Th17 cells and tissue remodeling in atopic and contact dermatitis

BACKGROUND: Eczematous skin lesions of atopic dermatitis (AD) as well as allergic and irritant contact dermatitis (ACD, ICD) are characterized by the same typical clinical signs, although due to different causes. In both AD and ACD, the presence of T helper 17 cells which play an important role in host defense, has been reported. Furthermore, IL-17 is involved in tissue repair and remodeling. This study aimed to investigate IL-17 expression in acute eczematous skin lesions and correlate it with markers of remodeling in AD, ACD, and ICD. METHODS: Skin specimens were taken from positive patch test reactions to aeroallergens, contact allergens, and irritants at days 2, 3, and 4. Inflammatory cells as well as the expression of cytokines and extracellular matrix proteins were evaluated by immunofluorescence staining and confocal microscopy. RESULTS: Allergic contact dermatitis and ICD were characterized by IFN-γ expression, whereas in AD lesions, IL-13 expression and high numbers of eosinophils were the prominent phenotype. Expression of IL-17, but also IL-21 and IL-22, was observed in all eczema subtypes. The number of IL-22+ T cells correlated with the number of eosinophils. Markers of remodeling such as MMP-9, procollagen-3, and tenascin C were observed in all acute eczematous lesions, while a correlation of IL-17+ T cell numbers with tenascin C-expressing cells and MMP-9+ eosinophils was apparent. CONCLUSION: The expression of IL-17 and related cytokines, such as IL-22, was demonstrated in acute eczematous lesions independent of their pathogenesis. Our results suggest a potential role for IL-17 in remodeling of the skin.

Cerebrospinal-fluid cytokine and chemokine profile in patients with pneumococcal and meningococcal meningitis

BACKGROUND Bacterial meningitis is characterized by an intense inflammatory reaction contributing to neuronal damage. The aim of this study was to obtain a comparative analysis of cytokines and chemokines in patients with pneumococcal (PM) and meningococcal meningitis (MM) considering that a clear difference between the immune response induced by these pathogens remains unclear. METHODS The cyto/chemokines, IL-1beta, IL-2, IL-6, TNF-alpha, IFN-gamma, IL-10, IL-1Ra, CXCL8/IL-8, CCL2/MCP-1, CLL3/MIP-1alpha, CCL4/MIP-1gamma and G-CSF, were measured in cerebrospinal fluid (CSF) samples from patients with PM and MM. Additionally, a literature review about the expression of cytokines in CSF samples of patients with MB was made. RESULTS Concerning cytokines levels, only IFN-gamma was significantly higher in patients with Streptococcus pneumoniae compared to those with Neisseria meningitidis, regardless of the time when the lumbar puncture (LP) was made. Furthermore, when samples were compared considering the timing of the LP, higher levels of TNF-alpha (P <0.05) were observed in MM patients whose LP was made within 48 h from the initial symptoms of disease. We also observed that the index of release of cyto/chemokines per cell was significantly higher in PM. From the literature review, it was observed that TNF-alpha, IL-1beta and IL-6 are the best studied cytokines, while reports describing the concentration of the cytokine IL-2, IL-1Ra, G-CSF and CCL4/MIP-1beta in CSF samples of patients with bacterial meningitis were not found. CONCLUSION The data obtained in this study and the previously published data show a similar profile of cytokine expression during PM and MM. Nevertheless, the high levels of IFN-gamma and the ability to release high levels of cytokines with a low number of cells are important factors to be considered in the pathogenesis of PM and thereby should be further investigated. Moreover, differences in the early response induced by the pathogens were observed. However, the differences observed are not sufficient to trigger changes in the current therapy of corticosteroids adopted in both the PM and MM.

The causative pathogen determines the inflammatory profile in cerebrospinal fluid and outcome in patients with bacterial meningitis

BACKGROUND The brain's inflammatory response to the infecting pathogen determines the outcome of bacterial meningitis (BM), for example, the associated mortality and the extent of brain injury. The inflammatory cascade is initiated by the presence of bacteria in the cerebrospinal fluid (CSF) activating resident immune cells and leading to the influx of blood derived leukocytes. To elucidate the pathomechanisms behind the observed difference in outcome between different pathogens, we compared the inflammatory profile in the CSF of patients with BM caused by Streptococcus pneumonia (n = 14), Neisseria meningitidis (n = 22), and Haemophilus influenza (n = 9). METHODS CSF inflammatory parameters, including cytokines and chemokines, MMP-9, and nitric oxide synthase activity, were assessed in a cohort of patients with BM from Burkina Faso. RESULTS Pneumococcal meningitis was associated with significantly higher CSF concentrations of IFN-γ , MCP-1, and the matrix-metalloproteinase (MMP-) 9. In patients with a fatal outcome, levels of TNF-α, IL-1 β, IL-1RA, IL-6, and TGF-α were significantly higher. CONCLUSION The signature of pro- and anti-inflammatory mediators and the intensity of inflammatory processes in CSF are determined by the bacterial pathogen causing bacterial meningitis with pneumococcal meningitis being associated with a higher case fatality rate than meningitis caused by N. meningitidis or H. influenzae.

Differential effects of interferon-gamma and tumor necrosis factor-alpha on Toxoplasma gondii proliferation in organotypic rat brain slice cultures.

Organotypic slice culture explants of rat cortical tissue infected with Toxoplasma gondii tachyzoites were applied as an in vitro model to investigate host-pathogen interactions in cerebral toxoplasmosis. The kinetics of parasite proliferation and the effects of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in infected organotypic cultures were monitored by light microscopy, transmission electron microscopy (TEM), and quantitative polymerase chain reaction (PCR) assay. As assessed by the loss of the structural integrity of the glial fibrillary acidic protein-intermediate filament network, tachyzoites infected and proliferated mainly within astrocytes, whereas neurons and microglia remained largely unaffected. Toxoplasma gondii proliferation was severely inhibited by IFN-y. However, this inhibition was not linked to tachyzoite-to-bradyzoite stage conversion. In contrast, TNF-alpha treatment resulted in a dramatically enhanced proliferation rate of the parasite. The cellular integrity in IFN-gamma-treated organotypic slice cultures was severely impaired compared with untreated and TNF-alpha-treated cultures. Thus, on infection of organotypic neuronal cultures, IFN-gamma and TNF-alpha exhibit largely detrimental effects, which could contribute to either inhibition or acceleration of parasite proliferation during cerebral toxoplasmosis.

Infection of organotypic slice cultures from rat central nervous tissue with Neospora caninum: an alternative approach to study host-parasite interactions

Neospora caninum is an apicomplexan parasite which has emerged as an important cause of bovine abortion worldwide. Abortion is usually triggered by reactivation of dormant bradyzoites during pregnancy and subsequent congenital infection of the foetus, where the central nervous system appears to be most frequently affected. We here report on an organotypic tissue culture model for Neospora infection which can be used to study certain aspects of the cerebral phase of neosporosis within the context of a three-dimensionally organised neuronal network. Organotypic slice cultures of rat cortical tissue were infected with N. caninum tachyzoites, and the kinetics of parasite proliferation, as well as the proliferation-inhibitory effect of interferon-gamma (IFN-gamma), were monitored by either immunofluorescence, transmission electron microscopy, and a quantitative PCR-assay using the LightCycler instrument, respectively. In addition, the neuronal cytoskeletal elements, namely glial acidic protein filaments as well as actin microfilament bundles were shown to be largely colocalising with the pseudocyst periphery. This organotypic culture model for cerebral neosporosis provides a system, which is useful to study the proliferation, ultrastructural characteristics, development, and the interactions of N. caninum within the context of neuronal tissue, which at the same time can be modulated and influenced under controlled conditions, and will be useful in the future to gain more information on the cerebral phase of neosporosis.

Matrix metalloproteinases: multifunctional effectors of inflammation in multiple sclerosis and bacterial meningitis

Matrix metalloproteinases (MMPs) are a family of Zn2+-dependent endopeptidases targeting extracellular matrix (ECM) compounds as well as a number of other proteins. Their proteolytic activity acts as an effector mechanism of tissue remodeling in physiologic and pathologic conditions, and as modulator of inflammation. In the context of neuro-inflammatory diseases, MMPs have been implicated in processes such as (a) blood-brain barrier (BBB) and blood-nerve barrier opening, (b) invasion of neural tissue by blood-derived immune cells, (c) shedding of cytokines and cytokine receptors, and (d) direct cellular damage in diseases of the peripheral and central nervous system. This review focuses on the role of MMPs in multiple sclerosis (MS) and bacterial meningitis (BM), two neuro-inflammatory diseases where current therapeutic approaches are insufficient to prevent severe disability in the majority of patients. Inhibition of enzymatic activity may prevent MMP-mediated neuronal damage due to an overactive or deviated immune response in both diseases. Downregulation of MMP release may be the molecular basis for the beneficial effect of IFN-beta and steroids in MS. Instead, synthetic MMP inhibitors offer the possibility to shut off enzymatic activity of already activated MMPs. In animal models of MS and BM, they efficiently attenuated clinical disease symptoms and prevented brain damage due to excessive metalloproteinase activity. However, the required target profile for the therapeutic use of this novel group of compounds in human disease is not yet sufficiently defined and may be different depending on the type and stage of disease. Currently available MMP inhibitors show little target-specificity within the MMP family and may lead to side-effects due to interference with physiological functions of MMPs. Results from human MS and BM indicate that only a restricted number of MMPs specific for each disease is up-regulated. MMP inhibitors with selective target profiles offer the possibility of a more efficient therapy of MS and BM and may enter clinical trials in the near future.

Genetic susceptibility to increased bacterial translocation influences the response to biological therapy in patients with Crohn's disease

OBJECTIVE: The aetiology of Crohn's disease (CD) has been related to nucleotide-binding oligomerisation domain containing 2 (NOD2) and ATG16L1 gene variants. The observation of bacterial DNA translocation in patients with CD led us to hypothesise that this process may be facilitated in patients with NOD2/ATG16L1-variant genotypes, affecting the efficacy of anti-tumour necrosis factor (TNF) therapies. DESIGN: 179 patients with Crohn's disease were included. CD-related NOD2 and ATG16L1 variants were genotyped. Phagocytic and bactericidal activities were evaluated in blood neutrophils. Bacterial DNA, TNFα, IFNγ, IL-12p40, free serum infliximab/adalimumab levels and antidrug antibodies were measured. RESULTS: Bacterial DNA was found in 44% of patients with active disease versus 23% of patients with remitting disease (p=0.01). A NOD2-variant or ATG16L1-variant genotype was associated with bacterial DNA presence (OR 4.8; 95% CI 1.1 to 13.2; p=0.001; and OR 2.4; 95% CI 1.4 to 4.7; p=0.01, respectively). This OR was 12.6 (95% CI 4.2 to 37.8; p=0.001) for patients with a double-variant genotype. Bacterial DNA was associated with disease activity (OR 2.6; 95% CI 1.3 to 5.4; p=0.005). Single and double-gene variants were not associated with disease activity (p=0.19). Patients with a NOD2-variant genotype showed decreased phagocytic and bactericidal activities in blood neutrophils, increased TNFα levels in response to bacterial DNA and decreased trough levels of free anti-TNFα. The proportion of patients on an intensified biological therapy was significantly higher in the NOD2-variant groups. CONCLUSIONS: Our results characterise a subgroup of patients with CD who may require a more aggressive therapy to reduce the extent of inflammation and the risk of relapse

IL28B expression depends on a novel TT/-G polymorphism which improves HCV clearance prediction

Approximately 3% of the world population is chronically infected with the hepatitis C virus (HCV), with potential development of cirrhosis and hepatocellular carcinoma. Despite the availability of new antiviral agents, treatment remains suboptimal. Genome-wide association studies (GWAS) identified rs12979860, a polymorphism nearby IL28B, as an important predictor of HCV clearance. We report the identification of a novel TT/-G polymorphism in the CpG region upstream of IL28B, which is a better predictor of HCV clearance than rs12979860. By using peripheral blood mononuclear cells (PBMCs) from individuals carrying different allelic combinations of the TT/-G and rs12979860 polymorphisms, we show that induction of IL28B and IFN-γ–inducible protein 10 (IP-10) mRNA relies on TT/-G, but not rs12979860, making TT/-G the only functional variant identified so far. This novel step in understanding the genetic regulation of IL28B may have important implications for clinical practice, as the use of TT/G genotyping instead of rs12979860 would improve patient management.

Influences of porcine circo-, arteriviruses and cathelicidins in plasmacytoid dendritic cell-derived interferon-alpha responses

Type I interferons (IFNs), mainly IFN-α/β play a crucial role in innate defense against viruses. In addition to their direct antiviral activity, type I IFNs have antitumoral and immunomodulatory effects. Although all cells are virtually able to induce IFN-α, the plasmacytoid dendritic cell (pDC) subset represents the ultimate producers of IFN-α as well as other proinflammatory cytokines. Due to the specific expression of TLR7 and TLR9 recognizing single-stranded (ss) RNA and unmethylated CpG motifs respectively, pDCs can secrete up to 1000 times more IFN-α than any cellular types. Additionally, it is well known that several cytokines including type I and II IFNs, Flt3-L, IL-4 and GM-CSF favor pDC-derived IFN-α responses to unmethylated CpG motifs. In a first step, we aimed to characterize and clarify the interactions of two porcine viruses with pDCs. The double-stranded DNA replicative forms of porcine circovirus type 2 (PCV2) were demonstrated to inhibit CpG-induced IFN- α by pDCs. Our study showed that none of the cytokines known to enhance pDC responsiveness can counter-regulate the PCV2-mediated inhibition of IFN-α induced by CpG, albeit IFN-γ significantly reduced the level of inhibition. Interestingly, the presence of IFN-γ enabled pDCs to induce IFN-α to low doses of PCV2. We also noted that after DNase treatment, PCV2 preparations were still able to stimulate pDCs. These data suggest that encapsulated viral ssDNA promotes the induction of IFN-α in pDCs treated with IFN-γ whereas free DNA, presumably as double-stranded forms, was responsible for inhibiting pDC responses. Regarding PRRSV, it has been reported that North American isolates did not induce and even inhibited IFN-α response in pDCs. However, PRRSV infection was also shown to lead to an induction of IFN-α in the serum and in the lungs suggesting that certain cells are responsive to the virus. Contrasting to previous reports we found that numerous PRRSV isolates directly induced IFN-α in pDCs. This response was still observed after UV-inactivation of viruses and required TLR7 signaling. The inhibition of CpG-induced IFN-α was weak and strain dependent, again contrasting with a previous report. We also observed that IFN-γ and IL-4 enhanced IFN-α response to two prototype strains, VR-2332 and LVP23. In summary, we demonstrated that both PCV2 and PRRSV promote IFN-α secretion in pDCs in vitro suggesting that IFN-α detected in PCV2- or PRRSV-infected animal might originate from pDCs. On the other hand, PRRSV replication is restricted to the macrophage (MΦ) lineage. These innate immune cells represent a heterogeneous population which can be induce to “classical” (M1) and “alternative” (M2) activated MΦ acquiring inflammatory or “wound-healing” functional properties, respectively. Nonetheless, little is known about the effect of polarization into M1 or M2 and the susceptibility of these cells to PRRSV. Thus, we examined the impact of cytokine on MΦ polarization into M1 or M2. Infections of these cells by several PRRSV isolates enabled the discrimination of PRRSV isolate in a genotype- and irulencedependent manner in M1 and IFN-β-activated MΦ. In contrast, the expression of PRRSV nucleocapsid in M2 or inactivated MΦ was indistinguishable among the PRRSV isolates tested. In the last part of my Thesis, we investigated the influence of three synthetic porcine cathelicidin peptides for their ability to deliver nucleic acid to pDCs. We reported that all cathelicidins tested can complex and quickly deliver nucleic acids resulting in IFN-α induction. Moreover, we show that the typical α- helical amphipathic conformation is required to mediate killing of bacteria but not for inducing IFN-α secretion by pDCs. Furthermore, we found that E.coli treated with one of these cathelicidins is able to induce significantly higher levels of IFN-α compared to a non-sense version of the peptide. These data suggest that cathelicidins could influence the immune response in a two-step process. First, these peptides target bacteria leading to cell lysis. In turn, cathelicidins form complexes and deliver extracellular microbial nucleic acids released into pDCs. These pDC-derived IFN-α responses could be of particular relevance in driving the adaptive immune responses against microbial infections.

Dominance of chemokine ligand 2 and matrix metalloproteinase-2 and -9 and suppression of pro-inflammatory cytokines in the epidural compartment after intervertebral disc extrusion in a canine model

BACKGROUND CONTEXT In canine intervertebral disc (IVD) disease, a useful animal model, only little is known about the inflammatory response in the epidural space. PURPOSE To determine messenger RNA (mRNA) expressions of selected cytokines, chemokines, and matrix metalloproteinases (MMPs) qualitatively and semiquantitatively over the course of the disease and to correlate results to neurologic status and outcome. STUDY DESIGN/SETTING Prospective study using extruded IVD material of dogs with thoracolumbar IVD extrusion. PATIENT SAMPLE Seventy affected and 13 control (24 samples) dogs. OUTCOME MEASURES Duration of neurologic signs, pretreatment, neurologic grade, severity of pain, and outcome were recorded. After diagnostic imaging, decompressive surgery was performed. METHODS Messenger RNA expressions of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF), interferon (IFN)γ, MMP-2, MMP-9, chemokine ligand (CCL)2, CCL3, and three housekeeping genes was determined in the collected epidural material by Panomics 2.0 QuantiGene Plex technology. Relative mRNA expression and fold changes were calculated. Relative mRNA expression was correlated statistically to clinical parameters. RESULTS Fold changes of TNF, IL-1β, IL-2, IL-4, IL-6, IL-10, IFNγ, and CCL3 were clearly downregulated in all stages of the disease. MMP-9 was downregulated in the acute stage and upregulated in the subacute and chronic phase. Interleukin-8 was upregulated in acute cases. MMP-2 showed mild and CCL2 strong upregulation over the whole course of the disease. In dogs with severe pain, CCL3 and IFNγ were significantly higher compared with dogs without pain (p=.017/.020). Dogs pretreated with nonsteroidal anti-inflammatory drugs revealed significantly lower mRNA expression of IL-8 (p=.017). CONCLUSIONS The high CCL2 levels and upregulated MMPs combined with downregulated T-cell cytokines and suppressed pro-inflammatory genes in extruded canine disc material indicate that the epidural reaction is dominated by infiltrating monocytes differentiating into macrophages with tissue remodeling functions. These results will help to understand the pathogenic processes representing the basis for novel therapeutic approaches. The canine IVD disease model will be rewarding in this process.

Effect of synthetic agonists of toll-like receptor 9 on canine lymphocyte proliferation and cytokine production in vitro.

Synthetic agonists of TLR9 containing novel DNA structures and R'pG (wherein R=1-(2'-deoxy-beta-d-ribofuranosyl)-2-oxo-7-deaza-8-methyl-purine) motifs, referred to as immune modulatory oligonucleotides (IMOs), have been shown to stimulate T(H)-1-type-immune responses and potently reverse allergen-induced T(H)-2 responses to T(H)-1 responses in vitro and in vivo in mice. In order to investigate the immunomodulatory potential of IMOs in dogs, canine peripheral blood mononuclear cells (PBMC) from healthy dogs were stimulated with three different IMOs and a control IMO, alone or in combination with concanavalin A (ConA). Lipopolysaccharide (LPS) was used as a positive control for B lymphocyte activation. Carboxyfluorescein diacetate succinimidyl ester and phenotype staining was used to tag proliferating T and B lymphocytes (CD5(+) and CD21(+)) by flow cytometry. Real-time PCR and ELISA were processed to assay cytokine production of IFN-gamma, IL-10, TGF-beta, IL-6 and IL-10. Like LPS, IMOs alone induced neither proliferation of CD5(+) T cells nor CD21(+) B cells, but both LPS and IMO had the capacity to co-stimulate ConA and induced proliferation of B cells. In combination with ConA, one of the IMOs (IMO1) also induced proliferation of T cells. IMO1 also significantly enhanced the expression of IFN-gamma on the mRNA and protein level in canine PBMC, whereas expression of IL-10, TGF-beta and IL-4 mRNAs was not induced by any of the IMOs. These results indicate that in canine PBMC from healthy dogs, IMO1 was able to induce a T(H)-1 immune response including T- and B-cell proliferation.

Role of MicroRNA Modulation in the Interferon-α/Ribavirin Suppression of HIV-1 In Vivo.

BACKGROUND Interferon-α (IFN-α) treatment suppresses HIV-1 viremia and reduces the size of the HIV-1 latent reservoir. Therefore, investigation of the molecular and immunologic effects of IFN-α may provide insights that contribute to the development of novel prophylactic, therapeutic and curative strategies for HIV-1 infection. In this study, we hypothesized that microRNAs (miRNAs) contribute to the IFN-α-mediated suppression of HIV-1. To inform the development of novel miRNA-based antiretroviral strategies, we investigated the effects of exogenous IFN-α treatment on global miRNA expression profile, HIV-1 viremia, and potential regulatory networks between miRNAs and cell-intrinsic anti-HIV-1 host factors in vivo. METHODS Global miRNA expression was examined in longitudinal PBMC samples obtained from seven HIV/HCV-coinfected, antiretroviral therapy-naïve individuals before, during, and after pegylated interferon-α/ribavirin therapy (IFN-α/RBV). We implemented novel hybrid computational-empirical approaches to characterize regulatory networks between miRNAs and anti-HIV-1 host restriction factors. RESULTS miR-422a was the only miRNA significantly modulated by IFN-α/RBV in vivo (p<0.0001, paired t test; FDR<0.037). Our interactome mapping revealed extensive regulatory involvement of miR-422a in p53-dependent apoptotic and pyroptotic pathways. Based on sequence homology and inverse expression relationships, 29 unique miRNAs may regulate anti-HIV-1 restriction factor expression in vivo. CONCLUSIONS The specific reduction of miR-422a is associated with exogenous IFN-α treatment, and likely contributes to the IFN-α suppression of HIV-1 through the enhancement of anti-HIV-1 restriction factor expression and regulation of genes involved in programmed cell death. Moreover, our regulatory network analysis presents additional candidate miRNAs that may be targeted to enhance anti-HIV-1 restriction factor expression in vivo.

TGF-βRI kinase activity mediates Emdogain-stimulated in vitro osteoclastogenesis.

OBJECTIVES Emdogain, containing an extract of fetal porcine enamel matrix proteins, is a potent stimulator of in vitro osteoclastogenesis. The underlying molecular mechanisms are, however, unclear. MATERIAL AND METHODS Here, we have addressed the role of transforming growth factor-beta receptor type 1 (TGF-βRI) kinase activity on osteoclastogenesis in murine bone marrow cultures. RESULTS Inhibition of TGF-βRI kinase activity with SB431542 abolished the effect of Emdogain on osteoclastogenesis induced by receptor activator of nuclear factor kappa-B ligand or tumor necrosis factor-alpha. SB431542 also suppressed the Emdogain-mediated increase of OSCAR, a co-stimulatory protein, and dendritic cell-specific transmembrane protein and Atp6v0d2, the latter two being involved in cell fusion. Similar to transforming growth factor-beta1 (TGF-β), Emdogain could not compensate for the inhibition of IL-4 and IFNγ on osteoclast formation. When using the murine macrophage cell line RAW246.7, SB431542 and the smad-3 inhibitor SIS3 blocked Emdogain-stimulated expression of the transcription factor NFATc1. CONCLUSIONS Taken together, the data suggest that TGF-βRI kinase activity is necessary to mediate in vitro effects of Emdogain on osteoclastogenesis. CLINICAL RELEVANCE Based on these in vitro data, we can speculate that at least part of the clinical effects of Emdogain on osteoclastogenesis is mediated via TGF-β signaling.

Hypoxic treatment of human dual placental perfusion induces a preeclampsia-like inflammatory response.

Preeclampsia is a human pregnancy-specific disorder characterized by a placental pro-inflammatory response in combination with an imbalance of angiogenic factors and clinical symptoms, including hypertension and proteinuria. Insufficient uteroplacental oxygenation in preeclampsia due to impaired trophoblast invasion during placentation is believed to be responsible for many of the molecular events leading to the clinical manifestations of this disease. We investigated the use of hypoxic treatment of the dual placental perfusion system as a model for preeclampsia. A modified perfusion technique allowed us to achieve a mean soluble oxygen tension within the intervillous space (IVS) of 5-7% for normoxia and <3% for hypoxia (as a model for preeclampsia). We assayed for the levels of different inflammatory cytokines, oxidative stress markers, as well as other factors, such as endothelin (ET)-1 that are known to be implicated as part of the inflammatory response in preeclampsia. Our results show a significant increase under hypoxia in the levels of different inflammatory cytokines, including IL-6 (P=0.002), IL-8 (P<0.0001), TNF-α (P=0.032) and IFN-γ (P=0.009) at 360 min in maternal venous samples (n=6). There was also a significant increase in ET-1 levels under hypoxia both on the maternal side at 30 min (P=0.003) and fetal side at 360 min (P=0.036) (n=6). Other markers of oxidative stress, including malondialdehyde and 8-iso-protaglandin F2α (P=0.009) also show increased levels. Overall, these findings indicate that exposure of ex vivo dually perfused placental tissue to hypoxia provides a useful model for mimicking the inflammatory response characteristic of preeclampsia. This would therefore provide a powerful tool for studying and further delineating the molecular mechanisms involved in the underlying pathophysiology of preeclampsia.

Cytotoxic CD8+ T cells stimulate hematopoietic progenitors by promoting cytokine release from bone marrow mesenchymal stromal cells.

Cytotoxic CD8(+) T cells (CTLs) play a major role in host defense against intracellular pathogens, but a complete clearance of pathogens and return to homeostasis requires the regulated interplay of the innate and acquired immune systems. Here, we show that interferon γ (IFNγ) secreted by effector CTLs stimulates hematopoiesis at the level of early multipotent hematopoietic progenitor cells and induces myeloid differentiation. IFNγ did not primarily affect hematopoietic stem or progenitor cells directly. Instead, it promoted the release of hematopoietic cytokines, including interleukin 6 from bone marrow mesenchymal stromal cells (MSCs) in the hematopoietic stem cell niche, which in turn reduced the expression of the transcription factors Runx-1 and Cebpα in early hematopoietic progenitor cells and increased myeloid differentiation. Therefore, our study indicates that, during an acute viral infection, CTLs indirectly modulate early multipotent hematopoietic progenitors via MSCs in order to trigger the temporary activation of emergency myelopoiesis and promote clearance of the infection.