PRC2 Regulated Atoh8 Is a Regulator of Intestinal Microfold Cell (M Cell) Differentiation.

Intestinal microfold cells (M cells) are a dynamic lineage of epithelial cells that initiate mucosal immunity in the intestine. They are responsible for the uptake and transcytosis of microorganisms, pathogens, and other antigens in the gastrointestinal tract. A mature M cell expresses a receptor Gp2 which binds to pathogens and aids in the uptake. Due to the rarity of these cells in the intestine, their development and differentiation remain yet to be fully understood. We recently demonstrated that polycomb repressive complex 2 (PRC2) is an epigenetic regulator of M cell development, and 12 novel transcription factors including Atoh8 were revealed to be regulated by the PRC2. Here, we show that Atoh8 acts as a regulator of M cell differentiation; the absence of Atoh8 led to a significant increase in the number of Gp2+ mature M cells and other M cell-associated markers such as Spi-B and Sox8. In vitro organoid analysis of RankL treated organoid showed an increase of mature marker GP2 expression and other M cell-associated markers. Atoh8 null mice showed an increase in transcytosis capacity of luminal antigens. An increase in M cell population has been previously reported to be detrimental to mucosal immunity because some pathogens like orally acquired prions have been able to exploit the transcytosis capacity of M cells to infect the host; mice with an increased population of M cells are also susceptible to Salmonella infections. Our study here demonstrates that PRC2 regulated Atoh8 is one of the factors that regulate the population density of intestinal M cell in the Peyer's patch.

A 1-year follow-up study on immunological changes following deep brain stimulation in patients with epilepsy.

The aim of this study was to evaluate the effects of deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS) on systemic inflammatory responses in patients with drug-resistant epilepsy (DRE). Twenty-two Finnish patients with ANT-DBS implantation were enrolled in this pilot study. Changes in plasma interleukin-6 (IL-6) and interleukin-10 (IL-10) levels were examined using generalized estimating equation models at seven time points (before DBS surgery and 1, 2, 3, 6, 9 and 12 months after implantation). In the whole group, the IL-6/IL-10 ratio decreased significantly over time following ANT-DBS, while the decrease in IL-6 levels and increase in IL-10 levels were not significant. In the responder and nonresponder groups, IL-6 levels remained unchanged during the follow-up. Responders had significantly lower pre-DBS IL-10 levels before the ANT-DBS treatment than nonresponders, but the levels significantly increased over time after the treatment. In addition, responders had a higher pre-DBS IL-6/IL-10 ratio than nonresponders, and the ratio decreased for both groups after treatment, but the decrease did not reach the level of statistical significance. The rate of decrease in the ratio per month tended to be higher in responders than in nonresponders. These results may highlight the anti-inflammatory properties of ANT-DBS treatment associated with its therapeutic effectiveness in patients with DRE. Additional studies are essential to evaluate the potential of the proinflammatory cytokine IL-6, the anti-inflammatory cytokine IL-10, and their ratio as biomarkers to evaluate the therapeutic response to DBS treatment, which could facilitate treatment optimization.

Proprotein convertase subtilisin/kexin type 9 regulates the production of acute-phase reactants from the liver.

BACKGROUND & AIMS: Proprotein convertase subtilisin/kexin type 9 (PCSK9) controls blood cholesterol levels by fostering the LDL receptor (LDLR) degradation in hepatocytes. Additionally, PCSK9 has been suggested to participate in immunoregulation by modulating cytokine production. We studied the immunological role of PCSK9 in Streptococcus pneumoniae bacteraemia in vivo and in a human hepatocyte cell line. METHODS: CRISPR/Cas9 mutagenesis was utilized to create pcsk9 knock-out (KO) zebrafish, which were infected with S pneumoniae to assess the role of PCSK9 for the survival of the fish and in the transcriptomic response of the liver. The direct effects of PCSK9 on the expression of acute-phase reaction (APR) genes were studied in HepG2 cells. RESULTS: The pcsk9 KO zebrafish lines (pcsk9tpu-13 and pcsk9tpu-2,+15 ) did not show developmental defects or gross phenotypical differences. In the S pneumoniae infected zebrafish, the mortality of pcsk9 KOs was similar to the controls. A liver-specific gene expression analysis revealed that a pneumococcal challenge upregulated pcsk9, and that the pcsk9 deletion reduced the expression of APR genes, including hepcidin antimicrobial peptide (hamp) and complement component 7b (c7b). Accordingly, silencing PCSK9 in vitro in HepG2 cells using small interfering RNAs (siRNAs) decreased HAMP expression. CONCLUSIONS: We demonstrate that PCSK9 is not critical for zebrafish survival in a systemic pneumococcal infection. However, PCSK9 deficiency was associated with the lower expression of APR genes in zebrafish and altered the expression of innate immunity genes in a human hepatocyte cell line. Overall, our data suggest an evolutionarily conserved function for PCSK9 in APR in the liver.

Identification of Novel Genetic Regulatory Region for Proprotein Convertase FURIN and Interferon Gamma in T Cells.

The proprotein convertase enzyme FURIN promotes the proteolytic maturation of pro-proteins and thereby it serves as an important factor for maintaining cellular homeostasis. In T cells, FURIN is critical for maintaining the T regulatory cell dependent peripheral immune tolerance and intact T helper cell polarization. The enzymatic activity of FURIN is directly associated with its expression levels, but genetic determinants for cell-type specific Furin gene regulation have remained elusive. By exploring the histone acetyltransferase p300 binding patterns in T helper cells, a putative regulatory region at ca. 20kB upstream of Furin gene was identified. When this region was deleted with CRISPR/Cas9 the production of Furin mRNA was significantly reduced in activated mouse T cells. Genome-wide RNA profiling by sequencing revealed that the novel Furin regulator region also impacted the expression of several genes that have previously been associated with the Th1 type hall mark cytokine IFNγ regulation or function. Finally, Furin genetic regulatory region was found to specifically promote the secretion of IFNγ by activated T cells. In sum, our data unravels the presence of Furin expression regulatory region in T cells that has characteristics of a super-enhancer for Th1 cell fate.

Modular vaccine platform based on the norovirus-like particle.

BACKGROUND: Virus-like particle (VLP) vaccines have recently emerged as a safe and effective alternative to conventional vaccine technologies. The strong immunogenic effects of VLPs can be harnessed for making vaccines against any pathogen by decorating VLPs with antigens from the pathogen. Producing the antigenic pathogen fragments and the VLP platform separately makes vaccine development rapid and convenient. Here we decorated the norovirus-like particle with two conserved influenza antigens and tested for the immunogenicity of the vaccine candidates in BALB/c mice. RESULTS: SpyTagged noro-VLP was expressed with high efficiency in insect cells and purified using industrially scalable methods. Like the native noro-VLP, SpyTagged noro-VLP is stable for months when refrigerated in a physiological buffer. The conserved influenza antigens were produced separately as SpyCatcher fusions in E. coli before covalent conjugation on the surface of noro-VLP. The noro-VLP had a high adjuvant effect, inducing high titers of antibody production against the antigens presented on its surface. CONCLUSIONS: The modular noro-VLP vaccine platform presented here offers a rapid, convenient and safe method to present various soluble protein antigens to the immune system for vaccination and antibody production purposes.

Safety and efficacy of AMG 714 in adults with coeliac disease exposed to gluten challenge: a phase 2a, randomised, double-blind, placebo-controlled study.

BACKGROUND: Interleukin 15 (IL-15) is implicated in the pathophysiology of coeliac disease. AMG 714 is the first anti-IL-15 monoclonal antibody to be investigated for the treatment of coeliac disease. We aimed to investigate the effects of AMG 714 in patients with coeliac disease who underwent gluten challenge. METHODS: This randomised, double-blind, placebo-controlled, parallel-group, phase 2a trial was done at three clinical sites in Finland. Inclusion criteria included age 18-80 years, a confirmed diagnosis of coeliac disease, and adherence to a gluten-free diet for at least 12 months before screening. Patients were randomly assigned (1:1:1) to 150 mg AMG 714, 300 mg AMG 714, or placebo using permuted blocks and stratified by study site and sex. Patients and study staff were masked to treatment assignment. Treatments were administered by two subcutaneous injections every 2 weeks for 10 weeks (total six doses). Patients without severe villous atrophy at baseline received a gluten challenge (2-4 g daily) during weeks 2-12. Small bowel biopsy samples were obtained for histological assessments at baseline and week 12. The primary efficacy endpoint was the percentage change from baseline to week 12 in villous height-to-crypt depth (VHCD) ratio. Secondary endpoints were CD3-positive intraepithelial lymphocyte density; clinical symptoms measured by gastrointestinal symptom rating scale (GSRS), coeliac disease GSRS, and Bristol stool form scale (BSFS); and changes in anti-tTG and anti-DGP antibodies from baseline. The primary analysis was done in the per-protocol 1 population of patients who received at least one dose of study drug and who underwent the gluten challenge. Safety analyses were done in all patients who received at least one dose of study drug. This trial is registered at ClinicalTrials.gov, NCT02637141 and EudraCT, 2015-003647-19. FINDINGS: Between April 13, 2016, and Nov 22, 2016, 64 patients were enrolled and randomly assigned to either the 150 mg AMG 714 group (n=22), the 300 mg AMG 714 group (n=22), or the placebo group (n=20). Two patients did not start treatment and two did not provide post-treatment biopsy samples. 49 patients underwent the gluten challenge (per-protocol 1 population) and 11 patients did not because of baseline villous atrophy. AMG 714 did not prevent mucosal injury due to gluten challenge. The least square mean difference in the relative change from baseline in VHCD ratio was -2·49% (95% CI -16·82 to 11·83; p=0·73) between 150 mg AMG 714 and placebo and 6·39% (-7·07 to 19·85; p=0·34) between 300 mg AMG 714 and placebo. Neither comparison was statistically significant. The density of CD3-positive intraepithelial lymphocytes increased in all groups, with smaller increases in the 300 mg group (-41·24% [95% CI -79·28 to -3·20] vs placebo, nominal p=0·03) but not the 150 mg group (-14·32% [-54·39 to 25·74], nominal p=0·47). Clinical symptoms were ameliorated with AMG 714 treatment between baseline and week 12, particularly diarrhoea as measured by the BSFS (nominal p=0·01 for 150 mg vs placebo, and nominal p=0·0002 for 300 mg vs placebo). Serum antibody titres for anti-tTG and anti-DGP antibodies increased in all three treatment groups, with no significant difference between AMG 714 and placebo. Treatment-emergent adverse events occurred in 21 (95%) patients in the 150 mg AMG 714 group, 0 (95%) in the 300 mg AMG 714 group, and 19 (100%) in the placebo group. The most common treatment-emergent adverse events were gastrointestinal disorders (17 [77%] participants in the 150 mg AMG 714 group, 16 [76%] in the 300 mg AMG 714 group, and 13 [68%] in the placebo group). Injection site reactions were the most common individual adverse event, reported in eight (36%) patients in the 150 mg AMG 714 group, 11 (52%) in the 300 mg group, and five (26%) in the placebo group. No serious adverse events occurred. INTERPRETATION: The primary endpoint, change in VHCD ratio from baseline after 12 weeks of treatment in patients with coeliac disease undergoing gluten challenge, was not significantly different between placebo and AMG 714 at either 150 mg or 300 mg. Effects on intraepithelial lymphocyte density and symptoms suggest that further research of AMG 714 may be warranted in patients with non-responsive coeliac disease. FUNDING: Celimmune and Amgen.

Intelectin 3 is dispensable for resistance against a mycobacterial infection in zebrafish (Danio rerio).

Tuberculosis is a multifactorial bacterial disease, which can be modeled in the zebrafish (Danio rerio). Abdominal cavity infection with Mycobacterium marinum, a close relative of Mycobacterium tuberculosis, leads to a granulomatous disease in adult zebrafish, which replicates the different phases of human tuberculosis, including primary infection, latency and spontaneous reactivation. Here, we have carried out a transcriptional analysis of zebrafish challenged with low-dose of M. marinum, and identified intelectin 3 (itln3) among the highly up-regulated genes. In order to clarify the in vivo significance of Itln3 in immunity, we created nonsense itln3 mutant zebrafish by CRISPR/Cas9 mutagenesis and analyzed the outcome of M. marinum infection in both zebrafish embryos and adult fish. The lack of functional itln3 did not affect survival or the mycobacterial burden in the zebrafish. Furthermore, embryonic survival was not affected when another mycobacterial challenge responsive intelectin, itln1, was silenced using morpholinos either in the WT or itln3 mutant fish. In addition, M. marinum infection in dexamethasone-treated adult zebrafish, which have lowered lymphocyte counts, resulted in similar bacterial burden in both WT fish and homozygous itln3 mutants. Collectively, although itln3 expression is induced upon M. marinum infection in zebrafish, it is dispensable for protective mycobacterial immune response.

Chemical-Induced Skin Carcinogenesis Model Using Dimethylbenz[a]Anthracene and 12-O-Tetradecanoyl Phorbol-13-Acetate (DMBA-TPA).

Cancer is one of the most devastating human diseases. Experimental cancer models are important to gain insight into the complex interplay of different cell types and genes in promoting tumor progression and to provide a platform for testing the efficacy of different therapeutic approaches. One of the most commonly used experimental inflammatory cancer models is the DMBA-TPA two-stage skin carcinogenesis model. Tumor formation is induced in this model by the topical application of two different chemicals, 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoyl phorbol-13-acetate (TPA), that together cause papilloma formation in the skin. As the primary outcome is papilloma formation in the skin, the model is an ideal, reliable, and reproducible way to address both tumor initiation (tumor-free survival) and tumor progression (number and size of visible tumors). The effects of the DMBA-TPA treatment are transmitted via an inflammatory mechanism, which makes this model especially suitable for studying the role of the immune system in tumor formation. However, this model is restricted to the skin and other surfaces where the chemicals can be applied on. A detailed protocol is provided in this article to use the model successfully.

Furin deficiency in myeloid cells leads to attenuated revascularization in a mouse-model of oxygen-induced retinopathy.

Ischemic retinopathy is a vision-threatening disease associated with chronic retinal inflammation and hypoxia leading to abnormal angiogenesis. Furin, a member of the proprotein convertase family of proteins, has been implicated in the regulation of angiogenesis due to its essential role in the activation of several angiogenic growth factors, including vascular endothelial growth factor-C (VEGF-C), VEGF-D and transforming growth factor - ß (TGF- ß). In the present study, we evaluated expression of furin in the retina and its role in retinal angiogenesis. As both inflammation and hypoxia contribute to angiogenesis, the role of furin was evaluated using myeloid-cell specific furin knockout (KO) mice (designated LysMCre-fur(fl/fl)) both in developmental retinal angiogenesis as well as in hypoxia-driven angiogenesis using the oxygen-induced retinopathy (OIR) model. In the retina, furin expression was detected in endothelial cells, macrophages and, to some extent, in neurons. The rate of angiogenesis was not different in LysMCre-fur(fl/fl) mice when compared to their wild-type littermates during development. In the OIR model, the revascularization of retina was significantly delayed in LysMCre-fur(fl/fl) mice compared to their wild-type littermates, while there was no compensatory increase in the preretinal neovascularization in LysMCre-fur(fl/fl) mice. These results demonstrate that furin expression in myeloid cells plays a significant role in hypoxia-induced angiogenesis in retina.

Myeloid cell expressed proprotein convertase FURIN attenuates inflammation.

The proprotein convertase enzyme FURIN processes immature pro-proteins into functional end- products. FURIN is upregulated in activated immune cells and it regulates T-cell dependent peripheral tolerance and the Th1/Th2 balance. FURIN also promotes the infectivity of pathogens by activating bacterial toxins and by processing viral proteins. Here, we evaluated the role of FURIN in LysM+ myeloid cells in vivo. Mice with a conditional deletion of FURIN in their myeloid cells (LysMCre-fur(fl/fl)) were healthy and showed unchanged proportions of neutrophils and macrophages. Instead, LysMCre-fur(fl/fl) mice had elevated serum IL-1ß levels and reduced numbers of splenocytes. An LPS injection resulted in accelerated mortality, elevated serum pro-inflammatory cytokines and upregulated numbers of pro-inflammatory macrophages. A genome-wide gene expression analysis revealed the overexpression of several pro-inflammatory genes in resting FURIN-deficient macrophages. Moreover, FURIN inhibited Nos2 and promoted the expression of Arg1, which implies that FURIN regulates the M1/M2-type macrophage balance. FURIN was required for the normal production of the bioactive TGF-ß1 cytokine, but it inhibited the maturation of the inflammation-provoking TACE and Caspase-1 enzymes. In conclusion, FURIN has an anti-inflammatory function in LysM+ myeloid cells in vivo.

[Innate lymphoid cells - a new group of immune cells]. / Luontaiset Iymfosyytit - uusi immuunisoluryhmä.

A new group of immune cells, innate lymphoid cells, i.e. ILC cells has recently been identified in the territory between the cells of innate and acquired immunity. While the understanding of their functioning and grouping still remains incomplete, their importance in defending the interfaces of the body seems clear. The central role of ILC cells is to sense danger signals in the body and modify immune responses on the basis of this information. In addition to understanding of the defense response, future research. on ILC cells is expected to provide information about the mechanisms of autoimmunity and allergic inflammation as well as disorders of immunity associated with cancer and obesity.

The Inflammatory Phenotype in Failed Metal-On-Metal Hip Arthroplasty Correlates with Blood Metal Concentrations.

INTRODUCTION: Hip arthroplasty is the standard treatment of a painful hip destruction. The use of modern metal-on-metal (MOM) bearing surfaces gained popularity in total hip arthroplasties during the last decade. Recently, worrisome failures due to adverse reaction to metal debris (ARMD), including pseudotumor response, have been widely reported. However, the pathogenesis of this reaction remains poorly understood. The aim of the present study was to investigate the ARMD response by flow cytometry approach. METHODS: Sixteen patients with a failed Articular Surface Replacement (ASR) hip prosthesis were included in the study. Samples of pseudotumor tissues collected during revision surgery were degraded by enzyme digestion and cells were typed by flow cytometry. Whole blood chromium and cobalt concentrations were analyzed with mass spectrometry before revision surgery. RESULTS: Flow cytometry analysis showed that the peri-implant pseudotumor tissue expressed two principal phenotypes, namely macrophage-dominated and T-lymphocyte-dominated response; the average portions being 54% (macrophages) and 25% (T-lymphocytes) in macrophage-dominated inflammation and 20% (macrophages) and 54% (T-lymphocytes) in T-lymphocyte-dominated response. The percentages of B-lymphocytes and granulocytes were lower in both phenotypes. Interestingly, the levels of blood chromium and cobalt were significantly higher in patients with macrophage-dominated response. CONCLUSIONS: The results suggest that the adverse tissue reactions induced by MOM wear particles contain heterogeneous pathogeneses and that the metal levels are an important factor in the determination of the inflammatory phenotype. The present results support the hypothesis that higher metal levels cause cytotoxicity and tissue injury and macrophages are recruited to clear the necrotic debris. On the other hand, the adverse response developed in association with lower metal levels is T-lymphocyte-dominated and is likely to reflect hypersensitivity reaction.

T-cell-expressed proprotein convertase FURIN inhibits DMBA/TPA-induced skin cancer development.

Proprotein convertases (PCSK) have a critical role in the body homeostasis as enzymes responsible for processing precursor proteins into their mature forms. FURIN, the first characterized member of the mammalian PCSK family, is overexpressed in multiple malignancies and the inhibition of its activity has been considered potential cancer treatment. FURIN has also an important function in the adaptive immunity, since its deficiency in T cells causes an impaired peripheral immune tolerance and accelerates immune responses. We addressed whether deleting FURIN from the immune cells would strengthen anticancer responses by subjecting mouse strains lacking FURIN from either T cells or macrophages and granulocytes to the DMBA/TPA two-stage skin carcinogenesis protocol. Unexpectedly, deficiency of FURIN in T cells resulted in enhanced and accelerated development of tumors, whereas FURIN deletion in macrophages and granulocytes had no effect. The epidermises of T-cell-specific FURIN deficient mice were significantly thicker with more proliferating Ki67+ cells. In contrast, there were no differences in the numbers of the T cells. The flow cytometric analyses of T-cell populations in skin draining lymph nodes showed that FURIN T-cell KO mice have an inherent upregulation of early activation marker CD69 as well as more CD4+CD25+Foxp3+ positive T regulatory cells. In the early phase of tumor promotion, T cells from the T-cell-specific FURIN knockout animals produced more interferon gamma, whereas at later stage the production of Th2- and Th17-type cytokines was more prominent than in wild-type controls. In conclusion, while PCSK inhibitors are promising therapeutics in cancer treatment, our results show that inhibiting FURIN specifically in T cells may promote squamous skin cancer development.

Regulation of Inflammatory Cytokine Production by MKP-5 in Macrophages.

Mitogen-activated protein kinases (MAPKs) include p38 MAPKs, c-Jun N-terminal kinases (JNKs) and Extracellular signal-regulated kinases (ERKs), and they regulate many cell processes, such as cell division, differentiation and release of inflammatory mediators. MAPK activity is controlled by mitogen-activated protein kinase phosphatases (MKPs), a phosphatase family with 11 members. MKP-1 is the most studied member of MKP family, and it is one of the anti-inflammatory factors induced by glucocorticoids. Less is known about the other MAPK phosphatases although they hold a promise as anti-inflammatory drug targets. In this study, we investigated the effect of MKP-5 on MAPK phosphorylation and cytokine production in J774 mouse macrophages. We used MKP-5 siRNA and an MKP-5 inhibitor (AS077234-4) to modulate MKP-5 function. We found that MKP-5 controlled p38 MAPK phosphorylation, but not that of JNK or ERK. In addition, the production of IL-6 and TNF was suppressed by MKP-5 in macrophages. Our results introduce a novel concept that compounds able to enhance MKP-5 expression and/or activity hold anti-inflammatory potential, because MKP-5 down-regulates the release of inflammatory mediators by controlling p38 MAPK activity.

The proprotein convertase subtilisin/kexin furinA regulates zebrafish host response against Mycobacterium marinum.

Tuberculosis is a chronic bacterial disease with a complex pathogenesis. An effective immunity against Mycobacterium tuberculosis requires both the innate and adaptive immune responses, including proper T helper (Th) type 1 cell function. FURIN is a proprotein convertase subtilisin/kexin (PCSK) enzyme, which is highly expressed in Th1 type cells. FURIN expression in T cells is essential for maintaining peripheral immune tolerance, but its role in the innate immunity and infections has remained elusive. Here, we utilized Mycobacterium marinum infection models in zebrafish (Danio rerio) to investigate how furin regulates host responses against mycobacteria. In steady-state furinAtd204e/+ fish reduced furinA mRNA levels associated with low granulocyte counts and elevated Th cell transcription factor expressions. Silencing furin genes reduced the survival of M. marinum-infected zebrafish embryos. A mycobacterial infection upregulated furinA in adult zebrafish, and infected furinAtd204e/+ mutants exhibited a proinflammatory phenotype characterized by elevated tumor necrosis factor a (tnfa), lymphotoxin alpha (lta) and interleukin 17a/f3 (il17a/f3) expression levels. The enhanced innate immune response in the furinAtd204e/+ mutants correlated with a significantly decreased bacterial burden in a chronic M. marinum infection model. Our data show that upregulated furinA expression can serve as a marker for mycobacterial disease, since it inhibits early host responses and consequently promotes bacterial growth in a chronic infection.

Therapeutic targeting of the Jak/STAT pathway.

Antibodies that block cytokine function provide a powerful therapeutic tool especially for the treatment of autoimmune diseases. Cytokines are a group of small hydrophilic glycoproteins that bind their receptors on the cell surface and subsequently activate intracellular signalling cascades, such as the JAK/STAT pathway. A bulk of evidence has demonstrated that genetic mutations in signalling molecules can cause immunodeficiencies and malignant cell growth. As a result, several drug companies have begun to develop therapeutics that inhibit the function of JAK tyrosine kinases. Currently, two JAK inhibitors, tofacitinib and ruxolitinib, are used in the clinic for treating rheumatoid arthritis and myeloproliferative diseases, respectively. Inhibiting JAK function has been shown to efficiently prevent the uncontrolled growth of cancerous cells and to harness overly active immune cells. In the future, other small molecule compounds are likely to come into clinical use, and intense work is ongoing to develop inhibitors that specifically target the constitutively active mutant JAKs. This MiniReview will summarize the basic features of the JAK/STAT pathway, its role in human disease and the therapeutic potential of JAK/STAT inhibitors.

S-layer protein mediates the stimulatory effect of Lactobacillus helveticus MIMLh5 on innate immunity.

The ability to positively affect host health through the modulation of the immune response is a feature of increasing importance in measuring the probiotic potential of a bacterial strain. However, the identities of the bacterial cell components involved in cross talk with immune cells remain elusive. In this study, we characterized the dairy strain Lactobacillus helveticus MIMLh5 and its surface-layer protein (SlpA) using in vitro and ex vivo analyses. We found that MIMLh5 and SlpA exert anti-inflammatory effects by reducing the activation of NF-κB on the intestinal epithelial Caco-2 cell line. On the contrary, MIMLh5 and SlpA act as stimulators of the innate immune system by triggering the expression of proinflammatory factors tumor necrosis factor alpha and COX-2 in the human macrophage cell line U937 via recognition through Toll-like receptor 2. In the same experiments, SlpA protein did not affect the expression of the anti-inflammatory cytokine interleukin-10. A similar response was observed following stimulation of macrophages isolated from mouse bone marrow or the peritoneal cavity. These results suggest that SlpA plays a major role in mediating bacterial immune-stimulating activity, which could help to induce the host's defenses against and responses toward infections. This study supports the concept that the viability of bacterial cells is not always essential to exert immunomodulatory effects, thus permitting the development of safer therapies for the treatment of specific diseases according to a paraprobiotic intervention.

Mycobacterium marinum causes a latent infection that can be reactivated by gamma irradiation in adult zebrafish.

The mechanisms leading to latency and reactivation of human tuberculosis are still unclear, mainly due to the lack of standardized animal models for latent mycobacterial infection. In this longitudinal study of the progression of a mycobacterial disease in adult zebrafish, we show that an experimental intraperitoneal infection with a low dose (≈ 35 bacteria) of Mycobacterium marinum, results in the development of a latent disease in most individuals. The infection is characterized by limited mortality (25%), stable bacterial loads 4 weeks following infection and constant numbers of highly organized granulomas in few target organs. The majority of bacteria are dormant during a latent mycobacterial infection in zebrafish, and can be activated by resuscitation promoting factor ex vivo. In 5-10% of tuberculosis cases in humans, the disease is reactivated usually as a consequence of immune suppression. In our model, we are able to show that reactivation can be efficiently induced in infected zebrafish by γ-irradiation that transiently depletes granulo/monocyte and lymphocyte pools, as determined by flow cytometry. This immunosuppression causes reactivation of the dormant mycobacterial population and a rapid outgrowth of bacteria, leading to 88% mortality in four weeks. In this study, the adult zebrafish presents itself as a unique non-mammalian vertebrate model for studying the development of latency, regulation of mycobacterial dormancy, as well as reactivation of latent or subclinical tuberculosis. The possibilities for screening for host and pathogen factors affecting the disease progression, and identifying novel therapeutic agents and vaccine targets make this established model especially attractive.

JAK Kinases in Health and Disease: An Update.

Janus kinases (Jaks) are critical signaling elements for a large subset of cytokines. As a consequence they play pivotal roles in the patho-physiology of many diseases including neoplastic and autoimmune diseases. Small molecule Jak inhibitors as therapeutic agents have become a reality and the palette of such inhibitors will likely expand. This review will summarize our current knowledge on these key enzymes and their associated pharmaceutical inhibitors.