Maternal Vertical Microbial Transmission During Skin-to-Skin Care

BACKGROUND

Skin-to-skin (STS) care may contribute to mother-to-infant vertical microbial transmission by enriching the preterm infant's microbiome.

PURPOSE

The purpose of this observational study was to define the impact of increased STS care duration on vertical microbial transmission and consequently modulate oral and intestinal microbial balance.

METHODS

Postpartum women and their preterm infants, 31 to 34 weeks' gestation (n = 25), were recruited for this study. Using 16S rRNA sequencing, we compared α- and β-diversity with the Shannon and Chao indexes and nonmetric multidimensional scaling, respectively, and relative abundance of microbial communities, which refers to the percentage of specific organisms in a community, from mother's chest skin, preterm infant's oral cavity, and preterm infant's stool samples. Effects of STS care on vertical transmission were determined by comparing oral and stool microbial population of preterm infants who received low exposure (<40 minutes) with that of preterm infants who received high exposure (>60 minutes).

RESULTS

Microbial composition, diversity, and relative abundance were different across the 3 sites. Oral microbial richness was less and stool richness was greater among the preterm infants in the high STS care group. Oral and intestinal microbial diversity and composition were different between the groups, with the relative abundance of Gemella and Aggregatibacter genera and Lachnospiraceae family significantly greater in the stool of the high STS care group.

IMPLICATIONS FOR PRACTICE

Results suggest that STS care may be an effective method to enhance microbial communities among preterm infants.

Centers for AIDS Research (CFAR) Diversity, Equity, and Inclusion Pathway Initiative (CDEIPI): Developing Career Pathways for Early-Stage Scholars From Racial and Ethnic Groups Underrepresented in HIV Science and Medicine

BACKGROUND

There is an urgent need to increase diversity among scientific investigators in the HIV research field to be more reflective of communities highly affected by the HIV epidemic. Thus, it is critical to promote the inclusion and advancement of early-stage scholars from racial and ethnic groups underrepresented in HIV science and medicine.

METHODS

To widen the HIV research career pathway for early-stage scholars from underrepresented minority groups, the National Institutes of Health supported the development of the Centers for AIDS Research (CFAR) Diversity, Equity, and Inclusion Pathway Initiative (CDEIPI). This program was created through partnerships between CFARs and Historically Black Colleges and Universities and other Minority Serving Institutions throughout the United States.

RESULTS

Seventeen CFARs and more than 20 Historically Black Colleges and Universities and Minority Serving Institutions have participated in this initiative to date. Programs were designed for the high school (8), undergraduate (13), post baccalaureate (2), graduate (12), and postdoctoral (4) levels. Various pedagogical approaches were used including didactic seminar series, intensive multiday workshops, summer residential programs, and mentored research internship opportunities. During the first 18 months of the initiative, 257 student scholars participated in CDEIPI programs including 150 high school, 73 undergraduate, 3 post baccalaureate, 27 graduate, and 4 postdoctoral students.

CONCLUSION

Numerous student scholars from a wide range of educational levels, geographic backgrounds, and racial and ethnic minority groups have engaged in CDEIPI programs. Timely and comprehensive program evaluation data will be critical to support a long-term commitment to this unique training initiative.

RING Program: The CFAR Diversity, Equity, and Inclusion Pathway Initiative

BACKGROUND

Case Western Reserve University (CWRU)/University Hospitals Cleveland Medical Center in Cleveland, OH, and the University of Pittsburgh (Pitt) in Pittsburgh, PA, forged a strategic alliance to form the Rustbelt Center for AIDS Research. The Rustbelt Center for AIDS Research developed a National Institutes of Health-supported diversity, equity, and inclusion pathway initiative termed the "Rustbelt Investigators for the Next Generation (RING) Program" that provides research training experiences for Puerto Rican students that will help them pursue a biomedical research career in HIV.

SETTING

The RING Program provides 10-week research training experiences in different disciplines of HIV/AIDS for under-represented minority undergraduate and masters students from 4 campuses (Río Piedras, Mayagüez, Humacao, and Cayey) at the University of Puerto Rico. Mentors are drawn from both CWRU and Pitt.

RESULTS

The RING Program recently completed our first wave of recruitment. Recruitment sessions were either virtual or on site at the University of Puerto Rico campuses and included an overview presentation, a Q&A session, and in-person interviews. We interviewed 32 eligible applicants and accepted 10 into the program, of which 9 were female. Five students were matched with faculty at CWRU and 5 with faculty at Pitt.

CONCLUSIONS

The RING Program is a comprehensive program in laboratory and implementation science that aims to enhance under-represented Hispanic undergraduate and masters students' passion for pursuing a biomedical research career in HIV.

Th17-Derived Cytokines Synergistically Enhance IL-17C Production by the Colonic Epithelium

Tightly regulated communication between the gastrointestinal epithelium and immune cells in the underlying lamina propria is critical for immune homeostasis and inflammation. IL-17C, produced by epithelial cells after exposure to inflammatory stimuli, facilitates cell-to-cell communication by promoting inflammatory responses in Th17 cells. In this study, we demonstrate that Th17-derived cytokines TNF-α, IL-17A, and IL-22 synergistically enhance IL-17C expression in both human-transformed colonic epithelial cell lines and primary non-inflammatory bowel disease colonic epithelial spheroids. This synergistic expression requires activation of the transcription factor NF-κB downstream of the TNF-α stimulus, evidenced by the reduction of IL-17C expression in the presence of an IκBα inhibitor. IL-17A and IL-22 enhance IL-17C expression through the activation of the transcription factor AP-1 in a p38 MAPK-dependent manner. Colonic spheroids derived from uninvolved epithelial of ulcerative colitis patients stimulated with TNF-α, IL-17A, and IL-22 show muted responses compared with non-inflammatory bowel disease spheroids, and inflamed spheroids yielded more IL-17C expression in the presence of TNF-α, and no response to IL-22 stimulation. Altogether, a role for IL-17C in activating Th17 cells combined with our findings of Th17-derived cytokine-driven synergy in the expression of IL-17C identifies a novel inflammatory amplification loop in the gastrointestinal tract between epithelial cells and Th17 cells.

Chronic opioid use modulates human enteric microbiota and intestinal barrier integrity

Over the past three decades the United States has experienced a devastating opioid epidemic. One of the many debilitating side effects of chronic opioid use is opioid-induced bowel dysfunction. We investigated the impact of methadone maintenance treatment (MMT) on the gut microbiome, the gut bacterial metabolite profile, and intestinal barrier integrity. An imbalance in key bacterial communities required for production of short-chain fatty acids (SCFAs), mucus degradation, and maintenance of barrier integrity was identified. Consistent with dysbiosis, levels of fecal SCFAs were reduced in MMT. We demonstrated that metabolites synthesized by Akkermansia muciniphila modulate intestinal barrier integrity in vitro by strengthening the pore pathway and regulating tight junction protein expression. This study provides essential information about the therapeutic potential of A. muciniphila and warrants development of new clinical strategies that aim to normalize the gut microbiome in individuals affected by chronic opioid use.

Oral immune dysfunction is associated with the expansion of FOXP3+PD-1+Amphiregulin+ T cells during HIV infection

Residual systemic inflammation and mucosal immune dysfunction persist in people living with HIV, despite treatment with combined anti-retroviral therapy, but the underlying immune mechanisms are poorly understood. Here we report that the altered immune landscape of the oral mucosa of HIV-positive patients on therapy involves increased TLR and inflammasome signaling, localized CD4+ T cell hyperactivation, and, counterintuitively, enrichment of FOXP3+ T cells. HIV infection of oral tonsil cultures in vitro causes an increase in FOXP3+ T cells expressing PD-1, IFN-γ, Amphiregulin and IL-10. These cells persist even in the presence of anti-retroviral drugs, and further expand when stimulated by TLR2 ligands and IL-1β. Mechanistically, IL-1β upregulates PD-1 expression via AKT signaling, and PD-1 stabilizes FOXP3 and Amphiregulin through a mechanism involving asparaginyl endopeptidase, resulting in FOXP3+ cells that are incapable of suppressing CD4+ T cells in vitro. The FOXP3+ T cells that are abundant in HIV-positive patients are phenotypically similar to the in vitro cultured, HIV-responsive FOXP3+ T cells, and their presence strongly correlates with CD4+ T cell hyper-activation. This suggests that FOXP3+ T cell dysregulation might play a role in the mucosal immune dysfunction of HIV patients on therapy.

Transcriptomic Analysis Reveals Receptor Subclass-Specific Immune Regulation of CD8+ T Cells by Opioids

Opioid peptides are released at sites of injury, and their cognate G protein-coupled opioid receptors (OR) are expressed on immune cells. Exposure of human circulating CD8⁺ T cells to selective OR agonists differentially regulates thousands of genes. Gene set enrichment analysis reveals that μ-OR more strongly regulates cellular processes than δ-OR. In TCR naive T cells, triggering μ-OR exhibits stimulatory and inhibitory patterns, yet when administered prior to TCR cross-linking, a μ-OR agonist inhibits activation. μ-OR, but not δ-OR, signaling is linked to upregulation of lipid, cholesterol, and steroid hormone biosynthesis, suggesting lipid regulation is a mechanism for immune suppression. Lipid rafts are cholesterol-rich, liquid-ordered membrane domains that function as a nexus for the initiation of signal transduction from surface receptors, including TCR and μ-OR. We therefore propose that μ-OR-specific inhibition of TCR responses in human CD8⁺ T cells may be mediated through alterations in lipid metabolism and membrane structure.

Regulation of Intestinal Epithelial Barrier and Immune Function by Activated T Cells

BACKGROUND & AIMS

Communication between T cells and the intestinal epithelium is altered in many diseases, causing T-cell activation, depletion, or recruitment, and disruption of the epithelium. We hypothesize that activation of T cells regulates epithelial barrier function by targeting the assembly of the tight junction complex.

METHODS

In a 3-dimensional and 2-dimensional co-culture model of activated T cells subjacent to the basolateral surface of an epithelial monolayer, the pore, leak, and unrestricted pathways were evaluated using transepithelial resistance and flux of fluorescently labeled tracers. T cells were acutely and chronically activated by cross-linking the T-cell receptor. Tight junction assembly and expression were measured using quantitative polymerase chain reaction, immunoblot, and immunofluorescence confocal microscopy.

RESULTS

Co-culture with acutely and chronically activated T cells decreased the magnitude of ion flux through the pore pathway, which was maintained in the presence of acutely activated T cells. Chronically activated T cells after 30 hours induced a precipitous increase in the magnitude of both ion and molecular flux, resulting in an increase in the unrestricted pathway, destruction of microvilli, expansion in cell surface area, and cell death. These fluctuations in permeability were the result of changes in the assembly and expression of tight junction proteins, cell morphology, and viability. Co-culture modulated the expression of immune mediators in the epithelium and T cells.

CONCLUSIONS

Bidirectional communication between T cells and epithelium mediates a biphasic response in barrier integrity that is facilitated by the balance between structural proteins partitioning in the mobile lateral phase vs the tight junction complex and cell morphology.

Decreased Enteric Bacterial Composition and Diversity in South American Crohn's Disease Vary With the Choice of Treatment Strategy and Time Since Diagnosis

BACKGROUND AND AIMS

The symptomology of Crohn's disease [CD], a chronic inflammatory disease of the digestive tract, correlates poorly with clinical, endoscopic or immunological assessments of disease severity. The prevalence of CD in South America is rising, reflecting changes in socio-economic stability. Many treatment options are available to CD patients, including biological agents and corticosteroids, each of which offers variable efficacy attributed to host genetics and environmental factors associated with alterations in the gut microbiota.

METHODS

Based on 16S rRNA gene sequencing and taxonomic differences, we compared the faecal microbial population of Brazilian patients with CD treated with corticosteroid or anti-tumour necrosis factor [anti-TNF] immunotherapy. Faecal calprotectin and plasma sCD14 levels were quantified as markers for local and systemic inflammation, respectively.

RESULTS

Anti-TNF treatment led to an increased relative abundance of Proteobacteria and a decreased level of Bacteroidetes. In contrast, corticoid treatment was associated with an increase in the relative abundance of Actinobacteria, which has been linked to inflammation in CD. Disruption of the faecal microbiota was related to decreased bacterial diversity and composition. Moreover, the choice of clinical regimen and time since diagnosis modulate the character of the resulting dysbiosis.

CONCLUSIONS

Enteric microbial populations in CD patients who have been treated are modulated by disease pathogenesis, local inflammatory microenvironment and treatment strategy. The dysbiosis that remains after anti-TNF treatment due to decreased bacterial diversity and composition abates restoration of the microbiota to a healthy state, suggesting that the identification and development of new clinical treatments for CD must include their capacity to normalize the gut microbiota.

Cowpea Mosaic Virus (CPMV)-Based Cancer Testis Antigen NY-ESO-1 Vaccine Elicits an Antigen-Specific Cytotoxic T Cell Response

Cancer vaccines are promising adjuvant immunotherapies that can stimulate the immune system to recognize tumor-associated antigens and eliminate the residual or recurring disease. The aberrant and restricted expression of highly immunogenic cancer testis antigen NY-ESO-1 in several malignancies, including triple-negative breast cancer, melanoma, myelomas, and ovarian cancer, makes NY-ESO-1 an attractive antigenic target for cancer vaccines. This study describes a NY-ESO-1 vaccine based on a bio-inspired nanomaterial platform technology, specifically a plant virus nanoparticle. The 30 nm icosahedral plant virus cowpea mosaic virus (CPMV) displaying multiple copies of human HLA-A2 restricted peptide antigen NY-ESO-1_157-165 exhibited enhanced uptake and activation of antigen-presenting cells and stimulated a potent CD8⁺ T cell response in transgenic human HLA-A2 expressing mice. CD8⁺ T cells from immunized mice exhibited antigen-specific proliferation and cancer cell cytotoxicity, highlighting the potential application of a CPMV-NY-ESO-1 vaccine against NY-ESO-1⁺ malignancies.

Noncoding RNAs modify GATA3-driven transcription, leading to the immune profiles seen in psoriasis and atopic dermatitis

Atopic dermatitis (AD) and psoriasis are clinical manifestations of immune dysregulation in the skin. Psoriasis is generally classified as a T cell-mediated, IFN-γ dependent disease, while AD is skewed toward interleukin (IL)-4 dependence. Consistent with these classifications are clinical observations that IL-4 improves psoriasis disease score and an IL-4 receptor blocking antibody is approved for treatment of severe AD. However, the immunobiology is far more complex, as IL-13, often produced by IL-4 dependent T cells, can be elevated in psoriasis. Since GATA3 controls both IL-4 and IL-13 expression, we propose that regulation of GATA3 differs between the two diseases, resulting in overlapping yet distinct cytokine profiles. Our meta-analysis of two RNA sequencing profiles for each disease identified a noncoding RNA of unknown function (NRUF) in all four datasets (p&lt;1×10−10). Upon analyzing 48 datasets of immune responses to viral infection in epithelial cells and leukocytes, we found IL-13 and NRUF expression levels are most strongly correlated in lymphocytes. In T cell lines, we found elevated expression of the NRUF noncoding RNA associates with IL-4 and IL-13. However, IL-31, which is elevated in AD independently from the GATA3/IL-4/IL-13 axis, is not correlated to NRUF expression, supporting our hypothesis that NRUF drives disease pathology via the GATA3/IL-4/IL-13-dependent inflammatory response. Using overexpression or silencing approaches, we have characterized the ability of this NRUF to direct cytokine polarization of T cells from healthy control and donors with AD or psoriasis. We propose this NRUF modulates these two cutaneous diseases by regulating GATA3-based IL-4/IL-13 balance in T cells.

Opioid-induced protein coding and noncoding transcriptome of human CD8+ T cells reveals opioid receptor subclass specific responses

Opioid peptides are released at sites of injury; their cognate G-protein coupled opioid receptors (OR) are expressed on immune cells. Conflicting reports attribute immunostimulatory and immunosuppressive activity to opioids. From a cohort of methadone patients and controls, we found that chronic opioid use disrupts CD8+ T cell subset balance, via decreased T Effector Memory RA+ cells. Exposure of CD8+ T cells ex vivo to a μ-OR or δ-OR agonist differentially regulates thousands of protein coding genes. Gene set enrichment analysis reveals that μ-OR more strongly regulates cellular processes, including immune response via interferon, IL-2, and mTOR signaling pathways. A striking finding is the linkage of μ-OR, but not δ-OR, signaling to the upregulation of lipid, cholesterol, and steroid biosynthesis. OR-specific gene signatures associate with different transcription factors, supporting our hypothesis that transcriptional regulation underlies cellular outcomes ascribed to individual ORs. The noncoding transcriptome of opioid exposed cells is largely unique to each OR; μ-OR regulates 53 long noncoding RNAs, while δ-OR regulates 59, with only three shared transcripts, one of which is inversely regulated. The noncoding RNA upregulated by both ORs enhances integrin expression and binding; the noncoding RNA downregulated by both ORs represses STAT signaling and apoptosis. Comparison of CD4 vs. CD8 T cell responses to ligation of all three ORs (μ, δ, κ) reveals lineage specific regulation of TNF-signaling and fatty acid metabolism in response to μ-OR, G protein and cytokine receptor signaling in response to δ-OR, and REDOX pathways in response κ-OR, indicating that opioid induced immune regulation is both cell type and OR specific.

Chronic Methadone Use Alters the CD8+ T Cell Phenotype In Vivo and Modulates Its Responsiveness Ex Vivo to Opioid Receptor and TCR Stimuli

Endogenous opioid peptides are released at sites of injury, and their cognate G protein-coupled opioid receptors (ORs) are expressed on immune cells. Although drugs of misuse appropriate ORs, conflicting reports indicate immunostimulatory and immunosuppressive activity, in that opioid users have elevated infection risk, opioids activate innate immune cells, and opioids attenuate inflammation in murine T cell-mediated autoimmunity models. The i.v. use of drugs transmits bloodborne pathogens, particularly viruses, making the study of CD8⁺ T cells timely. From a cohort of nonuser controls and methadone users, we demonstrate, via t-Stochastic Neighbor Embedding and k-means cluster analysis of surface marker expression, that chronic opioid use alters human CD8⁺ T cell subset balance, with notable decreases in T effector memory RA⁺ cells. Studying global CD8⁺ T cell populations, there were no differences in expression of OR and several markers of functionality, demonstrating the need for finer analysis. Purified CD8⁺ T cells from controls respond to opioids ex vivo by increasing cytoplasmic calcium, a novel finding for OR signal transduction, likely because of cell lineage. CD8⁺ T cells from controls exposed to μ-OR agonists ex vivo decrease expression of activation markers CD69 and CD25, although the same markers are elevated in μ-OR-treated cells from methadone users. In contrast to control cells, T cell subsets from methadone users show decreased expression of CD69 and CD25 in response to TCR stimulus. Overall, these results indicate a direct, selective role for opioids in CD8⁺ T cell immune regulation via their ability to modulate cell responses through the opioid receptors and TCRs.

Immune modulation caused by synthetic opioids during CD4+ T cell activation

Opioids are heavily prescribed medications used to treat chronic pain. Since their additional response includes euphoria, there is an exceedingly high addiction rate that has led to a country wide epidemic of opioid misuse. Opioid effects are not limited to the nervous system, since leukocytes express opioid receptors, which are G-protein coupled receptors known as μ, δ, and κ, suggesting that natural and synthetic opioids might regulate the immune system. Based on previously published reports, we hypothesized that opioids induce distinct regulatory pathways in CD4+ T cells that results in inhibition of the immune response. CD4+ T cells are isolated by negative selection from peripheral blood mononuclear cell and opioid receptor expression is assessed on resting and activated T cells using flow cytometry. Two models of opioid exposure in vitro were developed to study the effects of opioids on CD4+ T cell activation. Cells were treated with a δ opioid receptor specific agonist (DPDPE) for 24 h before or after activation and harvested 24 h after the second treatment and stained for expression of a well characterized early T cell activation marker – CD69. Cells treated with an opioid after activation showed no major shifts in CD69 intensity, suggesting opioids had no influence on a previously activated T cell. However, CD4+ T cells treated with an opioid before activation exhibited an increase in CD69 expression, suggesting an unexpected enhancement of T cell activation. In conclusion, opioids seem to play distinct biological activities depending on the activation state of the CD4+ T cell, and may function as both immunoinhibitory and immunostimulatory agents. Future studies will identify the mechanisms by which opioids regulate immunity.

Signaling from individual Opioid Receptors differentially modulates the functional and phenotypic potential of resting and activated human CD8+ T cells

Opioid use disorder is a worldwide epidemic. Endogenous opioids are released at sites of injury, and their cognate GPCR opioid receptors (OR) are expressed on immune cells; drugs of misuse appropriate these ORs. Conflicting published data show that opioid users have elevated risk of infection, opioids activate innate immune cells, and opioids attenuate murine T cell autoimmunity models. Intravenous drug use transmits blood borne pathogens, particularly viruses, making the study of CD8+ T cells pertinent to the crisis. Sequencing studies on leukocytes from heroin users show an altered transcriptome and a higher frequency of a SNP in a gene regulating long noncoding RNA. We demonstrate functional ORs (μ-, κ-, δ-subclasses) on human CD8+ T cells and employed unbiased analyses (flow cytometry with tSNE and transcriptome mapping) to study the effects of DPDPE (δ-OR agonist) and morphine (μ-OR biased agonist) on phenotype and activation status. Both agonists decrease activation markers on resting T cells, with δ-OR affecting naïve cells and μ-OR affecting naïve and memory cells. Pre-exposure to opioids changes the response to T cell receptor stimulation. Within 24 h, pre-exposure to either OR agonist decreases CD3, CD69, and CD25 expression. At 48 h, pre-exposure to μ-OR agonist downregulates CCR7 and CD27, while δ-OR agonist sustains CD3 expression. Regulation does not appear to be mediated by signaling cascades or calcium flux, suggesting a transcriptional mechanism: opioids dramatically modify the protein-coding and non-coding transcriptome of resting and activated T cells, with hundreds of non-coding RNAs showing increased expression. Selective engagement of OR represents a possible pathway to fine tune an immune response.

Plant viral nanoparticles-based HER2 vaccine: Immune response influenced by differential transport, localization and cellular interactions of particulate carriers

Cancer vaccines are designed to elicit an endogenous adaptive immune response that can successfully recognize and eliminate residual or recurring tumors. Such approaches can potentially overcome shortcomings of passive immunotherapies by generating long-lived therapeutic effects and immune memory while limiting systemic toxicities. A critical determinant of vaccine efficacy is efficient transport and delivery of tumor-associated antigens to professional antigen presenting cells (APCs). Plant viral nanoparticles (VNPs) with natural tropism for APCs and a high payload carrying capacity may be particularly effective vaccine carriers. The applicability of VNP platform technologies is governed by stringent structure-function relationships. We compare two distinct VNP platforms: icosahedral cowpea mosaic virus (CPMV) and filamentous potato virus X (PVX). Specifically, we evaluate in vivo capabilities of engineered VNPs delivering human epidermal growth factor receptor 2 (HER2) epitopes for therapy and prophylaxis of HER2⁺ malignancies. Our results corroborate the structure-function relationship where icosahedral CPMV particles showed significantly enhanced lymph node transport and retention, and greater uptake by/activation of APCs compared to filamentous PVX particles. These enhanced immune cell interactions and transport properties resulted in elevated HER2-specific antibody titers raised by CPMV- vs. PVX-based peptide vaccine. The 'synthetic virology' field is rapidly expanding with numerous platforms undergoing development and preclinical testing; our studies highlight the need for systematic studies to define rules guiding the design and rational choice of platform, in the context of peptide-vaccine display technologies.

Mucosal Regulatory T Cells and T Helper 17 Cells in HIV-Associated Immune Activation

Residual mucosal inflammation along with chronic systemic immune activation is an important feature in individuals infected with human immunodeficiency virus (HIV), and has been linked to a wide range of co-morbidities, including malignancy, opportunistic infections, immunopathology, and cardiovascular complications. Although combined antiretroviral therapy (cART) can reduce plasma viral loads to undetectable levels, reservoirs of virus persist, and increased mortality is associated with immune dysbiosis in mucosal lymphoid tissues. Immune-based therapies are pursued with the goal of improving CD4⁺ T-cell restoration, as well as reducing chronic immune activation in cART-treated patients. However, the majority of research on immune activation has been derived from analysis of circulating T cells. How immune cell alterations in mucosal tissues contribute to HIV immune dysregulation and the associated risk of non-infectious chronic complications is less studied. Given the significant differences between mucosal T cells and circulating T cells, and the immediate interactions of mucosal T cells with the microbiome, more attention should be devoted to mucosal immune cells and their contribution to systemic immune activation in HIV-infected individuals. Here, we will focus on mucosal immune cells with a specific emphasis on CD4⁺ T lymphocytes, such as T helper 17 cells and CD4⁺Foxp3⁺ regulatory T cells (T_regs), which play crucial roles in maintaining mucosal barrier integrity and preventing inflammation, respectively. We hypothesize that pro-inflammatory milieu in cART-treated patients with immune activation significantly contributes to enhanced loss of Th17 cells and increased frequency of dysregulated T_regs in the mucosa, which in turn may exacerbate immune dysfunction in HIV-infected patients. We also present initial evidence to support this hypothesis. A better comprehension of how pro-inflammatory milieu impacts these two types of cells in the mucosa will shed light on mucosal immune dysfunction and HIV reservoirs, and lead to novel ways to restore immune functions in HIV⁺ patients.

Toll-Like Receptor abundance in colonic epithelium is selectively altered in HIV disease and partially normalizes with effective Antiretroviral Therapy

Background

Since the intestinal mucosa and microbiome are disrupted in HIV disease, we studied the abundance of innate immune sensors, Toll-Like Receptors (TLR), in the epithelia of patients with Viremia, prior to antiretroviral therapy (ART) initiation, Immune Success (IS- &gt;500 CD4 T cells/ul after 2 years of ART; suppressed viremia), and Immune Failure (IF- &lt;350 CD4 T cells/ul after 2 years of ART; suppressed viremia). Viremia and IF show increased systemic immune activation; therefore, modulation of intestinal TLR abundance may offer a mechanism behind persistent inflammation in HIV.

Method

Immunofluorescence for TLR3, TLR4, and TLR9 on sections cut from paraffin embedded colonic biopsies of uninfected, viremic, IS, and IF was imaged with a DeltaVision microscope and quantified with Metamorph software.

Results

Viremic patients have significantly higher viral TLR9 and TLR3, and significantly lower bacterial TLR4, on the surface epithelium when compared to levels seen on uninfected control. Viremic patients have significantly higher TLR9, similar TLR3, and significantly lower TLR4 expression, in the crypts when compared to uninfected control. TLR9 abundance remains elevated in IF, while normalization occurs in IS. TLR3 abundance on surface epithelium and crypt is even more elevated in IF and IS, suggesting an effect of ART. TLR4 abundance on surface epithelium normalizes in IF and IS; in the crypt, in IS TLR4 decreases further.

Conclusion

Epithelial TLR abundance is selectively altered in HIV disease; effective ART partially normalizes some TLRs, and enhances TLR3. Mucosal TLR desensitization or hyper-vigilance, possibly caused by disrupted cytokine levels in the HIV+ colon, may contribute to systemic inflammation.

Risk factors of repeated infectious disease incidence among substance-dependent girls and boys court-referred to treatment

BACKGROUND

A small portion of Americans account for a disproportionate amount of the incidences of sexually transmitted infection observed over a short period of time. Studies with adults have begun to characterize this population, yet there is very little data on adolescent sexually transmitted infection repeaters (STIR). This study explores characteristics associated with STIR among 102 girls and 93 boys (aged 14-18) court-referred for residential treatment.

METHODS

Background characteristics, substance use disorders, risky and interpersonal behaviors, and history of sexually transmitted infections were collected at intake using valid and reliable instruments. A negative binomial logistic regression was performed to determine the background, risky behaviors, and social patterns associated with adolescent STIR.

RESULTS

Approximately two out of three adolescents (62%) did not use contraception the last time they had sex, and 15% had at least one sexually transmitted infection recorded in their medical chart. Sexually transmitted infection repeaters entered treatment with higher rates of cocaine abuse (13%) than youth without multiple infections (3%, p < 0.05). History of sexual abuse, having sex with a person who said no, higher exhibitionism, and social estrangement increased the odds of adolescent STIR. Main effects of exhibitionism and social estrangement on increased odds of STIR were more pronounced for sexually abused adolescents.

CONCLUSIONS

The findings suggest a need for incorporating HIV education during residential treatment to improve health outcomes and intervention strategies that further connectedness for youth and victims of sexual abuse.

The role of CXCL12 and CCL7 chemokines in immune regulation, embryonic development, and tissue regeneration

Chemotactic factors direct the migration of immune cells, multipotent stem cells, and progenitor cells under physiologic and pathologic conditions. Chemokine ligand 12 and chemokine ligand 7 have been identified and investigated in multiple studies for their role in cellular trafficking in the setting of tissue regeneration. Recent early phase clinical trials have suggested that these molecules may lead to clinical benefit in patients with chronic disease. Importantly, these two proteins may play additional significant roles in directing the migration of multipotent cells, such as mesenchymal stem cells and hematopoietic progenitor cells. This article reviews the functions of these two chemokines, focusing on recruitment to sites of injury, immune function modulation, and contributions to embryonic development. Additional research would provide valuable insight into the potential clinical application of these two proteins in stem cell therapy.

Circulating CD4(+) and CD8(+) T cells are activated in inflammatory bowel disease and are associated with plasma markers of inflammation

Inflammatory bowel disease (IBD) is characterized by damage to the gut mucosa and systemic inflammation. We sought to evaluate the role of chronic inflammation on circulating T-cell activation in human subjects with Crohn's disease and ulcerative colitis. We studied 54 patients with IBD and 28 healthy controls. T-cell activation and cycling were assessed in whole blood samples by flow cytometry. Levels of lipopolysaccharide (LPS) were measured in serum by Limulus amoebocyte lysate assay, and plasma levels of inflammatory markers and LPS-binding proteins were measured by ELISA. The proportions of circulating CD4(+) and CD8(+) T lymphocytes in cycle (Ki67(+) ) are increased in patients with IBD compared with these proportions in controls. CD8(+) T cells from patients with IBD are also enriched for cells that expressed CD38 and HLA-DR, and proportions of these cells are related to plasma levels of interleukin-6 and C-reactive protein in these patients. Intracellular interleukin-2 and interferon-γ levels were elevated in resting and polyclonally activated CD4(+) and CD8(+) T cells in patients with IBD when compared with levels from healthy controls. Surprisingly, we did not find increased levels of LPS in the serum of patients with IBD. We did, however, find a signature of recent microbial translocation, as levels of LPS-binding protein are increased in the plasma of patients with IBD compared with plasma levels in healthy controls; LPS-binding protein levels are also directly related to proportions of CD38 HLA-DR-expressing CD4(+) and CD8(+) T cells. Local damage to the gastrointestinal tract in IBD may result in systemic inflammation and T-cell activation.

Mitochondria-derived hydrogen peroxide selectively enhances T cell receptor-initiated signal transduction

T cell receptor (TCR)-initiated signal transduction is reported to increase production of intracellular reactive oxygen species, such as superoxide (O2˙(-)) and hydrogen peroxide (H2O2), as second messengers. Although H2O2 can modulate signal transduction by inactivating protein phosphatases, the mechanism and the subcellular localization of intracellular H2O2 as a second messenger of the TCR are not known. The antioxidant enzyme superoxide dismutase (SOD) catalyzes the dismutation of highly reactive O2˙(-) into H2O2 and thus acts as an intracellular generator of H2O2. As charged O2˙(-) is unable to diffuse through intracellular membranes, cells express distinct SOD isoforms in the cytosol (Cu,Zn-SOD) and mitochondria (Mn-SOD), where they locally scavenge O2˙(-) leading to production of H2O2. A 2-fold organelle-specific overexpression of either SOD in Jurkat T cell lines increases intracellular production of H2O2 but does not alter the levels of intracellular H2O2 scavenging enzymes such as catalase, membrane-bound peroxiredoxin1 (Prx1), and cytosolic Prx2. We report that overexpression of Mn-SOD enhances tyrosine phosphorylation of TCR-associated membrane proximal signal transduction molecules Lck, LAT, ZAP70, PLCγ1, and SLP76 within 1 min of TCR cross-linking. This increase in mitochondrial H2O2 specifically modulates MAPK signaling through the JNK/cJun pathway, whereas overexpressing Cu,Zn-SOD had no effect on any of these TCR-mediated signaling molecules. As mitochondria translocate to the immunological synapse during TCR activation, we hypothesize this translocation provides the effective concentration of H2O2 required to selectively modulate downstream signal transduction pathways.

Impairment of regulatory T-cell function in autoimmune thyroid disease

BACKGROUND

Autoimmune thyroid disease (AITD) pathogenesis may result from a loss of immune tolerance to thyroid antigens. Regulatory T cells (Tregs) control immune responses, prevent excessive inflammation, and may be dysfunctional in AITD. We investigated the role of Tregs in Hashimoto's thyroiditis (HT) and Graves' disease (GD), complicated by Down syndrome (DS). Our goal was to identify differences in CD4(+)CD25(high) Treg function or number in patients with GD and HT, compared to healthy controls (HC).

METHODS

Treg number was assessed by flow cytometric analysis in samples from 20 AITD patients (seven GD, 13 HT), nine HC, and seven individuals with DS, a genetic disorder associated with multiple autoimmune disorders including AITD. Treg function was assessed by the inhibition of proliferation (radioactive thymidine incorporation into DNA) of blood-derived T effector (Teff) cells by Tregs in a coculture. Various methods of stimulation were contrasted. Cytokine levels were determined in conditioned media from the co-cultures.

RESULTS

No differences were found in the frequency of Tregs as a percentage of CD4(+) cells between AITD and HC. AITD Tregs were less capable of inhibiting the proliferation of Teff cells when compared to HC; however, the impairment was dependent on the type of stimulation used. DS patients without AITD exhibited normal Treg function. We observed few differences in cytokine production between HC and AITD patients.

CONCLUSIONS

Tregs from AITD patients are partly dysfunctional, possibly explaining their autoimmunity. Future work will elucidate the diagnostic potential and pathophysiology of Tregs in AITD.

Human β-defensin 3 induces STAT1 phosphorylation, tyrosine phosphatase activity, and cytokine synthesis in T cells

The AMP hBD-3 stimulates numerous immune effector functions in myeloid cells and keratinocytes, predominantly through the MAPK signaling cascade. In contrast, hBD-3 was reported to neutralize the activation of T cells by antagonizing MAPK signaling initiated by SDF-1α through CXCR4. With the use of complementary proteomic and immunochemical approaches, we investigated possible stimulatory effects of hBD-3 on T cells and demonstrate that hBD-3 induces STAT1 tyrosine phosphorylation within 5 min yet is unable to induce MAPK activation. Inclusion of a PTPase inhibitor increased hBD-3-induced phosphorylation dramatically, suggesting that hBD-3 also stimulates PTPase activity concurrently. The increase in PTPase activity was confirmed by demonstrating that hBD-3 suppresses IFN-γ-induced STAT1 tyrosine phosphorylation but not STAT1 serine and ERK1/2 threonine phosphorylation and stimulates the translocation of SHP-2 into the nucleus within 15 min. The signaling pathways initiated by hBD-3 may lead to the observed enhancement of distinct T cell effector functions during TCR activation, such as the increase in IL-2 and IL-10, but not IFN-γ secretion. Thus, hBD-3 initiates distinct lineage-specific signaling cascades in various cells involved in host defense and induces a concurrent tyrosine kinase and tyrosine phosphatase signaling cascade that may activate simultaneously the targeted T cells and inhibit their response to other immune mediators. Furthermore, these results suggest that this evolutionarily conserved peptide, which exhibits a broad spectrum of antimicrobial and immunomodulatory activities, serves to integrate innate and adaptive immunity.

Human β-defensin 3 peptide is increased and redistributed in Crohn's ileitis

BACKGROUND

Antimicrobial peptides (AMPs) maintain a sterile environment in intestinal crypts, limiting microbial colonization and invasion. Decreased AMP expression is proposed to increase the risk for inflammatory bowel disease. Expression and function of inducible AMPs, human β-defensin 2 and 3 (hBD-2 and hBD-3), remain poorly characterized in healthy and chronically inflamed intestine.

METHODS

Peptide concentrations of hBD-2 and hBD-3 in serum and intestinal biopsies of subjects with ulcerative colitis and Crohn's disease (CD), and those of healthy subjects were measured by ELISA. Messenger RNA of hBD-2 and hBD-3 was quantified by quantitative PCR in biopsies from the terminal ileum (TI) of patients with CD and healthy controls. Peptide localization of hBD-3 in the TI was visualized by confocal microscopy.

RESULTS

Immunoreactive hBD-3 peptide is present in the TI and colon in healthy subjects. In the TI of patients with CD, hBD-3, but not hBD-2 peptide, is increased 4-fold, whereas hBD-2 peptide is elevated in the serum. Messenger RNA of hBD-3 in the CD TI remains unchanged and does not correlate with hBD-3 peptide expression. However, hBD-3 is localized to Paneth cell granules and the apical surface of the healthy columnar epithelium. In CD, hBD-3 peptide location switches to the basolateral surface of the columnar epithelium and is diffusely distributed within the lamina propria.

CONCLUSION

The peptide hBD-3 throughout the healthy gastrointestinal tract suggests a role in maintaining balance between host defenses and commensal microbiota. Increased and relocalized secretion of hBD-3 toward the lamina propria in the CD TI indicates possible local immunomodulation during chronic inflammation, whereas increased serum hBD-2 in CD implicates its systemic antimicrobial and immunomodulatory role.

Examining the positive effects of exercise in intubated adults in ICU: a prospective repeated measures clinical study

BACKGROUND

Determining the optimal timing and progression of mobility exercise has the potential to affect functional recovery of critically ill adults. This study compared standard care with care delivered using a mobility protocol. We examined the effects of exercise on vital signs and inflammatory biomarkers and the effects of the nurse-initiated mobility protocol on outcomes.

METHODS

Prospective, repeated measures study with a control (standard care) and intervention (protocol) period.

RESULTS

75 heterogeneous subjects admitted to a Medical or Surgical intensive care unit (ICU) were enrolled. In <5% of exercise periods, there was a concerning alteration in respiratory rate or peripheral oxygen saturation; no other adverse events occurred. Findings suggested the use of a protocol with one 20 minute episode of exercise daily for 2 or more days reduced ICU length of stay. Duration of exercise was linked to increased IL-10, suggesting brief episodes of low intensity exercise positively altered inflammatory dysregulation in this sample.

CONCLUSION

A growing body of evidence demonstrates that early, progressive exercise has significant benefits to intubated adults. These results should encourage clinicians to add mobility protocols to the care of ICU adults and lead to future studies to determine optimal "dosing" of exercise in ICU patients.

Mycobacterium tuberculosis ManLAM inhibits T-cell-receptor signaling by interference with ZAP-70, Lck and LAT phosphorylation

Immune evasion is required for Mycobacterium tuberculosis to survive in the face of robust CD4(+) T cell responses. We have shown previously that M. tuberculosis cell wall glycolipids, including mannose capped lipoarabinomannan (ManLAM), directly inhibit polyclonal murine CD4(+) T cell activation by blocking ZAP-70 phosphorylation. We extended these studies to antigen-specific murine CD4(+) T cells and primary human T cells and found that ManLAM inhibited them as well. Lck and LAT phosphorylation also were inhibited by ManLAM without affecting their localization to lipid rafts. Inhibition of proximal TCR signaling was temperature sensitive, suggesting that ManLAM insertion into T cell membranes was required. Thus, M. tuberculosis ManLAM inhibits antigen-specific CD4(+) T cell activation by interfering with very early events in TCR signaling through ManLAM's insertion in T cell membranes.

Stat3 phosphorylation mediates resistance of primary human T cells to regulatory T cell suppression

Human autoimmune diseases are characterized by systemic T cell dysfunction, resulting in chronically activated Th1 and Th17 cells that are inadequately suppressed by regulatory T cells (Tregs). IL-6, which is overexpressed in tissue and serum of patients with autoimmune diseases, inhibits human Treg function. We sought to determine the mechanism for the antitolerogenic properties of IL-6 by examining the signaling pathways downstream of IL-6R in primary human T cells. Inhibition of Stat3 signaling in MLCs containing IL-6 restores Treg-mediated suppression, demonstrating that IL-6-mediated loss of Treg suppression requires phosphorylation of Stat3. Cultures in which either effector T cells (Teffs) or Tregs were pretreated with Stat3 inhibitors indicate that phosphorylated (p)Stat3 is required in both T cell populations for IL-6-mediated reversal of Treg function. IL-21, which signals preferentially through pStat3, also reverses Treg suppression, in contrast to IL-27 and IFN-γ, which signal preferentially through Stat1 and do not inhibit Treg function. Interestingly, both Teffs and Tregs respond to IL-6 stimulation through strong Stat3 phosphorylation with minimal MAPK/Erk activation and moderate Stat1 phosphorylation. Finally, Teffs stimulated strongly through the TCR are also resistant to suppression by Tregs and show concurrent Stat3 phosphorylation. In these cultures, inhibition of pStat3 restores functional suppression by Tregs. Taken together, our findings suggest that an early dominance of Stat3 signaling, prior to subsequent T cell activation, is required for the loss of functional Treg suppression and that kinase-specific inhibitors may hold therapeutic promise in the treatment of autoimmune and chronic inflammatory diseases.

RETRACTED: REDOX regulation of IL-13 signaling in intestinal epithelial cells: usage of alternate pathways mediates distinct gene expression patterns

In the classic view interleukin-13 (IL-13) binds to a heterodimer protein complex of the IL-13Ralpha1 and IL-4Ralpha chains and signals through a Janus kinase 1 (JAK1)-signal transducer and activator of transcription 6 (STAT6) mechanism. We recently reported that IL-13 also signals through the IL-13Ralpha2 chain initiating all three mitogen activated protein kinase (MAPK) pathways, and the relative expression of IL-13Ralpha1 and IL-13Ralpha2 modulates one another's transduction pathway. Therefore we investigated whether generation of reactive oxygen species (ROS) as second messengers may serve as a common nexus between these two pathways emanating from the individual IL-13 receptor chains in intestinal epithelial cells (IEC). IL-13 stimulates intracellular ROS synthesis within 5min via IL-13Ralpha1-JAK1-STAT6- and IL-13Ralpha2-MEK1/2-ERK1/2-dependent activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-1 (NOX-1). IL-13-induced ROS generation in turn positively regulates phosphorylation of ERK1/2 and STAT6, yielding a feed forward amplification loop. IL-13 also stimulates the stable, long-term gene expression of two other NADPH oxidases, NOX-4 and DUOX-2, which along with constitutive NOX-1, might facilitate elevated, continuous production of ROS in IL-13-activated IEC. The contribution of each signal transduction pathway initiated by IL-13 engagement to such biological functions as wound healing, inflammation, and apoptosis was mapped for representative, responsive genes. Distinct usage patterns were observed, demonstrating not only that IL-13 signal transduction through STAT6, MAPK, and ROS is regulated in both an antagonistic and cyclic fashion, but also that each pathway plays a specific role in modulating the wound healing and anti-apoptotic capabilities of the intestinal epithelium.

Compromised gastrointestinal integrity in pigtail macaques is associated with increased microbial translocation, immune activation, and IL-17 production in the absence of SIV infection

Pigtail macaques (PTMs) rapidly progress to AIDS after simian immunodeficiency virus (SIV) infection. Given the strong association between human immunodeficiency virus (HIV) and SIV disease progression and microbial translocation and immune activation, we assessed whether high basal levels of immune activation and microbial translocation exist in PTMs. We found that before SIV infection, PTMs had high levels of microbial translocation that correlated with significant damage to the structural barrier of the gastrointestinal tract. Moreover, this increased microbial translocation correlated with high levels of immune activation and was associated with high frequencies of interleukin-17-producing T cells. These data highlight the relationship among mucosal damage, microbial translocation and systemic immune activation in the absence of SIV replication, and underscore the importance of microbial translocation in the rapid course of disease progression in SIV-infected PTMs. Furthermore, these data suggest that PTM may be an ideal model to study therapeutic interventions aimed at decreasing microbial translocation-induced immune activation.

Elevated IL-13Ralpha2 in intestinal epithelial cells from ulcerative colitis or colorectal cancer initiates MAPK pathway

BACKGROUND

Chronic inflammation in ulcerative colitis (UC) is a sizeable risk factor for colorectal cancer (CRC). Interleukin-13 (IL-13) is elevated in the UC mucosa and may induce dysregulated signaling in neighboring intestinal epithelial cells (IECs) and thus function as a tumorogenic cytokine.

METHODS

Expression of IL-13 receptor chains on IECs obtained from control or chronically inflamed mucosa and colonic tumors was quantified by flow cytometry and immunoblot. IL-13Ralpha1 and IL-13Ralpha2 expression was significantly increased on IEC from UC and CRC patients compared to control and Crohn's disease (CD) subjects. Purified IEC from these subjects and cell lines expressing varying ratios of IL-13Ralpha1 and IL-13Ralpha2 chains were stimulated with IL-13 in vitro to investigate by immunoblot the activation of the signal transducer and activator of transcription 6 (STAT6) and mitogen activated protein kinase (MAPK) signaling pathways.

RESULTS

Despite similarly elevated receptor expression in UC and CRC, IL-13 does not activate the STAT6 or MAPK pathways in UC, while in colonic tumors only the STAT6 pathway is activated. Using neutralizing antibodies and cell lines expressing a range of surface densities for IL-13Ralpha1 and IL-3Ralpha2, we demonstrate that IL-13Ralpha2 serves a dual role, initiating MAPK signaling at low concentrations and as an inhibitory, decoy receptor at high IL-13Ralpha2 to IL-13Ralpha1 ratios.

CONCLUSIONS

IL-13Ralpha2 is both a decoy receptor and induces MAPK signal transduction, depending on its relative expression and the local concentration of IL-13, which together modulate the balance and intensity of the signaling pathways initiated in UC and CRC.

Abstract LB-307: Overexpression of AXL as a novel acquired resistance mechanism in EGFR-mutated non-small cell lung cancer cells

Activating mutations of EGFR have been characterized as important mechanisms for carcinogenesis in a subset of EGFR-dependent non-small cell lung cancers (NSCLC). EGFR tyrosine kinase inhibitors (TKI), such as erlotinib and gefitinib, have dramatic clinical effects on EGFR-addicted lung cancers and are used as first-line therapy for EGFR-mutant tumors. However, this therapeutic sensitivity is invariably temporary and eventually all tumors acquire secondary resistance to the drugs and progress. Erlotinib-resistant EGFR mutations such as EGFR T790M and MET activation have been reported in drug-resistant tumors, but the mechanism of resistance remains unclear in a significant fraction of cases. Here we report a novel molecular mechanism leading to secondary resistance to erlotinib. HCC827, an EGFR-mutant and highly erlotinib-sensitive NSCLC cell line was exposed to increasing doses of erlotinib for 5 months and 2 subclonal cell lines were established, both of which grow well in the presence of high-dose erlotinib (15µM). In contrast to parental cells, the two erlotinib-resistant cell lines demonstrated sustained activation of Ras/Mek/Erk and Akt signaling pathways in the presence of erlotinib despite complete inhibition of EGFR phosphorylation. Sequencing of the entire EGFR gene sequence revealed no secondary changes, and expression of EGFR and MET, as well as MET activation did not differ from parental cells suggesting the presence of an alternative, novel mechanism of resistance. Gene expression profiling revealed a limited number of genes with altered expression levels which were verified by quantitative rt-PCR. We focused on the cell surface receptor tyrosine kinase, AXL (10-fold overexpressed in one resistant clone) given its known role in cell proliferation, angiogenesis and recent findings indicating its involvement in lapatinib-resistance in ErbB2-positive breast cancer. Prominent AXL overexpression was further confirmed in this clonal isolate on the protein level. siRNA-mediated downregulation of AXL reconstituted erlotinib-sensitivity, leading to cell death and was accompanied by inhibition of AKT activation. However, AXL knockdown in the absence of erlotinib did not have growth inhibitory effects on the cells. These results suggest that AXL signaling can serve as a backup control of proliferative pathways in our resistant cell models in the presence of EGFR inhibition serving as a novel paradigm of oncogenic switch. Mechanisms underlying overexpression of AXL and its restoration of TKI sensitivity are under investigation. Our results suggest that an oncogenic switch from EGFR-dependent to EGFR/AXL-codependent signaling can lead to secondary EGFR-TKI resistance in NSCLC, indicating that dual blockade of EGFR and AXL may serve as a novel therapeutic strategy for the treatment of EGFR-mutant lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-307.

Dual specificity phosphatase 6 (DUSP6) is an ETS-regulated negative feedback mediator of oncogenic ERK signaling in lung cancer cells

Mitogen-activated protein kinase (MAPK) pathway signaling plays an important role in the majority of non-small-cell lung cancers (NSCLCs). In a prior microarray analysis of epidermal growth factor receptor (EGFR) inhibition in NSCLC cell lines, we noted that several dual specificity phosphatases (DUSPs) were among the most highly and immediately regulated genes. DUSPs act as natural terminators of MAPK signal transduction and therefore, we hypothesized a tumor suppressive role via feedback mechanisms. In the current study, we focus on the assessment of DUSP6, a cytoplasmic DUSP with high specificity for extracellular signal-regulated kinase (ERK). We demonstrate that DUSP6 expression tracks in tandem with ERK inhibition and that regulation of DUSP6 is mediated at the promoter level by ETS1, a well-known nuclear target of activated ERK. Small interfering RNA knockdown in DUSP6-high H441 lung cancer cells significantly increased ERK activation and cellular proliferation, whereas plasmid-driven overexpression in DUSP6-low H1975 lung cancer cells significantly reduced ERK activation and cellular proliferation and promoted apoptosis. Also, DUSP6 overexpression synergized with EGFR inhibitor treatment in EGFR-mutant HCC827 cells. Our results indicate that DUSP6 expression is regulated by ERK signaling and that DUSP6 exerts antitumor effects via negative feedback regulation, pointing to an important feedback loop in NSCLC. Further studies assessing the tumor suppressive role of DUSP6 and strategies aimed at modulation of its activity are warranted.

IL-6 signaling in psoriasis prevents immune suppression by regulatory T cells

T memory/effector cells (Tmem/eff) isolated from psoriatic patients are chronically activated and poorly suppressed by regulatory T cells (Treg). The proinflammatory cytokine IL-6, which signals through Stat3, allows escape of Tmem/eff cells from Treg-mediated suppression in a murine system. We show here that IL-6 protein is markedly elevated and most highly expressed by CD31(+) endothelial cells and CD11c(+) dermal dendritic cells (DCs) in lesional psoriatic skin. We hypothesized that exposure to high IL-6 in lesional tissue may lead to the dampened Treg function observed in psoriasis patients. Indeed, we found that IL-6, but not other Stat3-activating cytokines, was necessary and sufficient to reverse human T cell suppression by Treg in an in vitro model using activated DCs as a source of IL-6. IL-6Ralpha and gp130 expression was significantly elevated in psoriatic effector T cells compared with normal controls. Overall, IL-6Ralpha expression on Treg exceeded that of effector T cells, and both populations phosphorylated Stat3 in response to IL-6. Phosphorylation of Stat3 in T cells contributes to Th17 differentiation and we identify cells within lesional tissue that coexpress CD3, IL-17, and IL-6, indicating that Th17 cells are present in vivo within the psoriatic Tmem/eff population and contribute to IL-6-mediated resistance to Treg suppression. Taken together, T lymphocytes trafficking into lesional psoriatic skin encounter high IL-6 from endothelial cells, DCs, and Th17 cells, enabling cutaneous T cell escape from Treg suppression and Th17 participation in inflammation. Targeting IL-6 signaling pathways in psoriasis may rebalance Treg/T effector activity and ameliorate disease.

Antigen-independent adhesion and cell spreading by inducible costimulator engagement inhibits T cell migration in a PI-3K-dependent manner

Engagement of the costimulatory protein ICOS activates effector/memory T cells in tissue by enhancing TCR-mediated proliferation and cytokine production. We now report that in an antigen-independent manner, ICOS also induces adhesion and spreading in human effector/memory T cells, consequently inhibiting cell migration. T cell spreading and elongation after ICOS ligation are accompanied by the formation of two types of actin-rich membrane protrusions: thin, finger-like structures similar to filopodia and short, discrete microspikes. Although filopodia/microspike formation occurs independently of the PI-3K signaling cascade, ICOS-mediated T cell elongation depends on PI-3K activity, which inhibits the accumulation of GTP-bound RhoA. Further inhibition of RhoA activation exacerbates the ICOS-mediated, elongated phenotype. We propose that in inflamed tissue, ICOS engagement by ICOS ligand on a professional or nonprofessional APC prevents the forward motility of the T cell by inhibiting RhoA-dependent uropod retraction. The resulting ICOS-induced T cell spreading and filopodia/microspike formation may promote antigen recognition by enhancing a T cell's scanning potential of an adherent APC surface.

TGF-beta inhibits IL-2 production and promotes cell cycle arrest in TCR-activated effector/memory T cells in the presence of sustained TCR signal transduction

TGF-beta signaling is critical for controlling naive T cell homeostasis and differentiation; however, the biological and biochemical changes induced by TGF-beta in effector/memory T cells are poorly defined. We show that although TGF-beta inhibits effector/memory peripheral blood T lymphoblast proliferation and IL-2 production, the intensity and kinetics for TCR-induced global tyrosine phosphorylation are markedly increased compared with that in untreated cells or naive T cells. After TCR ligation, tyrosine phosphorylation of proximal tyrosine kinases and docking proteins like linker for activation of T cells is maintained for >30 min in TGF-beta-primed cells compared with untreated cells where phosphorylation of these targets returned to basal levels by 10 min. Extended phosphorylation of linker for activation of T cells in treated peripheral blood T selectively prolongs ERK 1/2 signaling and phospholipase C-gamma1 activation leading to increased Ca(2+) flux. A kinase/phosphatase imbalance could not account for extended phosphorylation as CD45R, SHP-1, and SHP-2 expression remains unaltered. The contradiction between prolonged signal transduction and inhibition of proliferation is partially explained by the observation that TGF-beta priming results in ERK 1/2-independent p21 induction and decreased cyclin D1 expression leading to accumulation of T cells in G(0)/G(1) phases of the cell cycle and cell cycle arrest. Despite inhibition of T cell function by TGF-beta priming, TCR and cytokine signaling pathways are intact and selectively extended, suggesting that suppression in the effector/memory T cell is mediated by reprogramming signal transduction, rather than its inhibition as in the naive T cell.

Mucosal T-cell immunoregulation varies in early and late inflammatory bowel disease

BACKGROUND AND AIMS

Crohn's disease is a life-long form of inflammatory bowel disease (IBD) mediated by mucosal immune abnormalities. Understanding of the pathogenesis is limited because it is based on data from adults with chronic Crohn's disease. We investigated mucosal T-cell immunoregulatory events in children with early Crohn's disease.

METHODS

Mucosal biopsies and T-cell clones were derived from children experiencing the first attack of Crohn's disease, children with long-standing Crohn's disease, infectious colitis, and children without gut inflammation.

RESULTS

As in acute infectious colitis, interleukin (IL) 12 induced T cells from early Crohn's disease to acquire a strongly polarised T helper (Th) type 1 response characterised by high IFN-gamma production and IL12Rbeta2 chain expression. Th1 polarisation was not induced in clones from late Crohn's disease. Mucosal levels of IL12p40 and IL12Rbeta2 messenger RNA were significantly higher in children with early than late Crohn's disease. These results demonstrate that susceptibility to IL12-mediated modulation is strongly dependent on the stage of Crohn's disease.

CONCLUSIONS

At the onset of Crohn's disease mucosal T cells appear to mount a typical Th1 response that resembles an acute infectious process, and is lost with progression to late Crohn's disease. This suggests that mucosal T-cell immunoregulation varies with the course of human IBD. Patients with the initial manifestations of IBD may represent an ideal population in which immunomodulation may have optimal therapeutic efficacy.

Angiogenesis blockade as a new therapeutic approach to experimental colitis

BACKGROUND

Neoangiogenesis is a critical component of chronic inflammatory disorders. Inhibition of angiogenesis is an effective treatment in animal models of inflammation, but has not been tested in experimental colitis.

AIM

To investigate the effect of ATN-161, an anti-angiogenic compound, on the course of experimental murine colitis.

METHOD

Interleukin 10-deficient (IL10(-/-)) mice and wild-type mice were kept in ultra-barrier facilities (UBF) or conventional housing, and used for experimental conditions. Dextran sodium sulphate (DSS)-treated mice were used as a model of acute colitis. Mice were treated with ATN-161 or its scrambled peptide ATN-163. Mucosal neoangiogenesis and mean vascular density (MVD) were assessed by CD31 staining. A Disease Activity Index (DAI) was determined, and the severity of colitis was determined by a histological score. Colonic cytokine production was measured by ELISA, and lamina propria mononuclear cell proliferation by thymidine incorporation.

RESULT

MVD increased in parallel with disease progression in IL10(-/-) mice kept in conventional housing, but not in IL10(-/-) mice kept in UBF. Angiogenesis also occurred in DSS-treated animals. IL10(-/-) mice with established disease treated with ATN-161, but not with ATN-163, showed a significant and progressive decrease in DAI. The histological colitis score was significantly lower in ATN-161-treated mice than in scrambled peptide-treated mice. Inhibition of angiogenesis was confirmed by a significant decrease of MVD in ATN-161-treated mice than in ATN-163-treated mice. No therapeutic effects were observed in the DSS model of colitis. ATN-161 showed no direct immunomodulatory activity in vitro.

CONCLUSION

Active angiogenesis occurs in the gut of IL10(-/-) and DSS-treated colitic mice and parallels disease progression. ATN-161 effectively decreases angiogenesis as well as clinical severity and histological inflammation in IL10(-/-) mice but not in the DDS model of inflammatory bowel disease (IBD). The results provide the rational basis for considering anti-angiogenic strategies in the treatment of IBD in humans.

Cytokines in chronically critically ill patients after activity and rest

Inflammation, a common problem for patients in the intensive care unit (ICU), frequently is associated with serious and prolonged critical illnesses. To date, no study has examined whether physical activity influences inflammatory factors in critically ill adults. The objectives of this study were to (a) examine the relationships between type and duration of physical activity and serum levels of interleukin 6 (IL-6), a proinflammatory cytokine; IL-10, an anti-inflammatory cytokine; and their ratio and (b) determine if there are associations between cytokines or their ratio and activity or outcomes. This descriptive feasibility study investigated the approaches to measuring levels of physical activity and its relationship to serum levels of IL-6 and IL-10 and the ratio between them in patients with prolonged mechanical ventilation during periods of activity and rest. Measurements included serum IL-6 and IL-10 levels, direct observation and actigraphy, and prospective chart review. Ten critically ill patients who were mechanically ventilated for an average of 10 days in a large, urban, teaching hospital were enrolled. The average ratio of IL-6 to IL-10 improved after an average of 14.7 min of passive physical activity, typically multiple in-bed turns associated with hygiene. IL-6, IL-10, and their ratio were not associated with patient outcomes of weaning success or length of stay. High levels of IL-6 were associated with mortality. Cytokine balance may be improved by low levels of activity among patients with prolonged critical illness. The pattern of cytokines produced after activity may improve patients' recovery from prolonged critical illness and mechanical ventilation.

Maturation of the mucosal immune system underlies colitis susceptibility in interleukin-10-deficient (IL-10−/−) mice

Elevated mucosal IL-12/23p40 and IFN-gamma accompany early inflammation in IL-10-deficient (IL-10(-/-)) mice and then later decline while inflammation persists. This report addresses whether this cytokine profile reflects disease progression or inherent, age-related changes in mucosal immunity. IL-10(-/-) and wild-type (WT) mice were maintained in an ultrabarrier facility or transferred to conventional housing at 3, 12, or 30 weeks of age. Weight, stool changes, and histologic features were followed. Lamina propria mononuclear cells were cultured for cytokine analysis by ELISA. Ultrabarrier-housed IL-10(-/-) mice are statistically indistinguishable from WT mice by weight, disease activity index, and histologic inflammation. IL-10(-/-) mice but not WT, transferred at 3 weeks, develop colitis gradually, reaching a significant, sustained maximum by 15 weeks of age. Transfer at 12 weeks induces rapid disease onset in both strains, maximal at 15 weeks of age. Inflammation persists in IL-10(-/-), and WT recover. IL-10(-/-) and WT mice transferred at 30 weeks demonstrate transient diarrhea and weight loss but no chronic inflammation. Probiotics delay symptom onset only in the 12-week-old group. IFN-gamma production from ultrabarrier-housed IL-10(-/-) mice is elevated at 12 weeks of age, and older animals have decreased IFN-gamma and increased IL-4. IL-10 is important for suppressing inflammation after transfer at 3 weeks of age and limiting inflammation after transfer at 12 weeks but has little influence at 30 weeks of age. Colitis onset, progression, and response to probiotic therapy vary with immune system age, suggesting that a distinct, Th1-driven, age-dependent cytokine profile may contribute to increased colitis susceptibility in otherwise healthy mice.

Integrin-mediated cell adhesion and spreading engage different sources of reactive oxygen species

The tightly regulated production of intracellular reactive oxygen species (ROS) participates in several biologic processes such as cellular growth, programmed cell death, senescence, and adhesion. It is increasingly evident that the same enzymatic processes that were originally linked to ROS generation during host defence or apoptosis execution are also involved in redox-mediated signal transduction. We investigated in murine NIH3T3 fibroblasts the contribution of a variety of redox-dependent events during signal transduction initiated by integrin engagement due to fibronectin stimulation and report that a mitochondrial ROS release occurs, strictly confined to the early phase of extracellular matrix (ECM) contact (10 min). Besides, 5-lipoxygenase (5-LOX) is engaged by integrin receptor ligation as another ROS source, contributing to the more-intense, second ROS burst (45 min), possibly orchestrating the spreading of cells in response to ECM contact. To define a potential mechanism for ROS signaling, we demonstrate that on integrin recruitment, the Src homology-2 domain-containing phosphatase 2 (SHP-2) undergoes a reversible oxidization/inactivation to which mitochondrial and 5-lipoxygenase ROS contribute differentially. In keeping with a key role of oxidants during integrin signaling, the inactivation of SHP-2 prevents the dephosphorylation and inactivation of SHP-2 substrates (p125FAK and SHPS-1), thus enabling the continued propagation of the signal arising by integrin engagement.

Redox equilibrium in mucosal T cells tunes the intestinal TCR signaling threshold

Mucosal immune tolerance in the healthy intestine is typified by lamina propria T cell (LPT) functional hyporesponsiveness after TCR engagement when compared with peripheral blood T cell (PBT). When LPT from an inflamed intestine are activated through TCR cross-linking, their responsiveness is stronger. LPT are thus capable of switching from a tolerant to a reactive state, toggling between high and low thresholds of activation. We demonstrate that in normal LPT global tyrosine phosphorylation upon TCR cross-linking or an increase in intracellular H2O2, an inhibitor of protein tyrosine phosphatases, is muted. Thus, we propose that LPT have a greater reducing capacity than PBT, shifting the balance between kinases and protein tyrosine phosphatases in favor of the latter. Surface gamma-glutamyl transpeptidase, an indirect indicator of redox potential, and glutathione are significantly elevated in LPT compared with PBT, suggesting that elevated glutathione detoxifies TCR-induced reactive oxygen species. When glutathione is depleted, TCR-induced LPT tyrosine phosphorylation rises to PBT levels. Conversely, increasing glutathione in PBT attenuates tyrosine phosphorylation. In LPT isolated from inflamed mucosa, TCR cross-linking induces greater phosphorylation, and gamma-glutamyl transpeptidase levels are reduced compared with those from autologous noninflamed tissue. We conclude that the high TCR signaling threshold of mucosal T cells is tuned by intracellular redox equilibrium, whose dysregulation may mediate intestinal inflammation.

Eradication of Helicobacter pylori and resolution of gastritis in the gastric mucosa of IL-10-deficient mice

BACKGROUND

Helicobacter pylori has been shown to induce pronounced gastric inflammation in the absence of interleukin-10 (IL-10) by 6 weeks post inoculation. The ability of IL-10(-/-) mice to eradicate H. pylori has not been demonstrated, possibly due to early sacrifice. Therefore, the long-term effect of enhanced gastritis on H. pylori colonization was determined in IL-10(-/-) mice.

METHODS

C57BL/6 and IL-10(-/-) mice were infected with H. pylori and assessed for the degree of gastritis, bacterial load, and in vitro T-cell recall response at 4 and 16 weeks of infection.

RESULTS

Infection of IL-10(-/-) mice resulted in significantly more severe gastritis than wild-type control mice and eradication of H. pylori by 4 weeks post inoculation. By 16 weeks, the level of gastritis in IL-10(-/-) was reduced to the levels observed in wild-type mice. Splenocytes from IL-10(-/-) mice were prone to produce significantly greater amounts of IFN-gamma than wild-type mice when stimulated with bacterial antigens.

CONCLUSIONS

These results indicate that the host is capable of spontaneously eradicating H. pylori from the gastric mucosa when inflammation is elevated beyond the chronic inflammation induced in wild-type mice, and that the gastritis dissipates following bacterial eradication. Additionally, these data provide support for a model of gastrointestinal immunity in which naturally occurring IL-10-producing regulatory T cells modulate the host response to gastrointestinal bacteria.

Interleukin 10 extends the effectiveness of standard therapy during late sepsis with serum interleukin 6 levels predicting outcome

Patients with septic shock often display features of T cell hyporesponsiveness and immune suppression, which, if persistent, are associated with increased mortality. In the murine cecal ligation and puncture (CLP) model of sepsis, we previously reported that early treatment with the anti-inflammatory cytokine interleukin 10 (IL-10) delays the onset of irreversible shock, defined as the time at which rescue surgery to remove the necrotic cecum is no longer effective. Because IL-10 can be immunostimulatory for T cells, we hypothesized that in the CLP model, late IL-10 treatment after removal of the infectious nidus at the onset of irreversible shock would restore T cell responsiveness and increase survival. C57BL/6J mice were subjected to lethal CLP with and without rescue surgery, concurrent with IL-10 treatment, at the onset of irreversible shock. Survival and serum IL-6 levels were measured as markers of the response to treatment. Ten hours after intervention, all groups exhibited T cell hyporesponsiveness marked by impaired interferon (IFN)-gamma production by Con A-stimulated splenocytes. IL-6 levels at 10 h were related to outcome independent of treatment. By 25 h after intervention, only the dual treatment group of cecal removal and IL-10 exhibited T cell responsiveness that was similar to pre-CLP levels (P = 0.26) and had a 7-day survival of 90% (P < or = 0.002 compared with all other groups). Thus, even in the advanced stages of septic shock when standard therapies fail, treatment with IL-10 extends the therapeutic window. For an individual mouse, the efficacy of such treatment may be predicted by an early postintervention IL-6 level.

Ischemia/reperfusion: a clinically relevant model of intestinal injury yielding systemic inflammation

BACKGROUND/PURPOSE

Multisystem organ failure (MSOF) is a major cause of morbidity and mortality in the critically ill patient. Animal models of endotoxin-induced sepsis were used to develop therapeutic regimens, which thus far have failed in clinical trials. Because multiple etiologies of MSOF affect the intestine, the authors hypothesized that during sepsis the gut may act as a possible trigger of the inflammatory cascade. As ischemia and reperfusion of the small intestine disrupts gut barrier function, thereby activating systemic inflammatory responses, the authors evaluated a murine model of ischemia/reperfusion to investigate these systemic responses to local mucosal and epithelial injury.

METHODS

C57BL/10 and Balb/c mice underwent variable amounts of gut ischemia by superior mesenteric artery occlusion. Animals were evaluated for survival as well as gross and microscopic intestinal damage.

RESULTS

Maximal ischemic damage occurred in the distal jejunum and proximal ileum. More severe epithelial damage and transmural inflammation were observed in C57BL/10 mice, which correlated with a higher mortality.

CONCLUSIONS

This model mimics what is observed clinically with intestinal injury resulting from a progressive ischemic insult with eventual systemic manifestations. This reproducible model of systemic inflammation elicits variable responses from genetically different animals, the results of which may lead to a better understanding of MSOF.

Persistent elevation of serum interleukin-6 in intraabdominal sepsis identifies those with prolonged length of stay

BACKGROUND/PURPOSE

Elevated serum interleukin-6 (IL-6) levels in patients with intraabdominal sepsis have been associated with increased morbidity and mortality. The authors hypothesized that after surgical intervention a persistent elevation of IL-6 would more accurately reflect the inflammatory state and thus predict the subsequent time to recovery better than the preoperative value alone.

METHODS

Nineteen consecutive children with peritonitis and manifestations of the systemic inflammatory response syndrome were enrolled prospectively. IL-6 levels were determined from pre- and postoperative serum samples (within 12 to 24 hours) by enzyme-linked immunosorbant assay (ELISA). Patient postoperative length of stay (LOS) was recorded.

RESULTS

Before surgery, patient serum IL-6 levels ranged from 48 to 132,546 pg/mL. LOS ranged from 4 to 60 days, with subjects falling into 2 groups of < or =11 (n = 14) and > or =25 (n = 5) days. Using an IL-6 level greater than 500 pg/mL to predict a prolonged LOS (>11 days), a persistent elevation of IL-6 postoperatively appears to increase the likelihood of a prolonged LOS.

CONCLUSIONS

Persistent IL-6 levels greater than 500 pg/mL may be useful in identifying pediatric intraabdominal sepsis patients with prolonged LOS and presumably greater morbidity. Rapid identification of these patients may allow for novel therapeutic interventions.