Positive Francisella tularensis meningitis outcome despite delayed identification: a case report

Francisella tularensis is a Gram-negative bacteria, that may cause a zoonotic disease, tularemia. Here, we describe a patient case, where a previously healthy young woman in Northern Finland contacted health care because of fever and headache. Due to the symptoms and lack of further diagnostic tools in primary health care, she was transferred to University Hospital (UH) where ampicillin and ceftriaxone was given empirically. A cerebrospinal fluid sample (CSF) was drawn showing small Gram-negative rods that grew on chocolate agar after 2 days of incubation. Matrix-assisted laser-desorption-ionization time of-flight (Maldi-tof) did not provide identification, but the bacteria was interpreted as sensitive to ciprofloxacin and the treatment was changed to ciprofloxacin. During the time the patient was infected, there were several positive tularemia samples found in the area. Therefore, an in house tularemia nucleic acid method (PCR) was used on the bacterial culture. Additionally, 16S rDNA sequencing was performed and these methods identified the bacteria as F. tularensis. Fortunately, the patient recovered completely with ciprofloxacin and was discharged without any complications. Our case underlines the need to understand the limits of specific diagnostic methods, such as Maldi-tof, used in clinical laboratory settings. It also highlights the need of both clinicians and laboratory staff to be aware of the many clinical presentations of tularemia when working in an endemic area.

Comparison of the effect of autoclaved and non-autoclaved live soil exposure on the mouse immune system : Effect of soil exposure on immune system

BACKGROUND

. Lack of exposure to the natural microbial diversity of the environment has been linked to dysregulation of the immune system and numerous noncommunicable diseases, such as allergies and autoimmune disorders. Our previous studies suggest that contact with soil material, rich in naturally occurring microbes, could have a beneficial immunoregulatory impact on the immune system in mice and humans. However, differences in the immunomodulatory properties of autoclaved, sterile soil material and non-autoclaved, live soil material have not been compared earlier.

RESULTS

. In this study, we exposed C57BL/6 mice to autoclaved and live soil powders that had the same rich microbiota before autoclaving. We studied the effect of the soil powders on the mouse immune system by analyzing different immune cell populations, gene expression in the gut, mesenteric lymph nodes and lung, and serum cytokines. Both autoclaved and live soil exposure were associated with changes in the immune system. The exposure to autoclaved soil resulted in higher levels of Rorγt, Inos and Foxp3 expression in the colon. The exposure to live soil was associated with elevated IFN-γ concentration in the serum. In the mesenteric lymph node, exposure to live soil reduced Gata3 and Foxp3 expression, increased the percentage of CD8 + T cells and the expression of activation marker CD80 in XCR1+SIRPα- migratory conventional dendritic cell 1 subset.

CONCLUSIONS

. Our results indicate that exposure to the live and autoclaved soil powders is not toxic for mice. Exposure to live soil powder slightly skews the immune system towards type 1 direction which might be beneficial for inhibiting type 2-related inflammation. Further studies are warranted to quantify the impact of this exposure in experimental type 2 inflammation.

Low IL-13Rα1 Expression on Mast Cells Tunes Them Unresponsive to IL-13

Cytokine-mediated mast cell regulation enables precise optimization of their own pro-inflammatory cytokine production. During allergic inflammation, Interleukin(IL)-4 regulates mast cell functions, tissue-homing and proliferation, but the direct role of closely related IL-13 for mast cell activation remains unclear. Previous work has shown that mast cells are potent IL-13 producers, but here we show that mouse mast cells do not directly respond to IL-13 by Stat6 activation, as they do not express measurable amount of IL-13Rα1 mRNA. Consequently, IL-4 responses are mediated via type I IL-4R (IL-4/IL4Rα/γC) and IL-4-induced Stat6 activation is abolished in γC deficient mast cells. Type II IL-4R deficiency (IL-13Rα1 KO) has no effect on IL-4-induced Stat6 activation. In basophils, both IL-4 and IL-13 induce Stat6 activation in WT and γC deficient cells, while in type II IL-4R deficient basophils IL-4 signaling is impaired at low ligand concentration. Thus, mast cell and basophil sensitivity to IL-4/IL-13 is different and in mast cells, lack of IL-13Rα1 expression likely explains their unresponsiveness to IL-13.

FURIN regulates cytotoxic T lymphocyte effector function and memory cell transition in mice

The proprotein convertase subtilisin/kexins (PCSKs) regulate biological actions by cleaving immature substrate proteins. The archetype PCSK, FURIN, promotes the pathogenicity of viruses by proteolytically processing viral proteins. FURIN has also important regulatory functions in both innate and adaptive immune responses but its role in the CD8+ CTLs remains enigmatic. We used a T cell specific FURIN deletion in vivo to demonstrate that FURIN promotes host response against the CTL-dependent lymphocytic choriomeningitis virus by virtue of restricting viral burden and augmenting IFNG production. We also characterized Furin KO CD8+ T cells ex vivo, including after their activation with FURIN regulating cytokines IL12 or TGFB1. Furin KO CD8+ T cells show an inherently activated phenotype characterized by the up-regulation of effector genes and increased frequencies of CD44+, TNF+ and IFNG+ cells. In the activated CTLs FURIN regulates the productions of IL2, TNF and GZMB and the genes associated with the TGFBR-signaling pathway. FURIN also controls the expression of Eomes, Foxo1 and Bcl6 and the levels of ITGAE and CD62L, which implies a role in the development of CTL memory. Collectively, our data suggest that the T cell expressed FURIN is important for host responses in viral infections, CTL homeostasis/activation and memory development. This article is protected by copyright. All rights reserved.

IL-4, IL-13 and IFN-γ -induced genes in highly purified human neutrophils

Interleukin (IL)-4 and IL-13 are related cytokines with well-known specific roles in type 2 immune response. However, their effects on neutrophils are not completely understood. For this, we studied human primary neutrophil responses to IL-4 and IL-13. Neutrophils are dose-dependently responsive to both IL-4 and IL-13 as indicated by signal transducer and activator of transcription 6 (STAT6) phosphorylation upon stimulation, with IL-4 being more potent inducer of STAT6. IL-4-, IL-13- and Interferon (IFN)-γ-stimulated gene expression in highly purified human neutrophils induced both overlapping and unique gene expression in highly purified human neutrophils. IL-4 and IL-13 specifically regulate several immune-related genes, including IL-10, tumor necrosis factor (TNF) and leukemia inhibitory factor (LIF), while type1 immune response-related IFN-γ induced gene expression related for example, to intracellular infections. In analysis of neutrophil metabolic responses, oxygen independent glycolysis was specifically regulated by IL-4, but not by IL-13 or IFN-γ, suggesting specific role for type I IL-4 receptor in this process. Our results provide a comprehensive analysis of IL-4, IL-13 and IFN-γ -induced gene expression in neutrophils while also addressing cytokine-mediated metabolic changes in neutrophils.

Immunomodulatory Functions of Adipose Mesenchymal Stromal/Stem Cell Derived from Donors with Type 2 Diabetes and Obesity on CD4 T cells

For adipose stromal/stem cell (ASCs)-based immunomodulatory therapies, it is important to study how donor characteristics, such as obesity and type 2 diabetes (T2D), influence ASCs efficacy. Here, ASCs were obtained from two groups, donors and T2D and obesity (dASCs) or nondiabetic donors with normal-weight (ndASCs), and then cultured with anti-CD3/CD28-stimulated allogeneic CD4 T cells. ASCs were studied for the expression of the immunomodulators CD54, CD274, and indoleamine 2, 3 dioxygenase 1 (IDO) in inflammatory conditions. CD4 T cells cultured alone or in cocultures were assessed to evaluate proliferation, activation marker surface expression, apoptosis, the regulatory T cells (Tregs; CD4 + CD25 high FOXP3 +) frequency, and intracellular cytokine expression using flow cytometry. Modulation of T-cell subset cytokines was explored via ELISA. In inflammatory conditions, the expression of CD54, CD274 and IDO was significantly upregulated in ASCs, with no significant differences between ndASCs and dASCs. dASCs retained the potential to significantly suppress CD4 T-cell proliferation, with a slightly weaker inhibitory effect than ndASCs, which was associated with significantly reduced abilities to decrease IL-2 production and increase IL-8 levels in cocultures. Such attenuated potentials were significantly correlated with increasing body mass index. dASCs and ndASCs comparably reduced CD4 T-cell viability, HLA-DR expression, and interferon-gamma production and conversely increased CD69 expression, the Tregs percentage, and IL-17A production. Considerable amounts of the immunomodulators prostaglandin E2 (PGE2) and IL-6 were detected in the conditioned medium of cocultures. These findings suggest that ASCs obtained from donors with T2D and obesity are receptive to the inflammatory environment and able to modulate CD4 T cells accordingly.

Effect of inactivated nature‐derived microbial composition on mouse immune system

Introduction

The hygiene hypothesis suggests that decrease in early life infections due to increased societal‐level hygiene standards subjects one to allergic and autoimmune diseases. In this report, we have studied the effect of sterilized forest soil and plant‐based material on mouse immune system and gut microbiome.

Methods

Inbred C57Bl/6 mice maintained in normal sterile environment were subjected to autoclaved forest soil‐derived powder in their bedding for 1 h a day for 3 weeks. Immune response was measured by immune cell flow cytometry, serum cytokine enzyme‐linked immunoassay (ELISA) and quantitative polymerase chain reaction (qPCR) analysis. Furthermore, the mouse gut microbiome was analyzed by sequencing.

Results

When compared to control mice, mice treated with soil‐derived powder had decreased level of pro‐inflammatory cytokines namely interleukin (IL)−17F and IL‐21 in the serum. Furthermore, splenocytes from mice treated with soil‐derived powder expressed less IL‐1b, IL‐5, IL‐6, IL‐13, and tumor necrosis factor (TNF) upon cell activation. Gut microbiome appeared to be stabilized by the treatment.

Conclusions

These results provide insights on the effect of biodiversity on murine immune system in sterile environment. Subjecting mice to soil‐based plant and microbe structures appears to elicit immune response that could be beneficial, for example, in type 2 inflammation‐related diseases, that is, allergic diseases.

IFNγ suppresses the expression of GFI1 and thereby inhibits Th2 cell proliferation

While IFNγ is a well-known cytokine that actively promotes the type I immune response, it is also known to suppress the type II response by inhibiting the differentiation and proliferation of Th2 cells. However, the mechanism by which IFNγ suppresses Th2 cell proliferation is still not fully understood. We found that IFNγ decreases the expression of growth factor independent-1 transcriptional repressor (GFI1) in Th2 cells, resulting in the inhibition of Th2 cell proliferation. The deletion of the Gfi1 gene in Th2 cells results in the failure of their proliferation, accompanied by an impaired cell cycle progression. In contrast, the enforced expression of GFI1 restores the defective Th2 cell proliferation, even in the presence of IFNγ. These results demonstrate that GFI1 is a key molecule in the IFNγ-mediated inhibition of Th2 cell proliferation.

IL-13Rα1 Suppresses Tumor Progression in Two-stage Skin Carcinogenesis Model by Regulating Regulatory T Cells

Type 2-inflammation-related cytokine Interleukin (IL)-13 plays a protective role in experimental papilloma induction in mice. To understand mechanisms by which IL-13 contributes to papilloma formation we utilized IL-13Rα1 knockout (KO) mice in widely used DMBA/TPA two-stage skin carcinogenesis protocol that mimics the development of Squamous Cell Carcinoma (SCC). KO mice developed more papillomas and significantly faster than wild-type (WT) mice. Papilloma development reduced Tregs in WT mice, but substantially less in KO mice. In line with this, IL-2 and IL-10 levels decreased in WT mice, but not in KO mice. Furthermore, systemic IL-5 and Thymic Stromal Lymphopoietin (TSLP) levels were elevated, while IL-22 was decreased during papilloma formation in the skin of KO mice. Polymorphonuclear Myeloid-derived suppressor cells (PMN-MDSCs) were decreased in the KO mice at the early phase of papilloma induction. We demonstrate that IL-13Rα1 protects from papilloma development in chemically induced skin carcinogenesis and our results provide further insights into the protective role of functional IL-4 and IL-13 signaling via type II IL-4R in tumor development.

Challenges in investigation of diabetes-related aviation fatalities-an analysis of 1491 subsequent aviation fatalities in USA during 2011-2016

Diabetes mellitus (DM) could cause pilot incapacitation and result in aviation fatalities. The mechanisms could be directly as a consequence of acute hypoglycemia/subacute diabetic ketoacidosis (DKA) or indirectly as an acute cardiovascular event by contributing to the development of atherosclerosis in coronary or carotid and cerebral arteries. In this study, DM-related fatal flight accidents in the US National Transport Bureau's database between years 2011-2016 were analyzed with special emphasis on postmortem (PM) glucose levels and correlation of toxicological reports with anamnestic information on DM. Additionally, autopsy results on coronary arteries were reviewed. In 43 out of 1491 (~ 3%) fatal accidents pilots had DM. Postmortem glucose or glycated hemoglobin percentage (Hb1Ac) was measured in 12 of the 43 cases; while antidiabetic medication was found in 14 of the cases (only two of the cases had both glucose measurements and medication). With the increasing prevalence of DM, a possibility of pilot incapacitation due to DM or complications of DM should be actively studied, even if no anamnestic information of DM was available. While PM hypoglycemia is difficult to assess, we propose a systematic investigation based on measurement of glucose, Hb1Ac%, and ketone bodies, and documentation of atherosclerotic lesions in major arteries to identify or rule out DM as a cause of pilot incapacitation.

Tuning the Cytokine Responses: An Update on Interleukin (IL)-4 and IL-13 Receptor Complexes

Interleukin (IL)-4 and IL-13 are related cytokines that regulate many aspects of allergic inflammation. They play important roles in regulating the responses of lymphocytes, myeloid cells, and non-hematopoietic cells. In T-cells, IL-4 induces the differentiation of naïve CD4 T cells into Th2 cells, in B cells, IL-4 drives the immunoglobulin (Ig) class switch to IgG1 and IgE, and in macrophages, IL-4 and IL-13 induce alternative macrophage activation. This review gives a short insight into the functional formation of these cytokine receptors. I will discuss both the binding kinetics of ligand/receptor interactions and the expression of the receptor chains for these cytokines in various cell types; both of which are crucial factors in explaining the efficiency by which these cytokines induce intracellular signaling and gene expression. Work initiated in part by William (Bill) E. Paul on IL-4 some 30 years ago has now grown into a major building block of our current understanding of basic immunology and the immune response. This knowledge on IL-4 has growing clinical importance, as therapeutic approaches targeting the cytokine and its signal transduction are becoming a part of the clinical practice in treating allergic diseases. Just by reading the reference list of this short review, one can appreciate the enormous input Bill has had on shaping our understanding of the pathophysiology of allergic inflammation and in particular the role of IL-4 in this process.

R-Ras deficiency does not affect papain-induced IgE production in mice

Introduction

R‐Ras GTPase has recently been implicated in the regulation of immune functions, particularly in dendritic cell (DC) maturation, immune synapse formation, and subsequent T cell responses.

Methods

Here, we investigated the role of R‐Ras in allergen‐induced immune response (type 2 immune response) in Rras deficient (R‐Ras KO) and wild type (WT) mice.

Results

Initially, we found that the number of conventional DC's in the lymph nodes (LNs) was reduced in R‐Ras KO mice. The expression of co‐stimulatory CD80 and CD86 molecules on these cells was also reduced on DC's from the R‐Ras KO mice. However, there was no difference in papain‐induced immune response between the R‐Ras WT and KO as measured by serum IgE levels after the immunization. Interestingly, neither the DC number nor co‐stimulatory molecule expression was different between WT and R‐Ras KO animals after the immunization.

Conclusions

Taken together, despite having reduced number of conventional DC's in the R‐Ras KO mice and low expression of CD80 on DC's, the R‐Ras KO mice are capable of mounting papain‐induced IgE responses comparable to that of the WT mice. To our knowledge, this is the first report addressing potential differences in in vivo allergen responses regulated by the R‐Ras GTPase.

IL-7Rα Expression Regulates Murine Dendritic Cell Sensitivity to Thymic Stromal Lymphopoietin

Thymic stromal lymphopoietin (TSLP) and IL-7 are related cytokines that mediate growth and differentiation events in the immune system. They signal through IL-7Rα-containing receptors. Target cells of TSLP in Th2 responses include CD4 T cells and dendritic cells (DCs). Although it has been reported that expression of TSLP receptor (TSLPR) on CD4 T cells is required for OVA-induced lung inflammation, DCs have also been shown to be target cells of TSLP. In this study, we show that murine ex vivo splenic DCs are unresponsive to TSLP, as they fail to phosphorylate STAT5, but in vitro overnight culture, especially in presence of IL-4, renders DCs responsive to both TSLP and IL-7. This induced responsiveness is accompanied by dramatic upregulation of IL-7Rα on DCs with little change in expression of TSLPR or of γ_c In splenic DCs, the induction of IL-7Rα occurs mainly in CD8^- DCs. In vivo, we found that IL-4 has a differential regulatory role on expression of IL-7Rα depending on the cell type; IL-4 decreases IL-7Rα expression on CD4 T cells whereas it upregulates the expression on DCs. Our results indicate that the induction of IL-7Rα expression on DCs is critical for TSLP responsiveness and that IL-4 can upregulate IL-7Rα on DCs.

Cytokine-induced cytokine production by conventional and innate lymphoid cells

Innate immune and differentiated T cells produce signature cytokines in response to cytokine stimulation. Optimal production requires stimulation by an NF-κB inducer, most commonly an interleukin (IL)-1 family member, and a STAT activator. Usually, there is linkage between the IL-1 family member, the activated STAT and the cytokines produced: IFNγ producers respond to the IL-1 family member, IL-18 and IL-12, a STAT4 activator; IL-13 producers respond to IL-33 (although for ILC2 cells this may be replaced by IL-25) and STAT5 activators; for cells producing IL-17A or IL-22, the combination is IL-1 and a STAT3 inducer. Cytokine-induced cytokine production may have broad significance in orchestrating innate responses to distinct infectious agents and in maintaining inflammatory responses after elimination of the inciting antigen.

The transcription factor GATA3 actively represses RUNX3 protein-regulated production of interferon-gamma

The transcription factor GATA3 is crucial for the differentiation of naive CD4(+) T cells into T helper 2 (Th2) cells. Here, we show that deletion of Gata3 allowed the appearance of interferon-gamma (IFN-gamma)-producing cells in the absence of interleukin-12 (IL-12) and IFN-gamma. Such IFN-gamma production was transcription factor T-bet independent. Another T-box-containing transcription factor Eomes, but not T-bet, was induced both in GATA3-deficient CD4(+) T cells differentiated under Th2 cell conditions and in Th2 cells with enforced Runx3 expression, contributing to IFN-gamma production. GATA3 overexpression blocked Runx3-mediated Eomes induction and IFN-gamma production, and GATA3 protein physically interacted with Runx3 protein. Furthermore, we found that Runx3 directly bound to multiple regulatory elements of the Ifng gene and that blocking Runx3 function in either Th1 or GATA3-deficient "Th2" cells results in diminished IFN-gamma production by these cells. Thus, the Runx3-mediated pathway, actively suppressed by GATA3, induces IFN-gamma production in a STAT4- and T-bet-independent manner.

IRS-2 phosphorylation and association with p85 and Grb2 after engagement of type I IL-4 receptor (IL-4R). (38.2)

We previously showed that IL-4 elicited stronger tyrosine phosphorylation of insulin receptor substrate (IRS)-2 than IL-13. This IRS-2 phosphorylation difference was observed even at high concentrations of IL-13 and was due to the exclusive ability of IL-4 to bind to type I IL-4 Rs (IL-4Rα + γC). Furthermore, IL-4 but not IL-13, significantly augmented expression of a subset of alternatively-activated macrophage (AAM) genes, arginase I, found in inflammatory zone (FIZZ)1, and Ym1 in WT bone marrow-derived macrophages (BMM). In this study, we further analyzed signaling differences between IL-4 and IL-13 downstream of the IRS-2 pathway. IL-4 stimulation resulted in enhanced association of the p85 subunit of PI-3' kinase with IRS-2 as compared to IL-13, while only IL-4 induced the association of Grb2 with IRS-2 in WT BMM. Since IRS-2 activation leads to PI-3' K activation, we investigated the effect of wortmannin on induction of the AAM genes. IL-4-induced expression of FIZZ1 was suppressed by wortmannin to the levels induced by IL-13. Arginase I and Ym1 expression was unaffected by wortmannin. These data suggest that the type I IL-4R can direct site-specific phosphorylation of IRS-2, resulting in enhanced recruitment of adaptor molecules and augmented expression of a subset of AAM genes. In addition, they suggest these genes are differentially affected by the IRS-2/PI-3' K pathway. (PHS AI38985)

Type I IL-4Rs selectively activate IRS-2 to induce target gene expression in macrophages

Although interleukin-4 (IL-4) and IL-13 participate in allergic inflammation and share a receptor subunit (IL-4Ralpha), they have different functions. We compared cells expressing type I and II IL-4Rs with cells expressing only type II receptors for their responsiveness to these cytokines. IL-4 induced highly efficient, gammaC-dependent tyrosine phosphorylation of insulin receptor substrate 2 (IRS-2), whereas IL-13 was less effective, even when phosphorylation of signal transducer and activator of transcription 6 (STAT6) was maximal. Only type I receptor, gammaC-dependent signaling induced efficient association of IRS-2 with the p85 subunit of phosphoinositide 3-kinase or the adaptor protein growth factor receptor-bound protein 2. In addition, IL-4 signaling through type I IL-4Rs induced more robust expression of a subset of genes associated with alternatively activated macrophages than did IL-13. Thus, IL-4 activates signaling pathways through type I IL-4Rs qualitatively differently from IL-13, which cooperate to induce optimal gene expression.

Tuning sensitivity to IL-4 and IL-13: differential expression of IL-4Ralpha, IL-13Ralpha1, and gammac regulates relative cytokine sensitivity

Interleukin (IL)-4 and -13 are related cytokines sharing functional receptors. IL-4 signals through the type I (IL-4Rα/common γ-chain [γc]) and the type II (IL-4Rα/-13Rα1) IL-4 receptors, whereas IL-13 utilizes only the type II receptor. In this study, we show that mouse bone marrow–derived macrophages and human and mouse monocytes showed a much greater sensitivity to IL-4 than to IL-13. Lack of functional γc made these cells poorly responsive to IL-4, while retaining full responsiveness to IL-13. In mouse peritoneal macrophages, IL-4 potency exceeds that of IL-13, but lack of γc had only a modest effect on IL-4 signaling. In contrast, IL-13 stimulated greater responses than IL-4 in fibroblasts. Using levels of receptor chain expression and known binding affinities, we modeled the assemblage of functional type I and II receptor complexes. The differential expression of IL-4Rα, IL-13Rα1, and γc accounted for the distinct IL-4–IL-13 sensitivities of the various cell types. These findings provide an explanation for IL-13's principal function as an “effector” cytokine and IL-4's principal role as an “immunoregulatory” cytokine.