High levels of intracellular IL-4 are expressed in circulating apoptotic T cells in patients with tuberculosis and in community controls

Anti-human Interleukin(IL)-4 Clone 8D4-8 Cross-Reacts With Myosin-9 Associated With Apoptotic Cells and Should Not Be Used for Flow Cytometry Applications Querying IL-4 Expression

Interleukin(IL)-4 is produced by T cells and other leukocytes and is a critical mediator of monocyte and B cell responses. During routine flow cytometry panel validation for the investigation of intracellular cytokines, we observed unique IL-4 expression patterns associated with the widely available monoclonal antibody 8D4-8. Namely, IL-4 (8D4-8) expression was observed in the absence of cellular activation and enhanced following staurosporine exposure. Mass spectrometry analysis of immunoprecipitates from peripheral blood lymphocytes (PBL) revealed that 8D4-8 cross-reacts with the ubiquitous cytoskeletal protein myosin-9. We confirmed these results by western blotting immunoprecipitates, using immunofluorescence among staurosporine-treated Caco-2 cells, and by surface-labeling PBL for 8D4-8 and myosin-9 and analyzing by flow cytometry. Although previously reported from several independent groups, we found no evidence to support the hypothesis that IL-4 is produced by apoptotic cells. Rather, this appears to have been myosin-9. Our data indicate clone 8D4-8 should not be used in the flow cytometric study of IL-4. Furthermore, our work calls for a reevaluation of previous flow cytometric studies that have used this clone for IL-4 analysis and highlights the importance of validation in antibody-based assays.

Cord Blood CD8+ T Cells Have a Natural Propensity to Express IL-4 in a Fatty Acid Metabolism and Caspase Activation-Dependent Manner

How T cells differentiate in the neonate may critically determine the ability of the infant to cope with infections, respond to vaccines and avert allergies. Previously, we found that naïve cord blood CD4⁺ T cells differentiated toward an IL-4-expressing phenotype when activated in the presence of TGF-β and monocyte-derived inflammatory cytokines, the latter are more highly secreted by infants who developed food allergy. Here, we show that in the absence of IL-2 or IL-12, naïve cord blood CD8⁺ T cells have a natural propensity to differentiate into IL-4-producing non-classic T_C2 cells when they are activated alone, or in the presence of TGF-β and/or inflammatory cytokines. Mechanistically, non-classic T_C2 development is associated with decreased expression of IL-2 receptor alpha (CD25) and glycolysis, and increased fatty acid metabolism and caspase-dependent cell death. Consequently, the short chain fatty acid, sodium propionate (NaPo), enhanced IL-4 expression, but exogenous IL-2 or pan-caspase inhibition prevented IL-4 expression. In children with endoscopically and histologically confirmed non-inflammatory bowel disease and non-infectious pediatric idiopathic colitis, the presence of TGF-β, NaPo, and IL-1β or TNF-α promoted T_C2 differentiation in vitro. In vivo, colonic mucosa of children with colitis had significantly increased expression of IL-4 in CD8⁺ T cells compared with controls. In addition, activated caspase-3 and IL-4 were co-expressed in CD8⁺ T cells in the colonic mucosa of children with colitis. Thus, in the context of colonic inflammation and limited IL-2 signaling, CD8⁺ T cells differentiate into non-classic T_C2 that may contribute to the pathology of inflammatory/allergic diseases in children.

Potential of immunomodulatory agents as adjunct host-directed therapies for multidrug-resistant tuberculosis

Treatment of multidrug-resistant tuberculosis (MDR-TB) is extremely challenging due to the virulence of the etiologic strains of Mycobacterium tuberculosis (M. tb), the aberrant host immune responses and the diminishing treatment options with TB drugs. New treatment regimens incorporating therapeutics targeting both M. tb and host factors are urgently needed to improve the clinical management outcomes of MDR-TB. Host-directed therapies (HDT) could avert destructive tuberculous lung pathology, facilitate eradication of M. tb, improve survival and prevent long-term functional disability. In this review we (1) discuss the use of HDT for cancer and other infections, drawing parallels and the precedent they set for MDR-TB treatment, (2) highlight preclinical studies of pharmacological agents commonly used in clinical practice which have HDT potential, and (3) outline developments in cellular therapy to promote clinically beneficial immunomodulation to improve treatment outcomes in patients with pulmonary MDR-TB. The use of HDTs as adjuncts to MDR-TB therapy requires urgent evaluation.

Mycobacterium tuberculosis effectors interfering host apoptosis signaling

Tuberculosis remains a serious human public health concern. The coevolution between its pathogen Mycobacterium tuberculosis and human host complicated the way to prevent and cure TB. Apoptosis plays subtle role in this interaction. The pathogen endeavors to manipulate the apoptosis via diverse effectors targeting key signaling nodes. In this paper, we summarized the effectors pathogen used to subvert the apoptosis, such as LpqH, ESAT-6/CFP-10, LAMs. The interplay between different forms of cell deaths, such as apoptosis, autophagy, necrosis, is also discussed with a focus on the modes of action of effectors, and implications for better TB control.

Differential expression of interleukin-4 (IL-4) and IL-4 delta 2 mRNA, but not transforming growth factor beta (TGF-beta), TGF-beta RII, Foxp3, gamma interferon, T-bet, or GATA-3 mRNA, in patients with fast and slow responses to antituberculosis treatment

This study investigated interleukin-4 (IL-4), IL-4 delta 2, transforming growth factor beta (TGF-beta), TGF-beta RII, Foxp3, GATA-3, T-bet, and gamma interferon (IFN-gamma) transcription in peripheral blood samples of adult pulmonary tuberculosis patients prior to and after 1 week of therapy. Twenty patients with positive results for sputum culture for Mycobacterium tuberculosis were enrolled and treated with directly observed short-course antituberculosis chemotherapy. Early treatment response was assessed. At the end of the intensive phase of treatment (month 2), 12 patients remained sputum culture positive (slow responders) and 8 converted to a negative culture (fast responders). Only the expression levels of IL-4 (4-fold decrease) and IL-4 delta 2 (32-fold increase) changed significantly during the first week of therapy in the 20 patients. No baseline differences were present between the responder groups, but fast responders had significantly higher IL-4 transcripts than slow responders at week 1. Fast responders showed a 19-fold upregulation and slow responders a 47-fold upregulation of IL-4 delta 2 at week 1. Only slow responders also showed a significant decrease in IL-4 expression at week 1. There were no significant differences in expression of TGF-beta, TGF-beta RII, Foxp3, IFN-gamma, and GATA-3 between the groups. These data show that differential IL-4-related gene expression in the early stage of antituberculosis treatment accompanies differential treatment responses and may hold promise as a marker for treatment effect.