IL-22 participates in an innate anti-HIV-1 host-resistance network through acute-phase protein induction

Oral and anal microbiome from HIV-exposed individuals: role of host-associated factors in taxa composition and metabolic pathways

Evidence indicates that the microbiome plays a significant role in HIV immunopathogenesis and associated complications. This study aimed to characterize the oral and anal microbiome of Men who have Sex with Men (MSM) and Transgender Women (TGW), with and without HIV. One hundred and thirty oral and anal DNA-derived samples were obtained from 78 participants and subjected to shotgun metagenomics sequencing for further microbiome analysis. Significant differences in the microbiome composition were found among subjects associated with HIV infection, gender, sex behavior, CD4+ T-cell counts, antiretroviral therapy (ART), and the presence of HPV-associated precancerous anal lesions. Results confirm the occurrence of oncogenic viromes in this high HIV-risk population. The oral microbiome in HIV-associated cases exhibited an enrichment of bacteria associated with periodontal disease pathogenesis. Conversely, anal bacteria showed a significant decrease in HIV-infected subjects (Coprococcus comes, Finegoldia magna, Blautia obeum, Catenibacterium mitsuokai). TGW showed enrichment in species related to sexual transmission, which concurs that most recruited TGW are or have been sex workers. Prevotella bivia and Fusobacterium gonidiaformans were positively associated with anal precancerous lesions among HIV-infected subjects. The enrichment of Holdemanella biformis and C. comes was associated with detectable viral load and ART-untreated patients. Metabolic pathways were distinctly affected by predominant factors linked to sexual behavior or HIV pathogenesis. Gene family analysis identified bacterial gene signatures as potential prognostic and predictive biomarkers for HIV/AIDS-associated malignancies. Conclusions: Identified microbial features at accessible sites are potential biomarkers for predicting precancerous anal lesions and therapeutic targets for HIV immunopathogenesis.

Current Knowledge of Th22 Cell and IL-22 Functions in Infectious Diseases

T helper 22 (Th22) cells, a newly defined CD4+ T-cell lineage, are characterized by their distinct cytokine profile, which primarily consists of IL-13, IL-22 and TNF-α. Th22 cells express a wide spectrum of chemokine receptors, such as CCR4, CCR6 and CCR10. The main effector molecule secreted by Th22 cells is IL-22, a member of the IL-10 family, which acts by binding to IL-22R and triggering a complex downstream signaling system. Th22 cells and IL-22 have been found to play variable roles in human immunity. In preventing the progression of infections such as HIV and influenza, Th22/IL-22 exhibited protective anti-inflammatory characteristics, and their deleterious proinflammatory activities have been demonstrated to exacerbate other illnesses, including hepatitis B and Helicobacter pylori infection. Herein, we review the current understanding of Th22 cells, including their definition, differentiation and mechanisms, and the effect of Th22/IL-22 on human infectious diseases. According to studies on Th22 cells, Th22/IL-22 may be a promising therapeutic target and an effective treatment strategy for various infections.

The Progestin Medroxyprogesterone Acetate Affects HIV-1 Production in Human Lymphoid Tissue Explants in a Dose-Dependent and Glucocorticoid-like Fashion

The association between the use of the injectable contraceptive depot medroxyprogesterone acetate and HIV-1 susceptibility has been addressed mainly in respect to the changes occurring in the female genital mucosa and blood. However, one of the main sites of HIV-1 pathogenesis is lymphoid organs. To investigate the immunoregulatory effect of medroxyprogesterone acetate (MPA) at this site, human tonsillar tissue explants were infected ex vivo with either a CCR5 (BaL) or CXCR4 (LAI) HIV-1 variant and the release of p24_gag and cytokines was measured in culture supernatant. The response to MPA was compared with that elicited by treatment with progesterone (P4) and dexamethasone (DEX), which selectively binds the glucocorticoid receptor, in donor-matched explant cultures. MPA treatment reduced the replication of both tested HIV-1 strains as well as the production of the mediators of inflammation IL-1β, IL-17A and CCL5, but not CCL20, in a similar way to DEX, whereas P4 had no effect on HIV-1 replication. The magnitude of both MPA and DEX-mediated responses was proportional to the length of exposure and/or administered dose. Blockage of the progesterone and glucocorticoid receptors with mifepristone abolished all observed changes in HIV-1 and cytokine production, and was associated with increased IL-22 levels in HIV-infected explants. Our data indicate that elevated doses of MPA may affect the immune responses in lymphoid tissue in a glucocorticoid-like fashion with an immediate impact on local HIV-1 replication.

Role of Th22 Cells in Human Viral Diseases

Naive CD4⁺ T cells can differentiate into different cell subsets after receiving antigen stimulation, which secrete corresponding characteristic cytokines and thereby exert biological effects in various diseases. Th22 cells, a novel subset of CD4⁺ T cells, are different from Th1, Th2, Th17, and Treg cell subsets, which have been discovered in recent years. They can express CCR4, CCR6, and CCR10 molecules and secrete IL-22, IL-13, and TNF-α. They are not able to secrete IL-17, IL-4, and interferon-γ (IFN-γ). IL-22 is considered as a major effector molecule of Th22 cells whose functions and mechanisms of regulating cell differentiation have been constantly improved. In this review, we provide an overview of the origin, differentiation of Th22 cells. Moreover, we also describe the interrelationships between Th22 cells and Th17, Th1, and Th2 cells. Additionally, the role of Th22 cells were discussed in human diseases with virus infection, which will provide novel insight for the prevention and treatment of viral infection in human.

Regulatory roles of MicroRNA in shaping T cell function, differentiation and polarization

T lymphocytes are an integral component of adaptive immunity with pleotropic effector functions. Impairment of T cell activity is implicated in various immune pathologies including autoimmune diseases, AIDS, carcinogenesis, and periodontitis. Evidently, T cell differentiation and function are under robust regulation by various endogenous factors that orchestrate underlying molecular pathways. MicroRNAs (miRNA) are a class of noncoding, regulatory RNAs that post-transcriptionally control multiple mRNA targets by sequence-specific interaction. In this article, we will review the recent progress in our understanding of miRNA-gene networks that are uniquely required by specific T cell effector functions and provide miRNA-mediated mechanisms that govern the fate of T cells. A subset of miRNAs may act in a synergistic or antagonistic manner to exert functional suppression of genes and regulate pathways that control T cell activation and differentiation. Significance of T cell-specific miRNAs and their dysregulation in immune-mediated diseases is discussed. Exosome-mediated horizontal transfer of miRNAs from antigen presenting cells (APCs) to T cells and from one T cell to another T cell subset and their impact on recipient cell functions is summarized.

Serum level of interleukin-22 in patients with cutaneous warts: A case-control study

BACKGROUND

Warts are viral cutaneous infections caused by human papilloma virus (HPV), presented by verrucous growth over the skin surface. The immune response is considered to play a crucial role in HPV clearance. It depends on intact cellular immunity including natural killer (NK) cell and cytotoxic T cells. It has been clarified that T-helper (Th) 1 cytokines (interleukin (IL)-2, interferon-γ, and tumor necrosis factor-a) and IL-17 are involved in HPV clearance. IL-22 is one of IL-10 family of cytokines produced by NK cells, Th1, Th17, and Th22 cells. In the skin, IL-22 reduces keratinocyte cornification and enhances keratinocyte production of antimicrobial peptides. IL-22 overexpression has been demonstrated in various viral infections and skin inflammatory disorders.

AIM

The aim of this study was to assess serum levels of IL-22 in patients with warts and its association with their different clinical characteristics.

METHODS

The study included 20 patients with warts and 20 control subjects. Serum concentration of IL-22 was measured by enzyme-linked immune sorbent assay.

RESULTS

Serum levels of IL-22 were significantly higher in patients with warts than in control subjects (P < .001). The levels were significantly higher in patients with recurrent warts after prior treatment than in patients with first-time warts (P = .007). Moreover, a significant positive correlation was detected between serum levels of IL-22 and the number of warts (P = .017).

CONCLUSION

Serum level of IL-22 was elevated in patients with warts. Thus, IL-22 may have a crucial role in the antiviral immune response against this infection.

Natural killer cells play an important role in virus infection control: Antiviral mechanism, subset expansion and clinical application

With the global spread of coronavirus disease 2019 (COVID-19), the important role of natural killer (NK) cells in the control of various viral infections attracted more interest, via non-specific activation, such as antibody-dependent cell-mediated cytotoxicity (ADCC) and activating receptors, as well as specific activation, such as memory-like NK generation. In response to different viral infections, NK cells fight viruses in different ways, and different NK subsets proliferate. For instance, cytomegalovirus (CMV) induces NKG2C + CD57 + KIR+ NK cells to expand 3-6 months after hematopoietic stem cell transplantation (HSCT), but human immunodeficiency virus (HIV) induces KIR3DS1+/KIR3DL1 NK cells to expand in the acute phase of infection. However, the similarities and differences among these processes and their molecular mechanisms have not been fully discussed. In this article, we provide a summary and comparison of antiviral mechanisms, unique subset expansion and time periods in peripheral blood and tissues under different conditions of CMV, HIV, Epstein-Barr virus (EBV), COVID-19 and hepatitis B virus (HBV) infections. Accordingly, we also discuss current clinical NK-associated antiviral applications, including cell therapy and NK-related biological agents, and we state the progress and future prospects of NK cell antiviral treatment.

IL-22 suppresses HSV-2 replication in human cervical epithelial cells

Interleukin (IL)-22, a member of the IL-10 family, plays a role in antiviral immune responses to a number of viral infections. However, it is unclear whether IL-22 is involved in the mucosal immunity against herpes simplex virus 2 (HSV-2) infection in the female reproductive tract (FRT). In this study, we studied whether IL-22 could inhibit HSV-2 infection of human cervical epithelial cells (End1/E6E7 cells). We showed that End1/E6E7 cells express the functional IL-22 receptor complex (IL-22R1 and IL-10R2). When treated with IL-22, End1/E6E7 cells expressed the higher levels of IFN-stimulated genes (ISGs: ISG15, ISG56, OAS-1, OAS-2, and Mx2) than untreated cells. In addition, IL-22-treated cells produced higher levels of the tight junction proteins (ZO-1 and Occludin) than untreated cells. Mechanistically, IL-22 could activate the JAK/STAT signaling pathway by inducing the phosphorylation of STAT1 and STAT3. These observations indicate the potential of IL-22 as an anti-HSV-2 agent in the FRT mucosal innate immunity against HSV-2 infection.

Serum Amyloid A3 is required for normal lung development and survival following influenza infection

Serum amyloid A (SAA) proteins are a family of acute phase apolipoproteins implicated to directly modulate innate and adaptive immune responses. However, new studies comparing endogenous SAAs and recombinant forms of these proteins have questioned the function of SAA in inflammation and immunity. We generated SAA3 knockout mice to evaluate the contribution of SAA3 to lung development and immune-mediated lung disease. While SAA3 deficiency does not affect the generation of house dust mite-induced allergic asthma, mice lacking SAA3 develop adult-onset obesity, intrinsic airway hyperresponsiveness, increased inflammatory and fibrotic gene expression in the lung, and elevated levels of lung citrullinated proteins. Polyclonally stimulated CD4+ T cells from SAA3-/- mice exhibit impaired glycolytic activity, decreased TH2 and TH1 cytokine secretion, and elevated IL-17A production compared to wild type cells. Polyclonally stimulated CD8+ T cells from SAA3-/- mice also exhibit impaired glycolytic activity as well as a diminished capacity to produce IL-2 and IFNγ. Finally, SAA3-/- mice demonstrate increased mortality in response to H1N1 influenza infection, along with higher copy number of viral RNAs in the lung, a lack of CD8+ T cell IFNγ secretion, and decreased flu-specific antibodies. Our findings indicate that endogenous SAA3 regulates lung development and homeostasis, and is required for protection against H1N1 influenza infection.

NK Cells in HIV-1 Infection: From Basic Science to Vaccine Strategies

NK cells play a key role in immune response against HIV infection. These cells can destroy infected cells and contribute to adequate and strong adaptive immune responses, by acting on dendritic, T, B, and even epithelial cells. Increased NK cell activity reflected by higher cytotoxic capacity, IFN-γ and chemokines (CCL3, CCL4, and CCL5) production, has been associated with resistance to HIV infection and delayed AIDS progression, demonstrating the importance of these cells in the antiviral response. Recently, a subpopulation of NK cells with adaptive characteristics has been described and associated with lower HIV viremia and control of infection. These evidences, together with some degree of protection shown in vaccine trials based on boosting NK cell activity, suggest that these cells can be a feasible option for new treatment and vaccination strategies to overcome limitations that, classical vaccination approaches, might have for this virus. This review is focus on the NK cells role during the immune response against HIV, including all the effector mechanisms associated to these cells; in addition, changes including phenotypic, functional and frequency modifications during HIV infection will be pointed, highlighting opportunities to vaccine development based in NK cells effector functions.

Bacterial Lipoproteins Constitute the TLR2-Stimulating Activity of Serum Amyloid A

Studies comparing endogenous and recombinant serum amyloid A (SAA) have generated conflicting data on the proinflammatory function of these proteins. In exploring this discrepancy, we found that in contrast to commercially sourced recombinant human SAA1 (hSAA1) proteins produced in Escherichia coli, hSAA1 produced from eukaryotic cells did not promote proinflammatory cytokine production from human or mouse cells, induce Th17 differentiation, or stimulate TLR2. Proteomic analysis of E. coli-derived hSAA1 revealed the presence of numerous bacterial proteins, with several being reported or probable lipoproteins. Treatment of hSAA1 with lipoprotein lipase or addition of a lipopeptide to eukaryotic cell-derived hSAA1 inhibited or induced the production of TNF-α from macrophages, respectively. Our results suggest that a function of SAA is in the binding of TLR2-stimulating bacterial proteins, including lipoproteins, and demand that future studies of SAA employ a recombinant protein derived from eukaryotic cells.

Dual TLR2 and TLR7 agonists as HIV latency-reversing agents

The presence of a reservoir of latently infected cells in HIV-infected patients is a major barrier towards finding a cure. One active cure strategy is to find latency-reversing agents that induce viral reactivation, thus leading to immune cell recognition and elimination of latently infected cells, known as the shock-and-kill strategy. Therefore, the identification of molecules that reactivate latent HIV and increase immune activation has the potential to further these strategies into the clinic. Here, we characterized synthetic molecules composed of a TLR2 and a TLR7 agonist (dual TLR2/7 agonists) as latency-reversing agents and compared their activity with that of the TLR2 agonist Pam2CSK4 and the TLR7 agonist GS-9620. We found that these dual TLR2/7 agonists reactivate latency by 2 complementary mechanisms. The TLR2 component reactivates HIV by inducing NF-κB activation in memory CD4+ T cells, while the TLR7 component induces the secretion of TNF-α by monocytes and plasmacytoid dendritic cells, promoting viral reactivation in CD4+ T cells. Furthermore, the TLR2 component induces the secretion of IL-22, which promotes an antiviral state and blocks HIV infection in CD4+ T cells. Our study provides insight into the use of these agonists as a multipronged approach targeting eradication of latent HIV.

IL-17 and IL-22 production in HIV+ individuals with latent and active tuberculosis

BACKGROUND

IL-17 and IL-22 cytokines play an important role in protective immune responses against Mycobacterium tuberculosis (Mtb) infection. Information on the production of these cytokines and the factors that regulate their production in the context of human immunodeficiency virus (HIV) and latent tuberculosis infection (LTBI) or active tuberculosis disease (ATB) is limited. In the current study, we compared the production of these two cytokines by PBMC of HIV-LTBI+ and HIV + LTBI+ individuals in response to Mtb antigens CFP-10 (culture filtrate protein) and ESAT-6 (Early Secretory Antigenic Target). We also determined the mechanisms involved in their production.

METHODS

We cultured Peripheral Blood Mononuclear Cells (PBMCs) from HIV- individuals and HIV+ patients with latent tuberculosis and active disease with CFP-10 and ESAT-6. Production of IL-17, IL-22 and PD1 (Programmed Death 1), ICOS (Inducible T-cell Costimulator), IL-23R and FoxP3 (Forkhead box P3) expression on CD4+ T cells was measured.

RESULTS

In response to Mtb antigens CFP-10 and ESAT-6, freshly isolated PBMCs from HIV+ LTBI+ and HIV+ active TB patients produced less IL-17 and IL-22 and more IL-10, expressed less IL-23R, and more PD1 and expanded to more FoxP3+ cells. Active TB infection in HIV+ individuals further inhibited antigen specific IL-17 and IL-22 production compared to those with LTBI. Neutralization of PD1 restored IL-23R expression, IL-17 and IL-22 levels and lowered IL-10 production and reduced expansion of FoxP3 T cells.

CONCLUSIONS

In the current study we found that increased PD1 expression in HIV + LTBI+ and HIV+ active TB patients inhibits IL-17, IL-22 production and IL-23R expression in response to Mtb antigens CFP-10 and ESAT-6.

Serum amyloid A3 is required for normal weight and immunometabolic function in mice

Serum amyloid A (SAA) is an apolipoprotein that is robustly upregulated in numerous inflammatory diseases and has been implicated as a candidate pro-inflammatory mediator. However, studies comparing endogenous SAAs and recombinant forms of the acute phase protein have generated conflicting data on the function of SAA in immunity. We generated SAA3 knockout mice to evaluate the contribution of SAA3 to immune-mediated disease, and found that mice lacking SAA3 develop adult-onset obesity and metabolic dysfunction along with defects in innate immune development. Mice that lack SAA3 gain more weight, exhibit increased visceral adipose deposition, and develop hepatic steatosis compared to wild-type littermates. Leukocytes from the adipose tissue of SAA3-/- mice express a pro-inflammatory phenotype, and bone marrow derived dendritic cells from mice lacking SAA3 secrete increased levels of IL-1β, IL-6, IL-23, and TNFα in response to LPS compared to cells from wild-type mice. Finally, BMDC lacking SAA3 demonstrate an impaired endotoxin tolerance response and inhibited responses to retinoic acid. Our findings indicate that endogenous SAA3 modulates metabolic and immune homeostasis.

Evaluation of Different Parameters of Humoral and Cellular Immune Responses in HIV Serodiscordant Heterosexual Couples: Humoral Response Potentially Implicated in Modulating Transmission Rates

As the HIV/AIDS pandemic still progresses, understanding the mechanisms governing viral transmission as well as protection from HIV acquisition is fundamental. In this context, cohorts of HIV serodiscordant heterosexual couples (SDC) represent a unique tool. The present study was aimed to evaluate specific parameters of innate, cellular and humoral immune responses in SDC. Specifically, plasma levels of cytokines and chemokines, HIV-specific T-cell responses, gp120-specific IgG and IgA antibodies, and HIV-specific antibody-dependent cellular cytotoxicity (ADCC) activity were assessed in nine HIV-exposed seronegative individuals (ESN) and their corresponding HIV seropositive partners (HIV⁺-P), in eighteen chronically infected HIV subjects (C), nine chronically infected subjects known to be HIV transmitters (CT) and ten healthy HIV⁻ donors (HD). Very low magnitude HIV-specific cellular responses were found in two out of six ESN. Interestingly, HIV⁺-P had the highest ADCC magnitude, the lowest IgA levels and the highest IgG/IgA ratio, all compared to CT. Positive correlations between CD4⁺ T-cell counts and both IgG/IgA ratios and %ADCC killing uniquely distinguished HIV⁺-P. Additionally, evidence of IgA interference with ADCC responses from HIV⁺-P and CT is provided. These data suggest for the first time a potential role of ADCC and/or gp120-specific IgG/IgA balance in modulating heterosexual transmission. In sum, this study provides key information to understand the host factors that influence viral transmission, which should be considered in both the development of prophylactic vaccines and novel immunotherapies for HIV-1 infection.

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The evaluation of different immune parameters in HIV serodiscordant couples helped identify factors shaping transmission.

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Innate and cellular immune responses were apparently not involved in this scenario.

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HIV-specific ADCC, IgA titer and IgG/IgA balance were identified as factors involved in modulating viral transmission.

The existence of individuals that remain HIV negative despite being repeatedly exposed to the virus has long been described. To date, only homozygosis for a 32-base pair deletion in the ccr5 gene has been consistently shown to be a determinant of HIV resistance. Still, subjects bearing the WT ccr5 gene have also been described as resistant or less susceptible to HIV. Thus, other mechanisms must be involved in this phenomenon. The results presented here postulate ADCC and IgG/IgA ratio as potential mechanisms involved in modulating HIV transmission in the context of serodiscordant couples and inspire further investigations.

The Anti-Hiv Candidate Abx464 Dampens Intestinal Inflammation by Triggering Il-22 Production in Activated Macrophages

The progression of human immunodeficiency virus (HIV) is associated with mucosal damage in the gastrointestinal (GI) tract. This damage enables bacterial translocation from the gut and leads to subsequent inflammation. Dextran sulfate sodium (DSS-exposure) is an established animal model for experimental colitis that was recently shown to recapitulate the link between GI-tract damage and pathogenic features of SIV infection. The current study tested the protective properties of ABX464, a first-in-class anti-HIV drug candidate currently in phase II clinical trials. ABX464 treatment strongly attenuated DSS-induced colitis in mice and produced a long-term protection against prolonged DSS-exposure after drug cessation. Consistently, ABX464 reduced the colonic production of the inflammatory cytokines IL-6 and TNFα as well as that of the chemoattractant MCP-1. However, RNA profiling analysis revealed the capacity of ABX464 to induce the expression of IL-22, a cytokine involved in colitis tissue repair, both in DSS-treated mice and in LPS-stimulated bone marrow-derived macrophages. Importantly, anti-IL-22 antibodies significantly reduced the protective effect of ABX464 on colitis in DSS-treated mice. Because reduced IL-22 production in the gut mucosa is an established factor of HIV and DSS-induced immunopathogenesis, our data suggest that the anti-inflammatory properties of ABX464 warrant exploration in both HIV and inflammatory ulcerative colitis (UC) disease.

Impact of IL-22 gene polymorphism on human immunodeficiency virus infection in Han Chinese patients

BACKGROUND/PURPOSE

To analyze the polymorphism of the IL-22 gene in Han Chinese patients and to evaluate the influence of IL-22 polymorphism on human immunodeficiency virus (HIV) infection.

METHODS

IL-22 gene polymorphism was analyzed in 73 blood samples from healthy participants. The influence of the genotype and allele distribution of three single nucleotide polymorphisms (rs2227484, rs2227485, and rs2227513) of IL-22 on HIV infection was evaluated in 619 HIV seropositive patients and 619 healthy controls. To determine the association between the rs2227513 genotype and IL-22 levels in plasma, we randomly selected 29 HIV seropositive blood samples and 15 healthy blood samples and measured the levels of IL-22.

RESULTS

Nine single nucleotide polymorphism loci of the IL-22 gene were found (rs2227484, rs2227485, rs2227491, rs2227508, rs2227513, rs1179249, rs1179250, rs1179251, and rs1182844). Stratified analysis (by sex) showed a higher association of HIV infection and the A/G genotype and G allele at rs2227513 in women, but not in men (A/G genotype odds ratio = 5.24, 95% confidence interval = 1.13-24.27; allele G odds ratio = 5.27, 95% confidence interval 1.15-24.23). The rs2227513 A/G genotype was also associated with significantly higher levels of plasma IL-22, regardless of whether the patient was HIV seropositive or seronegative.

CONCLUSION

Our results suggest that IL-22 production in blood might act as a pathogenic factor in HIV infection.

The Role of IL-22 in Viral Infections: Paradigms and Paradoxes

Interleukin-22 (IL-22) is a member of the IL-10 family of cytokines. Hematopoietic cells express IL-22, and this cytokine signals through the heterodimeric IL-22 receptor expressed by non-hematopoietic cells. A growing body of evidence points toward a role for IL-22 in a diverse array of biological functions ranging from cellular proliferation, tissue protection and regeneration, and inflammation. In recent years, the role that IL-22 plays in antiviral immune responses has been examined in a number of infection models. Herein, we assess our current understanding of how IL-22 determines the outcome of viral infections and define common mechanisms that are evident from, sometimes paradoxical, findings derived from these studies. Finally, we discuss the potential therapeutic utility of IL-22 manipulation in the treatment and prevention of viral infections and associated pathologies.

TB/HIV pleurisy reduces Th17 lymphocyte proportion independent of the cytokine microenvironment

T-helper (Th) 17 cells are a pro-inflammatory subset of CD4(+) effector T-cells critical in mucosal immunity. Imbalances in Th17 cell proportion have been implicated in the pathogenesis of several diseases; however, this has not been adequately explored in tuberculosis (TB) and human immunodeficiency virus (HIV) co-infection. Since Th17 cells are predominantly mucosally associated, we assessed Th17 proportion and associated microenvironment in pleural effusions from patients co-infected with TB/HIV. Our results show that TB(+)HIV(+) pleurisy results in significantly reduced frequency of CD4(+)IL-17(+)RORC(+)STAT3(+) Th17 cells compared to TB(-)HIV(-)ex vivo (p = 0.0054) and was confirmed in conditioned media studies in vitro (p = 0.0001). This was not associated with alterations in Th17 polarising cytokines IL-6, IL-21 and IL-23 or changes in Th17 signature cytokines IL-17A and F. However, the mRNA expression of Th17 signalling molecules, IL-6 (p = 0.0022), IL-6R (p = 0.0247), IL-1β (p = 0.0022) and signal transducer and activator (STAT) 3 (p = 0.0022) were significantly upregulated. Notably, TB(+)HIV(+) pleural fluid contained significantly higher concentrations of IL-1β (p = 0.0008), IL-22 (p = 0.0115), IL-31 (p = 0.0210), TNF-α (p = 0.0251) and IFN-γ (p = 0.0026) than TB(-)HIV(-) pleural fluid ex vivo. Taken together, this suggests a reduced portion of Th17 lymphocytes in TB/HIV pleurisy is independent of locally mediated cytokine polarisation.

Biological and pathological activities of interleukin-22

Interleukin (IL)-22, a member of the IL-10 family, is a cytokine secreted by several types of immune cells including IL-22(+)CD4(+) T cells (Th22) and IL-22 expressing innate leukocytes (ILC22). Recent studies have demonstrated that IL-22 is a key component in mucosal barrier defense, tissue repair, epithelial cell survival, and proliferation. Furthermore, accumulating evidence has defined both protective and pathogenic properties of IL-22 in a number of conditions including autoimmune disease, infection, and malignancy. In this review, we summarize the expression and signaling pathway and functional characteristics of the IL-22 and IL-22 receptor axis in physiological and pathological scenarios and discuss the potential to target IL-22 signaling to treat human diseases.

Increased frequency of circulating Tc22/Th22 cells and polyfunctional CD38(-) T cells in HIV-exposed uninfected subjects

Some individuals are resistant to HIV-1 infection despite repeated exposure to the virus, suggesting the presence of a complex antiviral response. Innate factors like IL-22 exert gut mucosal protection and polyfunctional T cells have been associated with low progression in HIV infection; therefore, we evaluated the frequencies of CD4+ and CD8+ T cell-secreting cytokines, including Tc22/Th22 cells and polyfunctional T cells in HIV-1-exposed uninfected individuals (EUs), their HIV-1-infected partners and healthy controls. EUs exhibited an increased frequency of p15 Gag CD4+ IL-22+ secreting T cells, whereas HIV-infected partners demonstrated a high frequency of CD4+ IL-17+ T cells in response to p24. Similar responses of Th22 and Tc22 cells to Gag peptides and Staphylococcal enterotoxin B (SEB) stimulation were detected in the serodiscordant couples. However, polyfunctionality in HIV subjects was associated with an HIV Gag response of CD38+ T cells, whereas polyfunctionality for EUs was induced upon SEB stimulation by CD38- T cells. EUs demonstrated the presence of Tc22/Th22 cells and polyfunctional CD38- T cells with a low activation profile. These data suggest that SEB-induced polyfunctional CD4+ and CD8+ T cells together with Tc22/Th22 cells in EU individuals can provide an immunological advantage in the response to pathogens such as HIV-1.

Host candidate gene polymorphisms and associated clearance of P. falciparum amodiaquine and fansidar resistance mutants in children less than 5 years in Cameroon

BACKGROUND

In this post-hoc analysis, we determined the influence of single nucleotide polymorphisms in host candidate immune genes on the outcome of drug resistant malaria in Cameroon.

METHODS

Human DNA from 760 patients from a previous clinical trial was subjected to mass spectrometry-based single nucleotide polymorphism (SNP) genotyping. Allele frequencies of candidate immune genes were calculated for 62 SNPs on 17 human chromosomes for their possible involvement in clearance of drug-resistant parasites with the triple mutations of pfcrt76T, pfmdr86Y, and pfmdr1246Y (TY) and pfdhfr51I, pfdhfr59R, pfdhfr108N, and pfdhps437G (IRNG) which were determined by dotblot or PCR-restriction analysis. Differences in SNP frequencies and association analysis were carried out by comparing Chi-square odds ratios (ORs) and stratified by Mantel-Haenzel statistics. An adjusted P value (OR) <0·0008 was considered significant.

RESULTS

Post-treatment drug failure rates were amodiaquine (36·4%); sulpadoxine/pyrimethamine-amodiaquine combination (15·4%); and sulphadoxine/pyrimethamine (18·1%). SNPs in IL22, IL-4R1, and CD36 appeared to have been associated with clearance of resistant parasites [p  =  0·017, OR (C allele):1·44, 95% CI (OR): 1·06-1·95]; [P  =  0·014, OR  =  1·31, 95% CI (OR): 1·07-1·83]; [P  =  5·78×10(-5), OR  =  0·27, 95%CI (OR): 0·13-0·54], respectively, with high fever (>39°C for 48 hours) [IL-22, P  =  0·01, OR  =  1·5, 95% CI (OR): 1·8-2·1] and also in high frequency among the Fulani participants [P  =  0·006, OR  =  1·83, 95% CI (OR): 1·11-3·08)]. The CD36-1264 null allele was completely absent in the northern population.

CONCLUSION

Independent association of SNPs in IL22 and IL-4 with clearance of amodiaquine- and sulphadoxine/pyrimethamine-resistant parasites did not reach statistical significance, but may suggest that not all drug-resistant mutants are adversely affected by the same immune-mediated mechanisms of clearance.

Alternative effector-function profiling identifies broad HIV-specific T-cell responses in highly HIV-exposed individuals who remain uninfected

The characterization of host immune responses to human immunodeficiency virus (HIV) in HIV controllers and individuals with high exposure but seronegativity to HIV (HESN) is needed to guide the development of effective preventive and therapeutic vaccine candidates. However, several technical hurdles severely limit the definition of an effective virus-specific T-cell response. By using a toggle-peptide approach, which takes HIV sequence diversity into account, and a novel, boosted cytokine staining/flow cytometry strategy, we here describe new patterns of T-cell responses to HIV that would be missed by standard assays. Importantly, this approach also allows detection of broad and strong virus-specific T-cell responses in HESN individuals that are characterized by a T-helper type 1 cytokine-like effector profile and produce cytokines that have been associated with potential control of HIV infection, including interleukin 10, interleukin 13, and interleukin 22. These results establish a novel approach to improve the current understanding of HIV-specific T-cell immunity and identify cellular immune responses and individual cytokines as potential markers of relative HIV resistance. As such, the findings also help develop similar strategies for more-comprehensive assessments of host immune responses to other human infections and immune-mediated disorders.

The crystal structure of zebrafish IL-22 reveals an evolutionary, conserved structure highly similar to that of human IL-22

The class II cytokine family consists of small α-helical signaling proteins including the interleukin-10 (IL-10)/IL-22 family, as well as interferons (IFNs). They regulate the innate immune response and in addition have an important role in protecting epithelial tissues. Teleost fish possess a class II cytokine system surprisingly similar to that of humans, and thus zebrafish offers an attractive model organism for investigating the role of class II cytokines in inflammation. However, the evolution of class II cytokines is critical to understand if we are to take full advantage of zebrafish as a model system. The small size and fast evolution of these cytokines obscure phylogenetic analyses based purely on sequences, but one can overcome this obstacle by using information contained within the structure of those molecules. Here we present the crystal structure of IL-22 from zebrafish (zIL-22) solved at 2.1 Å, which displays a typical class II cytokine architecture. We generated a structure-guided alignment of vertebrate class II cytokines and used it for phylogenetic analysis. Our analysis suggests that IL-22 and IL-26 arose early during the evolution of the IL-10-like cytokines. Thus, we propose an evolutionary scenario of class II cytokines in vertebrates, based on genomic and structural data.

Neutrophils recruited by IL-22 in peripheral tissues function as TRAIL-dependent antiviral effectors against MCMV

During primary infection, murine cytomegalovirus (MCMV) spreads systemically, resulting in virus replication and pathology in multiple organs. This disseminated infection is ultimately controlled, but the underlying immune defense mechanisms are unclear. Investigating the role of the cytokine IL-22 in MCMV infection, we discovered an unanticipated function for neutrophils as potent antiviral effector cells that restrict viral replication and associated pathogenesis in peripheral organs. NK-, NKT-, and T cell-secreted IL-22 orchestrated antiviral neutrophil-mediated responses via induction in stromal nonhematopoietic tissue of the neutrophil-recruiting chemokine CXCL1. The antiviral effector properties of infiltrating neutrophils were directly linked to the expression of TNF-related apoptosis-inducing ligand (TRAIL). Our data identify a role for neutrophils in antiviral defense, and establish a functional link between IL-22 and the control of antiviral neutrophil responses that prevents pathogenic herpesvirus infection in peripheral organs.

Thioredoxins, glutaredoxins, and peroxiredoxins--molecular mechanisms and health significance: from cofactors to antioxidants to redox signaling

Thioredoxins (Trxs), glutaredoxins (Grxs), and peroxiredoxins (Prxs) have been characterized as electron donors, guards of the intracellular redox state, and "antioxidants". Today, these redox catalysts are increasingly recognized for their specific role in redox signaling. The number of publications published on the functions of these proteins continues to increase exponentially. The field is experiencing an exciting transformation, from looking at a general redox homeostasis and the pathological oxidative stress model to realizing redox changes as a part of localized, rapid, specific, and reversible redox-regulated signaling events. This review summarizes the almost 50 years of research on these proteins, focusing primarily on data from vertebrates and mammals. The role of Trx fold proteins in redox signaling is discussed by looking at reaction mechanisms, reversible oxidative post-translational modifications of proteins, and characterized interaction partners. On the basis of this analysis, the specific regulatory functions are exemplified for the cellular processes of apoptosis, proliferation, and iron metabolism. The importance of Trxs, Grxs, and Prxs for human health is addressed in the second part of this review, that is, their potential impact and functions in different cell types, tissues, and various pathological conditions.

Acute HIV-1 seroconversion with an unusual plasma biomarker profile

An unusual case of acute primary HIV-1 infection in a man with a high plasma viral load, a 51-fold increase in C-reactive protein, and antibodies against only gp160 is described. Numerous serum cytokine concentrations were elevated during HIV-1 seroconversion.

Serum amyloid A inhibits dendritic cell apoptosis to induce glucocorticoid resistance in CD4(+) T cells

Mediators produced by the airway epithelium control the activation, recruitment, and survival of pulmonary dendritic cells (DC) that present antigen to CD4(+) T cells during the genesis and exacerbation of allergic asthma. The epithelial-derived acute phase protein, serum amyloid A (SAA), induces DC maturation and TH17 polarization. TH17 responses are associated with severe forms of allergic asthma that are poorly controlled by corticosteroids. We sought to determine whether SAA would enhance the survival of DC during serum starvation and could then contribute to the development of a glucocorticoid-resistant phenotype in CD4(+) T cells. Bone marrow-derived dendritic cells (BMDC) that were serum starved in the presence of SAA were protected from activation of caspase-3 and released less lactate dehydrogenase. In comparison with untreated serum-starved BMDC, treatment with SAA downregulated mRNA expression of the pro-apoptotic molecule Bim, increased production of the pro-survival heat shock protein 70 (HSP70), and induced secretion of pro-inflammatory cytokines. SAA-treated BMDC that were serum starved for 48 h remained capable of presenting antigen and induced OTII CD4(+) T cells to secrete IL-17A, IL-17F, IL-21, IL-22, and IFNγ in the presence of ovalbumin. IL-17A, IL-17F, IL-21, and IFNγ production occurred even when the CD4(+) T cells were treated with dexamethasone (Dex), whereas glucocorticoid treatment abolished cytokine secretion by T cells cocultured with untreated serum-starved BMDC. Measurement of Dex-responsive gene expression demonstrated CD4(+) T cells as the target of glucocorticoid hyperresponsiveness manifest as a consequence of BMDC stimulation by SAA. Finally, allergic airway disease induced by SAA and antigen inhalation was unresponsive to Dex treatment. Our results indicate that apo-SAA affects DC to both prolong their viability and increase their inflammatory potential under apoptosis-inducing conditions. These findings reveal mechanisms through which SAA enhances the CD4(+) T-cell-stimulating capacity of antigen-presenting cells that may actively participate in the pathogenicity of glucocorticoid-resistant lung disease.

Interleukin-22 reduces lung inflammation during influenza A virus infection and protects against secondary bacterial infection

Interleukin-22 (IL-22) has redundant, protective, or pathogenic functions during autoimmune, inflammatory, and infectious diseases. Here, we addressed the potential role of IL-22 in host defense and pathogenesis during lethal and sublethal respiratory H3N2 influenza A virus (IAV) infection. We show that IL-22, as well as factors associated with its production, are expressed in the lung tissue during the early phases of IAV infection. Our data indicate that retinoic acid receptor-related orphan receptor-γt (RORγt)-positive αβ and γδ T cells, as well as innate lymphoid cells, expressed enhanced Il22 transcripts as early as 2 days postinfection. During lethal or sublethal IAV infections, endogenous IL-22 played no role in the control of IAV replication and in the development of the IAV-specific CD8(+) T cell response. During lethal infection, where wild-type (WT) mice succumbed to severe pneumonia, the lack of IL-22 did not accelerate or delay IAV-associated pathogenesis and animal death. In stark contrast, during sublethal IAV infection, IL-22-deficient animals had enhanced lung injuries and showed a lower airway epithelial integrity relative to WT littermates. Of importance, the protective effect of endogenous IL-22 in pulmonary damages was associated with a more controlled secondary bacterial infection. Indeed, after challenge with Streptococcus pneumoniae, IAV-experienced Il22(-/-) animals were more susceptible than WT controls in terms of survival rate and bacterial burden in the lungs. Together, IL-22 plays no major role during lethal influenza but is beneficial during sublethal H3N2 IAV infection, where it limits lung inflammation and subsequent bacterial superinfections.

IL-22 exacerbates the severity of CVB3-induced acute viral myocarditis in IL-17A-deficient mice

Interleukin (IL)-22 has either proinflammatory or tissue‑protective properties, depending on the nature of the affected tissue and the local cytokine milieu, including the presence or absence of IL-17A co-expression. We have previously demonstrated that IL-22 has critical anti-inflammatory and antiviral roles in mice with coxsackievirus B3 (CVB3)‑induced acute viral myocarditis (AVMC) in the presence of IL-17A. However, whether IL-17A determines the function of IL-22 in AVMC remains unknown. Therefore, the present study, in continuation of our previous investigations, aimed to determine whether IL-22 plays a distinctly different role in the absence of IL-17A in AVMC by using IL-17A-deficient mice. Results demonstrated that the neutralization of IL-22 in IL-17A‑deficient mice alleviated the severity of myocarditis. This was demonstrated by the lower pathological scores of heart sections and ratios of heart weight/body weight (HW/BW), reduced production of activator of transcription 3 (STAT3) and proinflammatory cytokines TNF-α and IL-6, followed by increased viral replication and decreased levels of the antiviral cytokine IFN-γ. Furthermore, the correlation between cardiac CVB3 RNA and IL-22 mRNA or IFN-γ mRNA was negative. In conclusion, IL-22 exacerbated the severity of AVMC and restrained viral replication in the absence of IL-17A. Spleen lymphocytes cultured with recombinant IL-17 (rIL-17) increased the production of IL-22. Combined with our previous data, these results indicate that IL-17A is not involved in regulating the antiviral role, however, may mediate the tissue-protective versus pathogenic properties of IL-22 in CVB3-induced AVMC in mice.

TH17 and TH22 cells: a confusion of antimicrobial response with tissue inflammation versus protection

Substantial progress in understanding mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumors, organ transplantation, chronic infections, and pregnancy is in an exciting developmental phase that might lead to a variety of targeted therapeutic approaches. Recent progress in the interaction between immune/inflammatory cell subsets through cytokines, particularly the extension of the knowledge on reciprocal regulation and counterbalance between subsets of T(H)1, T(H)2, T(H)9, T(H)17, T(H)22, T follicular helper cells and different subsets of regulatory T cells, as well as corresponding and co-orchestrating B-cell, natural killer cell, dendritic cell, and innate lymphoid cell subsets, offers new possibilities for immune intervention. Studies on new subsets confirm the important role of T cells in the instruction of tissue cells and also demonstrate the important role of feedback regulation for the polarization toward distinct T-cell subsets. T(H)17 and T(H)22 cells are 2 emerging T(H) cell subsets that link the immune response to tissue inflammation; IL-17A and IL-17F and IL-22 are their respective prototype cytokines. Although both cytokines play roles in immune defense to extracellular bacteria, IL-17 augments inflammation, whereas IL-22 plays a tissue-protective role. This review focuses on current knowledge on T(H)17 and T(H)22 cells and their role in inflammation, with special focus on the mechanisms of their generation and driving and effector cytokines, as well as their role in host defense, autoimmunity, and allergic diseases.

Increased expressions of IL-22 and Th22 cells in the coxsackievirus B3-Induced mice acute viral myocarditis

BACKGROUND

Recently, a new subset of T helper (Th) cell that predominantly secret cytokine interleukin-22 (IL-22) is identified, termed Th22 cells. The Th22 subset has been demonstrated to be involved in immunity and tissue inflammation. However, the existence of Th22 cells and role of IL-22 in acute viral myocarditis (AVMC) remain unknown.

METHODS

BALB/c mice were intraperitoneally (i.p) infected with CVB3 for establishing AVMC models. Control mice were treated with phosphate-buffered saline (PBS) i.p. On day 14 post injection, frequencies of splenic Th22 cells were determined, productions of IL-22 and expressions of IL-22R (IL-22 receptor) were measured. To further investigate the effects of IL-22, AVMC mice treated with Anti-IL-22 neutralizing antibody were explored. The severity of AVMC were monitored; the frequencies of Th22 cells, the expressions of IL-22 and IL-22R were investigated; in addition to IFN-γ, inflammatory cytokines IL-17, TNF-α, IL-6 as well as IL-1β, were evaluated. Cardiac viral replication were detected.

RESULTS

Compared with control group, significant elevations of circulating Th22 cells and IL-22, cardiac protein and mRNA of IL-22, and IL-22R1 were demonstrated in AVMC group. Treatment of AVMC mice with Anti-IL-22 Ab exacerbated the severity of viral myocarditis, verified by lower survival rate, higher HW/BW ratios and cardiac pathological scores. Anti-IL-22 Ab decreased the frequencies of Th22 cells and the levels of IL-22, and increased the expressions of cardiac IL-22R1. Up-regulations of IL-17, IL-6 and TNF-α, down-regulations of IFN-γ proteins and gene expressions in the plasma and myocardium, were observed in Anti-IL-22 Ab group. Furthermore, neutralization of IL-22 significantly promoted cardiac viral replication.

CONCLUSIONS

Our data indicate that the increased frequencies of IL-22-producing Th22 cells may play an important role in the pathogenesis of CVB3-induced mice AVMC, IL-22 may act as an myocardium-protective cytokine via the IL-22-IL-22R pathway, and suggest that targeting the Th22 cell and IL-22-IL-22R pathway could provide new therapeutic modalities for the treatment of CVB3-induced AVMC.

Interleukin-22 predicts severity and death in advanced liver cirrhosis: a prospective cohort study

BACKGROUND

Interleukin-22 (IL-22), recently identified as a crucial parameter of pathology in experimental liver damage, may determine survival in clinical end-stage liver disease. Systematic analysis of serum IL-22 in relation to morbidity and mortality of patients with advanced liver cirrhosis has not been performed so far.

METHODS

This is a prospective cohort study including 120 liver cirrhosis patients and 40 healthy donors to analyze systemic levels of IL-22 in relation to survival and hepatic complications.

RESULTS

A total of 71% of patients displayed liver cirrhosis-related complications at study inclusion. A total of 23% of the patients died during a mean follow-up of 196 ± 165 days. Systemic IL-22 was detectable in 74% of patients but only in 10% of healthy donors (P < 0.001). Elevated levels of IL-22 were associated with ascites (P = 0.006), hepatorenal syndrome (P < 0.0001), and spontaneous bacterial peritonitis (P = 0.001). Patients with elevated IL-22 (>18 pg/ml, n = 57) showed significantly reduced survival compared to patients with regular (≤18 pg/ml) levels of IL-22 (321 days versus 526 days, P = 0.003). Other factors associated with reduced overall survival were high CRP (≥2.9 mg/dl, P = 0.005, hazard ratio (HR) 0.314, confidence interval (CI) (0.141 to 0.702)), elevated serum creatinine (P = 0.05, HR 0.453, CI (0.203 to 1.012)), presence of liver-related complications (P = 0.028, HR 0.258, CI (0.077 to 0.862)), model of end stage liver disease (MELD) score ≥20 (P = 0.017, HR 0.364, CI (0.159 to 0.835)) and age (P = 0.011, HR 0.955, CI (0.922 to 0.989)). Adjusted multivariate Cox proportional-hazards analysis identified elevated systemic IL-22 levels as independent predictors of reduced survival (P = 0.007, HR 0.218, CI (0.072 to 0.662)).

CONCLUSIONS

In patients with liver cirrhosis, elevated systemic IL-22 levels are predictive for reduced survival independently from age, liver-related complications, CRP, creatinine and the MELD score. Thus, processes that lead to a rise in systemic interleukin-22 may be relevant for prognosis of advanced liver cirrhosis.

IL-22 signaling contributes to West Nile encephalitis pathogenesis

The Th17 cytokine, IL-22, regulates host immune responses to extracellular pathogens. Whether IL-22 plays a role in viral infection, however, is poorly understood. We report here that Il22(-/-) mice were more resistant to lethal West Nile virus (WNV) encephalitis, but had similar viral loads in the periphery compared to wild type (WT) mice. Viral loads, leukocyte infiltrates, proinflammatory cytokines and apoptotic cells in the central nervous system (CNS) of Il22(-/-) mice were also strikingly reduced. Further examination showed that Cxcr2, a chemokine receptor that plays a non-redundant role in mediating neutrophil migration, was significantly reduced in Il22(-/-) compared to WT leukocytes. Expression of Cxcr2 ligands, cxcl1 and cxcl5, was lower in Il22(-/-) brains than wild type mice. Correspondingly, neutrophil migration from the blood into the brain was attenuated following lethal WNV infection of Il22(-/-) mice. Our results suggest that IL-22 signaling exacerbates lethal WNV encephalitis likely by promoting WNV neuroinvasion.

In vitro antigen-specific induction of IL-22 in human subjects that resolved HCV infection

AIMS: To determine if in vitro production of IL-22 and IL-17 correlated with resolution of HCV infection. MATERIALS #ENTITYSTARTX00026; METHODS: Human peripheral blood cells isolated from a well-defined cohort of resolved and chronic HCV-infected subjects were used to measure HCV-, influenza- and mitogen-activated T-cell proliferation. In addition, IL-22 and IL-17 production was measured via ELISAs and flow cytometry. RESULTS: Resolved HCV subjects had a significantly higher T-cell proliferative response to recombinant NS3 protein compared with chronic HCV subjects. Resolved subjects had a dose-dependent IL-22 response to recombinant NS3 compared with chronic HCV subjects. CONCLUSION: IL-22 production is associated with antigen-specific induction of CD4 (+) T cells in individuals that resolved HCV infection, suggesting a potential role for IL-22 in HCV clearance.

Molecular mechanisms of HIV-1 infection in neonatal target cells

HIV-1-infected neonates and infants have a higher viral load and progress to symptomatic AIDS more rapidly than their own infected mothers, as well as other infected adults, with differences in clinical manifestations, recurrent bacterial infections and CNS disorders. Two major reasons have been attributed to this differential HIV pathogenesis and disease; the relative immaturity of the neonate’s immune system and it’s inability to contain the highly replicating and mutating HIV-1, and the more efficient replication of HIV-1 in neonatal cells than in adult target cells. In this context, it has been demonstrated that HIV-1 replicates more efficiently in neonatal (cord) blood monocytes/macrophages and T lymphocytes – including naive and memory T lymphocytes – compared with adult blood cells. We have also determined the mechanisms of the differential HIV-1 replication in cord versus adult blood monocytes/macrophages and T lymphocytes (naive and memory), finding that it was influenced at the level of HIV-1 gene expression. The increased HIV-1 gene expression in neonatal versus adult target cells was regulated by differential expression of host factors, transcription factors (NF-κB, E2F, HAT-1, TFIIE, Cdk9 and Cyclin T1), signal transducers (STAT3 and STAT5A) and cytokines (IL-1β, IL-6 and IL-10). We also showed that nuclear extracts from cord cells interacted with HIV-1 long terminal repeat cis-acting sequences, including NF-κB, NFAT, AP1 and NF-IL6, to a greater extent when compared with adult peripheral blood mononuclear cell nuclear extracts. Additionally, shRNA of retroviral origin for STAT3 and IL-6 downregulated both their own gene expression as well as that of HIV-1, indicating that these factors influenced the differential expression of HIV-1 genes in cord cells compared with adult cells. In addition, HIV-1 integration plays an important role in differential HIV-1 replication and gene expression in neonatal versus adult cells by integrating into more actively transcribed genes in neonates compared with adults. We characterized 468 HIV-1 integration sites within cord and adult blood T lymphocytes and monocytes/macrophages, including genes coding for cellular components, and those involved with maintenance of the intracellular environment, enzyme regulation, cellular metabolism, catalytic activity and cation transport, as well as several potential transcription factor binding sites at the sites of integration. Additionally, the genes at the integration sites, transcription factors and transcription binding sites were expressed at higher levels in cord than adult target cells. In summary, the increased HIV-1 gene expression and replication in neonatal target cells due to differential expression of host factors all contribute to an increased viral load and faster disease progression in neonates and infants when compared with similar situations in adult patients. Based on these findings, it may be possible to identify new viral and host targets for use in developing strategies for the treatment and prevention of HIV-1.

Dissecting the HIV-specific immune response: a systems biology approach

PURPOSE OF REVIEW

Several unique HIV-infected or HIV-resistant cohorts have been studied over the years to try and delineate the correlates of protection. Although several mechanisms have been put forward, studies aiming to integrate the different mechanisms into a comprehensive model are still lacking. Current systems biology approaches emphasize the importance of unifying independent datasets, provide tools that facilitate hypothesis formulation and testing, and direct us toward uncovering novel therapeutic targets by defining molecular networks perturbed during disease. This review will focus on the current findings that utilized systems biology techniques in order to identify correlates of protection from HIV disease progression and resistance to infection in unique cohorts of individuals as well as in nonhuman primate models of SIV infection.

RECENT FINDINGS

Using systems biology technologies and data analysis tools, the studies described herein have found that pathways implicated in survival, cell cycling, inflammation, and oxidative stress work in unison to limit pathology caused by chronic immune activation. This situation favors the survival of effector lymphocytes and limits the dissemination of viral particles in HIV elite controllers, exposed-uninfected individuals, and natural hosts of SIV infection.

SUMMARY

Systems and computational biology tools have clearly expanded our understanding of HIV pathogenesis by unifying independent observations and by giving us novel molecular targets to pursue. These molecular signatures have the potential to uncover correlates of protection in HIV disease and, in the era of personalized medicine, to determine predictive signatures of treatment efficacy and/or failure.

Role of IL-6 in the resolution of pancreatitis in obese mice

Obesity increases severity of acute pancreatitis and risk of pancreatic cancer. Pancreatitis and obesity are associated with elevated IL-6, a cytokine involved in inflammation and tumorigenesis. We studied the role of IL-6 in the response of lean and obese mice to pancreatitis induced by IL-12 + IL-18. Lean and diet-induced obese (DIO) WT and IL-6 KO mice and ob/ob mice pretreated with anti-IL-6 antibodies were evaluated at Days 1, 7, and 15 after induction of pancreatitis. Prolonged elevation of IL-6 in serum and visceral adipose tissue was observed in DIO versus lean WT mice, whereas circulating sIL-6R declined in DIO but not lean mice with pancreatitis. The severe inflammation and lethality of DIO mice were also observed in IL-6 KO mice. However, the delayed resolution of neutrophil infiltration; sustained production of CXCL1, CXCL2, and CCL2; prolonged activation of STAT-3; and induction of MMP-7 in the pancreas, as well as heightened induction of serum amylase A of DIO mice, were blunted significantly in DIO IL-6 KO mice. In DIO mice, production of OPN and TIMP-1 was increased for a prolonged period, and this was mediated by IL-6 in the liver but not the pancreas. Results obtained in IL-6 KO mice were confirmed in ob/ob mice pretreated with anti-IL-6 antibodies. In conclusion, IL-6 does not contribute to the increased severity of pancreatitis of obese mice but participates in delayed recovery from acute inflammation and may favor development of a protumorigenic environment through prolonged activation of STAT-3, induction of MMP-7, and sustained production of chemokines.

Uropathogenic Escherichia coli induces serum amyloid a in mice following urinary tract and systemic inoculation

Serum amyloid A (SAA) is an acute phase protein involved in the homeostasis of inflammatory responses and appears to be a vital host defense component with protective anti-infective properties. SAA expression remains poorly defined in many tissues, including the urinary tract which often faces bacterial challenge. Urinary tract infections (UTIs) are usually caused by strains of uropathogenic Escherichia coli (UPEC) and frequently occur among otherwise healthy individuals, many of whom experience bouts of recurrent and relapsing infections despite the use of antibiotics. To date, whether SAA is present in the infected urothelium and whether or not the induction of SAA can protect the host against UPEC is unclear. Here we show, using mouse models coupled with immunofluorescence microscopy and quantitative RT-PCR, that delivery of UPEC either directly into the urinary tract via catheterization or systemically via intraperitoneal injection triggers the expression of SAA. As measured by ELISA, serum levels of SAA1/2 were also transiently elevated in response to UTI, but circulating SAA3 levels were only up-regulated substantially following intraperitoneal inoculation of UPEC. In in vitro assays, physiological relevant levels of SAA1/2 did not affect the growth or viability of UPEC, but were able to block biofilm formation by the uropathogens. We suggest that SAA functions as a critical host defense against UTIs, preventing the formation of biofilms both upon and within the urothelium and possibly providing clinicians with a sensitive serological marker for UTI.

A common polymorphism in TLR3 confers natural resistance to HIV-1 infection

TLR3 recognizes dsRNA and activates antiviral immune responses through the production of inflammatory cytokines and type I IFNs. Genetic association studies have provided evidence concerning the role of a polymorphism in TLR3 (rs3775291, Leu412Phe) in viral infection susceptibility. We genotyped rs3775291 in a population of Spanish HIV-1-exposed seronegative (HESN) individuals who remain HIV seronegative despite repeated exposure through i.v. injection drug use (IDU-HESN individuals) as witnessed by their hepatitis C virus seropositivity. The frequency of individuals carrying at least one 412Phe allele was significantly higher in IDU-HESN individuals compared with that of a matched control sample (odds ratio for a dominant model = 1.87; 95% confidence interval, 1.06-3.34; p = 0.023). To replicate this finding, we analyzed a cohort of Italian, sexually HESN individuals. Similar results were obtained: the frequency of individuals carrying at least one 412Phe allele was significantly higher compared with that of a matched control sample (odds ratio, 1.79; 95% confidence interval, 1.05-3.08; p = 0.029). In vitro infection assays showed that in PBMCs carrying the 412Phe allele, HIV-1(Ba-L) replication was significantly reduced (p = 0.025) compared with that of Leu/Leu homozygous samples and was associated with a higher expression of factors suggestive of a state of immune activation (IL-6, CCL3, CD69). Similarly, stimulation of PBMCs with a TLR3 agonist indicated that the presence of the 412Phe allele results in a significantly increased expression of CD69 and higher production of proinflammatory cytokines including IL-6 and CCL3. The data of this study indicate that a common TLR3 allele confers immunologically mediated protection from HIV-1 and suggest the potential use of TLR3 triggering in HIV-1 immunotherapy.

Regulation and functions of the IL-10 family of cytokines in inflammation and disease

The IL-10 family of cytokines consists of nine members: IL-10, IL-19, IL-20, IL-22, IL-24, IL-26, and the more distantly related IL-28A, IL-28B, and IL-29. Evolutionarily, IL-10 family cytokines emerged before the adaptive immune response. These cytokines elicit diverse host defense mechanisms, especially from epithelial cells, during various infections. IL-10 family cytokines are essential for maintaining the integrity and homeostasis of tissue epithelial layers. Members of this family can promote innate immune responses from tissue epithelia to limit the damage caused by viral and bacterial infections. These cytokines can also facilitate the tissue-healing process in injuries caused by infection or inflammation. Finally, IL-10 itself can repress proinflammatory responses and limit unnecessary tissue disruptions caused by inflammation. Thus, IL-10 family cytokines have indispensable functions in many infectious and inflammatory diseases.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

Evolutionary divergence and functions of the human interleukin (IL) gene family

Cytokines play a very important role in nearly all aspects of inflammation and immunity. The term 'interleukin' (IL) has been used to describe a group of cytokines with complex immunomodulatory functions -- including cell proliferation, maturation, migration and adhesion. These cytokines also play an important role in immune cell differentiation and activation. Determining the exact function of a particular cytokine is complicated by the influence of the producing cell type, the responding cell type and the phase of the immune response. ILs can also have pro- and anti-inflammatory effects, further complicating their characterisation. These molecules are under constant pressure to evolve due to continual competition between the host's immune system and infecting organisms; as such, ILs have undergone significant evolution. This has resulted in little amino acid conservation between orthologous proteins, which further complicates the gene family organisation. Within the literature there are a number of overlapping nomenclature and classification systems derived from biological function, receptor-binding properties and originating cell type. Determining evolutionary relationships between ILs therefore can be confusing. More recently, crystallographic data and the identification of common structural motifs have led to a more accurate classification system. To date, the known ILs can be divided into four major groups based on distinguishing structural features. These groups include the genes encoding the IL1-like cytokines, the class I helical cytokines (IL4-like, γ-chain and IL6/12-like), the class II helical cytokines (IL10-like and IL28-like) and the IL17-like cytokines. In addition, there are a number of ILs that do not fit into any of the above groups, due either to their unique structural features or lack of structural information. This suggests that the gene family organisation may be subject to further change in the near future.

IL-22 production is regulated by IL-23 during Listeria monocytogenes infection but is not required for bacterial clearance or tissue protection

Listeria monocytogenes (LM) is a gram-positive bacterium that is a common contaminant of processed meats and dairy products. In humans, ingestion of LM can result in intracellular infection of the spleen and liver, which can ultimately lead to septicemia, meningitis, and spontaneous abortion. Interleukin (IL)-23 is a cytokine that regulates innate and adaptive immune responses by inducing the production of IL-17A, IL-17F, and IL-22. We have recently demonstrated that the IL-23/IL-17 axis is required for optimal recruitment of neutrophils to the liver, but not the spleen, during LM infection. Furthermore, these cytokines are required for the clearance of LM during systemic infection. In other infectious models, IL-22 induces the secretion of anti-microbial peptides and protects tissues from damage by preventing apoptosis. However, the role of IL-22 has not been thoroughly investigated during LM infection. In the present study, we show that LM induces the production of IL-22 in vivo. Interestingly, IL-23 is required for the production of IL-22 during primary, but not secondary, LM infection. Our findings suggest that IL-22 is not required for clearance of LM during primary or secondary infection, using both systemic and mucosal models of infection. IL-22 is also not required for the protection of LM infected spleens and livers from organ damage. Collectively, these data indicate that IL-22 produced during LM infection must play a role other than clearance of LM or protection of tissues from pathogen- or immune-mediated damage.

Spontaneous secretion of interleukin-17 and -22 by human cervical cells in Chlamydia trachomatis infection

To investigate whether IL-17A (IL-17) and IL-22 are produced in response to Chlamydia trachomatis infection, the cervical washes of 27 women with C. trachomatis infection and 17 C. trachomatis negative controls were collected. The levels of cytokines were determined in the cervical wash and in the supernatant of cervical and systemic cell cultures upon C. trachomatis antigen stimulation. C. trachomatis infection appeared to activate local IL-17 and IL-22 production more efficiently than IFN-γ production. In the cervical wash of infected women, median concentrations of IL-17 and -22 were 5- and 3-fold higher, respectively, than in negative controls. The spontaneous intracellular expression of these cytokines was analysed by flow cytometry in blood and cervical cells and 26% of cervical mononuclear cells from infected women were shown to produce IL-22 and 12% to coproduce IL-17 and IL-22. In addition, it was demonstrated that 20-25% of IL-22 producing and IL-17-IL-22 coproducing cervical CD4+ T cells expressed the mucosal homing receptor CCR6. These results suggest that CCR6 is involved in the migration of these cells to the cervix and that IL-17 and IL-22 might play a role in the immune response at the site of C. trachomatis infection.

Induction of a peptide with activity against a broad spectrum of pathogens in the Aedes aegypti salivary gland, following Infection with Dengue Virus

The ultimate stage of the transmission of Dengue Virus (DENV) to man is strongly dependent on crosstalk between the virus and the immune system of its vector Aedes aegypti (Ae. aegypti). Infection of the mosquito's salivary glands by DENV is the final step prior to viral transmission. Therefore, in the present study, we have determined the modulatory effects of DENV infection on the immune response in this organ by carrying out a functional genomic analysis of uninfected salivary glands and salivary glands of female Ae. aegypti mosquitoes infected with DENV. We have shown that DENV infection of salivary glands strongly up-regulates the expression of genes that encode proteins involved in the vector's innate immune response, including the immune deficiency (IMD) and Toll signalling pathways, and that it induces the expression of the gene encoding a putative anti-bacterial, cecropin-like, peptide (AAEL000598). Both the chemically synthesized non-cleaved, signal peptide-containing gene product of AAEL000598, and the cleaved, mature form, were found to exert, in addition to antibacterial activity, anti-DENV and anti-Chikungunya viral activity. However, in contrast to the mature form, the immature cecropin peptide was far more effective against Chikungunya virus (CHIKV) and, furthermore, had strong anti-parasite activity as shown by its ability to kill Leishmania spp. Results from circular dichroism analysis showed that the immature form more readily adopts a helical conformation which would help it to cause membrane permeabilization, thus permitting its transfer across hydrophobic cell surfaces, which may explain the difference in the anti-pathogenic activity between the two forms. The present study underscores not only the importance of DENV-induced cecropin in the innate immune response of Ae. aegypti, but also emphasizes the broad-spectrum anti-pathogenic activity of the immature, signal peptide-containing form of this peptide.

Dengue viruses (DENV) are generally maintained in a cycle which requires horizontal transmission via their arthropod vector, Ae. aegypti, to the vertebrate host. One important consequence of this process is the interference of the virus with the immune systems of both the mosquito and its host. While infection of humans causes disease, the presence of DENV in mosquitoes gives rise to life-long and persistent infection with active viral replication in the salivary glands. In the present study, we have evaluated the mosquito's immune response following DENV infection by analyzing the gene expression profile of infected and uninfected salivary glands. The results show that DENV infection activates signaling pathways and induces the expression of gene products that are involved in the innate immune response to DENV infection, and in particular a putative antibacterial cecropin-like peptide. The immature and mature forms of this peptide were found to be active against a variety of pathogens including DENV and Chikungunya viruses, as well as the Leishmania parasite. This study is the first to establish a comparative analysis of uninfected salivary glands and salivary glands of female Ae. aegypti mosquitoes infected with DENV. We demonstrate that certain DENV-induced peptides possess broad-spectrum anti-pathogenic activity and may have therapeutic potential in the treatment of human infectious disease.

IL-22 induces an acute-phase response

IL-22 is made by a unique set of innate and adaptive immune cells, including the recently identified noncytolytic NK, lymphoid tissue-inducer, Th17, and Th22 cells. The direct effects of IL-22 are restricted to nonhematopoietic cells, its receptor expressed on the surface of only epithelial cells and some fibroblasts in various organs, including parenchymal tissue of the gut, lung, skin, and liver. Despite this cellular restriction on IL-22 activity, we demonstrate that IL-22 induces effects on systemic biochemical, cellular, and physiological parameters. By utilizing adenoviral-mediated delivery of IL-22 and systemic administration of IL-22 protein, we observed that IL-22 modulates factors involved in coagulation, including fibrinogen levels and platelet numbers, and cellular constituents of blood, such as neutrophil and RBC counts. Furthermore, we observed that IL-22 induces thymic atrophy, body weight loss, and renal proximal tubule metabolic activity. These cellular and physiological parameters are indicative of a systemic inflammatory state. We observed that IL-22 induces biochemical changes in the liver including induction of fibrinogen, CXCL1, and serum amyloid A that likely contribute to the reported cellular and physiological effects of IL-22. Based on these findings, we propose that downstream of its expression and impact in local tissue inflammation, circulating IL-22 can further induce changes in systemic physiology that is indicative of an acute-phase response.

Interleukin-22: a cytokine produced by T, NK and NKT cell subsets, with importance in the innate immune defense and tissue protection

Interleukin (IL)-22 is a member of the IL-10 cytokine family that is produced by special immune cell populations, including Th22, Th1, and Th17 cells, classical and non-classical (NK-22) NK cells, NKT cells, and lymphoid tissue inducer cells. This cytokine does not influence cells of the hematopoietic lineage. Instead, its target cells are certain tissue cells from the skin, liver and kidney, and from organs of the respiratory and gastrointestinal systems. The main biological role of IL-22 includes the increase of innate immunity, protection from damage, and enhancement of regeneration. IL-22 can play either a protective or a pathogenic role in chronic inflammatory diseases depending on the nature of the affected tissue and the local cytokine milieu. This review highlights the primary effects of IL-22 on its target cells, its role in the defense against infections, in tumorigenesis, in inflammatory diseases and allergy as well as the potential of the therapeutic modulation of IL-22 action.

Th17 lineage commitment and HIV-1 pathogenesis

PURPOSE OF REVIEW

The present review emphasizes the requirement for functional genomic studies and studies in human immunology toward the identification of tissue-specific regulators of human Th17 lineage commitment and molecular determinants for HIV permissiveness in Th17 cells.

RECENT FINDINGS

Th17 cells play a beneficial role in immunity against bacteria and fungi and a deleterious role in autoimmune diseases. Commensal microbiota control Th17 differentiation in the gut. Th17 cells are depleted from the gut of HIV-infected individuals and their depletion is associated with microbial translocation, which is a cause for chronic immune activation and disease progression. Th17 cells are permissive to HIV infection and therefore play a dual role in HIV pathogenesis.

SUMMARY

The discovery of human Th17 lineage revised our thinking about CD4 T-cell heterogeneity and plasticity in the context of HIV pathogenesis. The present review highlights unsolved mysteries around the genetic control of differentiation and tissue-specific specialization of human Th17 cells. Systems biology studies are now required to provide a global view of transcriptional changes in Th17 subsets and mucosal tissues and to shed light on molecular mechanisms of Th17 depletion in HIV infection, with the final goal to identify new strategies to improve mucosal immunity in infected individuals.