Role of Granulocyte-Macrophage Colony-Stimulating Factor Production by T Cells during Mycobacterium tuberculosis Infection

ABSTRACT Mice deficient for granulocyte-macrophage colony-stimulating factor (GM-CSF−/−) are highly susceptible to infection with Mycobacterium tuberculosis, and clinical data have shown that anti-GM-CSF neutralizing antibodies can lead to increased susceptibility to tuberculosis in otherwise healthy people. GM-CSF activates human and murine macrophages to inhibit intracellular M. tuberculosis growth. We have previously shown that GM-CSF produced by iNKT cells inhibits growth of M. tuberculosis. However, the more general role of T cell-derived GM-CSF during infection has not been defined and how GM-CSF activates macrophages to inhibit bacterial growth is unknown. Here we demonstrate that, in addition to nonconventional T cells, conventional T cells also produce GM-CSF during M. tuberculosis infection. Early during infection, nonconventional iNKT cells and γδ T cells are the main source of GM-CSF, a role subsequently assumed by conventional CD4+ T cells as the infection progresses. M. tuberculosis-specific T cells producing GM-CSF are also detected in the peripheral blood of infected people. Under conditions where nonhematopoietic production of GM-CSF is deficient, T cell production of GM-CSF is protective and required for control of M. tuberculosis infection. However, GM-CSF is not required for T cell-mediated protection in settings where GM-CSF is produced by other cell types. Finally, using an in vitro macrophage infection model, we demonstrate that GM-CSF inhibition of M. tuberculosis growth requires the expression of peroxisome proliferator-activated receptor gamma (PPARγ). Thus, we identified GM-CSF production as a novel T cell effector function. These findings suggest that a strategy augmenting T cell production of GM-CSF could enhance host resistance against M. tuberculosis

IAP inhibitors enhance co-stimulation to promote tumor immunity

The inhibitor of apoptosis proteins (IAPs) have recently been shown to modulate nuclear factor κB (NF-κB) signaling downstream of tumor necrosis factor (TNF) family receptors, positioning them as essential survival factors in several cancer cell lines, as indicated by the cytotoxic activity of several novel small molecule IAP antagonists. In addition to roles in cancer, increasing evidence suggests that IAPs have an important function in immunity; however, the impact of IAP antagonists on antitumor immune responses is unknown. In this study, we examine the consequences of IAP antagonism on T cell function in vitro and in the context of a tumor vaccine in vivo. We find that IAP antagonists can augment human and mouse T cell responses to physiologically relevant stimuli. The activity of IAP antagonists depends on the activation of NF-κB2 signaling, a mechanism paralleling that responsible for the cytotoxic activity in cancer cells. We further show that IAP antagonists can augment both prophylactic and therapeutic antitumor vaccines in vivo. These findings indicate an important role for the IAPs in regulating T cell–dependent responses and suggest that targeting IAPs using small molecule antagonists may be a strategy for developing novel immunomodulating therapies against cancer

Post-intervention Status in Patients With Refractory Myasthenia Gravis Treated With Eculizumab During REGAIN and Its Open-Label Extension

OBJECTIVE: To evaluate whether eculizumab helps patients with anti-acetylcholine receptor-positive (AChR+) refractory generalized myasthenia gravis (gMG) achieve the Myasthenia Gravis Foundation of America (MGFA) post-intervention status of minimal manifestations (MM), we assessed patients' status throughout REGAIN (Safety and Efficacy of Eculizumab in AChR+ Refractory Generalized Myasthenia Gravis) and its open-label extension. METHODS: Patients who completed the REGAIN randomized controlled trial and continued into the open-label extension were included in this tertiary endpoint analysis. Patients were assessed for the MGFA post-intervention status of improved, unchanged, worse, MM, and pharmacologic remission at defined time points during REGAIN and through week 130 of the open-label study. RESULTS: A total of 117 patients completed REGAIN and continued into the open-label study (eculizumab/eculizumab: 56; placebo/eculizumab: 61). At week 26 of REGAIN, more eculizumab-treated patients than placebo-treated patients achieved a status of improved (60.7% vs 41.7%) or MM (25.0% vs 13.3%; common OR: 2.3; 95% CI: 1.1-4.5). After 130 weeks of eculizumab treatment, 88.0% of patients achieved improved status and 57.3% of patients achieved MM status. The safety profile of eculizumab was consistent with its known profile and no new safety signals were detected. CONCLUSION: Eculizumab led to rapid and sustained achievement of MM in patients with AChR+ refractory gMG. These findings support the use of eculizumab in this previously difficult-to-treat patient population. CLINICALTRIALSGOV IDENTIFIER: REGAIN, NCT01997229; REGAIN open-label extension, NCT02301624. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, after 26 weeks of eculizumab treatment, 25.0% of adults with AChR+ refractory gMG achieved MM, compared with 13.3% who received placebo

Minimal Symptom Expression' in Patients With Acetylcholine Receptor Antibody-Positive Refractory Generalized Myasthenia Gravis Treated With Eculizumab

The efficacy and tolerability of eculizumab were assessed in REGAIN, a 26-week, phase 3, randomized, double-blind, placebo-controlled study in anti-acetylcholine receptor antibody-positive (AChR+) refractory generalized myasthenia gravis (gMG), and its open-label extension

Novel Role of PPAR-Gamma in GM-CSF Induced Anti-Tumor Immunity

Granulocyte macrophage colony stimulating factor (GM-CSF) mediates context dependent anti- or pro-inflammatory functions through cells of the myeloid lineage. GM-CSF signaling induces the expression of the transcription factor peroxisome proliferator-activated receptor gamma (PPAR-γ). We examined the role PPAR-γ in myeloid cells in the anti-tumor response to GVAX, a GM-CSF based cancer immunotherapy using the B16 model of murine melanoma. We found that selective loss of PPAR-γ in the myeloid lineage using LysM-Cre reduces the efficacy of GVAX which could not be explained by known mechanisms. RNASeq of GVAX draining lymph node identified an increase in regulatory T-cells markers such as FoxP3 and coinhibitory receptors CTLA-4 and TIGIT in LysM-Cre; PPAR-γ fl mice (PPAR-γ KO). We confirmed by flow cytometry that Treg frequency was indeed increased in PPAR-γ KO lymph node with a strong reduction seen in the ratio of CD8 T-cells to regulatory T cell (CD8:Treg). Treg recruiting chemokines CCL17 and CCL22 were upregulated in the draining lymph node. Importantly, tumors in PPAR-γ KO mice had a reduced CD8:Treg ratio explaining the loss in GVAX efficacy. Pharmacological activation or inactivation of PPAR-γ in GM-CSF treated human PBMC showed conservation of the role of PPAR-γ in regulating T-cell numbers in humans. PPAR-γ agonism in mice, using the FDA-approved small molecule ligand rosiglitazone (Rosi), improved CD8:Treg ratios in the vaccine draining lymph node and tumors. The gain-of-function data suggested the Rosi could be used as an adjunct to immunotherapy. All intratumoral Treg expressed high levels of CTLA-4 and TIGIT. Thus, we tested the impact of Rosi on the response to GVAX and anti-CTLA-4 combination therapy. We found that Rosi improved the tumor incidence and overall survival of tumor bearing mice treated with GVAX and anti-CTLA4. Our data have identified a novel role of PPAR-γ in myeloid cells in regulating Treg numbers. This pathway is conserved in humans as seen in ex-vivo studies of PBMC. Further, we provide preclinical evidence that Rosi can be used to improve immunotherapeutic responses by increasing the ratio between intratumoral effector and regulatory cells

How to choose antibodies to visualize cells

Searching for antibodies and wondering how to choose? This flowchart describes the applications that can help you visualize cells and tissues, the different fixatives and how to choose antibodies. A companion blogpost and ReFigure with images of what your data will look like are in the References<div><br></div

Whole cell cancer vaccines

This is a lay cartoon to explain whole cell cancer vaccine

Human organ chips for regenerative pharmacology

Abstract Human organs‐on‐chips (organ chips) are small microfluidic devices that allow human cells to perform complex organ‐level functions in vitro by recreating multi‐cellular and multi‐tissue structures and applying in vivo‐like biomechanical cues. Human Organ Chips are being used for drug discovery and toxicology testing as an alternative to animal models which are ethically challenging and often do not predict clinical efficacy or toxicity. In this mini‐review, we summarize our presentation that reviewed the state of the art relating to these microfluidic culture devices designed to mimic specific human organ structures and functions, and the application of Organ Chips to regenerative pharmacology

Application of indigenous continuous positive airway pressure during one lung ventilation for thoracic surgery

During one lung ventilation (OLV) hypoxemia may occur due to ventilation-perfusion mismatch. It can be prevented with application of ventilation strategy that prevents atelectasis while minimally impairing perfusion of the dependant lung. Here, two cases are reported who required OLV and in whom hypoxemia could be prevented with the application of continuous positive airway pressure to the deflated or non-dependant lung, using an indigenous technique. We suggest use of this technique which is easy to be employed during the intraoperative period