Activation of the interleukin 6 gene by Mycobacterium tuberculosis or lipopolysaccharide is mediated by nuclear factors NF-IL6 and NF-kappa B

Modulation of Human Macrophages by Plasma from COVID-19 Patients Following BCG Vaccination: BATTLE Trial

Purpose

To analyze the interfering effect of plasma from COVID-19 convalescent adults vaccinated or not with intradermal Bacillus Calmette-Guérin (BCG) on human macrophages.

Methods

The BATTLE clinical trial (NCT04369794) was initiated in the 2020 SARS-CoV-2 pandemic to study the safety and efficacy of BCG revaccination of COVID-19 convalescent adults. We measured the expression induction of eleven COVID-19-related genes in human macrophages cultured in plasma taken from 22 BCG vaccinated and 17 placebo patients at baseline and 45 days post-intervention. Subgroup analysis was based on gender, age, job type (healthcare worker [HCW] vs non-HCW), and the presence of anosmia/dysgeusia.

Results

Compared to plasma from placebo counterparts, the plasma of BCG vaccinated patients increased the expression induction of interferon (IFN)β-1b (p = 0.042) in human macrophages. This increase was more pronounced in females and in healthcare workers (HCW) (p = 0.007 and 0.001, respectively). Interferon-induced transmembrane protein 3 (IFITM3) expression induction was increased by plasma from BCG vaccinated females, young age group, and HCWs (p = 0.004, 0.011, and 0.040, respectively). Interleukin (IL)-10 induction increased by the plasma of young BCG recipients (p = 0.008). Induction of IL-6 expression increased by non-HCW BCG recipients plasma but decreased by HCW BCG recipients plasma (p = 0.005). Baseline plasma of patients who presented with anosmia/dysgeusia at the time of admission induced lower angiotensin-converting enzyme 2 (ACE2) compared to those without the symptom (0.76 vs 0.97, p = 0.004). ACE2 expression induction significantly increased by plasma of BCG recipients if they had anosmia/dysgeusia on admission (p = 0.028).

Conclusion

The expressions of IFNβ-1b, IFITM3, IL-6, and IL-10 in human macrophages incubated with the plasma of COVID-19 convalescent patients were modulated by BCG. These modulations depended on subject-specific characteristics, including gender, age, clinical presentation (anosmia/dysgeusia), job type, and previous exposure to mycobacteria.

ER-α36 is involved in calycosin inhibition of IL-6 production in macrophages

The tumour microenvironment (TME) is crucial for tumour development and progression. Tumour-associated macrophages (TAMs) in the TME can promote tumour progression and metastasis by releasing cytokines, such as IL-6. Calycosin, a phytoestrogen that is one of the active compounds in Radix Astragali, has been shown to inhibit tumour growth and metastasis. However, the underlying mechanism by which calycosin inhibits tumour growth remains unclear. Thus, this study aimed to investigate the effect of calycosin on IL-6 production in peripheral blood mononuclear cell (PBMC)- and THP-1-derived macrophages and explore its potential mechanisms using co-immunoprecipitation, western blotting, immunofluorescence, chromatin immunoprecipitation and luciferase assays. We found that calycosin treatment substantially upregulated the expression of ER-α36, a variant of the ER, and reduced IL-6 production in macrophages. Mechanistically, ER-α36 physically interacted with NF-κBp65 and retained p65 in the cytoplasm to attenuate NF-κB function as an IL-6 transcriptional inducer. In conclusion, our result indicated that calycosin inhibited IL-6 production by enhancing ER-α36 expression and its interaction with p65, which attenuated NF-κB function as an IL-6 inducer. Therefore, calycosin can be developed as an effective agent for cancer therapy by targeting TAMs.

Isolation of Aloe saponaria-Derived Extracellular Vesicles and Investigation of Their Potential for Chronic Wound Healing

A chronic wound is caused by a failure to progress through the normal phases of wound repair in an orderly and timely manner. To induce skin regeneration while inhibiting chronic inflammation, numerous natural products, and in particular, plant-derived biomaterials, have been developed. Aloe saponaria, is known to contain flavonoid and phenolic acid compounds with anti-oxidative and anti-inflammatory properties. Here, we isolated extracellular vesicles (EVs) from Aloe saponaria by polyethylene glycol (PEG)-based precipitation and investigated their potential as a therapeutic for chronic wound healing. The Aloe saponaria-derived EVs (AS-EVs) showed no significant cytotoxicity on several cell types, despite a high level of intracellular uptake. When lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages were treated with AS-EVs, significant reductions in the expression of pro-inflammatory genes, such as interleukin-6 and interleukin-1β, were observed. Proliferation and migration of human dermal fibroblasts, as determined by the water-soluble tetrazolium salt-8 and transwell migration assay, respectively, were shown to be promoted by treatment with AS-EVs. It was also demonstrated that AS-EVs enhanced tube formation in human umbilical vein endothelial cells, indicating a stimulatory activity on angiogenesis; one of the crucial steps for effective wound healing. Collectively, our results suggest the potential of AS-EVs as a natural therapeutic for chronic wound healing.

Role of inflammation and oxidative stress in chemotherapy-induced neurotoxicity

Chemotherapeutic agents may adversely affect the nervous system, including the neural precursor cells as well as the white matter. Although the mechanisms are not completely understood, several hypotheses connecting inflammation and oxidative stress with neurotoxicity are now emerging. The proposed mechanisms differ depending on the class of drug. For example, toxicity due to cisplatin occurs due to activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), which alters hippocampal long-term potentiation. Free radical injury is also involved in the cisplatin-mediated neurotoxicity as dysregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) has been seen which protects against the free radical injury by regulating glutathione S-transferases and hemeoxygenase-1 (HO-1). Thus, correcting the imbalance between NF-κB and Nrf2/HO-1 pathways may alleviate cisplatin-induced neurotoxicity. With newer agents like bortezomib, peripheral neuropathy occurs due to up-regulation of TNF-α and IL-6 in the sensory neurons. Superoxide dismutase dysregulation is also involved in bortezomib-induced neuropathy. This article reviews the available literature on inflammation and oxidative stress in neurotoxicity caused by various classes of chemotherapeutic agents. It covers the conventional medicines like platinum compounds, vinca alkaloids, and methotrexate, as well as the newer therapeutic agents like immunomodulators and immune checkpoint inhibitors. A better understanding of the pathophysiology will lead to further advancement in strategies for management of chemotherapy-induced neurotoxicity.

IL-1β and TNFα Cooperativity in Regulating IL-6 Expression in Adipocytes Depends on CREB Binding and H3K14 Acetylation

IL-6 was found to be overexpressed in the adipose tissue of obese individuals, which may cause insulin resistance. However, the regulation of IL-6 in adipocytes in obesity setting remains to be explored. Since IL-1β and TNFα are increased in obese adipose tissue and promote inflammation, we investigated whether cooperation between IL-1β and TNFα influences the production of IL-6. Our data show that IL-1β and TNFα cooperatively enhance IL-6 expression in 3T3L-1 adipocytes. Similar results were seen in human adipocytes isolated from subcutaneous and visceral fat. Although adipocytes isolated from lean and obese adipose tissues showed similar responses for production of IL-6 when incubated with IL-1β/TNFα, secretion of IL-6 was higher in adipocytes from obese tissue. TNFα treatment enhanced CREB binding at CRE locus, which was further enhanced with IL-1β, and was associated with elevated histone acetylation at CRE locus. On the other hand, IL-1β treatments mediated C/EBPβ binding to NF-IL-6 consensus, but not sufficiently to mediate significant histone acetylation. Interestingly, treatment with both stimulatory factors amplifies CREB binding and H3K14 acetylation. Furthermore, histone acetylation inhibition by anacardic acid or curcumin reduces IL-6 production. Notably, inhibition of histone deacetylase (HDAC) activity by trichostatin A (TSA) resulted in the further elevation of IL-6 expression in response to combined treatment of adipocytes with IL-1β and TNFα. In conclusion, our results show that there is an additive interaction between IL-1β and TNFα that depends on CREB binding and H3K14 acetylation, and leads to the elevation of IL-6 expression in adipocytes, providing interesting pathophysiological connection among IL-1β, TNFα, and IL-6 in settings such as obesity.

Neuroinflammation in schizophrenia: the role of nuclear factor kappa B

Neuroinflammation, particularly in the dorsolateral prefrontal cortex, is well-established in a subset of people with schizophrenia, with significant increases in inflammatory markers including several cytokines. Yet the cause(s) of cortical inflammation in schizophrenia remains unknown. Clues as to potential microenvironmental triggers and/or intracellular deficits in immunoregulation may be gleaned from looking further upstream of effector immune molecules to transcription factors that control inflammatory gene expression. Here, we focus on the 'master immune regulator' nuclear factor kappa B (NF-κB) and review evidence in support of NF-κB dysregulation causing or contributing to neuroinflammation in patients. We discuss the utility of 'immune biotyping' as a tool to analyse immune-related transcripts and proteins in patient tissue, and the insights into cortical NF-κB in schizophrenia revealed by immune biotyping compared to studies treating patients as a single, homogenous group. Though the ubiquitous nature of NF-κB presents several hurdles for drug development, targeting this key immunoregulator with novel or repurposed therapeutics in schizophrenia is a relatively underexplored area that could aid in reducing symptoms of patients with active neuroinflammation.

Perturbation of the Actin Cytoskeleton in Human Hepatoma Cells Influences Interleukin-6 (IL-6) Signaling, but Not Soluble IL-6 Receptor Generation or NF-κB Activation

The transcription factor nuclear factor-kappa B (NF-κB) is critically involved in inflammation and cancer development. Activation of NF-κB induces the expression and release of several pro-inflammatory proteins, which include the cytokine interleukin-6 (IL-6). Perturbation of the actin cytoskeleton has been previously shown to activate NF-κB signaling. In this study, we analyze the influence of different compounds that modulate the actin cytoskeleton on NF-κB activation, IL-6 signaling and the proteolytic generation of the soluble IL-6 receptor (sIL-6R) in human hepatoma cells. We show that perturbation of the actin cytoskeleton is not sufficient to induce NF-κB activation and IL-6 secretion. However, perturbation of the actin cytoskeleton reduces IL-6-induced activation of the transcription factor STAT3 in Hep3B cells. In contrast, IL-6R proteolysis by the metalloprotease ADAM10 did not depend upon the integrity of the actin cytoskeleton. In summary, we uncover a previously unknown function of the actin cytoskeleton in IL-6-mediated signal transduction in Hep3B cells.

Studies of involvement of G-protein coupled receptor-3 in cannabidiol effects on inflammatory responses of mouse primary astrocytes and microglia

Cannabidiol (CBD) exhibits anti-inflammatory and neuroprotective properties and is suggested to be effective in the pre-clinical and clinical treatment of illnesses of the central nervous system (CNS). Two major types of CNS glial cells, astrocytes and microglia, play critical roles in the development and pathogenesis of CNS diseases. However, the mechanisms by which CBD plays an anti-inflammatory and neuroprotective role for these glial cells have not been fully elucidated. In this study, we examined the effects of CBD on the inflammatory response of mouse primary astrocytes and microglia. We also investigated whether the effect of CBD on cytokine release is mediated by the G protein coupled receptor 3 (GPR3), which was recently identified as a novel receptor for CBD. Our results showed that CBD inhibited inflammatory responses of astrocytes and microglia stimulated with lipopolysaccharide (LPS), a Toll-like receptor 4 (TLR4) ligand in vitro and in vivo. In addition, CBD reduced the phosphorylation of STAT3 and NF-κB signaling pathways in LPS-stimulated astrocytes. However, the inhibitory effect of CBD on pro-inflammatory cytokine production was independent of GPR3 expression in both types of glial cells. Thus, although CBD is effective in ameliorating the activation of astrocytes and microglia, its mechanism of action still requires further study. Our data support the concept that CBD may have therapeutic potential for neurological disorders that involve neuroinflammation.

Triptolide Modulates the Expression of Inflammation-Associated lncRNA-PACER and lincRNA-p21 in Mycobacterium tuberculosis-Infected Monocyte-Derived Macrophages

Triptolide is a diterpene triepoxide, which performs its biological activities via mechanisms including induction of apoptosis, targeting of pro-inflammatory cytokines, and reshaping of the epigenetic landscape of target cells. However, the targeting of long non-coding RNAs (lncRNAs) by triptolide has not yet been investigated, despite their emerging roles as key epigenetic regulators of inflammation and immune cell function during Mycobacterium tuberculosis (Mtb) infection. Hence, we investigated whether triptolide targets inflammation-associated lncRNA-PACER and lincRNA-p21 and how this targeting associates with Mtb killing within monocyte-derived macrophages (MDMs).Using RT-qPCR, we found that triptolide induced the expression of lincRNA-p21 but inhibited the expression of lncRNA-PACER in resting MDMs in a dose- and time-dependent manner. Moreover, Mtb infection induced the expression of lincRNA-p21 and lncRNA-PACER, and exposure to triptolide before or after Mtb infection led to further increase of Mtb-induced expression of these lncRNAs in MDMs. We further found that contrary to lncRNA-PACER, triptolide time- and dose-dependently upregulated Ptgs-2, which is a proximal gene regulated by lncRNA-PACER. Also, low-concentration triptolide inhibited the expression of cytokine IL-6, a known target of lincRNA-p21. Mtb infection induced the expression of IL-6 and Ptgs-2, and triptolide treatment further increased IL-6 but decreased Ptgs-2 expression in Mtb-infected MDMs. The inverse relation between the expression of these lncRNAs and their target genes is concordant with the conception that these lncRNAs mediate, at least partially, the cytotoxic and/or anti-inflammatory activities of triptolide in both resting and activated MDMs. Using the CFU count method, we found that triptolide decreased the intracellular growth of Mtb HN878. The alamarBlue assay showed that this decreased Mtb HN878 growth was not as a result of direct targeting of Mtb HN878 by triptolide, but rather evoking MDMs’ intracellular killing mechanisms which we speculate could include triptolide-induced enhancement of MDMs’ effector killing functions mediated by lncRNA-PACER and lincRNA-p21. Altogether, these results provide proof of the modulation of lncRNA-PACER and lincRNA-p21 expression by triptolide, and a possible link between these lncRNAs, the enhancement of MDMs’ effector killing functions and the intracellular Mtb-killing activities of triptolide. These findings prompt for further investigation of the precise contribution of these lncRNAs to triptolide-induced activities in MDMs.

Mycobacterium smegmatis Bacteria Expressing Mycobacterium tuberculosis-Specific Rv1954A Induce Macrophage Activation and Modulate the Immune Response

Mycobacterium tuberculosis (M. tb), the intracellular pathogen causing tuberculosis, has developed mechanisms that endow infectivity and allow it to modulate host immune response for its survival. Genomic and proteomic analyses of non-pathogenic and pathogenic mycobacteria showed presence of genes and proteins that are specific to M. tb. In silico studies predicted that M.tb Rv1954A is a hypothetical secretory protein that exhibits intrinsically disordered regions and possess B cell/T cell epitopes. Treatment of macrophages with Rv1954A led to TLR4-mediated activation with concomitant increase in secretion of pro-inflammatory cytokines, IL-12 and TNF-α. In vitro studies showed that rRv1954A protein or Rv1954A knock-in M. smegmatis (Ms_Rv1954A) activates macrophages by enhancing the expression of CD80 and CD86. An upregulation in the expression of CD40 and MHC I/II was noted in the presence of Rv1954A, pointing to its role in enhancing the association of APCs with T cells and in the modulation of antigen presentation, respectively. Ms_Rv1954A showed increased infectivity, induction of ROS and RNS, and apoptosis in RAW264.7 macrophage cells. Rv1954A imparted protection against oxidative and nitrosative stress, thereby enhancing the survival of Ms_Rv1954A inside macrophages. Mice immunized with Ms_Rv1954A showed that splenomegaly and primed splenocytes restimulated with Rv1954A elicited a Th1 response. Infection of Ms_Rv1954A in mice through intratracheal instillation leads to enhanced infiltration of lymphocytes in the lungs without formation of granuloma. While Rv1954A is immunogenic, it did not cause adverse pathology. Purified Rv1954A or Rv1954A knock-in M. smegmatis (Ms_Rv1954A) elicited a nearly two-fold higher titer of IgG response in mice, and PTB patients possess a higher IgG titer against Rv1954A, also pointing to its utility as a diagnostic marker for TB. The observed modulation of innate and adaptive immunity renders Rv1954A a vital protein in the pathophysiology of this pathogen.

Immunodominant Mycobacterium tuberculosis Protein Rv1507A Elicits Th1 Response and Modulates Host Macrophage Effector Functions

Mycobacterium tuberculosis (M. tb) persists as latent infection in nearly a quarter of the global population and remains the leading cause of death among infectious diseases. While BCG is the only vaccine for TB, its inability to provide complete protection makes it imperative to engineer BCG such that it expresses immunodominant antigens that can enhance its protective potential. In-silico comparative genomic analysis of Mycobacterium species identified M. tb Rv1507A as a “signature protein” found exclusively in M. tb. In-vitro (cell lines) and in-vivo experiments carried out in mice, using purified recombinant Rv1507A revealed it to be a pro-inflammatory molecule, eliciting significantly high levels of IL-6, TNF-α, and IL-12. There was increased expression of activation markers CD69, CD80, CD86, antigen presentation molecules (MHC I/MHCII), and associated Th1 type of immune response. Rv1507A knocked-in M. smegmatis also induced significantly higher pro-inflammatory Th1 response and higher survivability under stress conditions, both in-vitro (macrophage RAW264.7 cells) and in-vivo (mice). Sera derived from human TB patients showed significantly enhanced B-cell response against M. tb Rv1507A. The ability of M. tb Rv1507A to induce immuno-modulatory effect, B cell response, and significant memory response, renders it a putative vaccine candidate that demands further exploration.

Treatment of Virulent Mycobacterium tuberculosis and HIV Coinfected Macrophages with Gallium Nanoparticles Inhibits Pathogen Growth and Modulates Macrophage Cytokine Production

GaNP interrupts iron-mediated enzymatic reactions, leading to growth inhibition of virulent HIV-M. tuberculosis coinfection in macrophages, and also modulates release of cytokines that may contribute to HIV-TB pathogenesis. Macrophage-targeting GaNP are a promising therapeutic approach to provide sustained antimicrobial activity against HIV-M. tuberculosis coinfection.

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a global threat. The course of TB is negatively impacted by coexistent infection with human immunodeficiency virus type 1 (HIV). Macrophage infection with these pathogens modulates their production of pro- and anti-inflammatory cytokines, which could play a crucial role in pathogenesis. Despite the important role of macrophages in containing infection by a variety of microbes, both HIV and M. tuberculosis infect and replicate within these cells during the course of HIV-M. tuberculosis coinfection. Both M. tuberculosis and HIV require iron for growth and replication. We have previously shown that gallium encapsulated in nanoparticles, which interferes with cellular iron acquisition and utilization, inhibited the growth of HIV and an attenuated strain of M. tuberculosis within human monocyte-derived macrophages (MDMs) in vitro. Whether this was true for a fully virulent strain of M. tuberculosis and whether gallium treatment modulates cytokine production by HIV- and/or M. tuberculosis-infected macrophages have not been previously addressed. Therefore, coinfection of MDMs with HIV and a virulent M. tuberculosis strain (H37Rv) was studied in the presence of different gallium nanoparticles (GaNP). All GaNP were readily internalized by the MDMs, which provided sustained drug (gallium) release for 15 days. This led to significant growth inhibition of both HIV and M. tuberculosis within MDMs for up to 15 days after loading of the cells with all GaNP tested in our study. Cytokine analysis showed that HIV-M. tuberculosis coinfected macrophages secreted large amounts of interleukin 6 (IL-6) and IL-8 and smaller amounts of IL-1β, IL-4, and tumor necrosis factor alpha (TNF-α) cytokines. However, all GaNP were able to regulate the release of cytokines significantly. GaNP interrupts iron-mediated enzymatic reactions, leading to growth inhibition of HIV-M. tuberculosis coinfection in macrophages, and also modulates release of cytokines that may contribute to HIV-TB pathogenesis.

IMPORTANCE GaNP interrupts iron-mediated enzymatic reactions, leading to growth inhibition of virulent HIV-M. tuberculosis coinfection in macrophages, and also modulates release of cytokines that may contribute to HIV-TB pathogenesis. Macrophage-targeting GaNP are a promising therapeutic approach to provide sustained antimicrobial activity against HIV-M. tuberculosis coinfection.

Activation of Toll-like Receptor 2 (TLR2) induces Interleukin-6 trans-signaling

Signaling of the pleiotropic cytokine Interleukin-6 (IL-6) via its soluble IL-6R (sIL-6R) has been termed trans-signaling and is thought to be responsible for the pro-inflammatory properties of IL-6. The sIL-6R can be generated by alternative mRNA splicing or proteolytic cleavage of the membrane-bound IL-6R. However, which stimuli induce sIL-6R release and which endogenous signaling pathways are required for this process is poorly understood. Here, we show that activation of Toll-like receptor 2 (TLR2) on primary human peripheral blood mononuclear cells (PBMCs) and on the monocytic cell line THP-1 induces expression and secretion of IL-6 and the generation of sIL-6R. We show by flow cytometry that monocytes are a PBMC subset that expresses TLR2 in conjunction with the IL-6R and are the major cellular source for both IL-6 and sIL-6R. Mechanistically, we find that the metalloproteases ADAM10 and ADAM17 are responsible for cleavage of the IL-6R and therefore sIL-6R generation. Finally, we identify the Extracellular-signal Regulated Kinase (ERK) cascade as a critical pathway that differentially regulates both IL-6 and sIL-6R generation in monocytes.

A combined computational and experimental approach reveals the structure of a C/EBPβ-Spi1 interaction required for IL1B gene transcription

We previously reported that transcription of the human IL1B gene, encoding the proinflammatory cytokine interleukin 1β, depends on long-distance chromatin looping that is stabilized by a mutual interaction between the DNA-binding domains (DBDs) of two transcription factors: Spi1 proto-oncogene at the promoter and CCAAT enhancer-binding protein (C/EBPβ) at a far-upstream enhancer. We have also reported that the C-terminal tail sequence beyond the C/EBPβ leucine zipper is critical for its association with Spi1 via an exposed residue (Arg-232) located within a pocket at one end of the Spi1 DNA-recognition helix. Here, combining in vitro interaction studies with computational docking and molecular dynamics of existing X-ray structures for the Spi1 and C/EBPβ DBDs, along with the C/EBPβ C-terminal tail sequence, we found that the tail sequence is intimately associated with Arg-232 of Spi1. The Arg-232 pocket was computationally screened for small-molecule binding aimed at IL1B transcription inhibition, yielding l-arginine, a known anti-inflammatory amino acid, revealing a potential for disrupting the C/EBPβ-Spi1 interaction. As evaluated by ChIP, cultured lipopolysaccharide (LPS)-activated THP-1 cells incubated with l-arginine had significantly decreased IL1B transcription and reduced C/EBPβ's association with Spi1 on the IL1B promoter. No significant change was observed in direct binding of either Spi1 or C/EBPβ to cognate DNA and in transcription of the C/EBPβ-dependent IL6 gene in the same cells. These results support the notion that disordered sequences extending from a leucine zipper can mediate protein-protein interactions and can serve as druggable targets for regulating gene promoter activity.

Study of IL-6 and vitamin D3 in patients of pulmonary tuberculosis

BACKGROUND

Mycobacterium tuberculosis can grow in hostile intracellular environment of macrophages by actively evading macrophage-associated antibacterial activities. The stress response factor contributes this process by releasing inflammatory cytokine Interleukin 6 (IL-6). IL-6 screening of patients with TB may be useful to monitor the progress of infection and to infer the risk of progression to active disease. Vitamin D has a critical role in the innate immune system, in the circulating metabolite and supports induction of pleiotropic antimicrobial responses, through the production of antimicrobial peptides, particularly cathelicidin and its active metabolite. 1,25-dihydoxyvitamin D, has long been known to enhance immune response to mycobacteria. In this study, we have studied the role of IL-6 and Vitamin D3 in M. tuberculosis.

MATERIALS AND METHODS

Three groups involved in this study are Control, Category I (newly diagnosed TB) and MDR TB patients. The serum levels of IL-6 and vitamin D3 were measured using chemiluminescence and fully-automated enzyme-linked immunosorbent assay respectively.

RESULTS

The serum levels of IL-6 were significantly increased, whereas vitamin D3 decreased in TB multidrug-resistant group of patients compared to the newly diagnosed TB patients.

CONCLUSION

IL-6 appears to be the major cytokine elaborated by mycobacteria infection as well as play a role in the clinical manifestations and pathological events and hence may function as a potent biomarker of tuberculosis. Since, Vitamin D increases activity of cell-mediated immunity; it can be used as a supplementation during tuberculosis therapy.

Naegleria fowleri immunization modifies lymphocytes and APC of nasal mucosa

We investigated whether intranasal immunization with amoebic lysates plus cholera toxin modified the populations of T and B lymphocytes, macrophages and dendritic cells by flow cytometry from nose-associated lymphoid tissue (NALT), cervical lymph nodes (CN), nasal passages (NP) and spleen (SP). In all immunized groups, the percentage of CD4 was higher than CD8 cells. CD45 was increased in B cells from mice immunized. We observed IgA antibody-forming cell (IgA-AFC) response, mainly in NALT and NP. Macrophages from NP and CN expressed the highest levels of CD80 and CD86 in N. fowleri lysates with either CT or CT alone immunized mice, whereas dendritic cells expressed high levels of CD80 and CD86 in all compartment from immunized mice. These were lower than those expressed by macrophages. Only in SP from CT-immunized mice, these costimulatory molecules were increased. These results suggest that N. fowleri and CT antigens are taking by APCs, and therefore, protective immunity depends on interactions between APCs and T cells from NP and CN. Consequently, CD4 cells stimulate the differentiation from B lymphocytes to AFC IgA-positive; antibody that we previously found interacting with trophozoites in the nasal lumen avoiding the N. fowleri attachment to nasal epithelium.

Innate transcriptional effects by adjuvants on the magnitude, quality, and durability of HIV envelope responses in NHPs

Adjuvants have a critical role for improving vaccine efficacy against many pathogens, including HIV. Here, using transcriptional RNA profiling and systems serology, we assessed how distinct innate pathways altered HIV-specific antibody responses in nonhuman primates (NHPs) using 8 clinically based adjuvants. NHPs were immunized with a glycoprotein 140 HIV envelope protein (Env) and insoluble aluminum salts (alum), MF59, or adjuvant nanoemulsion (ANE) coformulated with or without Toll-like receptor 4 (TLR4) and 7 agonists. These were compared with Env administered with polyinosinic-polycytidylic acid:poly-L-lysine, carboxymethylcellulose (pIC:LC) or immune-stimulating complexes. Addition of the TLR4 agonist to alum enhanced upregulation of a set of inflammatory genes, whereas the TLR7 agonist suppressed expression of alum-responsive inflammatory genes and enhanced upregulation of antiviral and interferon (IFN) genes. Moreover, coformulation of the TLR4 or 7 agonists with alum boosted Env-binding titers approximately threefold to 10-fold compared with alum alone, but remarkably did not alter gene expression or enhance antibody titers when formulated with ANE. The hierarchy of adjuvant potency was established after the second of 4 immunizations. In terms of antibody durability, antibody titers decreased ∼10-fold after the final immunization and then remained stable after 65 weeks for all adjuvants. Last, Env-specific Fc-domain glycan structures and a series of antibody effector functions were assessed by systems serology. Antiviral/IFN gene signatures correlated with Fc-receptor binding across all adjuvant groups. This study defines the potency and durability of 8 different clinically based adjuvants in NHPs and shows how specific innate pathways can alter qualitative aspects of Env antibody function.

Thymoquinone (TQ) inhibits the replication of intracellular Mycobacterium tuberculosis in macrophages and modulates nitric oxide production

Background

Human tuberculosis, which is caused by the pathogen Mycobacterium tuberculosis, remains a major public health concern. Increasing drug resistance poses a threat of disease resurgence and continues to cause considerable mortality worldwide, which necessitates the development of new drugs with improved efficacy. Thymoquinone (TQ), an essential compound of Nigella sativa, was previously reported as an active anti-tuberculosis agent.

Methods

In this study, the effects of TQ on intracellular mycobacterial replication are examined in macrophages. In addition, its effect on mycobacteria-induced NO production and pro-inflammatory responses were investigated in Mycobacterium tuberculosis (MTB)-infected Type II human alveolar and human myeloid cell lines.

Results

TQ at concentrations ranging from 12.5 to 25 μg/mL and 6.25 to 12.5 μg/mL reduced intracellular M. tuberculosis H37Rv and extensively drug-resistant tuberculosis (XDR-TB) 72 h post-infection in RAW 264.7 cells. TQ treatment also produced a concentration-dependent reduction in nitric oxide production in both H37Rv and XDR-TB infected RAW 264.7 cells. Furthermore, TQ reduced the expression of inducible nitric oxide synthase (iNOS) and pro-inflammatory molecules such as tumor necrosis factor-alpha (TNF-α) and interlukin-6 (IL-6) in H37Rv-infected cells and eventually reduced pathogen-derived stress in host cells.

Conclusions

TQ inhibits intracellular H37Rv and XDR-TB replication and MTB-induced production of NO and pro-inflammatory molecules. Therefore, along with its anti-inflammatory effects, TQ represents a prospective treatment option to combat Mycobacterium tuberculosis infection.

Ga(III) Nanoparticles Inhibit Growth of both Mycobacterium tuberculosis and HIV and Release of Interleukin-6 (IL-6) and IL-8 in Coinfected Macrophages

Treatment of individuals coinfected with human immunodeficiency virus (HIV) type 1 and Mycobacterium tuberculosis is challenging due to the prolonged treatment requirements, drug toxicity, and emergence of drug resistance. Mononuclear phagocytes (MP; macrophages) are one of the natural reservoirs for both HIV and M. tuberculosis. Here, the treatment of HIV and M. tuberculosis coinfection was studied by preloading human macrophages with MP-targeted gallium (Ga) nanoparticles to limit subsequent simultaneous infection with both HIV and M. tuberculosis. Ga nanoparticles provided sustained drug release for 15 days and significantly inhibited the replication of both HIV and M. tuberculosis. Addition of Ga nanoparticles to MP already infected with M. tuberculosis or HIV resulted in a significant decrease in the magnitude of these infections, but the magnitude was less than that achieved with nanoparticle preloading of the MP. In addition, macrophages that were coinfected with HIV and M. tuberculosis and that were loaded with Ga nanoparticles reduced the levels of interleukin-6 (IL-6) and IL-8 secretion for up to 15 days after drug loading. Ga nanoparticles also reduced the levels of IL-6 and IL-8 secretion by ionomycin- and lipopolysaccharide-induced macrophages, likely by modulating the IκB kinase-β/NF-κB pathway. Delivery of Ga nanoparticles to macrophages is a potent long-acting approach for suppressing HIV and M. tuberculosis coinfection of macrophages in vitro and sets the stage for the development of new approaches to the treatment of these important infections.

Early Secreted Antigenic Target of 6-kDa of Mycobacterium tuberculosis Stimulates IL-6 Production by Macrophages through Activation of STAT3

As early secreted antigenic target of 6 kDa (ESAT-6) of Mycobacterium tuberculosis (Mtb) is an essential virulence factor and macrophages are critical for tuberculosis infection and immunity, we studied ESAT-6 stimulated IL-6 production by macrophages. ESAT-6 stimulated significantly higher IL-6 secretion by murine bone marrow derived macrophages (BMDM) compared to culture filtrate protein 10 kDa (CFP10) and antigen 85A. Polymyxin B, an LPS blocker, did not affect ESAT-6 stimulated macrophage IL-6 production. ESAT-6 but not Pam3CSK4 induced IL-6 by TLR2 knockout BMDM. ESAT-6 induced phosphorylation and DNA binding of STAT3 and this was blocked by STAT3 inhibitors but not by rapamycin. STAT3 inhibitors suppressed ESAT-6-induced IL-6 transcription and secretion without affecting cell viability. This was confirmed by silencing STAT3 in macrophages. Blocking neither IL-6Rα/IL-6 nor IL-10 affected ESAT-6-induced STAT3 activation and IL-6 production. Infection of BMDM and human macrophages with Mtb with esat-6 deletion induced diminished STAT3 activation and reduced IL-6 production compared to wild type and esat-6 complemented Mtb strains. Administration of ESAT-6 but not CFP10 induced STAT3 phosphorylation and IL-6 expression in the mouse lungs, consistent with expression of ESAT-6, IL-6 and phosphorylated-STAT3 in Mtb-infected mouse lungs. We conclude that ESAT-6 stimulates macrophage IL-6 production through STAT3 activation.

Discrimination between active and latent tuberculosis based on ratio of antigen-specific to mitogen-induced IP-10 production

Mycobacterium tuberculosis is the major causative agent of tuberculosis (TB). The gamma interferon (IFN-γ) release assay (IGRA) has been widely used to diagnose TB by testing cell-mediated immune responses but has no capacity for distinguishing between active TB and latent TB infection (LTBI). This study aims to identify a parameter that will help to discriminate active TB and LTBI. Whole-blood samples from 33 active TB patients, 20 individuals with LTBI, and 26 non-TB controls were applied to the commercial IFN-γ release assay, QuantiFERON-TB Gold In-Tube, and plasma samples were analyzed for interleukin-2 (IL-2), IL-6, IL-8, IL-10, IL-13, tumor necrosis factor-alpha (TNF-α), IFN-γ, monokine induced by IFN-γ (MIG), interferon gamma inducible protein 10 (IP-10), interferon-inducible T cell alpha chemoattractant (I-TAC), and monocyte chemoattractant protein 1 (MCP-1) by using a commercial cytometric bead array. The Mycobacterium tuberculosis antigen-specific production of most of the assayed cytokines and chemokines was higher in the active TB than in the LTBI group. The mitogen-induced responses were lower in the active TB than in the LTBI group. When the ratio of TB-specific to mitogen-induced responses was calculated, IL-2, IL-6, IL-10, IL-13, TNF-α, IFN-γ, MIG, and IP-10 were more useful in discriminating active TB from LTBI. In particular, most patients showed higher IP-10 production to Mycobacterium tuberculosis antigens than to mitogen at the individual level, and the ratio for IP-10 was the strongest indicator of active infection versus LTBI with 93.9% sensitivity and 90% specificity. In conclusion, the ratio of the TB-specific to the mitogen-induced IP-10 responses showed the most promising accuracy for discriminating active TB versus LTBI and should be further studied to determine whether it can serve as a biomarker that might help clinicians administer appropriate treatments.

TLR4-mediated brain inflammation halts neurogenesis: impact of hormonal replacement therapy

Experimental and epidemiological data show that the severity and the duration of brain inflammation are attenuated in females compared to males. This attenuated brain inflammation is ascribed to 17β-estradiol. However, several studies suggest that 17β-estradiol is also endowed with proinflammatory properties. The aim of the present study is to assess the effect of hormonal replacement therapies on lipopolysaccharide (LPS)-induced brain inflammation and its consequent effect on newly born neurons. Bilaterally ovariectomized rats received intrastriatal injection of LPS (250 ng/μl) and were subsequently given daily subcutaneous injections of either vehicle, 17β-estradiol (25 μg/kg) or 17β-estradiol and progesterone (5 mg/kg). Microglial activation and newly born neurons in the rostral migratory stream were monitored using double immunofluorescence. Nuclear factor κB (NFκB) signaling pathway and its target inflammatory proteins were assessed by either western blot [cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6)] or enzyme-linked immunosorbent assay [tumor necrosis factor-α (TNF-α)]. LPS-induced activation of microglia, promoted NFκB signaling pathway and enhanced the production of proinflammatory proteins (TNF-α and COX-2). These proinflammatory responses were not attenuated by 17β-estradiol injection. Supplementation of 17β-estradiol with progesterone significantly dampened these proinflammatory processes. Interestingly, LPS-induced brain inflammation dampened the number of newly born neurons in the rostral migratory stream. Administration of combined 17β-estradiol and progesterone resulted in a significantly higher number of newly born neurons when compared to those seen in rats given either vehicle or 17β-estradiol alone. These data strongly suggest that combined 17β-estradiol and progesterone, and not 17β-estradiol alone, rescues neurogenesis from the deleterious effect of brain inflammation likely via the inhibition of the signaling pathways leading to the activation of proinflammatory genes.

Three-dimensional in vitro models of granuloma to study bacteria-host interactions, drug-susceptibility, and resuscitation of dormant mycobacteria

Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium bovis, and Mycobacterium avium subsp. paratuberculosis can survive within host macrophages in a dormant state, encased within an organized aggregate of immune host cells called granuloma. Granulomas consist of uninfected macrophages, foamy macrophages, epithelioid cells, and T lymphocytes accumulated around infected macrophages. Within granulomas, activated macrophages can fuse to form multinucleated giant cells, also called giant Langhans cells. A rim of T lymphocytes surrounds the core, and a tight coat of fibroblast closes the structure. Several in vivo models have been used to study granuloma's structure and function, but recently developed in vitro models of granuloma show potential for closer observation of the early stages of host's responses to live mycobacteria. This paper reviews culture conditions that resulted in three-dimensional granulomas, formed by the adhesion of cell populations in peripheral blood mononuclear cells infected with mycobacteria. The similarities of these models to granulomas encountered in clinical specimens include cellular composition, granulomas' cytokine production, and cell surface antigens. A reliable in vitro dormancy model may serve as a useful platform to test whether drug candidates can kill dormant mycobacteria. Novel drugs that target dormancy-specific pathways may shorten the current long, difficult treatments necessary to cure mycobacterial diseases.

All-trans retinoic acid-triggered antimicrobial activity against Mycobacterium tuberculosis is dependent on NPC2

A role for vitamin A in host defense against Mycobacterium tuberculosis has been suggested through epidemiological and in vitro studies; however, the mechanism is unclear. In this study, we demonstrate that vitamin A-triggered antimicrobial activity against M. tuberculosis requires expression of NPC2. Comparison of monocytes stimulated with all-trans retinoic acid (ATRA) or 1,25-dihydroxyvitamin D3 (1,25D3), the biologically active forms of vitamin A and vitamin D, respectively, indicates that ATRA and 1,25D3 induce mechanistically distinct antimicrobial activities. Stimulation of primary human monocytes with ATRA did not result in expression of the antimicrobial peptide cathelicidin, which is required for 1,25D3 antimicrobial activity. In contrast, ATRA triggered a reduction in the total cellular cholesterol concentration, whereas 1,25D3 did not. Blocking ATRA-induced cellular cholesterol reduction inhibits antimicrobial activity as well. Bioinformatic analysis of ATRA- and 1,25D3-induced gene profiles suggests that NPC2 is a key gene in ATRA-induced cholesterol regulation. Knockdown experiments demonstrate that ATRA-mediated decrease in total cellular cholesterol content and increase in lysosomal acidification are both dependent upon expression of NPC2. Expression of NPC2 was lower in caseous tuberculosis granulomas and M. tuberculosis-infected monocytes compared with normal lung and uninfected cells, respectively. Loss of NPC2 expression ablated ATRA-induced antimicrobial activity. Taken together, these results suggest that the vitamin A-mediated antimicrobial mechanism against M. tuberculosis requires NPC2-dependent expression and function, indicating a key role for cellular cholesterol regulation in the innate immune response.

Interleukin-6: a potent biomarker of mycobacterial infection

Background

Human tuberculosis (TB), a chronic inflammatory disease is caused by Mycobacterium tuberculosis, a facultative intramacrophage pathogen. The highly complex interactions between mycobacteria and macrophages (MΦs), characterized in part by the induction and elaboration of several cytokines including IL-1, IL-6, IL-10, IL-12 p40 and IL-12 p70 are not yet fully understood. The cytokines are known to have important bearing on the pathogenesis and host defense during TB. We thus studied different patterns of cytokines elaborated by mouse peritoneal macrophages (PMs) following their interaction with live and heat-killed, virulent and avirulent, and pathogenic and non-pathogenic mycobacteria, in vitro.

Materials and methods

Pathogenic M. tuberculosis H37Rv (virulent) and M. tuberculosis H37Ra (avirulent), and non-pathogenic M. smegmatis were grown in complete Middle Brook 7H9 broth. For some experiments, mycobacteria were heat-killed (80°C; 20 min). The supernatants of cultured PMs, having ingested mycobacteria for 6 h, 24 h, 4 days and 7 days, were harvested for the quantification of IL-1, IL-6, IL-10, IL-12 p40 and IL-12 p70 by using a multiplex suspension cytokine array system.

Results

The PMs infected with heat-killed mycobacteria, as compared to their respective live counterparts, invariably elaborated significantly (p < 0.001) increased (approximately 2–3-fold) amounts of IL-6, at all the time-points studied, in vitro. Further, PMs infected with M. tuberculosis H37Ra, as compared to M. tuberculosis H37Rv, elaborated 4–5-fold more (p < 0.001) IL-6. Non-pathogenic M. smegmatis, as compared to pathogenic M. tuberculosis H37Ra and M. tuberculosis H37Rv, following infection, induced the PMs to elaborate highest (p < 0.001) amounts of IL-6 at all the time-points studied. Curiously, none of these mycobacteria-infected PMs elaborated IL-1, IL-10, IL-12 p40 and IL-12 p70, significantly.

Conclusion

IL-6 appears to be the only major cytokine elaborated by mycobacteria-infected PMs, in vitro, and thus may function as a potent biomarker of mycobacterial infection, either stand-alone or along with other cytokines.

GCN2-dependent metabolic stress is essential for endotoxemic cytokine induction and pathology

Activated inflammatory macrophages can express indoleamine 2,3-dioxygenase (IDO) and thus actively deplete their own tryptophan supply; however, it is not clear how amino acid depletion influences macrophage behavior in inflammatory environments. In this report, we demonstrate that the stress response kinase GCN2 promotes macrophage inflammation and mortality in a mouse model of septicemia. In vitro, enzymatic amino acid consumption enhanced sensitivity of macrophages to the Toll-like receptor 4 (TLR4) ligand lipopolysaccharide (LPS) with significantly increased interleukin 6 (IL-6) production. Tryptophan withdrawal induced the stress response proteins ATF4 and CHOP/GADD153; however, LPS stimulation rapidly enhanced expression of both proteins. Moreover, LPS-driven cytokine production under amino acid-deficient conditions was dependent on GCN2, as GCN2 knockout (GCN2KO) macrophages had a significant reduction of cytokine gene expression after LPS stimulation. To test the in vivo relevance of these findings, monocytic-lineage-specific GCN2KO mice were challenged with a lethal dose of LPS intraperitoneally (i.p.). The GCN2KO mice showed reduced inflammatory responses, with decreased IL-6 and IL-12 expression correlating with significant reduction in animal mortality. Thus, the data show that amino acid depletion stress signals (via GCN2) synergize with proinflammatory signals to potently increase innate immune responsiveness.

Cry1Ac protoxin from Bacillus thuringiensis promotes macrophage activation by upregulating CD80 and CD86 and by inducing IL-6, MCP-1 and TNF-α cytokines

Bacillus thuringiensis Cry1Ac protoxin (pCry1Ac) is a promising mucosal adjuvant, but its action mechanism is unknown. We examined in vivo whether pCry1Ac promotes the activation of macrophages in the peritoneum, spleen and mesenteric lymph nodes or in the lungs and bronchoalveolar lavage after intraperitoneal or intranasal pCry1Ac administration, respectively, in BALB/c mice. pCry1Ac upregulated the costimulatory molecules CD80 and CD86 in these macrophages, but with distinct kinetics. In vitro stimulation of resident macrophages with pCry1Ac upregulated CD80 and CD86 and enhanced the production of the pro-inflammatory cytokines TNF-α, IL-6 and MCP-1. To investigate whether the pCry1Ac-induced activation was mediated through MAPK pathways, we pretreated RAW 264.7 cells with signaling inhibitors of MEK, JNK and p38 MAPKs (PD98059, SP600125 and SB203580, respectively). pCry1Ac-induced upregulation of CD86 and CD80 was partially inhibited by the MEK inhibitor. While LPS-induced upregulation mechanisms of CD80 and CD86 appear to be different; as these were particularly inhibited by MEK and JNK inhibitors, respectively. pCry1Ac-induced IL-6 and MCP-1 production was especially inhibited with the p38 MAPK inhibitor, whereas TNF-α was only slightly inhibited upon treatment with JNK and p38 MAPK inhibitors. Therefore macrophage stimulation with pCry1Ac induced the upregulation of CD80 and CD86, and the production of IL-6, TNF-α and MCP-1, possibly, through the MEK and p38 MAPK pathways. It also promoted the nuclear translocation of NF-κB p50 and p65, the upregulation of MHC-II, and the activation of T CD4+ cells. These results suggest that pCry1Ac induced macrophage activation through mechanisms which differ partially from the LPS-induced.

Multifaceted Impact of Host C-C Chemokine CCL2 in the Immuno-Pathogenesis of HIV-1/M. tuberculosis Co-Infection

Active tuberculosis remains the leading cause of death among the HIV-1 seropositive individuals. Although significant success has been achieved in bringing down the number of HIV/AIDS-related mortality and morbidity following implementation of highly active anti-retroviral therapy (HAART). Yet, co-infection of Mycobacterium tuberculosis (Mtb) has posed severe clinical and preventive challenges in our efforts to eradicate the virus from the body. Both HIV-1 and Mtb commonly infect macrophages and trigger production of host inflammatory mediators that subsequently regulate the immune response and disease pathogenesis. These inflammatory mediators can impose beneficial or detrimental effects on each pathogen and eventually on host. Among these, inflammatory C–C chemokines play a central role in HIV-1 and Mtb pathogenesis. However, their role in lung-specific mechanisms of HIV-1 and Mtb interaction are poorly understood. In this review we highlight current view on the role of C–C chemokines, more precisely CCL2, on HIV-1: Mtb interaction, potential mechanisms of action and adverse clinical consequences in a setting HIV-1/Mtb co-infection. Targeting common chemokine regulators of HIV-1/Mtb pathogenesis can be an attractive and potential anti-inflammatory intervention in HIV/AIDS-related comorbidities.

Establishment and evaluation of a stable cattle type II alveolar epithelial cell line

Macrophages and dendritic cells are recognized as key players in the defense against mycobacterial infection. Recent research has confirmed that alveolar epithelial cells (AECs) also play important roles against mycobacterium infections. Thus, establishing a stable cattle AEC line for future endogenous immune research on bacterial invasion is necessary. In the present study, we first purified and immortalized type II AECs (AEC II cells) by transfecting them with a plasmid containing the human telomerase reverse trancriptase gene. We then tested whether or not the immortalized cells retained the basic physiological properties of primary AECs by reverse-transcription polymerase chain reaction and Western blot. Finally, we tested the secretion capacity of immortalized AEC II cells upon stimulation by bacterial invasion. The cattle type II alveolar epithelial cell line (HTERT-AEC II) that we established retained lung epithelial cell characteristics: the cells were positive for surfactants A and B, and they secreted tumor necrosis factor-α and interleukin-6 in response to bacterial invasion. Thus, the cell line we established is a potential tool for research on the relationship between AECs and Mycobacterium tuberculosis.

Effect of anti-tuberculosis therapy on polymorphic drug metabolizing enzyme CYP2C9 using phenytoin as a probe drug

OBJECTIVES

Patients on anti-tuberculosis therapy (ATT) are more prone to drug interactions in the presence of coexisting illnesses which warrant drug therapy. Rifampicin is a strong CYP enzyme inducer while isoniazid is a potent CYP inhibitor. The objective of the study was to find the net effect of one month ATT on CYP2C9 enzyme and to correlate it with respect to the CYP2C9 genetic polymorphisms.

MATERIALS AND METHODS

Forty eight newly diagnosed tuberculosis patients were included in the study based on the inclusion-exclusion criteria. Before commencing ATT, they were given a single dose of phenytoin 300 mg as a probe drug for CYP2C9. Blood sample was collected after three hours to carry out CYP2C9 genotyping by PCR-RFLP method. Phenotyping for CYP2C9 enzyme was done by measuring the ratio of phenytoin and its metabolite p-HPPH (para hydroxy phenyl hydantoin) by reverse phase HPLC (high performance liquid chromatography) method before and after one month of ATT.

RESULTS

In the CYP2C9*1*1 genotype, the mean plasma concentrations of phenytoin before and after one month of ATT were 5.2 ± 0.3 μg/ml and 3.5 ± 0.4 μg/ml respectively, a reduction by 33% showing significant induction (P < 0.001). There was also significant decrease in the metabolic ratio after one month of ATT from 23.2 ± 4.8 to 10.1 ± 1.9 (P < 0.001). The metabolic ratio was also observed to reduce significantly (P < 0.05) when the CYP2C9*1*2, CYP2C9*1*3, and CYP2C9*3*3 data were pooled together.

CONCLUSION

The presence of polymorphisms in the CYP2C9 gene does not affect the induction potential of ATT.

KLF4 modulates expression of IL-6 in dendritic cells via both promoter activation and epigenetic modification

The initiation and maintenance of the immune response require a coordinated regulation of signal transduction pathways. Identifying the mechanisms by which these pathways are controlled and modulated is a significant goal of immunology. In the present report, we show a novel role for the zinc finger transcription factor Kruppel-like factor 4 (KLF4) in the modulation of the inflammatory immune response via its regulation of IL-6. We analyzed the role of KLF4 in the production of IL-6 by dendritic cells. Our data indicate that KLF4 can act in a dual function manner. It acts as a transcription factor in that it can bind to and activate the IL-6 promoter at specific binding sites. KLF4 also has a role in the chromatin remodeling of the IL-6 promoter in that cells deficient in KLF4 exhibited a relative hypoacetylation. These results indicate a molecular role for KLF4 in modulating the intensity of the inflammatory response and help to explain its pleiotropic role in different settings.

An association study of TOLL and CARD with leprosy susceptibility in Chinese population

Previous genome-wide association studies (GWASs) identified multiple susceptibility loci that have highlighted the important role of TLR (Toll-like receptor) and CARD (caspase recruitment domain) genes in leprosy. A large three-stage candidate gene-based association study of 30 TLR and 47 CARD genes was performed in the leprosy samples of Chinese Han. Of 4363 SNPs investigated, eight SNPs showed suggestive association (P < 0.01) in our previously published GWAS datasets (Stage 1). Of the eight SNPs, rs2735591 and rs4889841 showed significant association (P < 0.001) in an independent series of 1504 cases and 1502 controls (Stage 2), but only rs2735591 (next to BCL10) showed significant association in the second independent series of 938 cases and 5827 controls (Stage 3). Rs2735591 showed consistent association across the three stages (P > 0.05 for heterogeneity test), significant association in the combined validation samples (P_corrected = 5.54 × 10⁻⁴ after correction for 4363 SNPs tested) and genome-wide significance in the whole GWAS and validation samples (P = 1.03 × 10⁻⁹, OR = 1.24). In addition, we demonstrated the lower expression of BCL10 in leprosy lesions than normal skins and a significant gene connection between BCL10 and the eight previously identified leprosy loci that are associated with NFκB, a major regulator of downstream inflammatory responses, which provides further biological evidence for the association. We have discovered a novel susceptibility locus on 1p22, which implicates BCL10 as a new susceptibility gene for leprosy. Our finding highlights the important role of both innate and adaptive immune responses in leprosy.

Characterization of NLRP12 during the in vivo host immune response to Klebsiella pneumoniae and Mycobacterium tuberculosis

The majority of nucleotide binding domain leucine rich repeats-containing (NLR) family members has yet to be functionally characterized. Of the described NLRs, most are considered to be proinflammatory and facilitate IL-1β production. However, a newly defined sub-group of NLRs that function as negative regulators of inflammation have been identified based on their abilities to attenuate NF-κB signaling. NLRP12 (Monarch-1) is a prototypical member of this sub-group that negatively regulates both canonical and noncanonical NF-κB signaling in biochemical assays and in colitis and colon cancer models. The role of NLRP12 in infectious diseases has not been extensively studied. Here, we characterized the innate immune response of Nlrp12^−/− mice following airway exposure to LPS, Klebsiella pneumoniae and Mycobacterium tuberculosis. In response to E. coli LPS, Nlrp12^−/− mice showed a slight decrease in IL-1β and increase in IL-6 production, but these levels were not statistically significant. During K. pneumoniae infection, we observed subtle differences in cytokine levels and significantly reduced numbers of monocytes and lymphocytes in Nlrp12^−/− mice. However, the physiological relevance of these findings is unclear as no overt differences in the development of lung disease were observed in the Nlrp12^−/− mice. Likewise, Nlrp12^−/− mice demonstrated pathologies similar to those observed in the wild type mice following M. tuberculosis infection. Together, these data suggest that NLRP12 does not significantly contribute to the in vivo host innate immune response to LPS stimulation, Klebsiella pneumonia infection or Mycobacterium tuberculosis.

1-Dehydro-[10]-gingerdione from ginger inhibits IKKβ activity for NF-κB activation and suppresses NF-κB-regulated expression of inflammatory genes

BACKGROUND AND PURPOSE

Pungent constituents of ginger (Zingiber officinale) have beneficial effects on inflammatory pain and arthritic swelling. However, the molecular basis for these pharmacological properties is only partially understood. Here, we investigated the molecular target of 1-dehydro-[10]-gingerdione (D10G), one of the pungent constituents of ginger, that mediates its suppression of NF-κB-regulated expression of inflammatory genes linked to toll-like receptor (TLR)-mediated innate immunity.

EXPERIMENTAL APPROACH

RAW 264.7 macrophages or primary macrophages-derived from bone marrows of C57BL/6 or C3H/HeJ mice were stimulated with the TLR4 agonist LPS in the presence of D10G. Catalytic activity of inhibitory κB (IκB) kinase β (IKKβ) was determined by a kinase assay and immunoblot analysis, and the expression of inflammatory genes by RT-PCR analysis and a promoter-dependent reporter assay.

KEY RESULTS

D10G directly inhibited the catalytic activity of cell-free IKKβ. Moreover, D10G irreversibly inhibited cytoplasmic IKKβ-catalysed IκBα phosphorylation in macrophages activated by TLR agonists or TNF-α, and also IKKβ vector-elicited NF-κB transcriptional activity in these cells. These effects of D10G were abolished by substitution of the Cys(179) with Ala in the activation loop of IKKβ, indicating a direct interacting site of D10G. This mechanism was shown to mediate D10G-induced disruption of NF-κB activation in LPS-stimulated macrophages and the suppression of NF-κB-regulated gene expression of inducible NOS, COX-2 and IL-6.

CONCLUSION AND IMPLICATIONS

This study demonstrates that IKKβ is a molecular target of D10G involved in the suppression of NF-κB-regulated gene expression in LPS-activated macrophages; this suggests D10G has therapeutic potential in NF-κB-associated inflammation and autoimmune disorders.

Arc of a vicious circle: pathways activated by Mycobacterium tuberculosis that target the HIV-1 long terminal repeat

In this review, we examine how a subset of signal transduction cascades initiated by Mycobacterium tuberculosis (Mtb) infection modulates transcription mediated by the human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR). We describe two distinct phases of signaling that target transcription factors known to bind the HIV-1 LTR, and thus drive viral transcription and replication, in cells of the Mtb-infected host. First, Mtb-derived molecules, including cell wall components and DNA, interact with a number of host pattern recognition receptors. Second, cytokines and chemokines secreted in response to Mtb infection initiate signal transduction cascades through their cognate receptors. Given the variation in cell wall components among distinct clinical Mtb strains, the initial pattern recognition receptor interaction leading to direct LTR activation and differential cytokine and chemokine production is likely to be an important aspect of Mtb strain-specific regulation of HIV-1 transcription and replication. Improved understanding of these molecular mechanisms in the context of bacterial and host genetics should provide key insights into the accelerated viral replication and disease progression characteristic of HIV/TB coinfection.

Inhibition by cigarette smoke of nuclear factor-κB-dependent response to bacteria in the airway

Although individuals exposed to cigarette smoke are more susceptible to respiratory infection, the effects of cigarette smoke on pulmonary defense are incompletely understood. Based on the observation that interactions between bacteria and host cells result in the expression of critical defense genes regulated by NF-κB, we hypothesized that cigarette smoke alters NF-κB function. In this study, primary human tracheobronchial epithelial cells were treated with cigarette smoke extract (CSE) and exposed to Haemophilus influenzae, and the effects of CSE on bacteria-induced signaling and gene expression were assessed. CSE inhibited high concentrations of induced NF-κB activation and the consequent expression of defense genes that occurred in airway epithelial cells in response to H. influenzae. This decreased activation of NF-κB was not attributable to cell loss or cytotoxicity. Glutathione augmentation of epithelial cells decreased the effects of CSE on NF-κB-dependent responses, as well as the effects on the inhibitor of κB and the inhibitor of κB kinase, which are upstream NF-κB regulators, suggesting the involvement of reactive oxygen species. The relevance of these findings for lung infection was confirmed using a mouse model of H. influenzae airway infection, in which decreased NF-κB pathway activation, keratinocyte chemoattractant (KC) chemokine expression, and neutrophil recruitment occurred in animals exposed to cigarette smoke. The results indicate that although cigarette smoke can cause inflammation in the lung, exposure to smoke inhibits the robust pulmonary defense response to H. influenzae, thereby providing one explanation for the increased susceptibility to respiratory bacterial infection in individuals exposed to cigarette smoke.

Expression of the Mycobacterium tuberculosis PPE37 protein in Mycobacterium smegmatis induces low tumour necrosis factor alpha and interleukin 6 production in murine macrophages

PPE37 is a member of the Mycobacterium tuberculosis proline-proline-glutamic acid (PPE) multigene family. Its expression is upregulated in bacteria that are phagocytosed by macrophages and is enhanced even more in bacteria isolated from the lungs of infected mice. This raises the possibility that PPE37 may play a role in the virulence of M. tuberculosis and led to this investigation of the function of PPE37. Recombinant bacterial strains, one expressing the M. tuberculosis PPE37 protein (Ms_ppe37) and another harbouring the vector alone (Ms_vec) were generated from the non-pathogenic Mycobacterium smegmatis. These bacterial strains were used to infect peritoneal exudate and bone marrow-derived macrophages. It was found that, despite the comparable intracellular survival between the two recombinant M. smegmatis strains, Ms_ppe37 induced a significantly lower level of tumour necrosis factor alpha and interleukin 6 in the infected macrophages compared with Ms_vec. Western blot analyses revealed that the activation levels of nuclear factor kappa B, mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase and MAPK/p38 were lower in macrophages infected with Ms_ppe37 than in macrophages infected with Ms_vec. These results suggest that PPE37 may have a potential role in interfering with the pro-inflammatory cytokine response of infected macrophages.

Calcitonin gene-related peptide as a regulator of neuronal CaMKII-CREB, microglial p38-NFκB and astroglial ERK-Stat1/3 cascades mediating the development of tolerance to morphine-induced analgesia

Tolerance to morphine-induced analgesia is an intractable phenomenon, often hindering its prolonged applications in the clinics. The enhanced pronociceptive actions of spinal pain-related molecules such as calcitonin gene-related peptide (CGRP) may underlie this phenomenon and could be a promising target for intervention. We demonstrate here how CGRP regulates the development of morphine analgesic tolerance at the spinal level. A 7-day treatment with morphine led to tolerance to its analgesic effects and enhanced expression of CGRP and its receptor subunits calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1). Activation of several cell-type-specific kinase transcription factor cascades is required to mediate this tolerance, including calcium/calmodulin-dependent protein kinase II (CaMKII) and cAMP response element-binding protein (CREB) in neurons, p38 and nuclear factor kappa B (NFκB) in microglia and extracellular signal-regulated protein kinase (ERK) and signal transducer and activator of transcription 1 and 3 (Stat1/3) in astrocytes, because inhibitors of CaMKII, p38 and ERK pathways correspondingly reduced the increases in phosphorylated CREB, acetylated-NFκB and phosphorylated Stat1/3 levels and attenuated the development of tolerance. Interestingly, these cascades were linked to the regulation of glutamatergic N-methyl-d-aspartate (NMDA) receptor expression. Chronic morphine-induced behavioural responses and biochemical events were all subjugated to modulation by disrupting CGRP receptor signaling. Together, these data suggest that CGRP contributes to the development of tolerance to morphine-induced analgesia by regulating the activation of the neuronal CaMKII-CREB, microglial p38-NFκB and astroglial ERK-Stat1/3 cascades. Targeting CGRP-associated signaling molecules may prolong or restore morphine's analgesic properties upon a chronic exposure.

STAT3, p38 MAPK, and NF-kappaB drive unopposed monocyte-dependent fibroblast MMP-1 secretion in tuberculosis

Tissue destruction characterizes infection with Mycobacterium tuberculosis (Mtb). Type I collagen provides the lung's tensile strength, is extremely resistant to degradation, but is cleaved by matrix metalloproteinase (MMP)-1. Fibroblasts potentially secrete quantitatively more MMP-1 than other lung cells. We investigated mechanisms regulating Mtb-induced collagenolytic activity in fibroblasts in vitro and in patients. Lung fibroblasts were stimulated with conditioned media from Mtb-infected monocytes (CoMTb). CoMTb induced sustained increased MMP-1 (74 versus 16 ng/ml) and decreased tissue inhibitor of metalloproteinase (TIMP)-1 (8.6 versus 22.3 ng/ml) protein secretion. CoMTb induced a 2.7-fold increase in MMP-1 promoter activation and a 2.5-fold reduction in TIMP-1 promoter activation at 24 hours (P = 0.01). Consistent with this, TIMP-1 did not co-localize with fibroblasts in patient granulomas. MMP-1 up-regulation and TIMP-1 down-regulation were p38 (but not extracellular signal-regulated kinase or c-Jun N-terminal kinase) mitogen-activated protein kinase-dependent. STAT3 phosphorylation was detected in fibroblasts in vitro and in tuberculous granulomas. STAT3 inhibition reduced fibroblast MMP-1 secretion by 60% (P = 0.046). Deletion of the MMP-1 promoter NF-κB-binding site abrogated promoter induction in response to CoMTb. TNF-α, IL-1β, or Oncostatin M inhibition in CoMTb decreased MMP-1 secretion by 65, 63, and 25%, respectively. This cytokine cocktail activated the same signaling pathways in fibroblasts and induced MMP-1 secretion similar to that induced by CoMTb. This study demonstrates in a cellular model and in patients with tuberculosis that in addition to p38 and NF-κB, STAT3 has a key role in driving fibroblast-dependent unopposed MMP-1 production that may be key in tissue destruction in patients.

Reduced Th17 response in patients with tuberculosis correlates with IL-6R expression on CD4+ T Cells

RATIONALE

Although it is well recognized that CD4(+) T cells and T helper (Th) 1 cytokines are critical in the cell-mediated response to Mycobacterium tuberculosis, it is also clear that this immunity alone is not enough. Understanding the roles of other T cell subsets and cytokines is essential for vaccine design and clinical immunotherapy against tuberculosis (TB).

OBJECTIVES

To investigate the clinical significance and possible regulatory mechanism of Th17 responses in human TB.

METHODS

The frequencies of IFN-gamma-, IL-4-, IL-17-, FoxP3- and IL-6 receptor (IL-6R)-expressing CD4(+) T cells in blood and/or pleural effusion samples of healthy donors, subjects with latent TB infection, and patients with active TB were analyzed by flow cytometry. Cytokines, transforming growth factor-beta and IL-6, in plasma and pleural fluid samples were determined by ELISA.

MEASUREMENTS AND MAIN RESULTS

The frequency of Th17 cells in patients with active TB is significantly lower than those in healthy donors and individuals with latent TB infection. Correlation analysis showed that reduced Th17 responses observed in patients with active TB was significantly correlated with the decreased expression of IL-6R on CD4(+) T cells, but did not correlate with the concentrations of the cytokines, transforming growth factor-beta and IL-6. Consistently; in vitro study showed that M. tuberculosis products inhibit the expression of IL-6R on CD4(+) T cells.

CONCLUSIONS

Our results demonstrate that reduced Th17 responses were associated with the clinical outcome of M. tuberculosis infection. Suppression of Th17 response through down-regulation of IL-6R expression may be an important mechanism in the development of active TB.

MADD, a splice variant of IG20, is indispensable for MAPK activation and protection against apoptosis upon tumor necrosis factor-alpha treatment

We investigated the physiological role of endogenous MAPK-activating death domain-containing protein (MADD), a splice variant of the IG20 gene, that can interact with TNFR1 in tumor necrosis factor-alpha (TNFalpha)-induced activation of NF-kappaB, MAPK, ERK1/2, JNK, and p38. Using exon-specific short hairpin RNAs expressing lentiviruses, we knocked down the expression of all IG20 splice variants or MADD, which is overexpressed in cancer cells. Abrogation of MADD expression rendered cells highly susceptible to TNFalpha-induced apoptosis in the absence of cycloheximide. It also resulted in a dramatic loss in TNFalpha-induced activation of MAPK without any apparent effect on NF-kappaB activation. This observation was substantiated by an accompanying loss in the activation of p90RSK, a key downstream target of MAPK, whereas the NF-kappaB-regulated interleukin 6 levels remained unaffected. Endogenous MADD knockdown, however, did not affect epidermal growth factor-induced MAPK activation thereby demonstrating the specific requirement of MADD for TNF receptor-mediated MAPK activation. Re-expression of short hairpin RNA-resistant MADD in the absence of endogenous IG20 expression rescued the cells from TNFalpha-induced apoptosis. The requirement for MADD was highly specific for TNFalpha-induced activation of MAPK but not the related JNK and p38 kinases. Loss of MADD expression resulted in reduced Grb2 and Sos1/2 recruitment to the TNFR1 complex and decreased Ras and MEKK1/2 activation. These results demonstrate the essential role of MADD in protecting cancer cells from TNFalpha-induced apoptosis by specifically activating MAPKs through Grb2 and Sos1/2 recruitment, and its potential as a novel cancer therapeutic target.

Interleukin-6 blood levels in sensitive and multiresistant tuberculosis

BACKGROUND

Interleukin-6 (IL-6) is a proinflammatory cytokine implicated in the immunopathogenesis of tuberculosis (TB). Multidrug resistance in tuberculosis is recognized worldwide as an important public health issue. The mechanism underlying TB pathogenesis in general and drug resistance in particular is not well understood, but it may be that IL-6 is one factor that enhances pathology in drug-resistant TB. The purpose of this study was to identify patterns of IL-6 production in active pulmonary TB with different sensitivity to standard drug therapy.

PATIENTS AND METHODS

IL-6 blood levels were studied in 38 patients with active pulmonary TB: 23 patients were very sensitive to specific chemotherapy (STB), and 15 were multiresistant (MDRTB). An ELISA assay (Biossource) was used to quantify IL-6 in the sera of 38 TB patients and 63 healthy blood donors.

RESULTS

The STB group was composed of 16 males (73.9%) and 7 females, MDRTB by 9 males (60%) and 6 females, and control group by 51 males (81%) and 12 females. The results showed a significant increase in IL-6 concentration in TB (median = 4.3 pg/ml, range 0.5-24) compared to that of healthy individuals (median = 0.5 pg/ml, range 0-2.8, p < 0.001). Additionally, IL-6 concentrations were increased in both STB (median = 4.1 pg/ml, range 0.5-24) and MDRTB (median = 5.1 pg/ml, range 0.5-12) groups in relation to controls (p < 0.001). In contrast, significant differences were not observed between STB and MDRTB groups (p > 0.05).

CONCLUSION

IL-6 levels were increased in pulmonary tuberculosis, independent of drug resistance.

Ah receptor and NF-kappaB interplay on the stage of epigenome

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that belongs to the basic helix-loop-helix/Per-ARNT-Sim (bHLH-PAS) family. Its ligands include many natural and synthetic compounds, some of which, such as polyhalogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons, are important environmental contaminants. NF-kappaB is a pleiotropic factor that regulates many physiological and pathophysiological processes including the immune and inflammatory responses. In the past decade, accumulating evidence suggests close interactions between AhR and NF-kappaB pathways, and these interactions are potentially important mechanisms for many pathological processes such as the chemical-induced immune dysfunctions, carcinogenesis and alteration of xenobiotic metabolism and disposition. AhR-NF-kappaB interaction has become a mechanistic linchpin linking certain pathological responses induced by environmental insults. Furthermore, the AhR-NF-kappaB interaction provides basis for therapeutic applications of certain AhR ligands to treat human diseases. The effects of AhR-NF-kappaB on the epigenome are an important area that is not well understood. In this review, I highlight current research regarding the AhR-NF-kappaB(RelA) interactions with emphasis on the epigenetic impacts of these interactions on chromatin modifications and transcription elongation control.

Diarctigenin, a lignan constituent from Arctium lappa, down-regulated zymosan-induced transcription of inflammatory genes through suppression of DNA binding ability of nuclear factor-kappaB in macrophages

Diarctigenin was previously isolated as an inhibitor of nitric oxide (NO) production in macrophages from the seeds of Arctium lappa used as an alternative medicine for the treatment of inflammatory disorders. However, little is known about the molecular basis of these effects. Here, we demonstrated that diarctigenin inhibited the production of NO, prostaglandin E(2), tumor necrosis factor-alpha, and interleukin (IL)-1beta and IL-6 with IC(50) values of 6 to 12 miciroM in zymosan- or lipopolysaccharide-(LPS) activated macrophages. Diarctigenin attenuated zymosan-induced mRNA synthesis of inducible NO synthase (iNOS) and also inhibited promoter activities of iNOS and cytokine genes in the cells. Because nuclear factor (NF)-kappaB plays a pivotal role in inflammatory gene transcription, we next investigated the effect of diarctigenin on NF-kappaB activation. Diarctigenin inhibited the transcriptional activity and DNA binding ability of NF-kappaB in zymosan-activated macrophages but did not affect the degradation and phosphorylation of inhibitory kappaB (IkappaB) proteins. Moreover, diarctigenin suppressed expression vector NF-kappaB p65-elicited NF-kappaB activation and also iNOS promoter activity, indicating that the compound could directly target an NF-kappa-activating signal cascade downstream of IkappaB degradation and inhibit NF-kappaB-regulated iNOS expression. Diarctigenin also inhibited the in vitro DNA binding ability of NF-kappaB but did not affect the nuclear import of NF-kappaB p65 in the cells. Taken together, diarctigenin down-regulated zymosan- or LPS-induced inflammatory gene transcription in macrophages, which was due to direct inhibition of the DNA binding ability of NF-kappaB. Finally, this study provides a pharmacological potential of diarctigenin in the NF-kappaB-associated inflammatory disorders.