Heat shock protein 90 associates with Toll‐like receptors 7/9 and mediates self‐nucleic acid recognition in SLE

Systemic lupus erythematosus (SLE) is a prototype systemic autoimmune disease, and disease activity is associated with serum IFN‐α level. Plasmacytoid dendritic cells (pDCs) sense microbial as well as self‐nucleic acids by TLRs 7 and 9 and produce a large amount of IFN‐α. Here, we show that heat shock protein 90 (Hsp90) associates with and delivers TLR7/9 from the ER to early endosomes for ligand recognition. Inhibition of Hsp90 by various approaches including the use of Hsp90 inhibitor, a geldanamycin derivative, suppressed the Hsp90 association with TLR7/9, which resulted in inhibition of IFN‐α production, leading to improvement of SLE symptoms in mice. Notably, we observed that serum Hsp90 is clearly increased in patients with active SLE compared with that in patients with inactive disease. Furthermore, we demonstrated that serum Hsp90 detected in SLE patients binds to self‐DNA and/or anti‐DNA Ab, thus leading to stimulation of pDCs to produce IFN‐α. Our data demonstrate that Hsp90 plays a crucial role in the pathogenesis of SLE and that an Hsp90 inhibitor will therefore provide a new therapeutic approach to SLE and other nucleic acid‐related autoimmune diseases.     

Self‐priming determines high type I IFN production by plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) are responsible for the robust and immediate production of type I IFNs during viral infection. pDCs employ TLR7 and TLR9 to detect RNA and CpG motifs present in microbial genomes. CpG‐A was the first synthetic stimulus available that induced large amounts of IFN‐α (type I IFN) in pDCs. CpG‐B, however, only weakly activates pDCs to produce IFN‐α. Here, we demonstrate that differences in the kinetics of TLR9 activation in human pDCs are essential for the understanding of the functional difference between CpG‐A and CpG‐B. While CpG‐B quickly induces IFN‐α production in pDCs, CpG‐A stimulation results in delayed yet maximal IFN‐α induction. Constitutive production of low levels of type I IFN in pDCs, acting in a paracrine and autocrine fashion, turned out to be the key mechanism responsible for this phenomenon. At high cell density, pDC‐derived, constitutive type I IFN production primes pDCs for maximal TLR responsiveness. This accounts for the high activity of higher structured TLR agonists that trigger type I IFN production in a delayed fashion. Altogether, these data demonstrate that high type I IFN production by pDCs cannot be simply ascribed to cell‐autonomous mechanisms, yet critically depends on the local immune context.     

Sca‐1 expression defines developmental stages of mouse pDCs that show functional heterogeneity in the endosomal but not lysosomal TLR9 response

Plasmacytoid dendritic cells (pDCs) play an important role in innate and adaptive immunity and were shown to be identical to previously described natural interferon (IFN)‐α‐producing cells. Here, we describe two functionally distinct pDC subpopulations that are characterized by the differential expression of stem cell antigen‐1 (Sca‐1; Ly‐6A/E). Sca‐1^? pDCs are mainly found in the BM, appear first during development, show a higher proliferative activity, and represent the more precursor phenotype. Sca‐1⁺ pDCs are mostly located in secondary lymphoid organs and represent a later developmental stage. Sca‐1^? pDCs give rise to an Sca‐1⁺ subset upon activation or in response to endogenous type I IFN. Interestingly, in contrast to Sca‐1^? pDCs, Sca‐1⁺ pDCs are defective in IFN‐α production upon endosomal TLR9 stimulation, whereas lysosomal signaling via TLR9 is functional in both subsets. Gene expression analysis revealed that osteopontin is strongly upregulated in Sca‐1^? pDCs. These data provide evidence for the molecular basis of the observed functional heterogeneity, as the intracellular isoform of osteopontin couples TLR9 signaling to IFN‐α expression. Taken together, our results indicate that Sca‐1^? pDCs are an early developmental stage of pDCs with distinct innate functions representing the true murine natural IFN‐α‐producing cells.     

Type I interferon potentiates T‐cell receptor mediated induction of IL‐10‐producing CD4+ T cells

Type I interferons (IFNs) have the dual ability to promote the development of the immune response and exert an anti‐inflammatory activity. We analyzed the integrated effect of IFN‐α, TCR signal strength, and CD28 costimulation on human CD4⁺ T‐cell differentiation into cell subsets producing the anti‐ and proinflammatory cytokines IL‐10 and IFN‐γ. We show that IFN‐α boosted TCR‐induced IL‐10 expression in activated peripheral CD45RA⁺CD4⁺ T cells and in whole blood cultures. The functional cooperation between TCR and IFN‐α efficiently occurred at low engagement of receptors. Moreover, IFN‐α rapidly cooperated with anti‐CD3 stimulation alone. IFN‐α, but not IL‐10, drove the early development of type I regulatory T cells that were mostly IL‐10⁺ Foxp3^? IFN‐γ^? and favored IL‐10 expression in a fraction of Foxp3⁺ T cells. Our data support a model in which IFN‐α costimulates TCR toward the production of IL‐10 whose level can be amplified via an autocrine feedback loop.     

Sequence independent interferon‐α induction by multimerized phosphodiester DNA depends on spatial regulation of Toll‐like receptor‐9 activation in plasmacytoid dendritic cells

Single‐stranded versus multimeric phosphorothioate‐modified CpG oligodeoxynucleotides (ODNs) undergo differential endosomal trafficking upon uptake into plasmacytoid dendritic cells (pDCs), correlating with Toll‐like receptor‐9‐dependent pDC maturation/activation (single‐stranded B‐type CpG ODN) or interferon‐α (IFN‐α) induction (multimeric A‐type CpG ODN), respectively. As was recently shown, IFN‐α production, other than by CpG ODNs, can also be induced in a sequence‐independent manner by phosphodiester (PD) ODNs multimerized by 3′ poly‐guanosine (poly‐G) tails. We investigate here the type of endosomal trafficking responsible for IFN‐α induction by natural PD ODN ligands. We show that 3′ extension with poly‐G tails leads to multimerization of single‐stranded PD ODNs and to enhanced cellular uptake into pDCs. While monomeric PD ODNs, which induce CpG‐dependent Toll‐like receptor‐9 stimulation and pDC maturation/activation, localized to late endosomal/lysosomal compartments, the poly‐G multimerized PD ODNs, which induce CpG‐independent IFN‐α production, located to vesicles with a distinct, ‘early’ endosomal phenotype. We conclude that poly‐G‐mediated multimerization of natural PD ODNs allows for sequence‐independent, Toll‐like receptor‐9‐dependent IFN‐α induction in pDCs by combining three distinct effects: relative protection of sensitive PD ODNs from extracellular and intracellular DNase degradation, enhanced cellular uptake and preferential early endosomal compartmentation.     

Lipopolysaccharide (LPS)‐induced Interferon (IFN)‐gamma Production by Decidual Mononuclear Cells (DMNC) is Interleukin (IL)‐2 and IL‐12 Dependent

Citation Negishi M, Izumi Y, Aleemuzzaman S, Inaba N, Hayakawa S. Lipopolysaccharide (LPS)‐induced interferon (IFN)‐gamma production by decidual mononuclear cells (DMNC) is interleukin (IL)‐2 and IL‐12 dependent. Am J Reprod Immunol 2011; 65: 20–27 Problem Th1‐shifted immune response is believed to be harmful for successful pregnancy because of activation of maternal cytotoxic T lymphocytes and natural killer cells. However, its effects on Toll‐like receptor (TLR)‐mediated innate immune response are so far unknown and this study has been undertaken to address the issue. Method of study Decidual tissues were obtained from 16 pregnant women undergoing elective termination during the first trimester pregnancy for socioeconomic reasons. Decidual Mononuclear Cells (DMNC) were stimulated with suboptimal doses of IL‐2 and IL‐12 with/without LPS, considered to be a TLR4 ligand, for 48 hr. Productions of IFN‐γ and tumor necrosis factor (TNF)‐α in culture supernatant were measured with ELISA. Results (i) IFN‐γ production was induced with LPS alone which was strongly up‐regulated in the presence of IL‐2 and IL‐12. (ii) TNF‐α was also induced by LPS but was not affected by the presence of IL‐2 and IL‐12. Conclusion IL‐2 and IL‐12 up‐regulated the production of IFN‐γ in DMNC through increasing their susceptibility to LPS. TNF‐α production is independent of such a mechanism.     

The role of IL‐28, IFN‐γ, and TNF‐α in predicting response to pegylated interferon/ribavirin in chronic HCV patients

The primary goal of HCV therapy is to achieve a sustained virological response (SVR). Many host and viral factors influence the treatment response. Cytokines play an important role in the defense against viral infections, where successful treatment of hepatitis C depends on a complex balance between pro‐ and anti‐inflammatory responses. In the present study, we investigated the relationship between the presence and percentage of some cytokines (IL‐28, IFN‐γ, and TNF‐α) regarding different clinicopathological parameters including response to therapy in chronic HCV patients using immunohistochemical technique. This study was carried out on 64 chronic HCV patients (34 responders and 30 non‐responders). Of cases, 54% showed IL‐28 expression, which was associated with low AST (p = 0.002) and low HAI score (p = 0.006). Of cases, 67 and 45% showed IFN‐γ and TNF‐α expression, respectively, where the median percentage of TNF‐α expression was higher in grade II spotty necrosis compared to grade I. Some inflammatory cytokines expressed by intrahepatic inflammatory cells in chronic HCV patients promote inflammation and injury (pro‐inflammatory) such as TNF‐α. Other cytokines aid in resolving inflammation and injury (anti‐inflammatory) such as IL‐28. The balance between these cytokines will determine the degree of inflammatory state. None of the investigated cytokines proved its clear cut role in affecting response to therapy, however, their levels varied between responders and non‐responders for further investigations to clarify.     

CCK8 negatively regulates the TLR9‐induced activation of human peripheral blood pDCs by targeting TRAF6 signaling

Plasmacytoid dendritic cells (pDCs) are specialized in rapid and massive secretion of type I interferon in response to foreign nuclei acids. Combined with their antigen presentation capacity, this powerful functionality enables pDCs to orchestrate innate and adaptive immune responses. Cholecystokinin octapeptide (CCK8) is a potent immunomodulator, whose role in pDCs function is unknown. In this study, we found that two different cholecystokinin receptors, CCK1R and CCK2R, are expressed on human peripheral blood pDCs. Exogenous CCK8 was able to modulate the TLR‐induced activation of pDCs, including phenotypic maturation, IFN‐α synthesis and secretion, and could also regulate the potential of pDCs to induce adaptive immune responses in vitro. CCK8 inhibited TLR9‐induced activation of tumor‐necrosis factor receptor‐associated factor 6, which is an important adapter protein in activation of interferon‐regulatory factor (IRF)5 and IRF7, possibly through CCK2R, by evoking the activity of protein kinase (PK)A and reducing the activity of PKC. All these results indicate that CCK8 can inhibit the TLR9‐induced phenotypic maturation and activation of pDCs, acting through CCK2R by modulating the tumor‐necrosis factor receptor‐associated factor 6 signaling pathways.     

PolyI:C plus IL‐2 or IL‐12 induce IFN‐γ production by human NK cells via autocrine IFN‐β

NK lymphocytes and type I IFN (IFN‐α/β) are major actors of the innate anti‐viral response that also influence adaptive immune responses. We evaluated type I IFN production by human NK cells in response to polyI:C, a potent type I IFN‐inducing TLR3 agonist. PolyI:C plus IL‐2/IL‐12 induced IFN‐β (but not IFN‐α) mRNA expression and protein production by highly pure human NK cells and by the human NK cell line NK92. Neutralizing anti‐IFNAR1 or anti‐IFN‐β Ab prevented the production of IFN‐γ induced by polyI:C plus IL‐2/IL‐12. Similarly, IFN‐γ production induced by polyI:C plus IL‐12 was reduced in NK cells isolated from IFNAR1^?/? compared with WT mice. The ability of polyI:C plus IL‐12 to induce IFN‐γ production was related to an increase of TLR3, Mda5 and IFNAR expression and by an increase of STAT1 and STAT4 phosphorylation. Collectively, these data demonstrate that NK cells, in response to polyI:C plus IL‐2/IL‐12, produce IFN‐β that induce, in an autocrine manner, the production of IFN‐γ and thereby highlight that NK cells may control the outcome of protective or injurious immune responses through type I IFN secretion.     

IFN‐β therapy modulates B‐cell and monocyte crosstalk via TLR7 in multiple sclerosis patients

The implication of B lymphocytes in the immunopathology of multiple sclerosis (MS) is increasingly recognized. Here we investigated the response of B cells to IFN‐β, a first‐line therapy for relapsing‐remitting MS patients, upon stimulation with TLR. IFN‐β restored the frequency of TLR7‐induced IgM and IgG‐secreting cells in MS patients to the levels found in healthy donors, showing a specific deficiency in the TLR7 pathway. However, no difference was observed in the TLR9 response. Furthermore, in MS‐derived PBMCs, TLR7‐mediated production of IL‐6 and the ex vivo expression of B‐cell‐activating factor of the TNF family, two crucial cytokines for B‐cell differentiation and survival, were induced by IFN‐β. Depletion of monocytes, which are key producers of both IL‐6 and B‐cell‐activating factor of the TNF family, showed that TLR7‐mediated B‐cell differentiation into Ig‐secreting cells is strongly dependent on the cross‐talk between B cells and monocytes. Accordingly, impaired expression of TLR7 mRNA was observed in PBMCs and monocytes isolated from MS‐affected individuals as compared with those from healthy donors, which was rescued by IFN‐β therapy. Collectively, our data unveil a novel TLR7‐regulated mechanism in in vivo IFN‐β‐stimulated whole leukocytes that could be exploited to define new TLR7‐based strategies for the treatment of MS.     

Lipoarabinomannan‐specific TNF‐α and IFN‐γ as markers of protective immunity against tuberculosis: a cohort study in an endemic setting

Lipoarabinomannan (LAM) is a virulent factor used for entry and survival of Mycobacterium tuberculosis (Mtb) in macrophages. Although the role of LAM for the diagnosis of tuberculosis (TB) has been extensively investigated, its cytokine response during natural Mtb infection in humans is largely unknown. In this study, LAM‐specific IFN‐γ, TNF‐α, and IL‐10 levels following whole blood assay were measured in untreated pulmonary TB patients, their contacts and community controls at baseline. In treated patients and contacts, cytokines were also measured at 6 and 12 months. At entry, 52.8% and 74.8% of controls and contacts were QFT‐GIT positive, respectively. At baseline, untreated TB patients and contacts had significantly lower IFN‐γ and TNF‐α response compared to community controls (p < 0.0001). Besides, untreated patients had significantly higher TNF‐α and IL‐10 response compared to their contacts (p < 0.0001). At 6 months, contacts and treated TB patients had significantly increased INF‐γ and TNF‐α response (p < 0.0001). In TB patients, IFN‐γ increased 10‐fold following chemotherapy suggesting its potential role for treatment monitoring. The data suggests that LAM might have an anti‐inflammatory effect during clinical TB and early Mtb infection. The data also suggests that LAM‐induced IFN‐γ and TNF‐α could be used as biomarkers of protective immunity.     

BST2/Tetherin is constitutively expressed on human thymocytes with the phenotype and function of Treg cells

In contrast to peripheral plasmacytoid DCs (pDCs), thymic pDCs constitutively express low levels of IFN‐α. This leads to induction of interferon secondary genes (ISGs) in medullary thymocytes, raising the question whether IFN‐α may play a role in T‐cell development. When characterizing further differences between peripheral and thymic pDCs, we found that thymic pDCs have a phenotype consistent with an “activated signature” including expression of TNF‐α and bone marrow stromal cell antigen 2 (BST2), but no expression of ILT7. Given that BST2 is induced by IFN‐α, and IFN‐α secretion is controlled by interaction between ILT7 and BST2, this regulatory pathway is apparently lost in thymic pDCs. Further, we also show that BST2 is constitutively expressed on a subset of medullary thymocytes at the mRNA and protein level reflecting a history of IFN‐α transduced signals. The majority of BST2⁺ thymocytes express CCR5 rendering them prevalent targets for R5‐tropic HIV infection. Moreover, BST2⁺ thymocytes express Foxp3 and CD25, consistent with the phenotype of natural Treg cells, and exert suppressive activity as they impair the proliferation of autologous CD3⁺ thymocytes. Collectively, our results suggest that low levels of IFN‐α secreted by thymic pDCs play an important role in the development of natural Treg cells.     

Activated γδ T cells inhibit osteoclast differentiation and resorptive activity in vitro

Extensive evidence suggests that the immune system exerts powerful effects on bone cells, particularly in chronic disease pathologies such as rheumatoid arthritis (RA). The chronic inflammatory state in RA, particularly the excessive production of T cell‐derived proinflammatory cytokines such as tumour necrosis factor (TNF)‐α and interleukin (IL)‐17, triggers bone erosions through the increased stimulation of osteoclast formation and activity. While evidence supports a role for IL‐17 and TNF‐α secreted by conventional CD4⁺ T cells in RA, recent evidence in animal models of RA have implicated γδ T cells as a major producer of pathogenic IL‐17. However, the capacity of γδ T cells to influence osteoclast formation and activity in humans has not yet been investigated widely. To address this issue we investigated the effects of γδ T cells on osteoclast differentiation and resorptive activity. We have demonstrated that anti‐CD3/CD28‐stimulated γδ T cells or CD4⁺ T cells inhibit human osteoclast formation and resorptive activity in vitro. Furthermore, we assessed cytokine production by CD3/CD28‐stimulated γδ T cells and observed a lack of IL‐17 production, with activated γδ T cells producing abundant interferon (IFN)‐γ. The neutralization of IFN‐γ markedly restored the formation of osteoclasts from precursor cells and the resorptive activity of mature osteoclasts, suggesting that IFN‐γ is the major factor responsible for the inhibitory role of activated γδ T cells on osteoclastogenesis and resorptive activity of mature osteoclasts. Our work therefore provides new insights on the interactions between γδ T cells and osteoclasts in humans.     

IFN‐λ‐mediated IL‐12 production in macrophages induces IFN‐γ production in human NK cells

With increasing interest in alternative options to interferon‐alpha‐based treatments, IFN‐λ has shown therapeutic promise in a variety of diseases. Although the antiviral activity of IFN‐λ has been extensively studied, there is limited knowledge regarding the immunological functions of IFN‐λ and how these differ from those of other classes of IFNs. In this study, we investigated the effects of IFN‐λ on primary human NK cells, both in a direct and indirect capacity. We demonstrate that in contrast to interferon‐alpha, IFN‐λ is unable to directly stimulate NK cells, due to the absence of IFN‐λ receptor chain 1 (IFN‐λR1) on NK cells. However, IFN‐λ, in combination with TLR4 challenge, is able to induce the production of select members of the IL‐12 family of cytokines in monocyte‐derived macrophages. We further show that through macrophage‐mediated IL‐12 production, IFN‐λ is able to indirectly affect NK cells and ultimately induce IFN‐γ production.     

Axl and MerTK receptor tyrosine kinases maintain human macrophage efferocytic capacity in the presence of viral triggers

The requirement to remove apoptotic cells is equally important in homeostasis and inflammatory disease. In particular, during viral infections large quantities of infected cells undergo apoptosis and need to be efficiently cleared by phagocytes to prevent secondary necrosis. Although specific roles of several apoptotic cell sensors, such as the TAM (Tyro3, Axl, MerTK) receptor family, have been characterized in mouse models, little is known about their regulation and involvement in apoptotic cell uptake (efferocytosis) by human macrophages under inflammatory conditions. We show that whereas pro‐inflammatory stimuli consistently downregulated MerTK expression in human monocyte‐derived macrophages (MDMs), stimuli indicative of a viral infection, interferon‐α (IFN‐α) and the TLR3 ligand poly(I:C), specifically induced Axl expression and promoted binding of the bridging molecule Gas6. Axl induction by IFN‐α and poly(I:C) was associated with higher MDM efferocytic capacity compared to cells treated with other pro‐inflammatory stimuli, such as LPS and IFN‐γ. While MerTK blocking antibody uniformly suppressed apoptotic cell uptake by MDMs, Axl blocking antibody significantly reduced efferocytosis by poly(I:C)‐stimulated MDMs, but not by resting MDMs. Our observations demonstrate that Axl induction during viral infections contributes to maintaining macrophage capacity to engulf apoptotic cells, which may have important consequences for resolution of anti‐viral immune responses.     

Association of ESAT‐6/CFP‐10‐induced IFN‐γ, TNF‐α and IL‐10 with clinical tuberculosis: evidence from cohorts of pulmonary tuberculosis patients,household contacts and community controls in an endemic setting

Mycobacterium tuberculosis (Mtb) early secreted protein antigen 6 (ESAT‐6) and culture filtrate protein 10 (CFP‐10) are among candidate vaccines against tuberculosis (TB). Results of experimental animal models show that these antigens are associated with induction of strong T cell immunity [interferon (IFN)‐γ production], while others report that these proteins as virulent factors involved in pathogenicity of Mtb infection. However, the role of ESAT‐6/CFP‐10 during natural Mtb infections in humans has not been established. In this paper we present results of a longitudinal study from an Mtb‐infected human population from an endemic setting. Whole blood assay was used to determine levels of IFN‐γ, tumour necrosis factor (TNF)‐α and interleukin (IL)‐10 against rESAT‐6/CFP‐10 in TB patients, household contacts and community controls. The levels of IFN‐γ, TNF‐α and IL‐10 against rESAT‐6/CFP‐10 at baseline were significantly higher in patients and community controls than in household contacts. In patients, no significant difference was observed in the level of these cytokines before and after chemotherapy whereas, in contacts, the level of these cytokines increased significantly and progressively over time. The study shows that the levels of IFN‐γ, TNF‐α and IL‐10 against rESAT‐6/CFP‐10 are depressed during Mtb infection or exposure but are elevated during clinical TB. Our findings from a study of naturally infected human population suggest that IFN‐γ, TNF‐α and IL‐10 against rESAT‐6/CFP‐10 are markers for clinical TB but not for protective immunity.     

Innate immune responses to human rotavirus in the neonatal gnotobiotic piglet disease model

Intestinal and systemic dendritic cell (DC) frequencies, serum and small intestinal content cytokines and uptake/binding of human rotavirus (HRV) virus‐like particles (VLP) were studied in HRV acutely infected or mock‐inoculated neonatal gnotobiotic piglets. Intestinal, mesenteric lymph node (MLN) and splenic plasmacytoid DCs (pDCs), conventional DCs (cDCs) and macrophages/monocytes were assessed by flow cytometry. In infected pigs, serum and small intestinal content interferon‐α (IFN‐α) were highest, interleukin‐12 (IL‐12) was lower and IL‐10, tumour necrosis factor‐α and IL‐6 were minimal. Compared with mock‐inoculated piglets, frequencies of total intestinal DCs were higher; splenic and MLN DC frequencies were lower. Most intestinal pDCs, but few cDCs, were IFN‐α⁺ and intestinal macrophages/monocytes were negative for IFN‐α. Serum IFN‐α levels and IFN‐α⁺ intestinal pDCs were highly correlated, suggesting IFN‐α production in vivo by intestinal pDCs (r = 0·8; P < 0·01). The intestinal pDCs and cDCs, but not intestinal macrophages/monocytes, of HRV‐infected piglets showed significantly lower VLP uptake/binding compared with mock‐inoculated piglets, suggesting higher activation of pDCs and cDCs in infected piglets. Both intestinal pDCs and cDCs were activated (IFN‐α⁺ and lower VLP binding) after HRV infection, suggesting their role in induction of HRV‐specific immunity. Dose‐effects of HRV on serum IFN‐α and IFN‐α⁺ DCs were studied by infecting piglets with 100‐fold higher HRV dose. A high dose increased parameters associated with inflammation (diarrhoea, intestinal pathology) but serum IFN‐α and IFN‐α⁺ DCs were similar between both groups. The pDCs have both anti‐ and pro‐inflammatory functions. Stimulation of the anti‐inflammatory effects of pDCs after the high dose, without increasing their pro‐inflammatory impacts, may be critical to reduce further immunopathology during HRV infection.     

Direct effect of dsRNA mimetics on cancer cells induces endogenous IFN‐β production capable of improving dendritic cell function

Viral double‐stranded RNA (dsRNA) mimetics have been explored in cancer immunotherapy to promote antitumoral immune response. Polyinosine–polycytidylic acid (poly I:C) and polyadenylic–polyuridylic acid (poly A:U) are synthetic analogs of viral dsRNA and strong inducers of type I interferon (IFN). We describe here a novel effect of dsRNA analogs on cancer cells: besides their potential to induce cancer cell apoptosis through an IFN‐β autocrine loop, dsRNA‐elicited IFN‐β production improves dendritic cell (DC) functionality. Human A549 lung and DU145 prostate carcinoma cells significantly responded to poly I:C stimulation, producing IFN‐β at levels that were capable of activating STAT1 and enhancing CXCL10, CD40, and CD86 expression on human monocyte‐derived DCs. IFN‐β produced by poly I:C‐activated human cancer cells increased the capacity of monocyte‐derived DCs to stimulate IFN‐γ production in an allogeneic stimulatory culture in vitro. When melanoma murine B16 cells were stimulated in vitro with poly A:U and then inoculated into TLR3^?/? mice, smaller tumors were elicited. This tumor growth inhibition was abrogated in IFNAR1^?/? mice. Thus, dsRNA compounds are effective adjuvants not only because they activate DCs and promote strong adaptive immunity, but also because they can directly act on cancer cells to induce endogenous IFN‐β production and contribute to the antitumoral response.     

IFN‐γ against the 38‐kDa antigen of Mycobacterium tuberculosis discriminates pulmonary tuberculosis from infection and infection from exposure: evidence from a study of human population in a high endemic setting

Mycobacterium tuberculosis (Mtb) 38‐kDa antigen is an immunogenic lipoprotein that induces strong T‐cell responses in experimental animals. However, there is limited information on the role of this antigen in human population. In this article, we present the dynamics of pro‐inflammatory (IFN‐γ and TNF‐α) and anti‐inflammatory cytokine (IL‐10) against the 38 kDa in cohorts of pulmonary TB (PTB) patients, household contacts (HHCs), and community controls (CCs) in a high endemic setting. Whole blood assay was used to determine the levels of cytokines in 149 patients, 149 HHCs, and 68 CCs at baseline, 6 months, and 12 months. At baseline, the level of IFN‐γ was significantly (p < 0.0001) higher in CCs and HHCs than in untreated patients. CCs had significantly (p < 0.05) higher level of IFN‐γ than HHCs. There was no significant difference between treated and untreated patients, and there was no significant change in HHCs over 12 months. At baseline, the levels of IL‐10 and TNF‐α were significantly (p < 0.0001) higher in patients than in HHCs and CCs. No significant change was observed between treated patients and untreated patients and HHCs over time. The study shows that IFN‐γ against the 38 kDa discriminates clinical TB from infection and infection from exposure, suggesting its potential for immune protection and diagnosis.