Tc17, a unique subset of CD8 T cells that can protect against lethal influenza challenge

Maternal and neonatal outcomes and clinical laboratory testing of pregnant women with COVID-19 during the BA.5.2/BF.7 surge

The impact of COVID-19 on pregnant women and newborns continues to be a critical societal concern. However, the majority of research focuses on the disease resulting from the early pandemic variants, without sufficient study on the more recent BA.5.2/BF.7. We retrospectively recruited pregnant women giving birth during the surge of the BA.5.2/BF.7 and analysed the risk impact of COVID-19 on maternal and neonatal outcomes. Furthermore, subjects matched through propensity scores were used for the analysis of clinical laboratory tests. A total of 818 pregnant women were enrolled, among 276 (33.7%) were diagnosed with SARS-CoV-2 during childbirth. COVID-19 significantly increased the risk of a hospital length of stay equal to or greater than seven days and neonatal admission to the neonatal intensive care unit, with an aHR of 2.03 (95% CI, 1.22-3.38) and 1.51 (95% CI, 1.12-2.03), respectively. In the analysis of 462 matched subjects, it was found that subjects infected with SARS-CoV-2 tended slight leucopenia and coagulation abnormalities. We found that during the surge of the BA.5.2/BF.7, COVID-19 increased the risk of maternal and neonatal outcomes among Chinese pregnant women. This finding offers significant insights to guide clinical practices involving pregnant women infected with the recently emerged Omicron subvariants.

Generation of Broad Protection against Influenza with Di-Tyrosine-Cross-Linked M2e Nanoclusters

Tyrosine cross-linking has recently been used to produce nanoclusters (NCs) from peptides to enhance their immunogenicity. In this study, NCs were generated using the ectodomain of the ion channel Matrix 2 (M2e) protein, a conserved influenza surface antigen. The NCs were administered via intranasal (IN) or intramuscular (IM) routes in a mouse model in a prime-boost regimen in the presence of the adjuvant CpG. After boost, a significant increase in anti-M2e IgG and its subtypes was observed in the serum and lungs of mice vaccinated through the IM and IN routes; however, significant enhancement in anti-M2e IgA in lungs was observed only in the IN group. Analysis of cytokine concentrations in stimulated splenocyte cultures indicated a Th1/Th17-biased response. Mice were challenged with a lethal dose of A/California/07/2009 (H1N1pdm), A/Puerto Rico/08/1934 (H1N1), or A/Hong Kong/08/1968 (H3N2) strains. Mice that received M2e NCs + CpG were significantly protected against these strains and showed decreased lung viral titers compared with the naive mice and M2e NC-alone groups. The IN-vaccinated group showed superior protection against the H3N2 strain as compared to the IM group. This research extends our earlier efforts involving the tyrosine-based cross-linking method and highlights the potential of this technology in enhancing the immunogenicity of short peptide immunogens.

Downregulation of Mirlet7 miRNA family promotes Tc17 differentiation and emphysema via de-repression of RORγt

Environmental air irritants including nanosized carbon black (nCB) can drive systemic inflammation, promoting chronic obstructive pulmonary disease (COPD) and emphysema development. The let-7 microRNA (Mirlet7 miRNA) family is associated with IL-17-driven T cell inflammation, a canonical signature of lung inflammation. Recent evidence suggests the Mirlet7 family is downregulated in patients with COPD, however, whether this repression conveys a functional consequence on emphysema pathology has not been elucidated. Here, we show that overall expression of the Mirlet7 clusters, Mirlet7b/Mirlet7c2 and Mirlet7a1/Mirlet7f1/Mirlet7d, are reduced in the lungs and T cells of smokers with emphysema as well as in mice with cigarette smoke (CS)- or nCB-elicited emphysema. We demonstrate that loss of the Mirlet7b/Mirlet7c2 cluster in T cells predisposed mice to exaggerated CS- or nCB-elicited emphysema. Furthermore, ablation of the Mirlet7b/Mirlet7c2 cluster enhanced CD8+IL17a+ T cells (Tc17) formation in emphysema development in mice. Additionally, transgenic mice overexpressing Mirlet7g in T cells are resistant to Tc17 and CD4+IL17a+ T cells (Th17) development when exposed to nCB. Mechanistically, our findings reveal the master regulator of Tc17/Th17 differentiation, RAR-related orphan receptor gamma t (RORγt), as a direct target of Mirlet7 in T cells. Overall, our findings shed light on the Mirlet7/RORγt axis with Mirlet7 acting as a molecular brake in the generation of Tc17 cells and suggest a novel therapeutic approach for tempering the augmented IL-17-mediated response in emphysema.

Antibody Responses to Influenza Vaccination are Diminished in Patients With Inflammatory Bowel Disease on Infliximab or Tofacitinib

BACKGROUND AND AIMS

We sought to determine whether six commonly used immunosuppressive regimens were associated with lower antibody responses after seasonal influenza vaccination in patients with inflammatory bowel disease [IBD].

METHODS

We conducted a prospective study including 213 IBD patients and 53 healthy controls: 165 who had received seasonal influenza vaccine and 101 who had not. IBD medications included infliximab, thiopurines, infliximab and thiopurine combination therapy, ustekinumab, vedolizumab, or tofacitinib. The primary outcome was antibody responses against influenza/A H3N2 and A/H1N1, compared to controls, adjusting for age, prior vaccination, and interval between vaccination and sampling.

RESULTS

Lower antibody responses against influenza A/H3N2 were observed in patients on infliximab (geometric mean ratio 0.35 [95% confidence interval 0.20-0.60], p = 0.0002), combination of infliximab and thiopurine therapy (0.46 [0.27-0.79], p = 0.0050), and tofacitinib (0.28 [0.14-0.57], p = 0.0005) compared to controls. Lower antibody responses against A/H1N1 were observed in patients on infliximab (0.29 [0.15-0.56], p = 0.0003), combination of infliximab and thiopurine therapy (0.34 [0.17-0.66], p = 0.0016), thiopurine monotherapy (0.46 [0.24-0.87], p = 0.017), and tofacitinib (0.23 [0.10-0.56], p = 0.0013). Ustekinumab and vedolizumab were not associated with reduced antibody responses against A/H3N2 or A/H1N1. Vaccination in the previous year was associated with higher antibody responses to A/H3N2. Vaccine-induced anti-SARS-CoV-2 antibody concentration weakly correlated with antibodies against H3N2 [r = 0.27; p = 0.0004] and H1N1 [r = 0.33; p < 0.0001].

CONCLUSIONS

Vaccination in both the 2020-2021 and 2021-2022 seasons was associated with significantly higher antibody responses to influenza/A than no vaccination or vaccination in 2021-2022 alone. Infliximab and tofacitinib are associated with lower binding antibody responses to influenza/A, similar to COVID-19 vaccine-induced antibody responses.

Ex Pluribus Unum: The CD4 T Cell Response against Influenza A Virus

Current Influenza A virus (IAV) vaccines, which primarily aim to generate neutralizing antibodies against the major surface proteins of specific IAV strains predicted to circulate during the annual 'flu' season, are suboptimal and are characterized by relatively low annual vaccine efficacy. One approach to improve protection is for vaccines to also target the priming of virus-specific T cells that can protect against IAV even in the absence of preexisting neutralizing antibodies. CD4 T cells represent a particularly attractive target as they help to promote responses by other innate and adaptive lymphocyte populations and can also directly mediate potent effector functions. Studies in murine models of IAV infection have been instrumental in moving this goal forward. Here, we will review these findings, focusing on distinct subsets of CD4 T cell effectors that have been shown to impact outcomes. This body of work suggests that a major challenge for next-generation vaccines will be to prime a CD4 T cell population with the same spectrum of functional diversity generated by IAV infection. This goal is encapsulated well by the motto 'ex pluribus unum': that an optimal CD4 T cell response comprises many individual specialized subsets responding together.

Comparative single-cell transcriptomic profile of hybrid immunity induced by adenovirus vector-based COVID-19 vaccines

In this study, antibody response and a single-cell RNA-seq analysis were conducted on peripheral blood mononuclear cells from five different groups: naïve subjects vaccinated with AZD1222 (AZ) or Ad5-nCoV (Cso), individuals previously infected and later vaccinated (hybrid) with AZD1222 (AZ-hb) or Ad5-nCoV (Cso-hb), and those who were infected and had recovered from COVID-19 (Inf). The results showed that AZ induced more robust neutralizing antibody responses than Cso. The single-cell RNA data revealed a high frequency of memory B cells in the Cso and Cso-hb. In contrast, AZ and AZ-hb groups exhibited the highest proportion of activated naïve B cells expressing CXCR4. Transcriptomic analysis of CD4+ and CD8+ T cells demonstrated a heterogeneous response following vaccination, hybrid immunity, or natural infection. However, a single dose of Ad5-nCoV was sufficient to strongly activate CD4+ T cells (naïve and memory) expressing ANX1 and FOS, similar to the hybrid response observed with AZ. An interesting finding was the robust activation of a subset of CD8+ T cells expressing GZMB, GZMH, and IFNG genes in the Cso-hb group. Our findings suggest that both vaccines effectively stimulated the cellular immune response; however, the Ad5-nCoV induced a more robust CD8+ T-cell response in previously infected individuals.

Downregulation of Let-7 miRNA promotes Tc17 differentiation and emphysema via de-repression of RORγt

Environmental air irritants including nanosized carbon black (nCB) can drive systemic inflammation, promoting chronic obstructive pulmonary disease (COPD) and emphysema development. The let-7 family of miRNAs is associated with IL-17-driven T cell inflammation, a canonical signature of lung inflammation. Recent evidence suggests the let-7 family is downregulated in patients with COPD, however, whether this repression conveys a functional consequence on emphysema pathology has not been elucidated. Here we show that overall expression of the let-7 miRNA clusters, let-7b/let-7c2 and let-7a1/let-7f1/let-7d, are reduced in the lungs and T cells of smokers with emphysema as well as in mice with cigarette smoke (CS)- or nCB-elicited emphysema. We demonstrate that loss of the let-7b/let-7c2-cluster in T cells predisposed mice to exaggerated CS- or nCB-elicited emphysema. Furthermore, ablation of the let-7b/let-7c2-cluster enhanced CD8+IL17a+ T cells (Tc17) formation in emphysema development in mice. Additionally, transgenic mice overexpressing let-7 in T cells are resistant to Tc17 and CD4+IL17a+ T cells (Th17) development when exposed to nCB. Mechanistically, our findings reveal the master regulator of Tc17/Th17 differentiation, RAR-related orphan receptor gamma t (RORγt), as a direct target of let-7 miRNA in T cells. Overall, our findings shed light on the let-7/RORγt axis with let-7 acting as a molecular brake in the generation of Tc17 cells and suggests a novel therapeutic approach for tempering the augmented IL-17-mediated response in emphysema.

Non-fatal outcomes of COVID-19 disease in pediatric organ transplantation associates with down-regulation of senescence pathways

This is a cross-sectional study examining kinetics and durability of immune response in children with solid organ transplants (SOTs) who had COVID-19 disease between November 2020 through June 2022, who were followed for 60-days at a single transplant center. Blood was collected between 1-14 (acute infection), and 15-60 days of a positive PCR (convalescence). SOT children with peripheral blood mononuclear cells (PBMC) cryopreserved before 2019 were non-infected controls (ctrls). PBMCs stimulated with 15-mer peptides from spike protein and anti-CD49d/anti-CD28. Testing done included mass cytometry, mi-RNA sequencing with confirmatory qPCR. 38 children formed the study cohort, 10 in the acute phase and 8 in the convalescence phase. 20 subjects were non-infected controls. Two subjects had severe disease. Subjects in the acute and convalescent phases were different subjects. The median age and tacrolimus level at blood draw was not significantly different. There was no death, and no subject was lost to follow-up. During acute infection CD57 expression was low in NKT, Th17 effector memory, memory Treg, CD4-CD8-, and γδT cells (p = 0.01, p = 0.04, p = 0.03, p = 0.03, p = 0.004 respectively). The frequencies of NK and Th2 effector memory cells increased (p = 0.01, p = 0.02) during acute infection. Non-switched memory B and CD8 central memory cell frequencies were decreased during acute infection (p = 0.02; p = 0.02), but the decrease in CD8 central memory cells did not persist. CD4-CD8- and CD14 monocyte frequencies increased during recovery (p = 0.03; p = 0.007). Our observations suggest down regulation of CD57 with absence of NK cell contraction protect against death from COVID-19 disease in children with SOTs.

HELIOS-expressing human CD8 T cells exhibit limited effector functions

Introduction

The transcription factor HELIOS is primarily known for its expression in CD4 regulatory T cells, both in humans and mice. In mice, HELIOS is found in exhausted CD8 T cells. However, information on human HELIOS+ CD8 T cells is limited and conflicting.

Methods

In this study, we characterized by flow cytometry and transcriptomic analyses human HELIOS+ CD8 T cells.

Results

These T cells primarily consist of memory cells and constitute approximately 21% of blood CD8 T cells. In comparison with memory HELIOS- T-BEThigh CD8 T cells that displayed robust effector functions, the memory HELIOS+ T-BEThigh CD8 T cells produce lower amounts of IFN-γ and TNF-α and have a lower cytotoxic potential. We wondered if these cells participate in the immune response against viral antigens, but did not find HELIOS+ cells among CD8 T cells recognizing CMV peptides presented by HLA-A2 and HLA-B7. However, we found HELIOS+ CD8 T cells that recognize a CMV peptide presented by MHC class Ib molecule HLA-E. Additionally, a portion of HELIOS+ CD8 T cells is characterized by the expression of CD161, often used as a surface marker for identifying TC17 cells. These CD8 T cells express TH17/TC17-related genes encoding RORgt, RORa, PLZF, and CCL20.

Discussion

Our findings emphasize that HELIOS is expressed across various CD8 T cell populations, highlighting its significance beyond its role as a transcription factor for Treg or exhausted murine CD8 T cells. The significance of the connection between HELIOS and HLA-E restriction is yet to be understood.

The Role of Interleukins in HBV Infection: A Narrative Review

Hepatitis B virus (HBV) infection is a worldwide medical issue with significant morbidity and mortality, as it is the main cause of chronic liver disease and hepatocellular carcinoma (HCC). Both innate and adaptive immune responses play a key role in HBV replication and suppression. Recently, the pathophysiological function of interleukins (IL) in the natural course of HBV has gained much attention as a result of the broad use of anti-interleukin agents for a variety of autoimmune diseases and the accompanying risk of HBV reactivation. We present a narrative review regarding the role of IL in HBV infection. Collectively, the pro-inflammatory ILs, namely IL-1, IL-5, IL-6, IL-12 and IL-21, seem to play a critical role in the suppression of HBV replication. In contrast, the anti-inflammatory cytokines IL-10, IL-23 and IL-35 probably act as HBV replication enhancers, while IL-17 has been correlated with HBV-related liver injury. Interestingly enough, IL-2, IL-4 and IL-12 have been tried as therapeutic options against HBV infection with contradictory results. Lastly, the role of IL-22 remains largely ill defined, although preliminary data suggest that it may play a significant role in HBV replication, proliferation and subsequent liver damage.

Th17-inducing dendritic cell vaccines stimulate effective CD4 T cell-dependent antitumor immunity in ovarian cancer that overcomes resistance to immune checkpoint blockade

BACKGROUND

Ovarian cancer (OC), a highly lethal cancer in women, has a 48% 5-year overall survival rate. Prior studies link the presence of IL-17 and Th17 T cells in the tumor microenvironment to improved survival in OC patients. To determine if Th17-inducing vaccines are therapeutically effective in OC, we created a murine model of Th17-inducing dendritic cell (DC) (Th17-DC) vaccination generated by stimulating IL-15 while blocking p38 MAPK in bone marrow-derived DCs, followed by antigen pulsing.

METHODS

ID8 tumor cells were injected intraperitoneally into mice. Mice were treated with Th17-DC or conventional DC (cDC) vaccine alone or with immune checkpoint blockade (ICB). Systemic immunity, tumor associated immunity, tumor size and survival were examined using a variety of experimental strategies.

RESULTS

Th17-DC vaccines increased Th17 T cells in the tumor microenvironment, reshaped the myeloid microenvironment, and improved mouse survival compared with cDC vaccines. ICB had limited efficacy in OC, but Th17-inducing DC vaccination sensitized it to anti-PD-1 ICB, resulting in durable progression-free survival by overcoming IL-10-mediated resistance. Th17-DC vaccine efficacy, alone or with ICB, was mediated by CD4 T cells, but not CD8 T cells.

CONCLUSIONS

These findings emphasize using biologically relevant immune modifiers, like Th17-DC vaccines, in OC treatment to reshape the tumor microenvironment and enhance clinical responses to ICB therapy.

CD8 T-cell subsets: heterogeneity, functions, and therapeutic potential

CD8 T cells play crucial roles in immune surveillance and defense against infections and cancer. After encountering antigenic stimulation, naïve CD8 T cells differentiate and acquire effector functions, enabling them to eliminate infected or malignant cells. Traditionally, cytotoxic T cells, characterized by their ability to produce effector cytokines and release cytotoxic granules to directly kill target cells, have been recognized as the constituents of the predominant effector T-cell subset. However, emerging evidence suggests distinct subsets of effector CD8 T cells that each exhibit unique effector functions and therapeutic potential. This review highlights recent advancements in our understanding of CD8 T-cell subsets and the contributions of these cells to various disease pathologies. Understanding the diverse roles and functions of effector CD8 T-cell subsets is crucial to discern the complex dynamics of immune responses in different disease settings. Furthermore, the development of immunotherapeutic approaches that specifically target and regulate the function of distinct CD8 T-cell subsets holds great promise for precision medicine.

The IL-17 family in diseases: from bench to bedside

The interleukin-17 (IL-17) family comprises six members (IL-17A-17F), and recently, all of its related receptors have been discovered. IL-17 was first discovered approximately 30 years ago. Members of this family have various biological functions, including driving an inflammatory cascade during infections and autoimmune diseases, as well as boosting protective immunity against various pathogens. IL-17 is a highly versatile proinflammatory cytokine necessary for vital processes including host immune defenses, tissue repair, inflammatory disease pathogenesis, and cancer progression. However, how IL-17 performs these functions remains controversial. The multifunctional properties of IL-17 have attracted research interest, and emerging data have gradually improved our understanding of the IL-17 signaling pathway. However, a comprehensive review is required to understand its role in both host defense functions and pathogenesis in the body. This review can aid researchers in better understanding the mechanisms underlying IL-17's roles in vivo and provide a theoretical basis for future studies aiming to regulate IL-17 expression and function. This review discusses recent progress in understanding the IL-17 signaling pathway and its physiological roles. In addition, we present the mechanism underlying IL-17's role in various pathologies, particularly, in IL-17-induced systemic lupus erythematosus and IL-17-related tumor cell transformation and metastasis. In addition, we have briefly discussed promising developments in the diagnosis and treatment of autoimmune diseases and tumors.

Baseline innate and T cell populations are correlates of protection against symptomatic influenza virus infection independent of serology

Evidence suggests that innate and adaptive cellular responses mediate resistance to the influenza virus and confer protection after vaccination. However, few studies have resolved the contribution of cellular responses within the context of preexisting antibody titers. Here, we measured the peripheral immune profiles of 206 vaccinated or unvaccinated adults to determine how baseline variations in the cellular and humoral immune compartments contribute independently or synergistically to the risk of developing symptomatic influenza. Protection correlated with diverse and polyfunctional CD4+ and CD8+ T, circulating T follicular helper, T helper type 17, myeloid dendritic and CD16+ natural killer (NK) cell subsets. Conversely, increased susceptibility was predominantly attributed to nonspecific inflammatory populations, including γδ T cells and activated CD16- NK cells, as well as TNFα+ single-cytokine-producing CD8+ T cells. Multivariate and predictive modeling indicated that cellular subsets (1) work synergistically with humoral immunity to confer protection, (2) improve model performance over demographic and serologic factors alone and (3) comprise the most important predictive covariates. Together, these results demonstrate that preinfection peripheral cell composition improves the prediction of symptomatic influenza susceptibility over vaccination, demographics or serology alone.

IL-18 is required for the TH1-adaptation of TREG cells and the selective suppression of TH17 responses in acute and chronic infections

Interleukin (IL)-18, a member of the IL-1 family of alarmins, is abundantly released in the lungs following influenza A (IAV) infections yet its role in orchestrating the local adaptive immune response remains ill defined. Through genetic disruption of the IL-18 receptor, we demonstrate that IL-18 not only promotes pulmonary TH1 responses but also influences regulatory T cells (TREG) function in the infected lungs. As the response unfolds, TREG cells accumulating in the lungs express Helios, T-bet, CXCR3, and IL-18R1 and produce interferon γ in the presence of IL-12. During IAV, IL-18R1 is required for TREG cells to control TH17, but not TH1, responses and promote a return to lung homeostasis, revealing a novel mechanism of selective suppression. Moreover, this observation was not limited to the lungs, as skin-localized TREG cells require an IL-18 signal to specifically suppress IL-17A production by TH17 and γδ T cells in a model of chronic cutaneous Leishmania major infection. Overall, these results uncover how IL-18 orchestrates the tissue adaptation of TREG cells to selectively favor TH1 over TH17 responses during TH1-driven immune responses and provide a novel perspective into how IL-18 dictates the immune response during viral and parasitic infections.

Friend or Foe - Tc17 cell generation and current evidence for their importance in human disease

The term Tc17 cells refers to interleukin 17 (IL-17)-producing CD8+ T cells. While IL-17 is an important mediator of mucosal defense, it is also centrally involved in driving the inflammatory response in immune-mediated diseases, such as psoriasis, multiple sclerosis, and inflammatory bowel disease. In this review, we aim to gather the current knowledge on the phenotypic and transcriptional profile, the in vitro and in vivo generation of Tc17 cells, and the evidence pointing towards a relevant role of Tc17 cells in human diseases such as infectious diseases, cancer, and immune-mediated diseases.

Interleukin-17 as a key player in neuroimmunometabolism

In mammals, interleukin (IL)-17 cytokines are produced by innate and adaptive lymphocytes. However, the IL-17 family has widespread expression throughout evolution, dating as far back as cnidaria, molluscs and worms, which predate lymphocytes. The evolutionary conservation of IL-17 suggests that it is involved in innate defence strategies, but also that this cytokine family has a fundamental role beyond typical host defence. Throughout evolution, IL-17 seems to have a major function in homeostatic maintenance at barrier sites. Most recently, a pivotal role has been identified for IL-17 in regulating cellular metabolism, neuroimmunology and tissue physiology, particularly in adipose tissue. Here we review the emerging role of IL-17 signalling in regulating metabolic processes, which may shine a light on the evolutionary role of IL-17 beyond typical immune responses. We propose that IL-17 helps to coordinate the cross-talk among the nervous, endocrine and immune systems for whole-body energy homeostasis as a key player in neuroimmunometabolism.

An Orf-Virus (ORFV)-Based Vector Expressing a Consensus H1 Hemagglutinin Provides Protection against Diverse Swine Influenza Viruses

Influenza A viruses (IAV-S) belonging to the H1 subtype are endemic in swine worldwide. Antigenic drift and antigenic shift lead to a substantial antigenic diversity in circulating IAV-S strains. As a result, the most commonly used vaccines based on whole inactivated viruses (WIVs) provide low protection against divergent H1 strains due to the mismatch between the vaccine virus strain and the circulating one. Here, a consensus coding sequence of the full-length of HA from H1 subtype was generated in silico after alignment of the sequences from IAV-S isolates obtained from public databases and was delivered to pigs using the Orf virus (ORFV) vector platform. The immunogenicity and protective efficacy of the resulting ORFVΔ121conH1 recombinant virus were evaluated against divergent IAV-S strains in piglets. Virus shedding after intranasal/intratracheal challenge with two IAV-S strains was assessed by real-time RT-PCR and virus titration. Viral genome copies and infectious virus load were reduced in nasal secretions of immunized animals. Flow cytometry analysis showed that the frequency of T helper/memory cells, as well as cytotoxic T lymphocytes (CTLs), were significantly higher in the peripheral blood mononuclear cells (PBMCs) of the vaccinated groups compared to unvaccinated animals when they were challenged with a pandemic strain of IAV H1N1 (CA/09). Interestingly, the percentage of T cells was higher in the bronchoalveolar lavage of vaccinated animals in relation to unvaccinated animals in the groups challenged with a H1N1 from the gamma clade (OH/07). In summary, delivery of the consensus HA from the H1 IAV-S subtype by the parapoxvirus ORFV vector decreased shedding of infectious virus and viral load of IAV-S in nasal secretions and induced cellular protective immunity against divergent influenza viruses in swine.

Protective Efficacy of a Mucosal Influenza Vaccine Formulation Based on the Recombinant Nucleoprotein Co-Administered with a TLR2/6 Agonist BPPcysMPEG

Current influenza vaccines target highly variable surface glycoproteins; thus, mismatches between vaccine strains and circulating strains often diminish vaccine protection. For this reason, there is still a critical need to develop effective influenza vaccines able to protect also against the drift and shift of different variants of influenza viruses. It has been demonstrated that influenza nucleoprotein (NP) is a strong candidate for a universal vaccine, which contributes to providing cross-protection in animal models. In this study, we developed an adjuvanted mucosal vaccine using the recombinant NP (rNP) and the TLR2/6 agonist S-[2,3-bispalmitoyiloxy-(2R)-propyl]-R-cysteinyl-amido-monomethoxyl-poly-ethylene-glycol (BPPcysMPEG). The vaccine efficacy was compared with that observed following parenteral vaccination of mice with the same formulation. Mice vaccinated with 2 doses of rNP alone or co-administered with BPPcysMPEG by the intranasal (i.n.) route showed enhanced antigen-specific humoral and cellular responses. Moreover, NP-specific humoral immune responses, characterized by significant NP-specific IgG and IgG subclass titers in sera and NP-specific IgA titers in mucosal territories, were remarkably increased in mice vaccinated with the adjuvanted formulation as compared with those of the non-adjuvanted vaccination group. The addition of BPPcysMPEG also improved NP-specific cellular responses in vaccinated mice, characterized by robust lymphoproliferation and mixed Th1/Th2/Th17 immune profiles. Finally, it is notable that the immune responses elicited by the novel formulation administered by the i.n. route were able to confer protection against the influenza H1N1 A/Puerto Rico/8/1934 virus.

Reduced numbers of regulatory T cells in chronic heart failure seems not to be restored by cardiac resynchronization therapy

BACKGROUND

T cells have been implicated in the development and progression of inflammatory processes in chronic heart failure (CHF). Cardiac resynchronization therapy (CRT) has beneficial effects on symptoms and cardiac remodeling in CHF. However, its impact on the inflammatory immune response remains controversial. We aimed to study the impact of CRT on T cells in heart failure (HF) patients.

METHODS

Thirty-nine HF patients were evaluated before CRT (T0) and six months later (T6). Quantification of T cells, their subsets, and their functional characterization, after in vitro stimulation, were evaluated by flow cytometry.

RESULTS

T regulatory (Treg) cells were decreased in CHF patients (healthy group (HG): 1.08 ± 0.50 versus (heart failure patients (HFP)-T0: 0.69 ± 0.40, P = 0.022) and remaining diminished after CRT (HFP-T6: 0.61 ± 0.29, P = 0.003). Responders (R) to CRT presented a higher frequency of T cytotoxic (Tc) cells producing IL-2 at T0 compared with non-responders (NR) (R: 36.52 ± 12.55 versus NR: 24.71 ± 11.66, P = 0.006). After CRT, HF patients presented a higher percentage of Tc cells expressing TNF-α and IFN-γ (HG: 44.50 ± 16.62 versus R: 61.47 ± 20.54, P = 0.014; and HG: 40.62 ± 15.36 versus R: 52.39 ± 18.66, P = 0.049, respectively).

CONCLUSION

The dynamic of different functional T cell subpopulations is significantly altered in CHF, which results in an exacerbated pro-inflammatory response. Even after CRT, it seems that the inflammatory condition underlying CHF continues to evolve with the progression of the disease. This could be due, at least in part, to the inability to restore Treg cells levels.

TRIAL REGISTRATION

Observational and prospective study with no trial registration.

IFNγ-IL-17+ CD8 T cells contribute to immunosuppression and tumor progression in human hepatocellular carcinoma

IL-17-producing CD8 (Tc17) T cells have been shown to play an important role in infection and chronic inflammation, however their implications in hepatocellular carcinoma (HCC) remain elusive. In this study, we performed cytometry by time-of-flight (CyTOF) and revealed the distinctive immunological phenotypes of two IFNγ⁺ and IFNγ^- Tc17 subsets that were preferentially enriched in human HCC. Single-cell RNA-sequencing analysis further revealed regulatory circuits governing the different phenotypes of these Tc17 subsets. In particular, we discovered that IFNγ^- Tc17 subset demonstrated pro-tumoral characteristics and expressed higher levels of CCL20. This corresponded to increased tumor infiltration of T regulatory cells (Treg) validated by immunohistochemistry in another independent HCC cohort, demonstrating the immunosuppressive functions of IFNγ^- Tc17 subset. Most importantly, higher intra-tumoral proportions of IFNγ^- Tc17 were associated with poorer prognosis in patients with HCC and this was further validated in The Cancer Genome Atlas (TCGA) HCC cohort. Taken together, this compendium of transcriptomic and proteomic data of Tc17 subsets sheds light on the immunosuppressive phenotypes of IFNγ^- Tc17 and its implications in HCC progression.

PD-1 limits differentiation and plasticity of Tc17 cells

Blockade of surface co-inhibitory receptor programmed cell death-1 (PD-1; CD279) has been established as an important immunotherapeutic approach to treat malignancies. On a cellular level, PD-1 is demonstrated to be of particular importance in inhibiting differentiation and effector function of cytotoxic Tc1 cells (CTLs). Nevertheless, the role of PD-1 in modulating interleukin (IL)-17-producing CD8⁺ T-cells (Tc17 cells), which generally display suppressed cytotoxic nature, is not well understood. To evaluate the impact of PD-1 in Tc17 responses, we examined its functioning using different in vitro and in vivo models. Upon activation of CD8⁺ T-cells in Tc17 environment, we found that PD-1 was rapidly expressed on the surface of CD8⁺ T-cells and triggered a T-cell-internal mechanism that inhibited the expression of IL-17 and Tc17-supporting transcription factors pSTAT3 and RORγt. Expression of type17-polarising cytokine IL-21 and the receptor for IL-23 were also suppressed. Intriguingly, adoptively transferred, PD-1^-/- Tc17 cells were highly efficient in rejection of established B16 melanoma in vivo and displayed Tc1 like characteristics ex vivo. When using IL-17A-eGFP reporter mice for in vitro fate tracking, IL-17A-eGFP expressing cells lacking PD-1 signaling upon re-stimulation with IL-12 quickly acquired Tc1 characteristics such as IFN-γ, and granzyme B expression, implicating lineage independent upregulation of CTL-characteristics that are needed for tumor control. In line with plasticity characteristics, absence of PD-1 signaling in Tc17 cells increased the expression of the stemness and persistence-associated molecules TCF1 and BCL6. Thus, PD-1 plays a central role in the specific suppression of Tc17 differentiation and its plasticity in relation to CTL-driven tumor rejection, which provides further explanation as to why the blockade of PD-1 is such an efficient therapeutic target for inducing tumor rejection.

IL-17 and IL-17-producing cells in protection versus pathology

IL-17 cytokine family members have diverse biological functions, promoting protective immunity against many pathogens but also driving inflammatory pathology during infection and autoimmunity. IL-17A and IL-17F are produced by CD4⁺ and CD8⁺ T cells, γδ T cells, and various innate immune cell populations in response to IL-1β and IL-23, and they mediate protective immunity against fungi and bacteria by promoting neutrophil recruitment, antimicrobial peptide production and enhanced barrier function. IL-17-driven inflammation is normally controlled by regulatory T cells and the anti-inflammatory cytokines IL-10, TGFβ and IL-35. However, if dysregulated, IL-17 responses can promote immunopathology in the context of infection or autoimmunity. Moreover, IL-17 has been implicated in the pathogenesis of many other disorders with an inflammatory basis, including cardiovascular and neurological diseases. Consequently, the IL-17 pathway is now a key drug target in many autoimmune and chronic inflammatory disorders; therapeutic monoclonal antibodies targeting IL-17A, both IL-17A and IL-17F, the IL-17 receptor, or IL-23 are highly effective in some of these diseases. However, new approaches are needed to specifically regulate IL-17-mediated immunopathology in chronic inflammation and autoimmunity without compromising protective immunity to infection.

The pathogenesis of cryptoglandular anal fistula: New insight into the immunological profile

AIM

The aetiology of cryptoglandular anal fistula (AF) is poorly understood. Evidence suggests that persistence and/or recurrence of the disease is more related to inflammatory than infectious factors. The aim of this study was to investigate the immune profile of cryptoglandular AF and to perform a histopathological characterization.

METHOD

Fistulectomy was performed in all patients; healthy ischioanal fat from the same patients was used as a control. Samples were evaluated by the Luminex xMAP system for the detection of 27 analytes. AF tissues were analysed using immunofluorescence. Staining was performed using primary antibodies to identify M1 inflammatory and M2 anti-inflammatory macrophages. Selective staining of total T lymphocytes and different T lymphocyte subsets was performed.

RESULTS

Twenty patients with AF underwent a fistulectomy. Specific cytokine pathways differentiated AF from healthy tissue: pro-inflammatory cytokines interleukin (IL)-1β, IL-4, IL-8 and IL-17 and the anti-inflammatory cytokine IL-10 were overexpressed in AF compared with controls. Chemokines involved in macrophage recruitment (CCL2, CCL3, CCL4) were higher in AF than in healthy fatty tissue. Moreover, we showed that Tc17 cells characterize AF patients, thus confirming the enzyme-linked immunosorbent assay data. Furthermore, elevated infiltration of CD68+ myeloid cells and a reduction of the M1/M2 ratio characterize AF patients.

CONCLUSION

A combination of inflammatory cytokines, chemokines and growth factors reside in the wound microenvironment of AF patients. For the first time an important prevalence of Tc17 cells and a reduction in the M1/M2 ratio was observed, thus suggesting new insights into the immunological characterization of AF patients.

CD8+ T Cell Phenotype and Function in Childhood and Adult-Onset Connective Tissue Disease

CD8+ T cells are cytotoxic lymphocytes that destroy pathogen infected and malignant cells through release of cytolytic molecules and proinflammatory cytokines. Although the role of CD8+ T cells in connective tissue diseases (CTDs) has not been explored as thoroughly as that of other immune cells, research focusing on this key component of the immune system has recently gained momentum. Aberrations in cytotoxic cell function may have implications in triggering autoimmunity and may promote tissue damage leading to exacerbation of disease. In this comprehensive review of current literature, we examine the role of CD8+ T cells in systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, polymyositis, and dermatomyositis with specific focus on comparing what is known about CD8+ T cell peripheral blood phenotypes, CD8+ T cell function, and CD8+ T cell organ-specific profiles in adult and juvenile forms of these disorders. Although, the precise role of CD8+ T cells in the initiation of autoimmunity and disease progression remains to be elucidated, increasing evidence indicates that CD8+ T cells are emerging as an attractive target for therapy in CTDs.

Immunomodulatory effects of probiotic Lactobacillus casei on GM-CSF-adjuvanted influenza DNA vaccine

Aim: This study investigates the protective efficacy of influenza DNA vaccine combined with a granulocyte macrophage-colony stimulating factor (GM-CSF) adjuvant, and probiotic Lactobacillus casei, an oral immunomodulator, in a BALB/c mice. Materials & methods: The mice were immunized with HA1 DNA vaccine along with GM-CSF and probiotic twice within a one-week interval. Results: The results showed that both adjuvants exert a synergistic effect in enhancing the humoral and cellular immune responses of the DNA vaccine. This combination also deceased IL-6 and IL-17A levels in the lung homogenates. The protection patterns were closely associated with influenza virus-specific splenocyte proliferative and serum IgG antibody (Ab) responses. Conclusion: The Findings demonstrate L. casei modulate balanced Th1/Th2 immune responses toward HA1 DNA vaccine adjuvanted by GM-CSF.

Distinct Immunological Profiles Help in the Maintenance of Salivary Secretory IgA Production in Mild Symptoms COVID-19 Patients

Background

Relevant aspects regarding the SARS-CoV-2 pathogenesis and the systemic immune response to this infection have been reported. However, the mucosal immune response of the upper airways two months after SARS-CoV-2 infection in patients with mild/moderate symptoms is still not completely described. Therefore, we investigated the immune/inflammatory responses of the mucosa of the upper airways of mild/moderate symptom COVID-19 patients two months after the SARS-CoV-2 infection in comparison to a control group composed of non-COVID-19 healthy individuals.

Methods

A cohort of 80 volunteers (age 37.2 ± 8.2), including non-COVID-19 healthy individuals (n=24) and COVID-19 patients (n=56) who presented mild/moderate symptoms during a COVID-19 outbreak in Brazil in November and December of 2020. Saliva samples were obtained two months after the COVID-19 diagnosis to assess the levels of SIgA by ELISA and the cytokines by multiplex analysis.

Results

Salivary levels of SIgA were detected in 39 volunteers into the COVID-19 group and, unexpectedly, in 14 volunteers in the control group. Based on this observation, we distributed the volunteers of the control group into without SIgA or with SIgA sub-groups, and COVID-19 group into without SIgA or with SIgA sub-groups. Individuals with SIgA showed higher levels of IL-10, IL-17A, IFN-γ, IL-12p70, IL-13, and IFN-α than those without SIgA. In intergroup analysis, the COVID-19 groups showed higher salivary levels of IL-10, IL-13, IL-17A, and IFN-α than the control group. No statistical differences were verified in the salivary levels of IL-6 and IFN-β. Lower IL-12p70/IL-10 and IFN-γ/IL-10 ratios were found in the control group without SIgA than the control group with SIgA and the COVID-19 group with SIgA.

Conclusion

We were able to present, for the first time, that associations between distinct immunological profiles can help the mucosal immunity to maintain the salivary levels of SIgA in COVID-19 patients two months after the SARS-CoV-2 infection.

Neuronal and Non-Neuronal GABA in COVID-19: Relevance for Psychiatry

Infection with SARS-CoV-2, the causative agent of the COVID-19 pandemic, originated in China and quickly spread across the globe. Despite tremendous economic and healthcare devastation, research on this virus has contributed to a better understanding of numerous molecular pathways, including those involving γ-aminobutyric acid (GABA), that will positively impact medical science, including neuropsychiatry, in the post-pandemic era. SARS-CoV-2 primarily enters the host cells through the renin–angiotensin system’s component named angiotensin-converting enzyme-2 (ACE-2). Among its many functions, this protein upregulates GABA, protecting not only the central nervous system but also the endothelia, the pancreas, and the gut microbiota. SARS-CoV-2 binding to ACE-2 usurps the neuronal and non-neuronal GABAergic systems, contributing to the high comorbidity of neuropsychiatric illness with gut dysbiosis and endothelial and metabolic dysfunctions. In this perspective article, we take a closer look at the pathology emerging from the viral hijacking of non-neuronal GABA and summarize potential interventions for restoring these systems.

Interleukin-6 blockade abrogates immunotherapy toxicity and promotes tumor immunity

Immune checkpoint blockade (ICB) therapy frequently induces immune-related adverse events. To elucidate the underlying immunobiology, we performed a deep immune analysis of intestinal, colitis, and tumor tissue from ICB-treated patients with parallel studies in preclinical models. Expression of interleukin-6 (IL-6), neutrophil, and chemotactic markers was higher in colitis than in normal intestinal tissue; T helper 17 (Th17) cells were more prevalent in immune-related enterocolitis (irEC) than T helper 1 (Th1). Anti-cytotoxic T-lymphocyte-associated antigen 4 (anti-CTLA-4) induced stronger Th17 memory in colitis than anti-program death 1 (anti-PD-1). In murine models, IL-6 blockade associated with improved tumor control and a higher density of CD4+/CD8+ effector T cells, with reduced Th17, macrophages, and myeloid cells. In an experimental autoimmune encephalomyelitis (EAE) model with tumors, combined IL-6 blockade and ICB enhanced tumor rejection while simultaneously mitigating EAE symptoms versus ICB alone. IL-6 blockade with ICB could de-couple autoimmunity from antitumor immunity.

Estradiol suppresses psoriatic inflammation in mice by regulating neutrophil and macrophage functions

BACKGROUND

Psoriasis is a common inflammatory skin disease resulting from dysregulation of the IL-23/T_H17 immune axis. The prevalence and severity of psoriasis is higher in men than in women, although the underlying reasons for this are unclear.

OBJECTIVE

We studied whether estradiol, a female hormone, plays protective roles in imiquimod-induced psoriatic inflammation in mice by regulating neutrophil and macrophage functions.

METHODS

Wild-type mice and conditional knockout mice were ovariectomized, supplemented with placebo or estradiol pellets, and an imiquimod-containing cream applied.

RESULTS

Mice without endogenous ovarian hormones exhibited exacerbated psoriatic inflammation including increased production of IL-17A and IL-1β, which was reversed by exogenously added estradiol. The suppressive effect of estradiol on the production of IL-1β and IL-17A was abolished in mice lacking estrogen receptors in neutrophils and macrophages (Esr1^f/fEsr2^f/fLysM-Cre+ mice). IL-1β, which is required for production of IL-17A in the psoriasis model, was mainly produced by neutrophils and inflammatory macrophages. Estradiol suppressed IL-1β production from neutrophils and macrophages in mice both in vivo and in vitro and from human neutrophils in vitro.

CONCLUSION

Our results suggest a novel mechanism for sex-dependent differences in psoriasis clinical phenotypes that may shed new light on the pathology of psoriasis.

Exhausted phenotype of circulating CD8+ T cell subsets in hepatitis B virus carriers

Background

Chronic hepatitis B virus (HBV) infection is characterized by the presence of dysfunctional exhausted CD8⁺ T cells that hamper viral control. We investigated the phenotypic heterogeneity of exhausted CD8⁺ T cells in HBV carriers.

Methods

We enrolled 31 HBV carriers and 23 healthy controls (HCs) in our study. Peripheral blood mononuclear cells (PBMCs) were isolated, and flow cytometry was used to determine the phenotypic distribution of CD8⁺ T cell subsets. Expression of cytokines such as TNF-α and IFN-γ was detected by quantitative reverse transcription–PCR, a fluorescence flow cytometry-based immunomicrobead assay and flow cytometry.

Results

There were no significant differences in the baseline characteristics between the 31 HBV carriers and the 23 sex- and age-matched HCs. CD8⁺ T cells exhibited higher levels of inhibitory receptors (TIM3 and PD1) in the HBV carriers than in the HCs (P < 0.05); in particular, Tfc cells (CXCR5⁺CD25⁻) expressed higher levels of TIM3 and PD1 than non-Tfc cells in the HBV carriers. In addition, among the subsets of Tc cells, the Tc17 (CXCR5⁻CD25⁻CCR6⁺) subset displayed increased expression of TIM3 and LAG3 in the HBV carriers. Our findings further showed that CD8⁺ T cells produced lower levels of IFN-γ, TNF-α, and Granzyme B. Paired analysis of the Tfc subset and the Tc subset indicated that higher levels of cytokines (IFN-γ and TNF-α) were produced by the Tfc subset in the HBV carriers. Among the Tc subsets, the Tc17 subset produced lower levels of cytokines.

Conclusion

The Tfc subset exhibited an enhanced exhausted phenotype but possessed some functional properties during chronic HBV infection, while the Tc subset showed a lower functional level. The identification of these unique subsets may provide a potential immunotherapeutic target in chronic HBV infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00488-2.

Bona Fide Th17 Cells without Th1 Functional Plasticity Protect against Influenza

Optimal transcriptional programming needed for CD4 T cells to protect against influenza A virus (IAV) is unclear. Most IAV-primed CD4 T cells fit Th1 criteria. However, cells deficient for the Th1 "master regulator," T-bet, although marked by reduced Th1 identity, retain robust protective capacity. In this study, we show that T-bet's paralog, Eomesodermin (Eomes), is largely redundant in the presence of T-bet but is essential for the residual Th1 attributes of T-bet-deficient cells. Cells lacking both T-bet and Eomes instead develop concurrent Th17 and Th2 responses driven by specific inflammatory signals in the infected lung. Furthermore, the transfer of T-bet- and Eomes-deficient Th17, but not Th2, effector cells protects mice from lethal IAV infection. Importantly, these polyfunctional Th17 effectors do not display functional plasticity in vivo promoting gain of Th1 attributes seen in wild-type Th17 cells, which has clouded evaluation of the protective nature of Th17 programming in many studies. Finally, we show that primary and heterosubtypic IAV challenge is efficiently cleared in T-bet- and Eomes double-deficient mice without enhanced morbidity despite a strongly Th17-biased inflammatory response. Our studies thus demonstrate unexpectedly potent antiviral capacity of unadulterated Th17 responses against IAV, with important implications for vaccine design.

LUNG group 2 innate lymphoid cells as a new adjuvant target to enhance intranasal vaccine efficacy against influenza

Group 2 innate lymphoid cells (ILC2) are a relatively new class of innate immune cells. Lung ILC2 are early responders that secrete type 2 cytokines in response to danger ‘alarmin’ signals such as interleukin (IL)‐33 and thymic stromal lymphopoietin. Being an early source of type 2 cytokines, ILC2 are a critical regulator of type 2 immune cells of both innate and adaptive immune responses. The immune regulatory functions of ILC2 were mostly investigated in diseases where T helper 2 inflammation predominates. However, in recent years, it has been appreciated that the role of ILC2 extends to other pathological conditions such as cancer and viral infections. In this review, we will focus on the potential role of lung ILC2 in the induction of mucosal immunity against influenza virus infection and discuss the potential utility of ILC2 as a target for mucosal vaccination.

The Age-Dependent Role of Th22, Tc22, and Tc17 Cells in the Severity of Pneumonia in COVID-19 Immunopathogenesis

Coronavirus disease 2019 (COVID-19) has clinical manifestations ranging from mild symptoms to respiratory failure, septic shock, and multi-organ failure. Lymphocytes are divided into different subtypes based on their cytokine production pattern. In this study, we investigated the role of cytokine expressions of CD4⁺ T (T helper [Th]1, Th2, Th17, Th22) and CD8⁺ T cell subtypes (T cytotoxic [Tc]1, Tc2, Tc17, Tc22) in the pathogenesis of COVID-19. Peripheral blood mononuclear cells (PBMCs) were extracted with Ficoll by density gradient centrifugation from blood samples of 180 COVID-19 patients (children and adults) and 30 healthy controls. PBMCs were stimulated with PMA and Ionomycin and treated with Brefeldin A in the fourth hour, and a 10-colored monoclonal antibody panel was evaluated at the end of the sixth hour using flow cytometry. According to our findings, the numbers of Th22 (CD3⁺, CD4⁺, and interleukin [IL]-22⁺) and Tc22 (CD3⁺, CD8⁺, IL-22⁺) cells increased in adult patients regardless of the level of pneumonia (mild, severe, or symptom-free) as compared with healthy controls (p < 0.05). In addition, the number of Tc17 (CD3⁺, CD8⁺, and IL-17A⁺) cells increased in low pneumonia and severe pneumonia groups compared with the healthy controls (p < 0.05). Both IL-22 and IL-17A production decreased during a follow-up within 6 weeks of discharge. Our findings suggest that the increase in only IL-22 expressed Tc22 cells in the 0-12 age group with a general symptom-free course and higher levels of Th22 and Tc22 in uncomplicated adult cases may indicate the protective effect of IL-22. On the contrary, the association between the severity of pneumonia and the elevation of Tc17 cells in adults may reveal the damaging effect of IL-22 when it is co-expressed with IL-17.

Adoptive transfer of IL-4 reprogrammed Tc17 cells elicits anti-tumor immunity through functional plasticity

Ability of IL-17-producing CD8⁺ T cells (Tc17) to transform into cytotoxic anti-tumor effectors makes them a promising candidate for immune effector cell (IEC) therapy. However, key factors regulating Tc17 reprograming remain poorly defined, hindering translation of Tc17-based IEC use from bench to bedside. We probed the effects of multiple cytokines and underlying signaling pathways on Tc17 cells and identified pivotal role for IL-4 and PI3K/AKT in promoting Tc17 transformation into cytotoxic IFN-γ-producing IECs, an effect dependent on Eomes expression. IL-4 not only triggered Tc17 cytotoxicity, but also induced cell expansion, which significantly improved the antitumor potential of Tc17 cells compared to that of IFN-γ-producing CD8⁺ T cells (Tc1) in a murine model. Furthermore, IL-4/AKT signaling drove the upregulation of the T-cell receptor-associated transmembrane adaptor 1 (Trat1) in Tc17 cells to promote IL-4-induced T-cell receptor stabilization and Tc17 cytotoxicity. Finally, we proposed a possible procedure to expand human Tc17 from peripheral blood of cancer patients, and confirmed the function of IL-4 in Tc17 reprogramming. Collectively, these results document a novel IL-4/AKT/Eomes/Trat1 axis that promotes expansion and transformation of Tc17 cells into cytotoxic effectors with a therapeutic potential. IL-4 priming of Tc17 cells should be further explored as a cell therapy engineering strategy to generate IECs to augment anti-tumor responses. This article is protected by copyright. All rights reserved.

Role of Th17 Cytokines in Airway Remodeling in Asthma and Therapy Perspectives

Airway remodeling is a frequent pathological feature of severe asthma leading to permanent airway obstruction in up to 50% of cases and to respiratory disability. Although structural changes related to airway remodeling are well-characterized, immunological processes triggering and maintaining this phenomenon are still poorly understood. As a consequence, no biotherapy targeting cytokines are currently efficient to treat airway remodeling and only bronchial thermoplasty may have an effect on bronchial nerves and smooth muscles with uncertain clinical relevance. Th17 cytokines, including interleukin (IL)-17 and IL-22, play a role in neutrophilic inflammation in severe asthma and may be involved in airway remodeling. Indeed, IL-17 is increased in sputum from severe asthmatic patients, induces the expression of "profibrotic" cytokines by epithelial, endothelial cells and fibroblasts, and provokes human airway smooth muscle cell migration in in vitro studies. IL-22 is also increased in asthmatic samples, promotes myofibroblast differentiation, epithelial-mesenchymal transition and proliferation and migration of smooth muscle cells in vitro. Accordingly, we also found high levels of IL-17 and IL-22 in a mouse model of dog-allergen induced asthma characterized by a strong airway remodeling. Clinical trials found no effect of therapy targeting IL-17 in an unselected population of asthmatic patients but showed a potential benefit in a sub-population of patients exhibiting a high level of airway reversibility, suggesting a potential role on airway remodeling. Anti-IL-22 therapies have not been evaluated in asthma yet but were demonstrated efficient in severe atopic dermatitis including an effect on skin remodeling. In this review, we will address the role of Th17 cytokines in airway remodeling through data from in vitro, in vivo and translational studies, and examine the potential place of Th17-targeting therapies in the treatment of asthma with airway remodeling.

Maternal-fetal immune responses in pregnant women infected with SARS-CoV-2

Pregnant women represent a high-risk population for severe/critical COVID-19 and mortality. However, the maternal-fetal immune responses initiated by SARS-CoV-2 infection, and whether this virus is detectable in the placenta, are still under investigation. Here we show that SARS-CoV-2 infection during pregnancy primarily induces unique inflammatory responses at the maternal-fetal interface, which are largely governed by maternal T cells and fetal stromal cells. SARS-CoV-2 infection during pregnancy is also associated with humoral and cellular immune responses in the maternal blood, as well as with a mild cytokine response in the neonatal circulation (i.e., umbilical cord blood), without compromising the T-cell repertoire or initiating IgM responses. Importantly, SARS-CoV-2 is not detected in the placental tissues, nor is the sterility of the placenta compromised by maternal viral infection. This study provides insight into the maternal-fetal immune responses triggered by SARS-CoV-2 and emphasizes the rarity of placental infection.

As pregnant women are considered vulnerable to SARSCoV-2 infection, it is important to investigate the actual risks involved. The authors show here that, while a T cell-dominant inflammatory response is observed at the maternal-foetal interface, the virus remains undetectable in the placenta but triggers specific immune responses in the neonatal (umbilical cord blood) circulation.

Pityriasis rosea, pityriasis rosea-like eruptions, and herpes zoster in the setting of COVID-19 and COVID-19 vaccination

Pityriasis rosea (PR), PR-like eruptions (PR-LE), and herpes zoster have been frequently reported during the COVID-19 pandemic and following COVID-19 vaccination. PR is a self-limiting exanthematous disease and herpes zoster is a treatable condition; therefore, their occurrence does not require discontinuation of the vaccination schedule. PR-LE is a hypersensitivity reaction and is, therefore, less predictable in its course. In the case of a booster dose, the clinical manifestation may not recur, may be different from PR-LE, or may present with systemic symptoms; however, in the case of PR-LE, the possibility of mild and predominantly cutaneous adverse events should not discourage all eligible candidates from receiving and completing the COVID-19 vaccination program, as such adverse reactions represent a small risk considering the possible severe and fatal outcome of COVID-19. We emphasize the relevance of looking for any viral reactivation in patients infected with SARS-CoV-2 who have skin eruptions. The search for viral reactivations could be useful not only for distinguishing between PR and PR-LE but also because viral reactivations may contribute to a patient's systemic inflammation and influence the course of the disease.

Tc17 CD8+ T cells accumulate in murine atherosclerotic lesions, but do not contribute to early atherosclerosis development

AIMS

CD8+ T cells can differentiate into subpopulations that are characterized by a specific cytokine profile, such as the Tc17 population that produces interleukin-17. The role of this CD8+ T-cell subset in atherosclerosis remains elusive. In this study, we therefore investigated the contribution of Tc17 cells to the development of atherosclerosis.

METHODS AND RESULTS

Flow cytometry analysis of atherosclerotic lesions from apolipoprotein E-deficient mice revealed a pronounced increase in RORγt+CD8+ T cells compared to the spleen, indicating a lesion-specific increase in Tc17 cells. To study whether and how the Tc17 subset affects atherosclerosis, we performed an adoptive transfer of Tc17 cells or undifferentiated Tc0 cells into CD8-/- low-density lipoprotein receptor-deficient mice fed a Western-type diet. Using flow cytometry, we showed that Tc17 cells retained a high level of interleukin-17A production in vivo. Moreover, Tc17 cells produced lower levels of interferon-γ than their Tc0 counterparts. Analysis of the aortic root revealed that the transfer of Tc17 cells did not increase atherosclerotic lesion size, in contrast to Tc0-treated mice.

CONCLUSION

These findings demonstrate a lesion-localized increase in Tc17 cells in an atherosclerotic mouse model. Tc17 cells appeared to be non-atherogenic, in contrast to their Tc0 counterpart.

Rationalizing heptadecaphobia: TH 17 cells and associated cytokines in cancer and metastasis

Cancer is one of the leading causes of death worldwide. When cancer patients are diagnosed with metastasis, meaning that the primary tumor has spread to at least one different site, their life expectancy decreases dramatically. In the past decade, the immune system´s role in fighting cancer and metastasis has been studied extensively. Importantly, immune cells and inflammatory reactions generate potent antitumor responses but also contribute to tumor development. However, the molecular and cellular mechanisms underlying this dichotomic interaction between the immune system and cancer are still poorly understood. Recently, a spotlight has been cast on the distinct subsets of immune cells and their derived cytokines since evidence has implicated their crucial impact on cancer development. T helper 17 cell (TH 17) cells, which express the master transcriptional factor Retinoic acid-receptor-related orphan receptor gamma t, are among these critical cell subsets and are defined by their production of type 3 cytokines, such as IL-17A, IL-17F, and IL-22. Depending on the tumor microenvironment, these cytokines can also be produced by other immune cell sources, such as T cytotoxic 17 cell, innate lymphoid cells, NKT cells, or γδ T cells. To date, a lot of data have been collected describing the divergent functions of IL-17A, IL-17F, and IL-22 in malignancies. In this comprehensive review, we discuss the role of these TH 17- and non-TH 17-derived type 3 cytokines in different tumor entities. Furthermore, we will provide a structured insight into the strict regulation and subsequent downstream mechanisms of these cytokines in cancer and metastasis.

Induction of Unique STAT Heterodimers by IL-21 Provokes IL-1RI Expression on CD8+ T Cells, Resulting in Enhanced IL-1β Dependent Effector Function

IL-1β plays critical roles in the priming and effector phases of immune responses such as the differentiation, commitment, and memory formation of T cells. In this context, several reports have suggested that the IL-1β signal is crucial for CTL-mediated immune responses to viral infections and tumors. However, little is known regarding whether IL-1β acts directly on CD8⁺ T cells and what the molecular mechanisms underlying expression of IL-1 receptors (IL-1Rs) on CD8⁺ T cells and features of IL-1R⁺CD8⁺ T cells are. Here, we provide evidence that the expression of IL-1R type I (IL-1RI), the functional receptor of IL-1β, is preferentially induced by IL-21 on TCR-stimulated CD8⁺ T cells. Further, IL-1β enhances the effector function of CD8⁺ T cells expressing IL-21-induced IL-1RI by increasing cytokine production and release of cytotoxic granules containing granzyme B. The IL-21-IL-1RI-IL-1β axis is involved in an augmented effector function through regulation of transcription factors BATF, Blimp-1, and IRF4. Moreover, this axis confers a unique effector function to CD8⁺ T cells compared to conventional type 1 cytotoxic T cells differentiated with IL-12. Chemical inhibitor and immunoprecipitation assay demonstrated that IL-21 induces a unique pattern of STAT activation with the formation of both STAT1:STAT3 and STAT3:STAT5 heterodimers, which are critical for the induction of IL-1RI on TCR-stimulated CD8⁺ T cells. Taken together, we propose that induction of a novel subset of IL-1RI-expressing CD8⁺ T cells by IL-21 may be beneficial to the protective immune response against viral infections and is therefore important to consider for vaccine design.

Chemogenetic modulation of sensory neurons reveals their regulating role in melanoma progression

Sensory neurons have recently emerged as components of the tumor microenvironment. Nevertheless, whether sensory neuronal activity is important for tumor progression remains unknown. Here we used Designer Receptors Exclusively Activated by a Designer Drug (DREADD) technology to inhibit or activate sensory neurons' firing within the melanoma tumor. Melanoma growth and angiogenesis were accelerated following inhibition of sensory neurons' activity and were reduced following overstimulation of these neurons. Sensory neuron-specific overactivation also induced a boost in the immune surveillance by increasing tumor-infiltrating anti-tumor lymphocytes, while reducing immune-suppressor cells. In humans, a retrospective in silico analysis of melanoma biopsies revealed that increased expression of sensory neurons-related genes within melanoma was associated with improved survival. These findings suggest that sensory innervations regulate melanoma progression, indicating that manipulation of sensory neurons' activity may provide a valuable tool to improve melanoma patients' outcomes.

Immunogenicity and Protective Potential of Mucosal Vaccine Formulations Based on Conserved Epitopes of Influenza A Viruses Fused to an Innovative Ring Nanoplatform in Mice and Chickens

Current inactivated vaccines against influenza A viruses (IAV) mainly induce immune responses against highly variable epitopes across strains and are mostly delivered parenterally, limiting the development of an effective mucosal immunity. In this study, we evaluated the potential of intranasal formulations incorporating conserved IAV epitopes, namely the long alpha helix (LAH) of the stalk domain of hemagglutinin and three tandem repeats of the ectodomain of the matrix protein 2 (3M2e), as universal mucosal anti-IAV vaccines in mice and chickens. The IAV epitopes were grafted to nanorings, a novel platform technology for mucosal vaccination formed by the nucleoprotein (N) of the respiratory syncytial virus, in fusion or not with the C-terminal end of the P97 protein (P97c), a recently identified Toll-like receptor 5 agonist. Fusion of LAH to nanorings boosted the generation of LAH-specific systemic and local antibody responses as well as cellular immunity in mice, whereas the carrier effect of nanorings was less pronounced towards 3M2e. Mice vaccinated with chimeric nanorings bearing IAV epitopes in fusion with P97c presented modest LAH- or M2e-specific IgG titers in serum and were unable to generate a mucosal humoral response. In contrast, N-3M2e or N-LAH nanorings admixed with Montanide™ gel (MG) triggered strong specific humoral responses, composed of serum type 1/type 2 IgG and mucosal IgG and IgA, as well as cellular responses dominated by type 1/type 17 cytokine profiles. All mice vaccinated with the [N-3M2e + N-LAH + MG] formulation survived an H1N1 challenge and the combination of both N-3M2e and N-LAH nanorings with MG enhanced the clinical and/or virological protective potential of the preparation in comparison to individual nanorings. Chickens vaccinated parenterally or mucosally with N-LAH and N-3M2e nanorings admixed with Montanide™ adjuvants developed a specific systemic humoral response, which nonetheless failed to confer protection against heterosubtypic challenge with a highly pathogenic H5N8 strain. Thus, while the combination of N-LAH and N-3M2e nanorings with Montanide™ adjuvants shows promise as a universal mucosal anti-IAV vaccine in the mouse model, further experiments have to be conducted to extend its efficacy to poultry.

Pre-treatment with chicken IL-17A secreted by bioengineered LAB vector protects chicken embryo fibroblasts against Influenza Type A Virus (IAV) infection

The recent advances in our understanding of the host factors in orchestrating qualitatively different immune responses against influenza Type A virus (IAV) have changed the perception of conventional approaches for controlling avian influenza virus (AIV) infection in chickens. Given that infection-induced pathogenicity and replication of influenza virus largely rely on regulating host immune responses, immunoregulatory cytokine profiles often determine the disease outcomes. However, in contrast to the function of other inflammatory cytokines, interleukin-17A (IL-17A) has been described as a 'double-edged sword', indicating that in addition to antiviral host responses, IL-17A has a distinct role in promoting viral infection. Therefore, in the present study, we investigated the chicken IL-17A mediated antiviral immune effects on IAVs infection in primary chicken embryo fibroblasts cells (CEFs). To this end, we first bioengineered a food-grade Lactic Acid Producing Bacteria (LAB), Lactococcus lactis (L. lactis), secreting bioactive recombinant chicken IL-17A (sChIL-17A). Next, the functionality of sChIL-17A was confirmed by transcriptional upregulation of several genes associated with antiviral host responses, including granulocyte-monocyte colony-stimulating factor (GM-CSF) (CSF3 in the chickens), interleukin-6 (IL-6), interferon-α (IFN-α), -β and -γ genes in primary CEFs cells. Consistent with our hypothesis that such a pro-inflammatory state may translate to immunoprotection against IAVs infection, we observed that sChIL-17A pre-treatment could significantly limit the viral replication and protect the primary CEFs cells against two heterotypic IAVs such as A/turkey/Wisconsin/1/1966(H9N2) and A/PR/8/1934(H1N1). Together, the data presented in this work suggest that exogenous application of sChIL-17A secreted by modified LAB vector may represent an alternative strategy for improving antiviral immunity against avian influenza virus infection in chickens.

A Distinctive Lineage-Negative Cell Population Produces IL-17A in Cutaneous Squamous Cell Carcinoma

Interleukin (IL)-17A is a key proinflammatory cytokine indicated in multiple pathologies, including skin tumorigenesis. While IL-17A is a signature cytokine of Th17 cells, IL-17A is also produced by other cell types, including type 3 innate lymphoid cells (ILC3s) in the skin, particularly in patients with psoriasis. Interestingly, we detect CD45⁺Lin^-(CD3^-CD14^-CD19^-CD20^-) IL-17A⁺ cells in the cutaneous squamous cell carcinomas (cSCCs) by flow cytometry of the cell suspensions prepared from tumor tissues. Consistently, we found CD3^-IL-17⁺ cells in tumor tissue of skin cSCCs by immunohistochemistry staining of serial sections of SCCs from both immunocompetent and immunocompromised patients (e.g., transplant patients on iatrogenic long-term immunosuppressive therapy). In several immunocompromised patients, the CD3^-IL-17⁺ cells consist of over 90% of the total IL-17⁺ cells in the tumor tissue. Furthermore, these CD3^-IL-17⁺ cells are negatively stained for SMA, CD11b, and CD19, suggesting that they are unlikely to be fibroblast, myeloid cells, or B cells. Taken together, we found a population of lineage-negative IL-17A-producing cells present in the cSCCs, which share the "CD45⁺Lin^-" features with ILCs. This study suggests that IL-17A can be produced by immune cell populations other than T cells in skin SCCs.

Tissue-resident-like CD4+ T cells secreting IL-17 control Mycobacterium tuberculosis in the human lung

T cell immunity is essential for the control of tuberculosis (TB), an important disease of the lung, and is generally studied in humans using peripheral blood cells. Mounting evidence, however, indicates that tissue-resident memory T cells (Trms) are superior at controlling many pathogens, including Mycobacterium tuberculosis (M. tuberculosis), and can be quite different from those in circulation. Using freshly resected lung tissue, from individuals with active or previous TB, we identified distinct CD4+ and CD8+ Trm-like clusters within TB-diseased lung tissue that were functional and enriched for IL-17-producing cells. M. tuberculosis-specific CD4+ T cells producing TNF-α, IL-2, and IL-17 were highly expanded in the lung compared with matched blood samples, in which IL-17+ cells were largely absent. Strikingly, the frequency of M. tuberculosis-specific lung T cells making IL-17, but not other cytokines, inversely correlated with the plasma IL-1β levels, suggesting a potential link with disease severity. Using a human granuloma model, we showed the addition of either exogenous IL-17 or IL-2 enhanced immune control of M. tuberculosis and was associated with increased NO production. Taken together, these data support an important role for M. tuberculosis-specific Trm-like, IL-17-producing cells in the immune control of M. tuberculosis in the human lung.

Human NK cells prime inflammatory DC precursors to induce Tc17 differentiation

Adaptive immune responses are acknowledged to evolve from innate immunity. However, limited information exists regarding whether encounters between innate cells direct the generation of specialized T-cell subsets. We aim to understand how natural killer (NK) cells modulate cell-mediated immunity in humans. We found that human CD14+CD16- monocytes that differentiate into inflammatory dendritic cells (DCs) are shaped at the early stages of differentiation by cell-to-cell interactions with NK cells. Although a fraction of monocytes is eliminated by NK-cell-mediated cytotoxicity, the polarization of interferon-γ (IFN-γ) at the NKp30-stabilized synapses triggers a stable IFN-γ signature in surviving monocytes that persists after their differentiation into DCs. Notably, NK-cell-instructed DCs drive the priming of type 17 CD8+ T cells (Tc17) with the capacity to produce IFN-γ and interleukin-17A. Compared with healthy donors, this cellular network is impaired in patients with classical NK-cell deficiency driven by mutations in the GATA2 gene. Our findings reveal a previously unrecognized connection by which Tc17-mediated immunity might be regulated by NK-cell-mediated tuning of antigen-presenting cells.

Regulatory T Cells Play a Role in a Subset of Idiopathic Preterm Labor/Birth and Adverse Neonatal Outcomes

Regulatory T cells (Tregs) have been exhaustively investigated during early pregnancy; however, their role later in gestation is poorly understood. Herein, we report that functional Tregs are reduced at the maternal-fetal interface in a subset of women with idiopathic preterm labor/birth, which is accompanied by a concomitant increase in Tc17 cells. In mice, depletion of functional Tregs during late gestation induces preterm birth and adverse neonatal outcomes, which are rescued by the adoptive transfer of such cells. Treg depletion does not alter obstetrical parameters in the mother, yet it increases susceptibility to endotoxin-induced preterm birth. The mechanisms whereby depletion of Tregs induces adverse perinatal outcomes involve tissue-specific immune responses and mild systemic maternal inflammation, together with dysregulation of developmental and cellular processes in the placenta, in the absence of intra-amniotic inflammation. These findings provide mechanistic evidence supporting a role for Tregs in the pathophysiology of idiopathic preterm labor/birth and adverse neonatal outcomes.

Maternal-Fetal Immune Responses in Pregnant Women Infected with SARS-CoV-2

Pregnant women are a high-risk population for severe/critical COVID-19 and mortality. However, the maternal-fetal immune responses initiated by SARS-CoV-2 infection, and whether this virus is detectable in the placenta, are still under investigation. Herein, we report that SARS-CoV-2 infection during pregnancy primarily induced specific maternal inflammatory responses in the circulation and at the maternal-fetal interface, the latter being governed by T cells and macrophages. SARS-CoV-2 infection during pregnancy was also associated with a cytokine response in the fetal circulation (i.e. umbilical cord blood) without compromising the cellular immune repertoire. Moreover, SARS-CoV-2 infection neither altered fetal cellular immune responses in the placenta nor induced elevated cord blood levels of IgM. Importantly, SARS-CoV-2 was not detected in the placental tissues, nor was the sterility of the placenta compromised by maternal viral infection. This study provides insight into the maternal-fetal immune responses triggered by SARS-CoV-2 and further emphasizes the rarity of placental infection.