IL-1β-mediated adaptive reprogramming of endogenous human cardiac fibroblasts to cells with immune features during fibrotic remodeling

The source and roles of fibroblasts and T-cells during maladaptive remodeling and myocardial fibrosis in the setting of pulmonary arterial hypertension (PAH) have been long debated. We demonstrate, using single-cell mass cytometry, a subpopulation of endogenous human cardiac fibroblasts expressing increased levels of CD4, a helper T-cell marker, in addition to myofibroblast markers distributed in human fibrotic RV tissue, interstitial and perivascular lesions in SUGEN/Hypoxia (SuHx) rats, and fibroblasts labeled with pdgfrα CreERt2/+ in R26R-tdTomato mice. Recombinant IL-1β increases IL-1R, CCR2 receptor expression, modifies the secretome, and differentiates cardiac fibroblasts to form CD68-positive cell clusters. IL-1β also activates stemness markers, such as NANOG and SOX2, and genes involved in dedifferentiation, lymphoid cell function and metabolic reprogramming. IL-1β induction of lineage traced primary mouse cardiac fibroblasts causes these cells to lose their fibroblast identity and acquire an immune phenotype. Our results identify IL-1β induced immune-competency in human cardiac fibroblasts and suggest that fibroblast secretome modulation may constitute a therapeutic approach to PAH and other diseases typified by inflammation and fibrotic remodeling.

Bifidobacteria shape antimicrobial T-helper cell responses during infancy and adulthood

Microbial infections early in life are challenging for the unexperienced immune system. The SARS-CoV-2 pandemic again has highlighted that neonatal, infant, child, and adult T-helper(Th)-cells respond differently to infections, and requires further understanding. This study investigates anti-bacterial T-cell responses against Staphylococcus aureus aureus, Staphylococcus epidermidis and Bifidobacterium longum infantis in early stages of life and adults and shows age and pathogen-dependent mechanisms. Beside activation-induced clustering, T-cells stimulated with Staphylococci become Th1-type cells; however, this differentiation is mitigated in Bifidobacterium-stimulated T-cells. Strikingly, prestimulation of T-cells with Bifidobacterium suppresses the activation of Staphylococcus-specific T-helper cells in a cell-cell dependent manner by inducing FoxP3+CD4+ T-cells, increasing IL-10 and galectin-1 secretion and showing a CTLA-4-dependent inhibitory capacity. Furthermore Bifidobacterium dampens Th responses of severely ill COVID-19 patients likely contributing to resolution of harmful overreactions of the immune system. Targeted, age-specific interventions may enhance infection defence, and specific immune features may have potential cross-age utilization.

Exploring the Regulatory Role of XIST-microRNAs/mRNA Network in Circulating CD4+ T Cells of Hepatocellular Carcinoma Patients

Hepatocellular carcinoma (HCC) is one of the most common cancers and the main cause of cancer-related death globally. Immune dysregulation of CD4⁺ T cells has been identified to play a role in the development of HCC. Nevertheless, the underlying molecular pathways of CD4⁺ T cells in HCC are not completely known. Thus, a better understanding of the dysregulation of the lncRNA-miRNA/mRNA network may yield novel insights into the etiology or progression of HCC. In this study, circulating CD4⁺ T cells were isolated from the whole blood of 10 healthy controls and 10 HCC patients for the next-generation sequencing of the expression of lncRNAs, miRNAs, and mRNAs. Our data showed that there were different expressions of 34 transcripts (2 lncRNAs, XISTs, and MIR222HGs; 29 mRNAs; and 3 other types of RNA) and 13 miRNAs in the circulating CD4⁺ T cells of HCC patients. The expression of lncRNA-XIST-related miRNAs and their target mRNAs was confirmed using real-time quantitative polymerase chain reaction (qPCR) on samples from 100 healthy controls and 60 HCC patients. The lncRNA-miRNA/mRNA regulation network was created using interaction data generated from ENCORI and revealed there are positive correlations in the infiltration of total CD4⁺ T cells, particularly resting memory CD4⁺ T cells, and negative correlations in the infiltration of Th1 CD4⁺ T cells.

PD-1/PD-L1 Control of Antigen-Specifically Activated CD4 T-Cells of Neonates

Newborns are highly susceptible to infections; however, the underlying mechanisms that regulate the anti-microbial T-helper cells shortly after birth remain incompletely understood. To address neonatal antigen-specific human T-cell responses against bacteria, Staphylococcus aureus (S. aureus) was used as a model pathogen and comparatively analyzed in terms of the polyclonal staphylococcal enterotoxin B (SEB) superantigen responses. Here, we report that neonatal CD4 T-cells perform activation-induced events upon S. aureus/APC-encounter including the expression of CD40L and PD-1, as well as the production of Th1 cytokines, concomitant to T-cell proliferation. The application of a multiple regression analysis revealed that the proliferation of neonatal T-helper cells was determined by sex, IL-2 receptor expression and the impact of the PD-1/PD-L1 blockade. Indeed, the treatment of S. aureus-activated neonatal T-helper cells with PD-1 and PD-L1 blocking antibodies revealed the specific regulation of the immediate neonatal T-cell responses with respect to the proliferation and frequencies of IFNγ producers, which resembled in part the response of adults’ memory T-cells. Intriguingly, the generation of multifunctional T-helper cells was regulated by the PD-1/PD-L1 axis exclusively in the neonatal CD4 T-cell lineage. Together, albeit missing memory T-cells in neonates, their unexperienced CD4 T-cells are well adapted to mount immediate and strong anti-bacterial responses that are tightly controlled by the PD-1/PD-L1 axis, thereby resembling the regulation of recalled memory T-cells of adults.

Inflammatory Macrophage Interleukin-1β Mediates High-Fat Diet-Induced Heart Failure With Preserved Ejection Fraction

Diabetes mellitus (DM) is a main risk factor for diastolic dysfunction (DD) and heart failure with preserved ejection fraction. High-fat diet (HFD) mice presented with diabetes mellitus, DD, higher cardiac interleukin (IL)-1β levels, and proinflammatory cardiac macrophage accumulation. DD was significantly ameliorated by suppressing IL-1β signaling or depleting macrophages. Mice with macrophages unable to adopt a proinflammatory phenotype were low in cardiac IL-1β levels and were resistant to HFD-induced DD. IL-1β enhanced mitochondrial reactive oxygen species (mitoROS) in cardiomyocytes, and scavenging mitoROS improved HFD-induced DD. In conclusion, macrophage-mediated inflammation contributed to HFD-associated DD through IL-1β and mitoROS production.

Determining the Protective Efficacy of Toll-Like Receptor Ligands to Minimize H9N2 Avian Influenza Virus Transmission in Chickens

Low-pathogenicity avian influenza viruses (AIV) of the H9N2 subtype can infect and cause disease in chickens. Little is known about the efficacy of immune-based strategies for reducing the transmission of these viruses. The present study investigated the efficacy of Toll-like receptor (TLR) ligands (CpG ODN 2007 and poly(I:C)) to reduce H9N2 AIV transmission from TLR-treated seeder (trial 1) or inoculated chickens (trial 2) to naive chickens. The results from trial 1 revealed that a low dose of CpG ODN 2007 led to the highest reduction in oral shedding, and a high dose of poly(I:C) was effective at reducing oral and cloacal shedding. Regarding transmission, the recipient chickens exposed to CpG ODN 2007 low-dose-treated seeder chickens showed a maximum reduction in shedding with the lowest number of AIV+ chickens. The results from trial 2 revealed a maximum reduction in oral and cloacal shedding in the poly(I:C) high-dose-treated chickens (recipients), followed by the low-dose CpG ODN 2007 group. In these two groups, the expression of type I interferons (IFNs), protein kinase R (PKR), interferon-induced transmembrane protein 3 (IFITM3), viperin, and (interleukin) IL-1β, IL-8, and 1L-18 was upregulated in the spleen, cecal tonsils and lungs. Hence, TLR ligands can reduce AIV transmission in chickens.

Plausible Role of NLRP3 Inflammasome and Associated Cytokines in Pathogenesis of Rheumatic Heart Disease

Rheumatic heart disease (RHD) is a post-streptococcal sequela caused by Streptococcus pyogenes. The global burden of disease is high among people with low socio-economic status, with significant cases emerging every year despite global eradication efforts. The current treatment includes antibiotic therapies to target strep throat and rheumatic fever and valve replacement strategies as a corrective measure for chronic RHD patients. Valvular damage and valve calcification are considered to be the end-stage processes of the disease resulting from impairment of the endothelial arrangement due to immune infiltration. This immune infiltration is mediated by a cascade of events involving NLRP3 inflammasome activation. NLRP3 inflammasome is activated by wide range of stimuli including bacterial cell wall components like M proteins and leukocidal toxins like nicotinamide dehydrogenase (NADase) and streptolysin O (SLO) and these play a major role in sustaining the virulence of Streptococcus pyogenes and progression of RHD. In this review, we are discussing NLRP3 inflammasome and its plausible role in the pathogenesis of RHD by exploiting the host-pathogen interaction mainly focusing on the NLRP3 inflammasome-mediated cytokines IL-1β and IL-18. Different therapeutic approaches involving NLRP3 inflammasome inactivation, caspase-1 inhibition, and blockade of IL-1β and IL-18 are discussed in this review and may be promising for treating RHD patients.

The female reproductive tract microbiotas, inflammation, and gynecological conditions

The intricate interactions between the host cells, bacteria, and immune components that reside in the female reproductive tract (FRT) are essential in maintaining reproductive tract homeostasis. Much of our current knowledge surrounding the FRT microbiota relates to the vaginal microbiota, where ‘health’ has long been associated with low bacterial diversity and Lactobacillus dominance. This concept has recently been challenged as women can have a diverse vaginal microbial composition in the absence of symptomatic disease. The structures of the upper FRT (the endocervix, uterus, Fallopian tubes, and ovaries) have distinct, lower biomass microbiotas than the vagina; however, the existence of permanent microbiotas at these sites is disputed. During homeostasis, a balance exists between the FRT bacteria and the immune system that maintains immune quiescence. Alterations in the bacteria, immune system, or local environment may result in perturbances to the FRT microbiota, defined as dysbiosis. The inflammatory signature of a perturbed or “dysbiotic” FRT microbiota is characterized by elevated concentrations of pro-inflammatory cytokines in cervical and vaginal fluid. It appears that vaginal homeostasis can be disrupted by two different mechanisms: first, a shift toward increased bacterial diversity can trigger vaginal inflammation, and second, local immunity is altered in some manner, which disrupts the microbiota in response to an environmental change. FRT dysbiosis can have negative effects on reproductive health. This review will examine the increasing evidence for the involvement of the FRT microbiotas and inflammation in gynecologic conditions such as endometriosis, infertility, and endometrial and ovarian cancer; however, the precise mechanisms by which bacteria are involved in these conditions remains speculative at present. While only in their infancy, the use of antibiotics and probiotics to therapeutically alter the FRT microbiota is being studied and is discussed herein. Our current understanding of the intimate relationship between immunity and the FRT microbiota is in its early days, and more research is needed to deepen our mechanistic understanding of this relationship and to assess how our present knowledge can be harnessed to assist in diagnosis and treatment of gynecologic conditions.

Scorpion venom exhibits adjuvant effect by eliciting HBsAg-specific Th1 immunity through neuro-endocrine interactions

The Hottentotta rugiscutis scorpion venom (Hrv) contains neurotoxins, which elicit a strong innate immune response through the activation of the Hypothalamus-pituitary-adrenal axis, which could improve the quality of adaptive immunity. Hence, the Hrv was used as an adjuvant for the Hepatitis-B virus surface antigen (HBsAg) and assessed its ability in the activation of innate (NGF, CORT, cellularity, NO) and adaptive (IgM, IgG, IgG1/IgG2a/IgG2b/IgG3, Th1/Th2 cytokines, avidity) immunity. Here, the Hrv and HBsAg were given in the mixed form (HBsAg-Hrv) as well as in a separate form (HBsAg+Hrv). The NGF levels in plasma/spleen and CORT in plasma were found to be elevated optimally at 5 h and 6 h post-Hrv injection, respectively. Further studies showed that CORT and NGF levels were also highly upregulated in the HBsAg-Hrv group. The HBsAg-specific IgM titer was found to be increased in the HBsAg+Hrv group and total IgG was relatively similar among alum and Hrv-test groups, but IgG2a/IgG2b/IgG3 levels were higher along with IL-1β in HBsAg-Hrv groups. The study showed that the venom from H. rugiscutis acts as a vaccine adjuvant for HBsAg to develop strong antigen-specific Th1 immunity. The Hrv also enhances the antibody-avidity which may improve the neutralizing ability of antibodies with systemic infectious agents. The study also elucidated that the venom acts by neuroendocrine-immune mechanism and majorly impacts splenocytes through NGF and corticosterone.

miR-218-5p Induces Interleukin-1β and Endovascular Trophoblast Differentiation by Targeting the Transforming Growth Factor β-SMAD2 Pathway

The acquisition of an endovascular trophoblast (enEVT) phenotype is essential for normal placental development and healthy pregnancy. MicroRNAs (miRNAs) are small noncoding RNAs that play critical roles in regulating gene expression. We have recently reported that miR-218-5p promotes enEVT differentiation and spiral artery remodeling in part by targeting transforming growth factor β2 (TGFβ2). We also identified IL1B, which encodes interleukin 1β (IL1β), as one of the most highly upregulated genes by miR-218-5p. In this study, we investigated how miR-218-5p regulates IL1B expression and IL1β secretion and the potential role of IL1β in enEVT differentiation. Using two cell lines derived from extravillous trophoblasts (EVTs), HTR-8/SVneo and Swan 71, we found that stable overexpression of miR-218-5p precursor, mir-218-1, or transient transfection of miR-218-5p mimic, significantly increased IL1B mRNA and IL1β protein levels in cells and conditioned media. We also showed that miR-218-5p directly interacted with SMAD2 3'UTR and reduced SMAD2 at mRNA and protein levels. Knockdown of SMAD2 induced IL1B expression and attenuated the inhibitory effect of TGFβ2 on IL1B expression. On the other hand, overexpression of SMAD2 reduced IL1β levels and blocked the stimulatory effects of miR-218-5p on IL1B expression, trophoblast migration and endothelial-like network formation. In addition, treatment of trophoblasts with IL1β induced the formation of endothelial-like networks and the expression of enEVT markers in a dose-dependent manner. These results suggest that miR-218-5p inhibits the TGFβ/SMAD2 pathway to induce IL1β and enEVT differentiation. Finally, low doses of IL1β also inhibited the expression of miR-218-5p, suggesting the existence of a negative feedback regulatory loop. Taken together, our findings suggest a novel interactive miR-218-5p/TGFβ/SMAD2/IL1β signaling nexus that regulates enEVT differentiation.

Mycobacterium tuberculosis RpfE-Induced Prostaglandin E2 in Dendritic Cells Induces Th1/Th17 Cell Differentiation

Prostaglandin E2 (PGE2) is an important biological mediator involved in the defense against Mycobacterium tuberculosis (Mtb) infection. Currently, there are no reports on the mycobacterial components that regulate PGE2 production. Previously, we have reported that RpfE-treated dendritic cells (DCs) effectively expanded the Th1 and Th17 cell responses simultaneously; however, the mechanism underlying Th1 and Th17 cell differentiation is unclear. Here, we show that PGE2 produced by RpfE-activated DCs via the MAPK and cyclooxygenase 2 signaling pathways induces Th1 and Th17 cell responses mainly via the EP4 receptor. Furthermore, mice administered intranasally with PGE2 displayed RpfE-induced antigen-specific Th1 and Th17 responses with a significant reduction in bacterial load in the lungs. Furthermore, the addition of optimal PGE2 amount to IL-2-IL-6-IL-23p19-IL-1β was essential for promoting differentiation into Th1/Th17 cells with strong bactericidal activity. These results suggest that RpfE-matured DCs produce PGE2 that induces Th1 and Th17 cell differentiation with potent anti-mycobacterial activity.

Immune-checkpoint blockade of CTLA-4 (CD152) in antigen-specific human T-cell responses differs profoundly between neonates, children, and adults

The monoclonal antibody against CTLA-4, Ipilimumab, is a first-in-class immune-checkpoint inhibitor approved for treatment of advanced melanoma in adults but not extensively studied in children. In light of the fact that the immune response early in life differs from that of adults, we have applied a human in vitro model stimulating CD4⁺ T-cells from neonates, children (1–5 years), and adults antigen-specifically with Staphylococcus aureus (S. aureus) for assessment of CTLA-4 blockade early in life. We show that T-cell proliferation as well as frequencies of antigen-specific T-cells (CD40L⁺CD4⁺) were enhanced in neonatal T-cells upon CTLA-4 blockade showing a larger variance within the group (F-test p < .0001). Using machine learning algorithm Random Forest, adult and neonatal T-cell responses can be unambiguously categorized (F1 score-0.75) on the basis of their cytokine (co-)expression. Blockade of CTLA-4 enhanced frequencies of IL-8, IFNγ, and IL-10 producers among CD40L⁺ T-cells. Of note, antigen-specific T-cells from neonates displayed higher cytokine coproduction at baseline, while T-cells from children caught up to neonates, and adults to baseline of children upon CTLA-4 blockade. These findings reveal that in neonatal T-cells blockade of CTLA-4 mainly unleashes the antigen-specific capacity by increasing the numbers of responding T-cells, whereas in children and adults it promotes the coexpression of cytokines by individual T-cells. Thus, CTLA-4 blockade boosts antitumor immunity through different mechanisms depending on the patients’ age. These data implicate a strong impact of the developmental stage of the T-cell compartment on the effects of immune-checkpoint therapy.

Metformin ameliorates scleroderma via inhibiting Th17 cells and reducing mTOR-STAT3 signaling in skin fibroblasts

Scleroderma is an autoimmune disease that causes dermal fibrosis. It occurs when collagen accumulates in tissue as a result of persistent inflammation. Th17 cells and pro-inflammatory cytokines such as IL-1β, IL-6, IL-17, and TNF-α play important roles in the pathogenesis of scleroderma. Because metformin, a medication used to treat diabetes, has effective immunoregulatory functions, we investigated its therapeutic function in scleroderma. Mice in a model of bleomycin-induced scleroderma were treated with metformin for 2 weeks. Histological assessment demonstrated protective effects of metformin against scleroderma. Metformin decreased the expression of pro-inflammatory factors in dermal tissue and lymphocytes. It also decreased mRNA expression of pro-inflammatory cytokines (IL-1β, IL-6, IL-17, and TNF-α) and fibrosis-inducing molecules both in vivo and in vitro. These results suggest that metformin treatment has anti-inflammatory effects on lymphocytes via the inhibition of IL-17 and cytokines related to Th17 differentiation, such as IL-1β, IL-6, and TNF-α. To investigate how metformin modulates the inflammatory process in skin fibroblasts, we measured mTOR-STAT3 signaling in skin fibroblasts and found that phosphorylated mTOR and phosphorylated STAT3 protein expression were decreased by metformin treatment. These results suggest that metformin has potential to treat scleroderma by inhibiting pro-inflammatory cytokines and anti-inflammatory activity mediated by mTOR-STAT3 signaling.

Genetics and Pathogenetic Role of Inflammasomes in Philadelphia Negative Chronic Myeloproliferative Neoplasms: A Narrative Review

The last decade has been very important for the quantity of preclinical information obtained regarding chronic myeloproliferative neoplasms (MPNs) and the following will be dedicated to the translational implications of the new biological acquisitions. The overcoming of the mechanistic model of clonal evolution and the entry of chronic inflammation and dysimmunity into the new model are the elements on which to base a part of future therapeutic strategies. The innate immune system plays a major role in this context. Protagonists of the initiation and regulation of many pathological aspects, from cytokine storms to fibrosis, the NLRP3 and AIM2 inflammasomes guide and condition the natural history of the disease. For this reason, MPNs share many biological and clinical aspects with non-neoplastic diseases, such as autoimmune disorders. Finally, cardiovascular risk and disturbances in iron metabolism and myelopoiesis are also closely linked to the role of inflammasomes. Although targeted therapies are already being tested, an increase in knowledge on the subject is desirable and potentially translates into better care for patients with MPNs.

The Role and Impact of Extracellular Vesicles in the Modulation and Delivery of Cytokines during Autoimmunity

Cytokines and extracellular vesicles are two methods of initiating and maintaining cellular crosstalk. The role of cytokines in the initiation, progression, and resolution of inflammation has been well studied and more so, their pathophysiological role in the development of autoimmune disease. In recent years, the impact of extracellular vesicles on the progression of autoimmunity has become more widely appreciated. In this review, we discuss the mechanisms that allow extracellular vesicles of various sources to modulate cytokine production, and release, and how extracellular vesicles might be involved in the direct delivery and modulation of cytokine levels. Moreover, we explore what challenges are faced by current therapies and the promising future for extracellular vesicles as therapeutic agents in conditions driven by immune dysregulation.

Children From the Age of Three Show a Developmental Switch in T-Cell Differentiation

Every sixth child suffers from hypertrophy of the adenoid, a secondary lymphoid organ, at least once in childhood. Little is known about the impact of pathogen-provocation vs. developmental impact on T-cell responses after 1 year of age. Therefore, developmental and infection-driven influences on the formation of T-cell-compartments and -multifunctionality in adenoids were analyzed taking into account patient's history of age and inflammatory processes. Here, we show that in adenoids of 102 infants and children similar frequencies of naïve, effector, and memory T-cells were accumulated, whereby history of suffering from subsequent infection symptoms resulted in lower frequencies of CD4⁺ and CD8⁺ T-cells co-expressing several cytokines. While patients suffering from sole nasal obstruction had balanced Th1- and Th17-compartments, Th1 dominated in patients with concomitant upper airway infections. In addition, analysis of cytokine co-expressing CD4⁺ and CD8⁺ T-cells showed that children at the age of three or older differed significantly from those being 1- or 2-years old, implicating a developmental switch in T-cell differentiation at that age. Yet, dissecting age and infectious history of the patients revealed that while CD8⁺ T-cell differentiation seems to be triggered by development, CD4⁺ T-cell functionality is partly impaired by infections. However, this functionality recovers by the age of 3 years. Thus, 3 years of age seems to be a critical period in an infant's life to develop robust T-cell compartments of higher quality. These findings identify important areas for future research and distinguish an age period in early childhood when to consider adjusting the choice of treatment of infections.

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.

miR-486 is modulated by stretch and increases ventricular growth

Perturbations in biomechanical stimuli during cardiac development contribute to congenital cardiac defects such as hypoplastic left heart syndrome (HLHS). This study sought to identify stretch-responsive pathways involved in cardiac development. miRNA-Seq identified miR-486 as being increased in cardiomyocytes exposed to cyclic stretch in vitro. The right ventricles (RVs) of patients with HLHS experienced increased stretch and had a trend toward higher miR-486 levels. Sheep RVs dilated from excessive pulmonary blood flow had 60% more miR-486 compared with control RVs. The left ventricles of newborn mice treated with miR-486 mimic were 16.9%-24.6% larger and displayed a 2.48-fold increase in cardiomyocyte proliferation. miR-486 treatment decreased FoxO1 and Smad signaling while increasing the protein levels of Stat1. Stat1 associated with Gata-4 and serum response factor (Srf), 2 key cardiac transcription factors with protein levels that increase in response to miR-486. This is the first report to our knowledge of a stretch-responsive miRNA that increases the growth of the ventricle in vivo.

The cytokine environment influence on human skin-derived T cells

Skin resident T cells provide immediate immunologic responses at their specific location and play a role in the pathogenesis of skin diseases such as psoriasis. Recently, IL-9-producing T cells were described as a major T-cell subtype present in the skin, but knowledge on the biology and in situ regulation of this T-cell subtype is scarce. Here, we investigated the cytokine influence on skin T cells with focus on IL-9-producing T cells because a better understanding of their biology may identify novel therapeutic approaches. Healthy human skin biopsies were cultured either in the presence of IL-2, IL-4, and TGF-β [T helper (T_h)9-promoting condition (T_h9-PC)] or IL-2 and IL-15 [standard condition (SC)]. Paired analysis of enzymatically isolated skin T cells and emigrated T cells after 4 wk of skin culture showed significant alterations of T-cell phenotypes, cytokine production, and IL-9-producing T-cell frequency. RNA sequencing analysis revealed differentially regulated pathways and identified CXCL8 and CXCL13 as top up-regulated genes in T_h9-PC compared with SC. Functionally supernatant of stimulated skin-derived T cells, CXCL8 and CXCL13 increased neutrophil survival. We report that the cytokine environment alters skin-derived T-cell phenotype and functional properties.-Kienzl, P., Polacek, R., Reithofer, M., Reitermaier, R., Hagenbach, P., Tajpara, P., Vierhapper, M., Gschwandtner, M., Mildner, M. Jahn-Schmid, B., Elbe-Bürger, A. The cytokine environment influence on human skin-derived T cells.

Maternal Influence and Murine Housing Confound Impact of NLRP1 Inflammasome on Microbiome Composition

The NLRP1 inflammasome attenuates inflammatory bowel disease (IBD) progression and colitis-associated tumorigenesis. A possible mechanism postulates that the lack of the NLRP1 inflammasome creates permissive niches in the gut for pathogenic bacteria to flourish, causing dysbiosis and increased IBD susceptibility. To evaluate this hypothesis, we characterized the gut microbiome of wild-type, Nlrp1b-/-, and Asc-/- mice under naïve conditions by sequencing the V3 region of the 16s rRNA gene. For both genetically modified mouse lines, the microbiome composition reflected overrepresentation of bacteria associated with dysbiosis relative to wild-type animals. Measurement of short- and medium-chain fatty acids by mass spectrometry further revealed significant differences between genotypes. However, prior to concluding that the NLRP1 inflammasome plays a role in regulating the composition of the microbiome, we evaluated two additional strategies for cohousing wild-type and Nlrp1b-/- mice: breeding homozygous parents and cohousing at weaning, and breeding from heterozygous parents and cohousing littermates. We found that maternal influence was the greater predictor of microbiome composition rather than genotype. With the rise in microbiome research across disciplines, our study should be viewed as a cautionary example that illustrates the importance of careful breeding and housing strategies when evaluating host-microbiome interactions.

Enhancement of mouse contact hypersensitivity appears with a short chain triacylglycerol but not with a long chain one

The prevalence of skin allergies could be partly due to the increased exposure to chemicals from consumer products. Chemicals that can enhance hypersensitivity caused by other chemicals are the focus of this study. We have demonstrated that phthalate esters with short chain alcohols enhance fluorescein isothiocyanate (FITC)-induced contact hypersensitivity (CHS) in a mouse model. We have also found that tributyrin, a triacylglycerol (TAG) with three butyric acids, enhances sensitization to FITC. To elucidate such an enhanced skin sensitization might be based on a general feature of TAG, we compared tributyrin and triolein, a natural TAG, as to an adjuvant effect on FITC-CHS. Triolein is the dominant TAG in olive oil and contains long chain mono-unsaturated fatty acids. Unlike tributyrin and dibutyl phthalate (DBP), triolein did not exhibit an adjuvant effect. With triolein, enhancement of FITC-presenting CD11c⁺ dendritic cell trafficking to draining lymph nodes was weak, and the activation status of DC, as revealed as CD86 expression, was low. We found a difference in the pattern of skin cytokine production, i.e., that thymic stromal lymphopoietin was produced with DBP and interleukin-1β with tributyrin. Triolein did not induce either of these cytokines. This illustrates that the adjuvant effect of tributyrin on FITC-CHS is not a general phenomenon for TAGs. Although beneficial effects may be expected through oral administration of tributyrin, the effect on skin immune systems should be considered.

Developmental induction of human T-cell responses against Candida albicans and Aspergillus fumigatus

The origin of human T-cell responses against fungal pathogens early in life is not clearly understood. Here, we show that antifungal T-cell responses are vigorously initiated within the first years of life against lysates and peptides of Candida albicans or Aspergillus fumigatus, presented by autologous monocytes. The neonatal responding T-cell pool consists of 20 different TCR-V_β families, whereas infant and adult pools display dramatically less variability. Although we demonstrate no bias for anti-fungal IL-4 expression early in life, there was a strong bias for anti-fungal IL-17 production. Of note, only T-cells from neonates and infants show an immediate co-expression of multiple cytokines. In addition, only their T-cells co-express simultaneously transcription factors T-bet and RORγt in response to fungi and subsequently their target genes IL-17 and IFNγ. Thus, T-cells of neonates and infants are predetermined to respond quickly with high plasticity to fungal pathogens, which might give an excellent opportunity for therapeutic interventions.

Targeting JAK2 reduces GVHD and xenograft rejection through regulation of T cell differentiation

Janus kinase 2 (JAK2) signal transduction is a critical mediator of the immune response. JAK2 is implicated in the onset of graft-versus-host disease (GVHD), which is a significant cause of transplant-related mortality after allogeneic hematopoietic cell transplantation (allo-HCT). Transfer of JAK2^-/- donor T cells to allogeneic recipients leads to attenuated GVHD yet maintains graft-versus-leukemia. Th1 differentiation among JAK2^-/- T cells is significantly decreased compared with wild-type controls. Conversely, iTreg and Th2 polarization is significantly increased among JAK2^-/- T cells. Pacritinib is a multikinase inhibitor with potent activity against JAK2. Pacritinib significantly reduces GVHD and xenogeneic skin graft rejection in distinct rodent models and maintains donor antitumor immunity. Moreover, pacritinib spares iTregs and polarizes Th2 responses as observed among JAK2^-/- T cells. Collectively, these data clearly identify JAK2 as a therapeutic target to control donor alloreactivity and promote iTreg responses after allo-HCT or solid organ transplantation. As such, a phase I/II acute GVHD prevention trial combining pacritinib with standard immune suppression after allo-HCT is actively being investigated (https://clinicaltrials.gov/ct2/show/NCT02891603).

Immunomodulatory Effect of Tremella Polysaccharides against Cyclophosphamide-Induced Immunosuppression in Mice

Polysaccharides are closely associated with immune regulation, but there are different polysaccharide effects from different sources. In this study, the aim was to investigate the effect of tremella polysaccharides (TP) in cyclophosphamide-induced immunodeficient mice. We observed the thymus and spleen index, liver and spleen pathological changes, and the levels of IL-2, IL-12, INF-γ, TGF-β and Ig G in serum, and we also noted the mRNA expression of IL-1β, IL-4, IL-12 and TGF-β in liver and spleen. Besides, we also measured the best effects of different doses of TP (Low-TP was 20 mg/kg·BW, Middle-TP was 40 mg/kg·BW, and High-TP was 80 mg/kg·BW) on cyclophosphamide-induced immunosuppressed mice. The results were remarkable, and suggested that TP had a significant effect for enhancing immunity in cyclophosphamide-induced immunosuppression, and the immune enhancement of High-TP had the best results in TP-treated mice. It could significantly increase the thymus and spleen index, alleviate pathological features of immunosuppression such as the arrangement of liver sinusoid and hepatic plates was disordered, massive inflammatory cells infiltrated and fatty degeneration of hepatocytes in liver, and red pulp and white pulp were intermixed, splenic corpuscles demolished and disappeared, splenic sinusoid extended, and lymphocytes of spleen were reduced in spleen. Besides, it could also up-regulate serum levels of IL-2, IL-12, INF-γ and Ig G, reduce the level of TGF-β in serum, markedly promote mRNA expression of IL-1β, IL-4 and IL-12 in liver and spleen, and suppress mRNA expression of TGF-β. Above all, TP showed preventive effect for cyclophosphamide-induced immunosuppressed mice.

The Goldilocks Conundrum: NLR Inflammasome Modulation of Gastrointestinal Inflammation during Inflammatory Bowel Disease

Recent advances have revealed significant insight into inflammatory bowel disease (IBD) pathobiology. Ulcerative colitis and Crohn's disease, the chronic relapsing clinical manifestations of IBD, are complex disorders with genetic and environmental influences. These diseases are associated with the dysregulation of immune tolerance, excessive inflammation, and damage to the epithelial cell barrier. Increasing evidence indicates that pattern recognition receptors, including Toll-like receptors (TLRs) and nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs), function to maintain immune system homeostasis, modulate the gastrointestinal microbiome, and promote proper intestinal epithelial cell regeneration and repair. New insights have revealed that NLR family members are essential components in maintaining this immune system homeostasis. To date, the vast majority of studies associated with NLRs have focused on family members that form a multiprotein signaling platform called the inflammasome. These signaling complexes are responsible for the cleavage and activation of the potent pleotropic cytokines IL-1β and IL-18, and they facilitate a unique form of cell death defined as pyroptosis. In this review, we summarize the current paradigms associated with NLR inflammasome maintenance of immune system homeostasis in the gastrointestinal system. New concepts related to canonical and noncanonical inflammasome signaling, as well as the implications of classical and alternative inflammasomes in IBD pathogenesis, are also reviewed.

Cancer cells induce interleukin-22 production from memory CD4+ T cells via interleukin-1 to promote tumor growth

IL-22 has been identified as a cancer-promoting cytokine that is secreted by infiltrating immune cells in several cancer models. We hypothesized that IL-22 regulation would occur at the interface between cancer cells and immune cells. Breast and lung cancer cells of murine and human origin induced IL-22 production from memory CD4+ T cells. In the present study, we found that IL-22 production in humans is dependent on activation of the NLRP3 inflammasome with the subsequent release of IL-1β from both myeloid and T cells. IL-1 receptor signaling via the transcription factors AhR and RORγt in T cells was necessary and sufficient for IL-22 production. In these settings, IL-1 induced IL-22 production from a mixed T helper cell population comprised of Th1, Th17, and Th22 cells, which was abrogated by the addition of anakinra. We confirmed these findings in vitro and in vivo in two murine tumor models, in primary human breast and lung cancer cells, and in deposited expression data. Relevant to ongoing clinical trials in breast cancer, we demonstrate here that the IL-1 receptor antagonist anakinra abrogates IL-22 production and reduces tumor growth in a murine breast cancer model. Thus, we describe here a previously unrecognized mechanism by which cancer cells induce IL-22 production from memory CD4+ T cells via activation of the NLRP3 inflammasome and the release of IL-1β to promote tumor growth. These findings may provide the basis for therapeutic interventions that affect IL-22 production by targeting IL-1 activity.

CD4+ T cells in atherosclerosis: Regulation by platelets

Atherosclerosis is an inflammatory and thrombotic disease, in which both CD4+ T cells and platelets play important roles throughout all stages of atherogenesis. CD4+ T cells are the most abundant T cells present in atherosclerotic lesions. They are primarily seen as type 1 T helper (Th1) cells, while the other CD4+ T cell subsets Th2, Th17, and regulatory T (Treg) cells are also found in the lesions with lower frequencies. CD4+ T effector cells release various cytokines, which exert paracrine or autocrine effects among different CD4+ T cell subsets and other lesional cells and subsequently modulate inflammatory processes in the lesions. Platelets are instrumental in thrombosis and haemostasis, but also play important regulatory roles in immune response, inflammation, and angiogenesis. The present review summarises the current knowledge and/or understanding on how platelets regulate recruitment, activation, differentiation, and cytokine production of different CD4+ T cell subsets, as well as impacts of the platelet-CD4+ T cell interactions on atherogenesis. The research perspectives of platelet-CD4+ T cell interaction in atherosclerosis are also discussed.

Identification of new CpG oligodeoxynucleotide motifs that induce expression of interleukin-1β and nitric oxide in avian macrophages

Unmethylated CpG motifs are known to stimulate mammalian toll-like receptor-9 expressing cells such as macrophages. However, the magnitude of immune-stimulation by CpG-motif can be sequence- and host-specific, implying the importance of identifying new immune-stimulatory motifs. This study aimed to determine the frequency distribution of 256 unique hexamers CpG-motifs in the Salmonella genome and to characterize their immune-stimulatory activity in avian host. We synthesized 256 CpG oligodeoxynucleotides (CpG-ODNs) each containing triplicates of a unique hexamer CpG-motif and tested their ability to induce expression of pro-inflammatory cytokine IL-1β in avian macrophages using q-RT PCR in four rounds of screening assays. CpG-ODNs that induced significantly higher IL-1β expression were also subjected to Griess assay to determine their ability to induce nitric oxide (NO) production in avian macrophages. This analysis resulted in identification of 7 CpG-ODNs that consistently induced IL-1β expression and NO production in avian macrophages at a level similar to the expression achieved using commercially available PTO-CpG-ODN 2007 and LPS derived from Salmonella. To the best of our knowledge, this is the first report showing comprehensive screening of all possible unique CpG hexamer (n=256) motifs for their ability to induce IL-1β expression and NO production in avian macrophages. We also show that the newly identified CpG-motifs with high immune-stimulatory activity are widely distributed in Salmonella genome. The CpG-ODNs identified in this study may serve as promising immunoprophylactics to potentiate innate responses in chickens against Salmonella and other infectious agents.

Gain-of-function STAT1 mutations are associated with intracranial aneurysms

Chronic mucocutaneous candidiasis, characterized by persistent or recurrent fungal infections, represents the clinical hallmark in gain-of-function (GOF) signal transducer and activator of transcription 1 (STAT1) mutation carriers. Several cases of intracranial aneurysms have been reported in patients with GOF STAT1 mutation but the paucity of reported cases likely suggested this association still as serendipity. In order to endorse this association, we link the development of intracranial aneurysms with STAT1 GOF mutation by presenting the two different cases of a patient and her mother, and demonstrate upregulated phosphorylated STAT4 and IL-12 receptor β1 upon stimulation in patient's blood cells. We also detected increased transforming growth factor (TGF)-β type 2 receptor expression, particularly in CD14⁺ cells, and a slightly higher phosphorylation rate of SMAD3. In addition, the mother of the patient developed disseminated bacille Calmette-Guérin disease after vaccination, speculating that GOF STAT1 mutations may confer a predisposition to weakly virulent mycobacteria.

Basic biology and role of interleukin-17 in immunity and inflammation

Interleukin-17 (also known as interleukin-17A) is a key cytokine that links T-cell activation to neutrophil mobilization and activation. As such, interleukin-17 can mediate protective innate immunity to pathogens or contribute to the pathogenesis of inflammatory diseases, such as psoriasis and rheumatoid arthritis. This review summarizes the basic biology of interleukin-17 and discusses its emerging role in periodontal disease. The current burden of evidence from human and animal model studies suggests that the net effect of interleukin-17 signaling promotes disease development. In addition to promoting neutrophilic inflammation, interleukin-17 has potent pro-osteoclastogenic effects that are likely to contribute to the pathogenesis of periodontitis, rheumatoid arthritis and other diseases involving bone immunopathology. Systemic treatments with anti-interleukin-17 biologics have shown promising results in clinical trials for psoriasis and rheumatoid arthritis; however, their impact on the highly prevalent periodontal disease has not been investigated or reported. Future clinical trials, preferably using locally administered interleukin-17 blockers, are required to implicate conclusivelyinterleukin-17 in periodontitis and, more importantly, to establish an effective adjunctive treatment for this oral inflammatory disease.

T Cells of Infants Are Mature, but Hyporeactive Due to Limited Ca2+ Influx

CD4 T cells in human infants and adults differ in the initiation and strength of their responses. The molecular basis for these differences is not yet understood. To address this the principle key molecular events of TCR- and CD28-induced signaling in naive CD4 T cells, such as Ca²⁺ influx, NFAT expression, phosphorylation and translocation into the nucleus, ERK activation and IL-2 response, were analyzed over at least the first 3 years of life. We report dramatically reduced IL-2 and TNFα responses in naive CD31⁺ T cells during infancy. Looking at the obligatory Ca²⁺ influx required to induce T cell activation and proliferation, we demonstrate characteristic patterns of impairment for each stage of infancy that are partly due to the differential usage of Ca²⁺ stores. Consistent with those findings, translocation of NFATc2 is limited, but still dependent on Ca²⁺ influx as demonstrated by sensitivity to cyclosporin A (CsA) treatment. Thus weak Ca²⁺ influx functions as a catalyst for the implementation of restricted IL-2 response in T cells during infancy. Our studies also define limited mobilization of Ca²⁺ ions as a characteristic property of T cells during infancy. This work adds to our understanding of infants’ poor T cell responsiveness against pathogens.

Generation and Expansion of T Helper 17 Lymphocytes Ex Vivo

CD4(+) T helper (Th) lymphocytes are essential elements of the complex cellular networks regulating the initiation, development, and termination of adaptive immune responses. Different independent and specialized subsets of Th cells can be distinguished based on their dedicated transcription factor and cytokine expression profiles. Th17 lymphocytes have been described about a decade ago as CD4(+) Th cells producing high quantity of IL-17A as a signature cytokine. Since their initial discovery, Th17 have drawn intense scrutiny for their dominant role in the pathogenesis of multiple autoimmune, infectious diseases and allergy. The influence of Th17 lymphocytes in cancer remains however ambiguous. The plethoric functions of Th17 may rely on the remarkable plasticity of these cells, endowed with the ability to trans-differentiate into other Th subpopulations depending on the environmental cytokine context. The possibility to generate Th17 ex vivo has facilitated the elucidation of the signals and transcription factors required for their differentiation and functions and has allowed for the evaluation of their functions following adoptive transfer in vivo. Several protocols have been developed to produce Th17 in vitro. The intent of this chapter is to provide examples of procedures for generating and expanding Th17 ex vivo.

Proinflammatory T cells and IL-17 stimulate osteoblast differentiation

The local immune response is important to consider when the aim is to improve bone regeneration. Recently T lymphocytes and their associated cytokines have been identified as regulators in fracture callus formation, but it is not known whether T cells affect bone progenitor cells directly. The goal of this in vitro study was to investigate the role of different T cell subsets and their secreted factors on the osteogenic differentiation of human mesenchymal stem cells (MSCs). Significant increases in the alkaline phosphatase activity and the subsequent matrix mineralization by MSCs were found after their exposure to activated T cells or activated T cell-derived conditioned medium. Blocking IFN-γ in the conditioned medium abolished its pro-osteogenic effect, while blocking TGF-β further enhanced osteogenesis. The relative contribution of an anti- or proinflammatory T cell phenotype in MSC osteogenic differentiation was studied next. Enrichment of the fraction of anti-inflammatory regulatory T cells had no beneficial osteogenic effect. In contrast, soluble factors derived from enriched T helper 17 cells upregulated the expression of osteogenic markers by MSCs. IL-17A, and IL-17F, their main proinflammatory cytokines, similarly exhibited strong osteogenic effects when exposed directly to MSCs. IL-17A in particular showed a synergistic action together with bone morphogenetic protein 2. These results indicate that individual T cell subsets, following their activation, affect osteoblast maturation in a different manner through the production of soluble factors. From all T cells, the proinflammatory T cells, including the T helper 17 cells, are most stimulatory for osteogenesis.

Differential T Cell Cytokine Receptivity and Not Signal Quality Distinguishes IL-6 and IL-10 Signaling during Th17 Differentiation

How a large number of cytokines differentially signal through a small number of signal transduction pathways is not well resolved. This is particularly true for IL-6 and IL-10, which act primarily through STAT3 yet induce dissimilar transcriptional programs leading alternatively to pro- and anti-inflammatory effects. Kinetic differences in signaling, sustained to IL-10 and transient to IL-6, are critical to this in macrophages. T cells are also key targets of IL-6 and IL-10, yet how differential signaling in these cells leads to divergent cellular fates is unclear. We show that, unlike for macrophages, signal duration cannot explain the distinct effects of these cytokines in T cells. Rather, naive, activated, activated-rested, and memory CD4(+) T cells differentially express IL-6 and IL-10 receptors in an activation state-dependent manner, and this impacts downstream cytokine effects. We show a dominant role for STAT3 in IL-6-mediated Th17 subset maturation. IL-10 cannot support Th17 differentiation because of insufficient cytokine receptivity rather than signal quality. Enforced expression of IL-10Rα on naive T cells permits an IL-10-generated STAT3 signal equivalent to that of IL-6 and equally capable of promoting Th17 formation. Similarly, naive T cell IL-10Rα expression also allows IL-10 to mimic the effects of IL-6 on both Th1/Th2 skewing and Tfh cell differentiation. Our results demonstrate a key role for the regulation of receptor expression rather than signal quality or duration in differentiating the functional outcomes of IL-6 and IL-10 signaling, and identify distinct signaling properties of these cytokines in T cells compared with myeloid cells.

Peripheral and Hepatic Vein Cytokine Levels in Correlation with Non-Alcoholic Fatty Liver Disease (NAFLD)-Related Metabolic, Histological, and Haemodynamic Features

BACKGROUND

Haemodynamic impairment, inflammatory mediators and glucose metabolism disturbances have been implicated in the pathogenesis of Non-Alcoholic Fatty Liver Disease (NAFLD).

AIM

To investigate the cytokine profile in NAFLD patients in peripheral (P) and hepatic venous (HV) blood and to compare with histology, haemodynamic and metabolic parameters.

METHODS

40 obese patients with an indication for a transjugular liver biopsy were enrolled. Besides an extended liver and metabolic work-up, interleukin (IL) 1B, IL4, IL6, IL10, IL23, tumour necrosis factor (TNF) α and interferon (INF) γ were measured in plasma obtained from P and HV blood by means of multiplex immunoassay. The T helper (Th)1/Th2, the macrophage M1/M2 and the IL10/IL17a ratios were calculated.

RESULTS

A decrease of the P-IL10/IL17-ratio and an increase of the P-M1/M2-ratio (p<0.05) were observed in NASH versus no-NASH patients. A P-M1/M2-ratio increase was detected also in patients with portal hypertension in comparison with patients without it (p<0.05). Moreover diabetic patients showed an increase of the P-Th1/Th2-ratio in comparison with non-diabetic ones (p<0.05). The P-M1/M2 ratio positively correlated with steatosis grade (r = 0.39, p = 0.02) and insulin (r = 0.47, p = 0.003). The HV-M1/M2 ratio positively correlated with fasting insulin and Hepatic Venous Pressure Gradient (r = 0.47, p = 0.003). IL6 correlated with the visceral fat amount (r = 0.36, p = 0.02). The P- and HV-IL10/IL17 ratios negatively correlated with fasting insulin (respectively r = -0.4, p = 0.005 and r = 0.4, p = 0.01).

CONCLUSIONS

A proinflammatory cytokine state is associated with more disturbed metabolic, histological, and haemodynamic features in NAFLD obese patients. An increase of the M1/M2 ratio and a decrease of the IL10/IL17 ratio play a key role in this process.

FTY720 (fingolimod) treatment tips the balance towards less immunogenic antigen-presenting cells in patients with multiple sclerosis

OBJECTIVE

We aimed to clarify whether fingolimod has direct effects on antigen-presenting cells in multiple sclerosis patients.

METHODS

Frequency and phenotype of directly ex vivo dendritic cells and monocytes were analyzed in 43 individuals, including fingolimod-treated and untreated multiple sclerosis patients as well as healthy subjects. These cells were further stimulated with lipopolysaccharide to determine functional effects of fingolimod treatment.

RESULTS

Absolute numbers of CD1c+ dendritic cells and monocytes were not significantly reduced in fingolimod-treated patients indicating that fingolimod did not block the migration of antigen-presenting cells to peripheral blood. CD86 was upregulated on CD1c+ dendritic cells and thus their activation was not impaired under fingolimod treatment. Quantitative analyses of gene transcription in cells and protein content in supernatants from ex vivo CD1c+ dendritic cells and monocytes, however, showed lower secretion of TNFα, IL1-β and IL-6 upon lipopolysaccharide-stimulation. These results could be matched with CD4+MOG-specific transgenic T cells exhibiting reduced levels of TNFα and IFN-γ but not IL-4 upon stimulation with murine dendritic cells loaded with MOG, when treated with fingolimod.

CONCLUSIONS

Our data indicate that fingolimod - apart from trapping lymphocytes in lymph nodes - exerts its disease-modulating activity by rebalancing the immune tolerance networks by modulation of antigen-presenting cells.

Immune regulators of inflammation in obesity-associated type 2 diabetes and coronary artery disease

PURPOSE OF REVIEW

To summarize current work identifying inflammatory components that underlie associations between obesity-associated type 2 diabetes and coronary artery disease.

RECENT FINDINGS

Recent studies implicate immune cells as drivers of pathogenic inflammation in human type 2 diabetes. Inflammatory lymphocytes characterize unhealthy adipose tissue, but regional adipose volume, primarily visceral and pericardial fat, also predict severity and risk for obesity-associated coronary artery disease. Having a greater understanding of shared characteristics between inflammatory cells from different adipose tissue depots and a more accessible tissue, such as blood, will facilitate progress toward clinical translation of our appreciation of obesity as an inflammatory disease.

SUMMARY

Obesity predisposes inflammation and metabolic dysfunction through multiple mechanisms, but these mechanisms remain understudied in humans. Studies of obese patients have identified disproportionate impacts of specific T cell subsets in metabolic diseases like type 2 diabetes. On the basis of demonstration that adipose tissue inflammation is depot-specific, analysis of adiposity by waist-to-hip ratio or MRI will increase interpretive value of lymphocyte-focused studies and aid clinicians in determining which obese individuals are at highest risk for coronary artery disease. New tools to combat obesity-associated coronary artery disease and other comorbidities will stem from identification of immune cell-mediated inflammatory networks that are amenable to pharmacological interventions.

CD4+ T cells from human neonates and infants are poised spontaneously to run a nonclassical IL-4 program

Senescence or biological aging impacts a vast variety of molecular and cellular processes. To date, it is unknown whether CD4(+) Th cells display an age-dependent bias for development into specific subpopulations. In this study, we show the appearance of a distinct CD4(+) T cell subset expressing IL-4 at an early stage of development in infant adenoids and cord blood that is lost during aging. We identified by flow cytometric, fluorescent microscopic, immunoblot, and mass spectrometric analysis a population of CD4(+) T cells that expressed an unglycosylated isoform of IL-4. This T cell subpopulation was found in neonatal but not in adult CD4(+) T cells. Furthermore, we show that the mRNA of the Th2 master transcription factor GATA3 is preferentially expressed in neonatal CD4(+) T cells. The Th2 phenotype of the IL-4(+)CD4(+) T cells could be reinforced in the presence of TGF-β. Although the IL-4(+)CD4(+) T cells most likely originate from CD31(+)CD4(+) T recent thymic emigrants, CD31 was downregulated prior to secretion of IL-4. Notably, the secretion of IL-4 requires a so far unidentified trigger in neonatal T cells. This emphasizes that cytokine expression and secretion are differentially regulated processes. Our data support the hypothesis of an endogenously poised cytokine profile in neonates and suggest a link between cytokine production and the developmental stage of an organism. The determination of the IL-4 isoform-expressing cells in humans might allow the identification of Th2 precursor cells, which could provide novel intervention strategies directed against Th2-driven immunopathologies such as allergies.

IL-17A in hepatitis B infection: friend or foe?

Hepatitis B virus (HBV) is one of the most prevalent and infectious agents that leads to liver disease in humans. Five clinical forms of HBV infection exist, including fulminant, acute, chronic, asymptomatic and occult. The chronic, asymptomatic and occult forms are long-term infections that can lead to hepatocellular carcinoma (HCC) and liver cirrhosis. The mechanisms responsible for progression of these forms of the infection to HCC and liver cirrhosis are not yet clearly understood or characterised. However, genetic and immunological parameters may play important roles in the disease. IL-17A is an important cytokine involved in early immune responses against fungal and bacterial infections, but its role in the response against viral infections is yet to be fully clarified. The crucial roles of IL-17A in the pathogenesis of autoimmune and destructive immune-related diseases have been documented and may provide insights into its functions during hepatitis infection. Therefore, the aim of this review was to address the recent information regarding the status and association of IL-17A during hepatitis B infection and its related disorders, including HCC and liver cirrhosis.

Boswellic acids reduce Th17 differentiation via blockade of IL-1β-mediated IRAK1 signaling

Interferon-gamma producing CD4(+) T (Th1) cells and IL-17-producing CD4(+) T (Th17) cells are involved in the pathogenesis of several autoimmune diseases including multiple sclerosis. Therefore, the development of treatment strategies controlling the generation and expansion of these effector cells is of high interest. Frankincense, the resin from trees of the genus Boswellia, and particularly its prominent bioactive compound acetyl-11-keto-β-boswellic acid (AKBA), have potent anti-inflammatory properties. Here, we demonstrate that AKBA is able to reduce the differentiation of human CD4(+) T cells to Th17 cells, while slightly increasing Th2- and Treg-cell differentiation. Furthermore, AKBA reduces the IL-1β-triggered IL-17A release of memory Th17 cells. AKBA may affect IL-1β signaling by preventing IL-1 receptor-associated kinase 1 phosphorylation and subsequently decreasing STAT3 phosphorylation at Ser727, which is required for Th17-cell differentiation. The effects of AKBA on Th17 differentiation and IL-17A release make the compound a good candidate for potential treatment of Th17-driven diseases.

The multifaceted role of Th17 lymphocytes and their associated cytokines in cancer

While the role of T helper 17 lymphocytes (Th17) in the pathogenesis of autoimmune diseases and in infectious immunity has been relatively well defined, the impact of these cells and their associated cytokines on cancer development is still under debate. Although multiple reports have indicated that Th17 can promote anticancer immunity, others have argued that these cells may exhibit tumor-promoting properties. This dichotomy in the function of Th17 lymphocytes in cancer may be related to the versatile nature of these cells, being capable of differentiating into either proinflammatory Th1 or suppressive FoxP3-expressing Treg cells or hybrid T cell subsets depending on the underlying environmental conditions. In the current review, we examine the role of Th17 lymphocytes and Th17-associated cytokines in cancer and discuss how factors that control their final lineage commitment decision may influence the balance between their tumor-promoting versus tumor-suppressing properties.

Immune privilege as an intrinsic CNS property: astrocytes protect the CNS against T-cell-mediated neuroinflammation

Astrocytes have many functions in the central nervous system (CNS). They support differentiation and homeostasis of neurons and influence synaptic activity. They are responsible for formation of the blood-brain barrier (BBB) and make up the glia limitans. Here, we review their contribution to neuroimmune interactions and in particular to those induced by the invasion of activated T cells. We discuss the mechanisms by which astrocytes regulate pro- and anti-inflammatory aspects of T-cell responses within the CNS. Depending on the microenvironment, they may become potent antigen-presenting cells for T cells and they may contribute to inflammatory processes. They are also able to abrogate or reprogram T-cell responses by inducing apoptosis or secreting inhibitory mediators. We consider apparently contradictory functions of astrocytes in health and disease, particularly in their interaction with lymphocytes, which may either aggravate or suppress neuroinflammation.

Regulation of IL-17A production is distinct from IL-17F in a primary human cell co-culture model of T cell-mediated B cell activation

Improper regulation of B cell responses leads to excessive production of antibodies and contributes to the development of autoimmune disease. T helper 17 (Th17) cells also drive the development of autoimmune disease, but the role of B cells in shaping Th17 cell-mediated immune responses, as well as the reciprocal regulation of B cell responses by IL-17 family cytokines, remains unclear. The aim of this study was to characterize the regulation of IL-17A and IL-17F in a model of T cell-dependent B cell activation. Stimulation of primary human B cell and peripheral blood mononuclear cell (BT) co-cultures with α-IgM and a non-mitogenic concentration of superantigens for three days promoted a Th17 cell response as evidenced by increased expression of Th17-related gene transcripts, including Il17f, Il21, Il22, and Il23r, in CD4 T cells, as well as the secretion of IL-17A and IL-17F protein. We tested the ability of 144 pharmacologic modulators representing 91 different targets or pathways to regulate IL-17A and IL-17F production in these stimulated BT co-cultures. IL-17A production was found to be preferentially sensitive to inhibition of the PI3K/mTOR pathway, while prostaglandin EP receptor agonists, including PGE2, increased IL-17A concentrations. In contrast, the production of IL-17F was inhibited by PGE2, but selectively increased by TLR2 and TLR5 agonists. These results indicate that IL-17A regulation is distinct from IL-17F in stimulated BT co-cultures and that this co-culture approach can be used to identify pathway mechanisms and novel agents that selectively inhibit production of IL-17A or IL-17F.

Age-related differences in the expression of circulating microRNAs: miR-21 as a new circulating marker of inflammaging

Circulating microRNAs (miRs) have been investigated as diagnostic/prognostic biomarkers in human diseases. However, little is known about their expression throughout the aging process. Eleven healthy individuals aged 20, 80 and 100 years underwent miR plasma profiling. The validation cohort consisted of 111 healthy adults (CTR) aged 20-105 years and included 30 centenarians. In addition, 34 patients with cardiovascular disease (CVD) and 15 healthy centenarian offspring (CO) were enrolled. An exploratory factorial analysis grouped the miRs into three main factors: factor 1 primarily higher in 20-year-old subjects, but these differences did not reach statistical significance, factor 2 primarily higher in octogenarians and factor 3 primarily higher in centenarians. MiR-21, the most highly expressed miR of factors 2 and 3, was further validated, confirming the differences in the age groups. MiR-21 expression was higher in the CVD patients and lower in the CO compared to the age-matched CTR. MiR-21 was correlated with C-reactive protein and fibrinogen levels. TGF-β signaling was the predicted common pathway targeted by miRs of factors 2 and 3. TGF-βR2 mRNA, a validated miR-21 target, showed the highest expression in the leukocytes from a subset of the octogenarians. Our findings suggest that miR-21 may be a new biomarker of inflammation.

The periprosthetic capsule and connective tissue diseases: a piece in the puzzle of autoimmune/autoinflammatory syndrome induced by adjuvants

Breast prostheses have been criticized for being responsible for triggering systemic autoimmune disease. The presence of breast implants causes a natural foreign body reaction characterized by the infiltration of macrophages and T-cells. Using PubMed, Medline and eMedicine, we performed a systematic literature review on the stages of periprosthetic capsule formation and cells involved in order to understand which immunological pathways could be responsible for giving rise to, and the development of, connective tissue disease such as systemic sclerosis. We focused on the relationship between tissue growth factor- β, interleukin (IL)-1, IL-6 and T helper 17 or T regulatory cells, as well as on their effects on the different steps of capsular tissue formation. A disturbance in the modulation of these key cytokines may be responsible, in susceptible individuals, for a perpetuation of the inflammatory reaction which can locally lead to capsular contracture and at the systemic level may contribute to triggering autoimmune diseases.