Toll-like receptor 2 induces pathogenicity in Th17 cells and reveals a role for IPCEF in regulating Th17 cell migration

Pathogenic Th17 cells drive inflammation in autoimmune disease, yet the molecular programming underlying Th17 cell pathogenicity remains insufficiently understood. Activation of Toll-like receptor 2 (TLR2) increases Th17 cell inflammatory potential, but little is known regarding the mechanistic outcomes of TLR2 signaling in Th17 cells. Here, we demonstrate that TLR2 is comparable to IL-23 in inducing pathogenicity and increasing the migratory capacity of Th17 cells. We perform RNA sequencing of Th17 cells stimulated though the TLR2 pathway and find differential expression of several genes linked with the Th17 genetic program as well as genes not previously associated with pathogenic Th17 cells, including Ipcef1. Enforced expression of Ipcef1 in Th17 cells abolishes the TLR2-dependent increases in migratory capacity and severely impairs the ability of Th17 cells to induce experimental autoimmune encephalomyelitis. This study establishes the importance of the TLR2 signaling pathway in inducing Th17 cell pathogenicity and driving autoimmune inflammation.

Toll-like Receptor 2 induces pathogenicity in Th17 cells

CD4+ T cells, especially Th17 cells, are instrumental in the development and progression of autoimmune diseases, such as multiple sclerosis (MS), psoriasis, and rheumatoid arthritis. While pathogenic Th17 cells drive inflammation in autoimmunity, the molecular programming underlying their pathogenicity remains insufficiently understood. Furthermore, very little is known regarding the role of the pattern recognition receptor TLR2 in Th17 pathogenicity. We have previously shown that activation of TLR2 with PAM3CSK4 during Th17 differentiation results in increased production of IL-17A and IL-17F and significantly increases the proliferation of Th17 cells in vitro. Herein, we show that TLR2 induces pathogenicity in Th17 cells, similar to what has been shown for IL-23. TLR2 signaling results in increased encephalitogenic migration of Th17 cells, in addition to increased cytokine production. To further investigate the effect of TLR2 activation on Th17 cells, we utilized RNA sequencing and found 390 genes that are upregulated and 355 genes that are downregulated following TLR2 signaling in Th17 cells. Several of these genes we have identified are important regulators that either increase or restrain the inflammatory potential of Th17 cells. We further address the role of TLR2 in Th17-mediated autoimmune disease using experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We show that encephalitogenic Th17 cells expanded with a TLR2 agonist induced EAE disease to the same extent as those expanded with IL-23. Altogether, this study establishes TLR2 signaling as crucial for induction of pathogenic Th17 cells in autoimmune disease.

Thpok suppresses pathogenic cytokine production by Th17 cells in autoimmune disease

CD4+ T cells, including Th17 cells, are instrumental in the development and progression of autoimmune diseases such as multiple sclerosis. While pathogenic Th17 cells drive inflammation in autoimmunity, the molecular programming underlying their pathogenicity remains insufficiently understood. Through RNA-sequencing, we have identified the transcription factor Thpok (Zbtb7b), also known as the CD4 lineage determination factor, as an apparent negative regulator of Th17 pathogenicity. Thpok expression is maintained in peripheral CD4+ T cells and assists in formation of memory CD4+ T cells. Furthermore, Thpok expression in CD4+ T cells represses cytotoxic genes and contributes to the Th17 response during intestinal inflammation. Herein we show Thpok is upregulated in pathogenic Th17 cells both in vitro and in vivo. In addition, we show increased expression of Thpok results in reduced production of IL-17, while conversely, loss of Thpok results in higher inflammatory potential of Th17 cells. Moreover, we have demonstrated that Thpok expression in Th17 cells in vivo functions to inhibit the development of experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. Altogether this study establishes Thpok as a suppressor of the autoimmune inflammatory function of Th17 cells.

Fatty acid synthase regulates the pathogenicity of Th17 cells

T cell activation and effector function is characterized by changes in metabolism. Altered metabolism is common to almost all types of activated T cells, but fatty acid synthesis seems to especially drive the formation of Th17 cells. Indeed, research has demonstrated that inhibition of early fatty acid synthesis through targeting of acetyl-CoA carboxylase (ACC1) can inhibit Th17 cell formation and instead promote the generation of regulatory T cells. Fatty acid synthase (FASN) is downstream of ACC, and previous studies have shown that FASN activity influences both cancer and inflammation. However, it remains to be determined whether FASN is a viable target for inhibiting Th17 cell function. Here, we demonstrate that FASN is a critical metabolic control for the generation of inflammatory subsets of Th17 cells. Conversely, inhibiting FASN function promotes IFN-γ production by Th1 and Th1-like Th17 cells. In vivo, inhibition of FASN, specifically in Th17 cells, leads to reduction of experimental autoimmune encephalomyelitis disease. These studies demonstrate the necessity of FASN in the autoimmune inflammatory function of Th17 cells.

TLR Function in Murine CD4(+) T Lymphocytes and Their Role in Inflammation

Toll-like receptor (TLR) signaling represents an evolutionary-conserved mechanism allowing for the rapid detection of broad molecular patterns that are common to different groups of pathogens. TLRs are traditionally associated with cells of the innate immune response where ligation of a TLR alone can lead to cellular activation and the initialization of an immune response. Cells of adaptive immunity, namely different classes of T and B lymphocytes, are also known to express a variety of TLRs. Conversely, the functional and signaling outcomes of TLRs are decidedly different in cells of the adaptive immune response. T lymphocytes generally have substantially lower TLR expression compared to innate cells, suggesting that TLRs function in a highly specialized capacity in this cell type. Certain TLRs act in a co-stimulatory capacity on T cells, amplifying activation only in the presence of simultaneous T-cell receptor engagement. However, the full array of TLR signaling events and outcomes in T lymphocytes remains poorly understood. Here, we describe a few methods for investigating the general function of TLRs on T lymphocytes in vitro and in vivo with an emphasis on the study of CD4(+) T cells. Most of these procedures can be adapted for the study of TLR signaling on other classes of lymphocytes as well.

Mouse Naïve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Antigen inexperienced (naïve) CD4(+) T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition of cognate antigen presented on MHC class II. The cytokine signals present in the environment at the time of TCR activation are a major factor in determining the effector fate of a naïve CD4(+) T cell. Although the cytokine environment during naïve T cell activation may be complex and involve both redundant and opposing signals in vivo, the addition of various cytokine combinations during naive CD4(+) T cell activation in vitro can readily promote the establishment of effector T helper lineages with hallmark cytokine and transcription factor expression. Such differentiation experiments are commonly used as a first step for the evaluation of targets believed to promote or inhibit the development of certain CD4(+) T helper subsets. The addition of mediators, such as signaling agonists, antagonists, or other cytokines, during the differentiation process can also be used to study the influence of a particular target on T cell differentiation. Here, we describe a basic protocol for the isolation of naïve T cells from mouse and the subsequent steps necessary for polarizing naïve cells to various T helper effector lineages in vitro.

Interleukin-17B Antagonizes Interleukin-25-Mediated Mucosal Inflammation

The interleukin-17 (IL-17) family of cytokines has emerged as a critical player in inflammatory diseases. Among them, IL-25 has been shown to be important in allergic inflammation and protection against parasitic infection. Here we have demonstrated that IL-17B, a poorly understood cytokine, functions to inhibit IL-25-driven inflammation. IL-17B and IL-25, both binding to the interleukin-17 receptor B (IL-17RB), were upregulated in their expression after acute colonic inflammation. Individual inhibition of these cytokines revealed opposing functions in colon inflammation: IL-25 was pathogenic but IL-17B was protective. Similarly opposing phenotypes were observed in Citrobacter rodentium infection and allergic asthma. Moreover, IL-25 was found to promote IL-6 production from colon epithelial cells, which was inhibited by IL-17B. Therefore, our data demonstrate that IL-17B is an anti-inflammatory cytokine in the IL-17 family.

IFI16 restricts HSV-1 replication by accumulating on the hsv-1 genome, repressing HSV-1 gene expression, and directly or indirectly modulating histone modifications

Interferon-γ inducible factor 16 (IFI16) is a multifunctional nuclear protein involved in transcriptional regulation, induction of interferon-β (IFN-β), and activation of the inflammasome response. It interacts with the sugar-phosphate backbone of dsDNA and modulates viral and cellular transcription through largely undetermined mechanisms. IFI16 is a restriction factor for human cytomegalovirus (HCMV) and herpes simplex virus (HSV-1), though the mechanisms of HSV-1 restriction are not yet understood. Here, we show that IFI16 has a profound effect on HSV-1 replication in human foreskin fibroblasts, osteosarcoma cells, and breast epithelial cancer cells. IFI16 knockdown increased HSV-1 yield 6-fold and IFI16 overexpression reduced viral yield by over 5-fold. Importantly, HSV-1 gene expression, including the immediate early proteins, ICP0 and ICP4, the early proteins, ICP8 and TK, and the late proteins gB and Us11, was reduced in the presence of IFI16. Depletion of the inflammasome adaptor protein, ASC, or the IFN-inducing transcription factor, IRF-3, did not affect viral yield. ChIP studies demonstrated the presence of IFI16 bound to HSV-1 promoters in osteosarcoma (U2OS) cells and fibroblasts. Using CRISPR gene editing technology, we generated U2OS cells with permanent deletion of IFI16 protein expression. ChIP analysis of these cells and wild-type (wt) U2OS demonstrated increased association of RNA polymerase II, TATA binding protein (TBP) and Oct1 transcription factors with viral promoters in the absence of IFI16 at different times post infection. Although IFI16 did not alter the total histone occupancy at viral or cellular promoters, its absence promoted markers of active chromatin and decreased those of repressive chromatin with viral and cellular gene promoters. Collectively, these studies for the first time demonstrate that IFI16 prevents association of important transcriptional activators with wt HSV-1 promoters and suggest potential mechanisms of IFI16 restriction of wt HSV-1 replication and a direct or indirect role for IFI16 in histone modification.

Monitoring exposure to solvent vapour in the workplace using a video-visualization technique

A video-visualization technique, using a combination of a fast-response, direct-reading, personal gas monitor (photo-ionization detector) and synchronized video monitoring (with a standard camcorder), has been applied to assess exposure to solvents in various industries. The objective is to understand how short-term peaks occur and how they can be controlled to minimise both short-term exposure and their contribution to long-term exposure. The technique was employed to identify peaks associated with work activities and their contribution to total exposure arising from use of tetrachloroethene in a dry cleaning establishment. The exposure and video data are simultaneously displayed on computer and the information is disseminated on CD (and video), forming the basis of a detailed occupational hygiene assessment or training material.

Mercury contamination incident

BACKGROUND

The aim of this paper is to describe an incident where elemental mercury led to widespread contamination and the exposure of 225 individuals and confirmed toxicity in 19 individuals. The paper describes the incident and difficulties found in trying to assess the risk to individuals and to identify and decontaminate the residences involved.

METHODS

All individuals exposed to elemental mercury in the incident were followed up for 15 months.

RESULTS

Thirty-seven individuals were found to be 'at risk' and 13 were symptomatic of mercury poisoning. Five patients required chelation therapy. The incident was closed when the risk of poisoning and re-exposure was minimized.

CONCLUSION

Incident management depends on early effective communication and collaboration between all agencies involved.

Computer-aided video exposure monitoring

A computer-aided video exposure monitoring system was used to record exposure information. The system comprised a handheld camcorder, portable video cassette recorder, radio-telemetry transmitter/receiver, and handheld or notebook computers for remote data logging, photoionization gas/vapor detectors (PIDs), and a personal aerosol monitor. The following workplaces were surveyed using the system: dry cleaning establishments--monitoring tetrachoroethylene in the air and in breath; printing works--monitoring white spirit type solvent; tire manufacturing factory--monitoring rubber fume; and a slate quarry--monitoring respirable dust and quartz. The system based on the handheld computer, in particular, simplified the data acquisition process compared with earlier systems in use by our laboratory. The equipment is more compact and easier to operate, and allows more accurate calibration of the instrument reading on the video image. Although a variety of data display formats are possible, the best format for videos intended for educational and training purposes was the review-preview chart superimposed on the video image of the work process. Recommendations for reducing exposure by engineering or by modifying work practice were possible through use of the video exposure system in the dry cleaning and tire manufacturing applications. The slate quarry work illustrated how the technique can be used to test ventilation configurations quickly to see their effect on the worker's personal exposure.

Heparin-induced platelet aggregation vs platelet factor 4 enzyme-linked immunosorbent assay in the diagnosis of heparin-induced thrombocytopenia-thrombosis

Thrombosis occurs in an unpredictable subset of patients with heparin-induced thrombocytopenia (HIT). The diagnosis of HIT requires clinical suspicion and laboratory confirmation. Although the "gold-standard" diagnostic test is considered to be the serotonin release assay (SRA), most laboratories use heparin-induced platelet aggregation (HIPA), which is highly specific but reported to be less sensitive than the SRA. Recently, the heparin-platelet factor 4 (PF4) enzyme-linked immunosorbent assay (ELISA) has been reported to have comparable sensitivity to the SRA. We compared the HIPA and PF4 ELISA in serum samples from 146 patients examined for HIT and assessed whether either test predicted thrombotic risk. Results for 81 patients were positive for HIPA, PF4 ELISA, or both. Of these, 91% were HIPA-positive, while only 60% were PF4 ELISA-positive. Clinical information was available on 63 patients, 17 of whom had thrombotic events (10 venous, 6 arterial, and 1 both). Neither the HIPA nor the PF4 ELISA predicted thrombotic risk, but the HIPA proved to be a more sensitive test for laboratory confirmation.

Methodology and characterization of an in vitro perfusion model for the mouse ovary

Perfusion of intact ovaries in vitro has proved to be a suitable model for the study of ovarian events, such as ovulation and corpus luteum function, with advantages over cell culture systems of preserved three-dimensional structure with intact intercellular communication. This methodology has been described for several larger experimental animals. Development of genetically manipulated mouse strains and the larger availability of recombinant proteins and monoclonal antibodies in this species prompted the development of a mouse ovary perfusion system. In the present study, we describe the methodology for perfusion of mouse ovaries in vitro and characterize the model with respect to steroidogenesis, ovulatory efficiency and morphology. Swiss mice (30-45 g) were synchronized with a single injection of a GnRH agonist and laparotomy was performed on the morning of pro-oestrus. The right ovary and its vasculature, after cannulation on the arterial side, were surgically isolated and transferred to a recirculating perfusion system, and were perfused for 20 h. The ultrastructure of the ovaries after 20 h of perfusion was examined by transmission electron microscopy, which showed well-preserved cellular organelles and nuclei and distinct tight junctions between endothelial cells. Unstimulated ovaries did not ovulate and secreted small quantities of progesterone. After addition of hCG (50 iu) or ovine LH (0.1 microgram ml-1), ovulations were observed in all perfused ovaries (2.6 +/- 0.5 and 2.0 +/- 0.3 ovulations per treated ovary, respectively). There was a distinct rise in progesterone output after hormone addition. When a phosphodiesterase inhibitor, isobutylmethylxanthine (0.2 mumol l-1), was added in combination with LH, the ovulation rate (7.4 +/- 1.2) was similar to that in vivo and progesterone secretion was further increased compared with other treatments. Since the mouse has become a very important experimental animal in medical research and we have the ability to genetically manipulate this species, this methodology for perfusing mouse ovaries in vitro may be a useful tool in future studies of ovarian physiology.

Bilateral chylothorax following thymectomy: resolution following unilateral drainage

Chylothorax is a rare complication of thymectomy. Following thymectomy for myasthenia gravis, our patient developed bilateral chylous pleural effusions. The presence of a "mediastinal window" allowed adequate drainage with a unilateral chest tube.

Airway obstruction by anterior mediastinal mass. Successful management by percutaneous aspiration

An anterior mediastinal mass producing extrinsic airway obstruction was successfully managed by percutaneous needle aspiration, decompressing the mass and relieving the airway obstruction. This allowed safe induction of general endotracheal anesthesia and excision of the mass by a sternotomy approach.

Increasing halothane concentration abolishes anesthesia-associated arrhythmias in cats and dogs

Fifteen cats and 6 dogs developed ventricular arrhythmias during halothane anesthesia. Halothane was administered by precision vaporizer, using a semiclosed anesthetic system. Cardiac arrhythmias were diagnosed within 5 to 10 minutes after a surgical plane of anesthesia was achieved. Arrhythmias in 9 of 15 cats and 3 of 6 dogs were converted to sinus rhythm by increasing the inspired halothane concentration. Conversion to sinus rhythm occurred within 4 minutes. Cardiac arrhythmias were reestablished in 8 of 9 cats and 2 of 3 dogs, after decreasing the inspired halothane concentration to its original value. Increasing the inspired halothane concentration can convert anesthetic-associated ventricular arrhythmias to sinus rhythm in dogs and cats.