppression, which is a significant cause of death. Currently, there is a lack of prognostic biomarkers for immunosuppression in burn patients. This study was conducted to identify immune-related genes that are prognosis biomarkers in post-burn immunosuppression and potential targets for immunotherapy. Methods We downloaded the gene expression profiles and clinical data of 213 burn patients and 79 healthy samples from the Gene Expression Omnibus (GEO) database. Immune infiltration analysis was used to identify the proportion of circulating immune cells. Functional enrichment analyses were carried out to identify immune-related genes that were used to build miRNA-mRNA networks to screen key genes. Next, we carried out correlation analysis between immune cells and key genes that were then used to construct logistic regression models in GSE77791 and were validated in GSE19743. Finally, we determined the expression of key genes in burn patients using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Results A total of 745 differently expressed genes were screened out: 299 were up-regulated and 446 were down-regulated. The number of Th-cells (CD4+) decreased while neutrophils increased in burn patients. The enrichment analysis showed that down-regulated genes were enriched in the T-cell activation pathway, while up-regulated genes were enriched in neutrophil activation response in burn patients. We screened out key genes (NFATC2, RORA, and CAMK4) that could be regulated by miRNA. The expression of key genes was related to the proportion of Th-cells (CD4+) and survival, and was an excellent predictor of prognosis in burns with an area under the curve (AUC) value of 0.945. Finally, we determined that NFATC2, RORA, and CAMK4 were down-regulated in burn patients. Conclusion We found that NFATC2, RORA, and CAMK4 were likely prognostic biomarkers in post-burn immunosuppression and potential immunotherapeutic targets to convert Th-cell dysfunction.

Adaptive Immune System in Fish

The immune system of all jawed vertebrates is composed of two major subsystems, the innate (non-specific) and adaptive (specific) immune system. The innate immune system is the first to respond to infectious agents; however, it does not provide longlasting protection. The adaptive immune system is activated later and responds to pathogens with specificity and memory. The main components of the adaptive immune system, including T cell receptors (TCRs), major histocompatibility complex (MHC), immunoglobulins (Igs), and recombination-activating gene (RAG) arose in the first jawed fish (cartilaginous and teleost fish). This review explores and discusses components of the adaptive immune system in teleost fish and recent developments in comparative immunology. Similar to mammals, the adaptive immune system in teleost fish is divided into two components: cellular-mediated responses and humoralmediated responses. T cells, the principal elements of cellular-mediated adaptive immune responses, differentiate into effector helper T (Th) cells or effector cytotoxic T cells (CTLs). The central elements involved in the differentiation of Th subsets in mammals, cytokines and master transcription factors, have also been identified in teleost fish. In addition, each subset of Th cells, defined with a particular cytokine to control the immune responses, has been described in teleost fish. Similarly, to mammals, CTLs contribute to cellular cytotoxicity in teleost fish. B cells act as a central player in humoral-mediated adaptive immunity by producing opsonizing, neutralizing and complement-binding antibodies and inducing antibody-dependent cellular cytotoxicity (ADCC). Three classes of antibodies named IgM, IgD, and IgT/Z have been characterized in teleost fish. The presence of an adaptive immune system and consequent immune memory in teleost fish allows vaccination, the most appropriate method for disease control in aquaculture. Immunological studies in fish provide a comprehensive assessment of the fish immune system, which is crucial for understanding the evolution of the mammalian immune system.

Th22 and Tfh Cell Elevation Is Associated with Clinical Response of Photopheresis Therapy in Patients with Steroid-Refractory/ Resistant Graft-Versus-Host Disease (GvHD)

In patients with steroid-refractory/resistant graft-versus-host disease (GvHD), extracorporeal photopheresis (ECP) has been identified as a promising therapeutic strategy due to its safety profile and convincing clinical response rates. While previous studies have reported on the role of Th1, Th2 and Treg cells in ECP therapy, further comprehensive analysis of T helper cells is necessary to provide better understanding of the underlying mechanisms. In this study, we thus investigated the influence of long-term ECP treatment on both Th cells as well as on immune checkpoint molecules and apoptosis. Overall, we investigated 27 patients with GvHD treated by ECP therapy, containing 13 patients with acute GvHD and 14 patients with chronic GvHD. 10/13 (76.9%) of aGvHD and 9/14 (64.3%) of cGvHD patients clinically responded to ECP therapy. Three (23.1%) patients reached CR and seven (53.8%) patients achieved PR under ECP treatment in patients with aGvHD, while in patients with cGvHD CR was achieved in one (7.1%) and PR in eight (57.1%) patients. Stabilization of disease was observed in five (35.7%) patients. On an immunological level, aGvHD, cGvHD and healthy donors (HD) patients showed different profiles of Th populations. In GvHD patients, significantly higher levels for Th2 (aGvHD vs. HD: 36.26% vs. 13.88%, p = 0.014; cGvHD vs. HD: 30.71% vs. 13.88%, p = 0.026), Th17 (aGvHD vs. HD: 19.21% vs. 7.49%, p = 0.038), Th22 (aGvHD vs. HD: 1.22% vs. 0.11%，p = 0.011; cGvHD vs. HD: 0.64% vs. 0.11%, p = 0.012) and GM-CSF + Th cells (aGvHD vs. HD: 1.15% vs. 0.14%, p = 0.022; cGvHD vs. HD: 0.84% vs. 0.14%，p = 0.012) and clearly lower levels for T follicular helper (Tfh) cells including Th1- (aGvHD vs. HD: 0.37% vs. 2.04%, p = 0.002; cGvHD vs. HD: 1.28% vs. 2.04%, p = 0.03) and Th2-like cells (aGvHD vs. HD: 1.17% vs. 4.19%, p = 0.033) were observed in comparison to HDs. This suggests Th cells account for a crucial role in GvHD pathogenesis. ECP therapy was able to accelerate recovery of Tfh cells, including Th1- (Time point 1 vs. Time point 2 in aGvHD: 0.37% vs. 0.97%, p = 0.028), Th2- (T1 vs. T2 in aGvHD: 1.17% vs. 1.35%, p = 0.049; T1 vs. T2 in cGvHD: 2.08% vs. 3.15%, p = 0.048) and Th17-like Tfh cells (T1 vs. T2 in aGvHD: 1.82% vs. 2.70%, p = 0.034), facilitating immune reconstitution after allo-HSCT and thereby alleviating GvHD. Clinical response in aGvHD patients was strongly associated with elevation of Th22 cells by ECP therapy showing 51% upregulation (T1 vs. T2: 0.86% vs. 1.3%，p=0.007). In addition, we also found that the expression of the Fas receptor on effector T cells could be further upregulated with ECP treatment (T1 vs. T2 in cGvHD: 49.65% vs. 56.46%, p = 0.011), which increases the susceptibility of these effectors T cells to Fas-mediated apoptosis. This could lead to the elimination of these overactivated effector T cells and the perseverance of immunological tolerance by triggering activation-induced cell death. In addition, a reduction of Tim-3-expressing effector T cells, which are associated with the severity of GvHD, with ECP therapy (T1 vs. T2 for aGvHD: 18.09% vs. 15.10%, p = 0.044) was discovered. In conclusion, ECP therapy exerts immunomodulatory effects by promoting balanced immune reconstitution and inducing immune tolerance, making it an attractive and promising treatment option for patients with GvHD. Disclosures Schubert: Gilead: Consultancy. Hegenbart: Alnylam: Honoraria; Akcea: Honoraria; Janssen: Consultancy, Research Funding; Prothena: Research Funding; Pfizer: Consultancy, Honoraria. Schönland: Prothena: Honoraria, Other: Travel grants; Takeda: Honoraria, Other: Travel grants; Pfizer: Honoraria; Janssen: Honoraria, Other: Travel grants, Research Funding; Sanofi: Research Funding. Müller-Tidow: Pfizer: Research Funding; Bioline: Research Funding; Janssen: Consultancy, Research Funding. Dreger: Riemser: Consultancy, Research Funding, Speakers Bureau; Bluebird Bio: Consultancy; Roche: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; BMS: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Janssen: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau. Schmitt: MSD: Membership on an entity's Board of Directors or advisory committees; Hexal: Other: Travel grants, Research Funding; Kite Gilead: Other: Travel grants; TolerogenixX: Current holder of individual stocks in a privately-held company; Bluebird Bio: Other: Travel grants; Novartis: Other: Travel grants, Research Funding; Apogenix: Research Funding. Schmitt: Therakos/Mallinckrodt: Research Funding; TolerogenixX Ltd: Current Employment; Jazz Pharmaceuticals: Other: Travel grant; Hexal: Other: Travel grant.

The Study on the Regulation of Th Cells by MSCs Through the JAK-STAT Signaling Pathway to Protect Naturally Aged Sepsis Model Rats

Background: Sepsis is the leading cause of death among patients, especially elderly patients, in intensive care units worldwide. However, there is no effective treatment for sepsis in the aging population. Therefore, we designed such a study to confirm the protective effect of MSCs against sepsis in the elderly and to explore its mechanisms.Methods: In this study, we established a sepsis model using naturally aged SD rats and injected 5×106 umbilical cord-derived MSCs via the tail vein. Each group of rats was analyzed for survival, examined for biochemical parameters, stained for organ histology, and analyzed for the Th cell subpopulation ratio and inflammatory cytokine levels by flow cytometry. Western blotting was performed to detect the activity of the JAK-STAT signaling pathway. We designed in vitro experiments to confirm the regulatory role of MSCs, and verified the possible mechanism using JAK/STAT inhibitors. Results: The results revealed that the 72 h survival rate of sepsis rats treated with MSCs was significantly increased, organ damage and inflammatory infiltration were reduced, the levels of organ damage indicators were decreased, the ratios of Th1/Th2 and Th17/Treg in peripheral blood and spleen were significantly decreased, the levels of pro-inflammatory cytokines such as IL-6 were decreased, the levels of anti-inflammatory cytokines such as IL-10 were increased, and the levels of STAT1 and STAT3 phosphorylation were reduced. These results were validated in in vitro experiments. Conclusions: Therefore, this study confirms that MSCs can control the inflammatory response induced by sepsis by regulating Th cells and inflammatory factors, and that this leads to reduction of tissue damage, protection of organ functions and ultimately improvement of survival in aged sepsis model rats. Inhibition of the JAK-STAT signaling pathway may be an important mechanism for their action.

Targeting of Janus Kinases Limits Pro-Inflammatory but Also Immunosuppressive Circuits in the Crosstalk between Synovial Fibroblasts and Lymphocytes

Crosstalk between synovial fibroblasts (SF) and immune cells plays a central role in the development of rheumatoid arthritis (RA). Janus kinase inhibitors (JAKi) have proven efficacy in the treatment of RA, although clinical responses are heterogeneous. Currently, little is known regarding how JAKi affect pro- and anti-inflammatory circuits in the bidirectional interplay between SF and immune cells. Here, we examined the effects of tofacitinib, baricitinib and upadacitinib on crosstalk between SF and T or B lymphocytes in vitro and compared them with those of biologic disease modifying anti-rheumatic drugs (bDMARDs). JAKi dose-dependently suppressed cytokine secretion of T helper (Th) cells and decreased interleukin (IL)-6 and matrix metalloproteinase (MMP)3 secretion of SF stimulated by Th cells. Importantly, JAK inhibition attenuated the enhanced memory response of chronically stimulated SF. Vice versa, JAKi reduced the indoleamine-2,3-dioxygenase (IDO)1-mediated suppression of T cell-proliferation by SF. Remarkably, certain bDMARDs were as efficient as JAKi in suppressing the IL-6 and MMP3 secretion of SF stimulated by Th (adalimumab, secukinumab) or B cells (canakinumab) and combining bDMARDs with JAKi had synergistic effects. In conclusion, JAKi limit pro-inflammatory circuits in the crosstalk between SF and lymphocytes; however, they also weaken the immunosuppressive functions of SF. Both effects were dose-dependent and may contribute to heterogeneity in clinical response to treatment.

Granulocytic myeloid-derived suppressor cells inhibit T follicular helper cells during experimental Schistosoma japonicum infection

Background CD4+ T helper (Th) cells play critical roles in both host humoral and cellular immunity against parasitic infection and in the immunopathology of schistosomiasis. T follicular helper (Tfh) cells are a specialized subset of Th cells involved in immunity against infectious diseases. However, the role of Tfh cells in schistosome infection is not fully understood. In this study, the dynamics and roles of Tfh cell regulation were examined. We demonstrated that granulocytic myeloid-derived suppressor cells (G-MDSC) can suppress the proliferation of Tfh cells. Methods The levels of Tfh cells and two other Th cells (Th1, Th2) were quantitated at different Schistosoma japonicum infection times (0,3, 5, 8, 13 weeks) using flow cytometry. The proliferation of Tfh cells stimulated by soluble egg antigen (SEA) and soluble worm antigen (SWA) in vivo and in vitro were analyzed. Tfh cells were co-cultured with MDSC to detect the proliferation of Tfh cells labelled by 5(6)-carboxyfluorescein diacetate N-succinimidyl ester. We dynamically monitored the expression of programmed cell death protein 1 (PD-1) on the surface of Tfh cells and programmed cell death ligand 1 (PD-L1) on the surface of MDSC at different infection times (0, 3, 5, 8 weeks). Naïve CD4+ T cells (in Tfh cell differentiation) were co-cultured with G-MDSC or monocytic MDSC in the presence, or in the absence, of PD-L1 blocking antibody. Results The proportion of Tfh cells among CD4+ T cells increased gradually with time of S. japonicum infection, reaching a peak at 8 weeks, after which it decreased gradually. Both SEA and SWA caused an increase in Tfh cells in vitro and in vivo. It was found that MDSC can suppress the proliferation of Tfh cells. The expression of PD-1 on Tfh cells and PD-L1 from MDSC cells increased with prolongation of the infection cycle. G-MDSC might regulate Tfh cells through the PD-1/PD-L1 pathway. Conclusions The reported study not only reveals the dynamics of Tfh cell regulation during S. japonicum infection, but also provides evidence that G-MDSC may regulate Tfh cells by PD-1/PD-L1. This study provides strong evidence for the important role of Tfh cells in the immune response to S. japonicum infection. Graphical abstract

Abstract 26: IL-17 Causes Hypertension, Reduced Fetal Weight And Natural Killer Cell Activation In The Absence Of T Cells

Preeclampsia (PE) is characterized by new onset hypertension (HTN), intrauterine growth restriction (IUGR), multi-organ dysfunction, and is associated with increased inflammatory cytokines, such as interleukin 17 (IL-17). More recent studies demonstrate a role for mitochondrial (mt) dysfunction/mtROS in the pathogenesis of PE. Although we have shown T helper cells from a rat model of PE cause HTN and mt dysfunction the causative factors for mt dysfunction are still being identified. In addition, we have shown that IL-17 cause HTN, IUGR and activate natural killer (NK) cells, and cause mt dysfunction in pregnant Sprague Dawley rats. However, in our previous studies we couldn’t differentiate the effect of activated TH cells versus IL-17 to cause these characteristics of PE. The athymic nude rat model lacks mature T cells but does have other components of the immune system, and will thus allow us to examine the role of IL-17 in the absence of TH cells in the pathophysiology of PE. We hypothesize that in the absence of T cells IL-17 induces HTN, NK cell activation and IUGR which is associated with renal and placental mt dysfunction during pregnancy. To test our hypothesis, IL-17 (150 pg/day) was infused via osmotic minipumps inserted on gestation day (GD) 14. Blood pressure (MAP) and mt function were measured on GD19 and were compared to untreated pregnant (NP) athymic nude rats. In response to IL-17; MAP increased from 95±4mmHg in NP(n=6) to 115±2 in NP+IL-17(n=6) (p<0.001); pup weight decreased from 1.46±0.2 g in NP (n=6) to 0.98±0.07g in NP+IL-17 (n=6) (p<0.05); NK cell activation increased from 0±0 %lymphocytes in NP (n=3) to 0.4±0.1% lymphocytes in NP+IL-17 rats (n=6). Interestingly, placental mtROS reduced 54% fold compared to NP and renal mtROS reduced 51.2% compared to NP. ATP production increased from 15.53±1.6 pmol of O2/sec/mg in NP (n=3) to 105.5±91 pmol of O2/sec/mg in NP+IL-17 (n=3) in the placenta, and from 1196±460 pmol of O2/sec/mg in NP (n=4) to 2016±951 pmol of O2/sec/mg NP+IL17 (n=4) in the kidney. These results show that although IL-17 induces HTN, IUGR, and NK cell activation independent of T cells, T cells are necessary for reduced mitochondrial function observed in PE and in rat models of placental ischemia.

Chondrocytes from Osteoarthritis Patients Adopt Distinct Phenotypes in Response to Central TH1/TH2/TH17 Cytokines

Chronic low-grade inflammation plays a central role in the pathogenesis of osteoarthritis (OA), and several pro- and anti-inflammatory cytokines have been implicated to mediate and regulate this process. Out of these cytokines, particularly IFNγ, IL-1β, IL-4 and IL-17 are associated with different phenotypes of T helper (TH) cells and macrophages, both examples of cells known for great phenotypic and functional heterogeneity. Chondrocytes also display various phenotypic changes during the course of arthritis. We set out to study the hypothesis of whether chondrocytes might adopt polarized phenotypes analogous to TH cells and macrophages. We studied the effects of IFNγ, IL-1β, IL-4 and IL-17 on gene expression in OA chondrocytes with RNA-Seq. Chondrocytes were harvested from the cartilage of OA patients undergoing knee replacement surgery and then cultured with or without the cytokines for 24 h. Total RNA was isolated and sequenced, and GO (Gene Ontology) functional analysis was performed. We also separately investigated genes linked to OA in recent genome wide expression analysis (GWEA) studies. The expression of more than 2800 genes was significantly altered in chondrocytes treated with IL-1β [in the C(IL-1β) phenotype] with a fold change (FC) > 2.5 in either direction. These included a large number of genes associated with inflammation, cartilage degradation and attenuation of metabolic signaling. The profile of genes differentially affected by IFNγ (the C(IFNγ) phenotype) was relatively distinct from that of the C(IL-1β) phenotype and included several genes associated with antigen processing and presentation. The IL-17-induced C(IL-17) phenotype was characterized by the induction of a more limited set of proinflammatory factors compared to C(IL-1β) cells. The C(IL-4) phenotype induced by IL-4 displayed a differential expression of a rather small set of genes compared with control, primarily those associated with TGFβ signaling and the regulation of inflammation. In conclusion, our results show that OA chondrocytes can adopt diverse phenotypes partly analogously to TH cells and macrophages. This phenotypic plasticity may play a role in the pathogenesis of arthritis and open new therapeutic avenues for the development of disease-modifying treatments for (osteo)arthritis.

CD4 + T cells in inflammatory diseases : pathogenic T-helper cells and the CD69–Myl9 system

CD4 + T cells direct immune responses against infectious microorganisms but are also involved in the pathogenesis of inflammatory diseases. In the last two to three decades, various researchers have identified and characterized several functional CD4 + T cell subsets, including T-helper 1 (Th1), Th2, Th9 and Th17 cells and regulatory T (Treg) cells. In this mini-review, we introduce the concept of pathogenic Th cells that induce inflammatory diseases with a model of disease induction by a population of pathogenic Th cells; “pathogenic Th population disease-induction model”. We will focus on Th2 cells that induce allergic airway inflammation—pathogenic Th2 cells (Tpath2 cells)—and discuss the nature of Tpath2 cells that shape the pathology of chronic inflammatory diseases. Various Tpath2 cell subsets have been identified and their unique features are summarized in mouse and human systems. Second, we will discuss how Th cells migrate and are maintained in chronic inflammatory lesions. We propose a model known as the “CD69–Myl9 system”. CD69 is a cell surface molecule expressed on activated T cells and interaction with its ligand myosin light chain 9 (Myl9) is required for the induction of inflammatory diseases. Myl9 molecules in the small vessels of inflamed lungs may play a crucial role in the migration of activated T cells into inflammatory lesions. Emerging evidence may provide new insight into the pathogenesis of chronic inflammatory diseases and contribute to the development of new therapeutic strategies for intractable inflammatory disorders.