The Expiry of Humira® Market Exclusivity and the Entry of Adalimumab Biosimilars in Europe: An Overview of Pricing and National Policy Measures.

Background: From October 2018, adalimumab biosimilars could enter the European market. However, in some countries, such as Netherlands, high discounts reported for the originator product may have influenced biosimilar entry. Objectives: The aim of this paper is to provide a European overview of (list) prices of originator adalimumab, before and after loss of exclusivity; to report changes in the reimbursement status of adalimumab products; and discuss relevant policy measures. Methods: Experts in European countries received a survey consisting of three parts: 1) general financing/co-payment of medicines, 2) reimbursement status and prices of originator adalimumab, and availability of biosimilars, and 3) policy measures related to the use of adalimumab. Results: In May 2019, adalimumab biosimilars were available in 24 of the 30 countries surveyed. Following introduction of adalimumab biosimilars, a number of countries have made changes in relation to the reimbursement status of adalimumab products. Originator adalimumab list prices varied between countries by a factor of 2.8 before and 4.1 after loss of exclusivity. Overall, list prices of originator adalimumab decreased after loss of exclusivity, although for 13 countries list prices were unchanged. When reported, discounts/rebates on originator adalimumab after loss of exclusivity ranged from 0% to approximately 26% (Romania), 60% (Poland), 80% (Denmark, Italy, Norway), and 80-90% (Netherlands), leading to actual prices per pen or syringe between €412 (Finland) and €50 - €99 (Netherlands). To leverage competition following entry of biosimilar adalimumab, only a few countries adopted measures specifically for adalimumab in addition to general policies regarding biosimilars. In some countries, a strategy was implemented even before loss of exclusivity (Denmark, Scotland), while others did not report specific measures. Conclusion: Even though originator adalimumab is the highest selling product in the world, few countries have implemented specific policies and practices for (biosimilar) adalimumab. Countries with biosimilars on the market seem to have competition lowering list or actual prices. Reported discounts varied widely between countries.

Type I and III Interferon in the Gut: Tight Balance between Host Protection and Immunopathology.

The intestinal mucosa forms an active interface to the outside word, facilitating nutrient and water uptake and at the same time acts as a barrier toward the highly colonized intestinal lumen. A tight balance of the mucosal immune system is essential to tolerate harmless antigens derived from food or commensals and to effectively defend against potentially dangerous pathogens. Interferons (IFN) provide a first line of host defense when cells detect an invading organism. Whereas type I IFN were discovered almost 60 years ago, type III IFN were only identified in the early 2000s. It was initially thought that type I IFN and type III IFN performed largely redundant functions. However, it is becoming increasingly clear that type III IFN exert distinct and non-redundant functions compared to type I IFN, especially in mucosal tissues. Here, we review recent progress made in unraveling the role of type I/III IFN in intestinal mucosal tissue in the steady state, in response to mucosal pathogens and during inflammation.

Intestinal Epithelial Cell Tyrosine Kinase 2 Transduces IL-22 Signals To Protect from Acute Colitis.

In the intestinal tract, IL-22 activates STAT3 to promote intestinal epithelial cell (IEC) homeostasis and tissue healing. The mechanism has remained obscure, but we demonstrate that IL-22 acts via tyrosine kinase 2 (Tyk2), a member of the Jak family. Using a mouse model for colitis, we show that Tyk2 deficiency is associated with an altered composition of the gut microbiota and exacerbates inflammatory bowel disease. Colitic Tyk2(-/-) mice have less p-STAT3 in colon tissue and their IECs proliferate less efficiently. Tyk2-deficient primary IECs show reduced p-STAT3 in response to IL-22 stimulation, and expression of IL-22-STAT3 target genes is reduced in IECs from healthy and colitic Tyk2(-/-) mice. Experiments with conditional Tyk2(-/-) mice reveal that IEC-specific depletion of Tyk2 aggravates colitis. Disease symptoms can be alleviated by administering high doses of rIL-22-Fc, indicating that Tyk2 deficiency can be rescued via the IL-22 receptor complex. The pivotal function of Tyk2 in IL-22-dependent colitis was confirmed in Citrobacter rodentium-induced disease. Thus, Tyk2 protects against acute colitis in part by amplifying inflammation-induced epithelial IL-22 signaling to STAT3.

Noncanonical Effects of IRF9 in Intestinal Inflammation: More than Type I and Type III Interferons.

The interferon (IFN)-stimulated gene factor 3 (ISGF3) transcription factor with its Stat1, Stat2, and interferon regulatory factor 9 (IRF9) subunits is employed for transcriptional responses downstream of receptors for type I interferons (IFN-I) that include IFN-α and IFN-ß and type III interferons (IFN-III), also called IFN-λ. Here, we show in a murine model of dextran sodium sulfate (DSS)-induced colitis that IRF9 deficiency protects animals, whereas the combined loss of IFN-I and IFN-III receptors worsens their condition. We explain the different phenotypes by demonstrating a function of IRF9 in a noncanonical transcriptional complex with Stat1, apart from IFN-I and IFN-III signaling. Together, Stat1 and IRF9 produce a proinflammatory activity that overrides the benefits of the IFN-III response on intestinal epithelial cells. Our results further suggest that the CXCL10 chemokine gene is an important mediator of this proinflammatory activity. We thus establish IFN-λ as a potentially anticolitogenic cytokine and propose an important role for IRF9 as a component of noncanonical Stat complexes in the development of colitis.

TRIF signaling drives homeostatic intestinal epithelial antimicrobial peptide expression.

Recent results indicate a significant contribution of innate immune signaling to maintain mucosal homeostasis, but the precise underlying signal transduction pathways are ill-defined. By comparative analysis of intestinal epithelial cells isolated from conventionally raised and germ-free mice, as well as animals deficient in the adaptor molecules MyD88 and TRIF, the TLR3 and TLR4, as well as the type I and III IFN receptors, we demonstrate significant TLR-mediated signaling under homeostatic conditions. Surprisingly, homeostatic expression of Reg3γ and Paneth cell enteric antimicrobial peptides critically relied on TRIF and, in part, TLR3 but was independent of IFN receptor signaling. Reduced antimicrobial peptide expression was associated with significantly lower numbers of Paneth cells and a reduced Paneth cell maturation and differentiation factor expression in TRIF mutant compared with wild-type epithelium. This phenotype was not transferred to TRIF-sufficient germ-free animals during cohousing. Low antimicrobial peptide expression in TRIF-deficient mice caused reduced immediate killing of orally administered bacteria but was not associated with significant alterations in the overall composition of the enteric microbiota. The phenotype was rapidly restored in a TRIF-independent fashion after transient epithelial damage. Our results identify TRIF signaling as a truly homeostatic pathway to maintain intestinal epithelial barrier function revealing fundamental differences in the innate immune signaling between mucosal homeostasis and tissue repair.

Interleukin-13-mediated paneth cell degranulation and antimicrobial peptide release.

Paneth cell-derived enteric antimicrobial peptides significantly contribute to antibacterial host defense and host-microbial homeostasis. Regulation occurs by enzymatic processing and release into the small intestinal lumen, but the stimuli involved are incompletely understood. Here, the capacity of various microbial and immune stimuli to induce antimicrobial peptide release from small intestinal tissue was systematically evaluated using antibacterial activity testing, immunostaining for Paneth cell granules and mass spectrometry. We confirmed the stimulatory activity of the muscarinic receptor agonist carbachol and the nucleotide-binding oligomerization domain ligand muramyl dipeptide. In contrast, no release of antibacterial activity was noted after treatment with the Toll-like receptor ligands poly(I:C), lipopolysaccharide or CpG, and the cytokines interleukin (IL)-15, IL-22, IL-28 and interferon-γ. Rapid Paneth cell degranulation and antimicrobial activity release, however, was observed after stimulation with the endogenous mediators IL-4 and IL-13. This process required phosphatidylinositol 3-kinase and was associated with protein kinase B phosphorylation in Paneth cells. Flow cytometric analysis confirmed expression of the IL-13 receptor α1 on isolated Paneth cells. Our findings identify a novel role of IL-13 as inducer of Paneth cell degranulation and enteric antimicrobial peptide release. IL-13 may thus contribute to mucosal antimicrobial host defense and host microbial homeostasis.

MicroRNA-146a-mediated downregulation of IRAK1 protects mouse and human small intestine against ischemia/reperfusion injury.

Intestinal ischemia/reperfusion (I/R) injury causes inflammation and tissue damage and is associated with high morbidity and mortality. Uncontrolled activation of the innate immune system through toll-like receptors (Tlr) plays a key role in I/R-mediated tissue damage but the underlying mechanisms have not been fully resolved. Here, we identify post-transcriptional upregulation of the essential Tlr signalling molecule interleukin 1 receptor-associated kinase (Irak) 1 as the causative mechanism for post-ischemic immune hyper-responsiveness of intestinal epithelial cells. Increased Irak1 protein levels enhanced epithelial ligand responsiveness, chemokine secretion, apoptosis and mucosal barrier disruption in an experimental intestinal I/R model using wild-type, Irak1(-/-) and Tlr4(-/-) mice and ischemic human intestinal tissue. Irak1 accumulation under hypoxic conditions was associated with reduced K48 ubiquitination and enhanced Senp1-mediated deSUMOylation of Irak1. Importantly, administration of microRNA (miR)-146a or induction of miR-146a by the phytochemical diindolylmethane controlled Irak1 upregulation and prevented immune hyper-responsiveness in mouse and human tissue. These findings indicate that Irak1 accumulation triggers I/R-induced epithelial immune hyper-responsiveness and suggest that the induction of miR-146a offers a promising strategy to prevent I/R tissue injury.

Sustained generation of nitric oxide and control of mycobacterial infection requires argininosuccinate synthase 1.

Nitric oxide (NO) defends against intracellular pathogens, but its synthesis must be regulated due to cell and tissue toxicity. During infection, macrophages import extracellular arginine to synthesize NO, generating the byproduct citrulline. Accumulated intracellular citrulline is thought to fuel arginine synthesis catalyzed by argininosuccinate synthase (Ass1) and argininosuccinate lyase (Asl), which would lead to abundant NO production. Instead, we find that citrulline is exported from macrophages during early stages of NO production with <2% retained for recycling via the Ass1-Asl pathway. Later, extracellular arginine is depleted, and Ass1 expression allows macrophages to synthesize arginine from imported citrulline to sustain NO output. Ass1-deficient macrophages fail to salvage citrulline in arginine-scarce conditions, leading to their inability to control mycobacteria infection. Thus, extracellular arginine fuels rapid NO production in activated macrophages, and citrulline recycling via Ass1 and Asl is a fail-safe system that sustains optimum NO production.

Age-dependent TLR3 expression of the intestinal epithelium contributes to rotavirus susceptibility.

Rotavirus is a major cause of diarrhea worldwide and exhibits a pronounced small intestinal epithelial cell (IEC) tropism. Both human infants and neonatal mice are highly susceptible, whereas adult individuals remain asymptomatic and shed only low numbers of viral particles. Here we investigated age-dependent mechanisms of the intestinal epithelial innate immune response to rotavirus infection in an oral mouse infection model. Expression of the innate immune receptor for viral dsRNA, Toll-like receptor (Tlr) 3 was low in the epithelium of suckling mice but strongly increased during the postnatal period inversely correlating with rotavirus susceptibility, viral shedding and histological damage. Adult mice deficient in Tlr3 (Tlr3(-/-)) or the adaptor molecule Trif (Trif(Lps2/Lps2)) exerted significantly higher viral shedding and decreased epithelial expression of proinflammatory and antiviral genes as compared to wild-type animals. In contrast, neonatal mice deficient in Tlr3 or Trif did not display impaired cell stimulation or enhanced rotavirus susceptibility. Using chimeric mice, a major contribution of the non-hematopoietic cell compartment in the Trif-mediated antiviral host response was detected in adult animals. Finally, a significant age-dependent increase of TLR3 expression was also detected in human small intestinal biopsies. Thus, upregulation of epithelial TLR3 expression during infancy might contribute to the age-dependent susceptibility to rotavirus infection.

Establishment of intestinal homeostasis during the neonatal period.

The intestinal mucosa faces the challenge of regulating the balance between immune tolerance towards commensal bacteria, environmental stimuli and food antigens on the one hand, and induction of efficient immune responses against invading pathogens on the other hand. This regulatory task is of critical importance to prevent inappropriate immune activation that may otherwise lead to chronic inflammation, tissue disruption and organ dysfunction. The most striking example for the efficacy of the adaptive nature of the intestinal mucosa is birth. Whereas the body surfaces are protected from environmental and microbial exposure during fetal life, bacterial colonization and contact with potent immunostimulatory substances start immediately after birth. In the present review, we summarize the current knowledge on the mechanisms underlying the transition of the intestinal mucosa during the neonatal period leading to the establishment of a stable, life-long host-microbial homeostasis. The environmental exposure and microbial colonization during the neonatal period, and also the influence of maternal milk on the immune protection of the mucosa and the role of antimicrobial peptides, are described. We further highlight the molecular mechanisms of innate immune tolerance in neonatal intestinal epithelium. Finally, we link the described immunoregulatory mechanisms to the increased susceptibility to inflammatory and infectious diseases during the neonatal period.

Cesarean delivery is associated with celiac disease but not inflammatory bowel disease in children.

The postnatal period represents a particularly dynamic phase in the establishment of the host-microbial homeostasis. The sterile protected intestinal mucosa of the fetus becomes exposed to and subsequently colonized by a complex and diverse bacterial community. Both, the exposure to microbial ligands and the bacterial colonization have been described to differ between neonates born vaginally or by cesarean delivery. These differences might influence the development of the mucosal immune system, the establishment of a stable intestinal host-microbial homeostasis, and ultimately contribute to the risk to acquire immune mediated diseases later in life. Indeed, an increased risk for atopic diseases such as allergic rhinitis and asthma was reported in children born by cesarean delivery. Our recent study described an association between cesarean delivery and celiac disease. Here we summarize the available information on postnatal microbial colonization and the influence of the mode of delivery on flora composition and host microbial homeostasis. We discuss possible consequences of the mode of delivery on epithelial barrier function and the establishment of the mucosal immune system and speculate on functional links between flora alterations and the development of inappropriate host immune responses that may contribute to enteric inflammatory diseases. 

IFN-lambda determines the intestinal epithelial antiviral host defense.

Type I and type III IFNs bind to different cell-surface receptors but induce identical signal transduction pathways, leading to the expression of antiviral host effector molecules. Despite the fact that type III IFN (IFN-λ) has been shown to predominantly act on mucosal organs, in vivo infection studies have failed to attribute a specific, nonredundant function. Instead, a predominant role of type I IFN was observed, which was explained by the ubiquitous expression of the type I IFN receptor. Here we comparatively analyzed the role of functional IFN-λ and type I IFN receptor signaling in the innate immune response to intestinal rotavirus infection in vivo, and determined viral replication and antiviral gene expression on the cellular level. We observed that both suckling and adult mice lacking functional receptors for IFN-λ were impaired in the control of oral rotavirus infection, whereas animals lacking functional receptors for type I IFN were similar to wild-type mice. Using Mx1 protein accumulation as marker for IFN responsiveness of individual cells, we demonstrate that intestinal epithelial cells, which are the prime target cells of rotavirus, strongly responded to IFN-λ but only marginally to type I IFN in vivo. Systemic treatment of suckling mice with IFN-λ repressed rotavirus replication in the gut, whereas treatment with type I IFN was not effective. These results are unique in identifying a critical role of IFN-λ in the epithelial antiviral host defense.

Conventional dendritic cells mount a type I IFN response against Candida spp. requiring novel phagosomal TLR7-mediated IFN-ß signaling.

Human fungal pathogens such as the dimorphic Candida albicans or the yeast-like Candida glabrata can cause systemic candidiasis of high mortality in immunocompromised individuals. Innate immune cells such as dendritic cells and macrophages establish the first line of defense against microbial pathogens and largely determine the outcome of infections. Among other cytokines, they produce type I IFNs (IFNs-I), which are important modulators of the host immune response. Whereas an IFN-I response is a hallmark immune response to bacteria and viruses, a function in fungal pathogenesis has remained unknown. In this study, we demonstrate a novel mechanism mediating a strong IFN-ß response in mouse conventional dendritic cells challenged by Candida spp., subsequently orchestrating IFN-α/ß receptor 1-dependent intracellular STAT1 activation and IFN regulatory factor (IRF) 7 expression. Interestingly, the initial IFN-ß release bypasses the TLR 4 and TLR2, the TLR adaptor Toll/IL-1R domain-containing adapter-inducing IFN-ß and the ß-glucan/phagocytic receptors dectin-1 and CD11b. Notably, Candida-induced IFN-ß release is strongly impaired by Src and Syk family kinase inhibitors and strictly requires completion of phagocytosis as well as phagosomal maturation. Strikingly, TLR7, MyD88, and IRF1 are essential for IFN-ß signaling. Furthermore, in a mouse model of disseminated candidiasis we show that IFN-I signaling promotes persistence of C. glabrata in the host. Our data uncover for the first time a pivotal role for endosomal TLR7 signaling in fungal pathogen recognition and highlight the importance of IFNs-I in modulating the host immune response to C. glabrata.

Dendritic cells require STAT-1 phosphorylated at its transactivating domain for the induction of peptide-specific CTL.

Phosphorylation of transcription factor STAT-1 on Y701 regulates subcellular localization whereas phosphorylation of the transactivating domain at S727 enhances transcriptional activity. In this study, we investigate the impact of STAT-1 and the importance of transactivating domain phosphorylation on the induction of peptide-specific CTL in presence of the TLR9-dependent immune adjuvant IC31. STAT-1 deficiency completely abolished CTL induction upon immunization, which was strongly reduced in animals carrying the mutation of the S727 phospho-acceptor site. A comparable reduction of CTL was found in mice lacking the type I IFN (IFN-I) receptor, whereas IFN-gamma-deficient mice behaved like wild-type controls. This finding suggests that S727-phosphorylated STAT-1 supports IFN-I-dependent induction of CTL. In adoptive transfer experiments, IFN-I- and S727-phosphorylated STAT-1 were critical for the activation and function of dendritic cells. Mice with a T cell-specific IFN-I receptor ablation did not show impaired CTL responses. Unlike the situation observed for CTL development S727-phosphorylated STAT-1 restrained proliferation of naive CD8(+) T cells both in vitro and following transfer into Rag-deficient mice. In summary, our data reveal a dual role of S727-phosphorylated STAT-1 for dendritic cell maturation as a prerequisite for the induction of CTL activity and for T cell autonomous control of activation-induced or homeostatic proliferation.

Characterization of the interferon-producing cell in mice infected with Listeria monocytogenes.

Production of type I interferons (IFN-I, mainly IFNalpha and IFNbeta) is a hallmark of innate immune responses to all classes of pathogens. When viral infection spreads to lymphoid organs, the majority of systemic IFN-I is produced by a specialized "interferon-producing cell" (IPC) that has been shown to belong to the lineage of plasmacytoid dendritic cells (pDC). It is unclear whether production of systemic IFN-I is generally attributable to pDC irrespective of the nature of the infecting pathogen. We have addressed this question by studying infections of mice with the intracellular bacterium Listeria monocytogenes. Protective innate immunity against this pathogen is weakened by IFN-I activity. In mice infected with L. monocytogenes, systemic IFN-I was amplified via IFN-beta, the IFN-I receptor (IFNAR), and transcription factor interferon regulatory factor 7 (IRF7), a molecular circuitry usually characteristic of non-pDC producers. Synthesis of serum IFN-I did not require TLR9. In contrast, in vitro-differentiated pDC infected with L. monocytogenes needed TLR9 to transcribe IFN-I mRNA. Consistent with the assumption that pDC are not the producers of systemic IFN-I, conditional ablation of the IFN-I receptor in mice showed that most systemic IFN-I is produced by myeloid cells. Furthermore, results obtained with FACS-purified splenic cell populations from infected mice confirmed the assumption that a cell type with surface antigens characteristic of macrophages and not of pDC is responsible for bulk IFN-I synthesis. The amount of IFN-I produced in the investigated mouse lines was inversely correlated to the resistance to lethal infection. Based on these data, we propose that the engagement of pDC, the mode of IFN-I mobilization, as well as the shaping of the antimicrobial innate immune response by IFN-I differ between intracellular pathogens.

Novel functions of type I interferons revealed by infection studies with Listeria monocytogenes.

Infection of cells and mice with Listeria monocytogenes stimulates production of type I interferons (IFN). These in turn sensitise the Listeria host to lethal sequelae of infection with these bacteria. Here, we summarise recent findings on the production and biological effects of type I IFN in the course of L. monocytogenes infection.

IFN-beta increases listeriolysin O-induced membrane permeabilization and death of macrophages.

Type I IFN (IFN-I) signaling is detrimental to cells and mice infected with Listeria monocytogenes. In this study, we investigate the impact of IFN-I on the activity of listeriolysin O (LLO), a pore-forming toxin and virulence protein released by L. monocytogenes. Treatment of macrophages with IFN-beta increased the ability of sublytic LLO concentrations to cause transient permeability of the plasma membrane. At higher LLO concentrations, IFN-beta enhanced the complete breakdown of membrane integrity and cell death. This activity of IFN-beta required Stat1. Perturbation of the plasma membrane by LLO resulted in activation of the p38MAPK pathway. IFN-beta pretreatment enhanced LLO-mediated signaling through this pathway, consistent with its ability to increase membrane damage. p38MAPK activation in response to LLO was independent of TLR4, a putative LLO receptor, and inhibition of p38MAPK neither enhanced nor prevented LLO-induced death. IFN-beta caused cells to express increased amounts of caspase 1 and to produce a detectable caspase 1 cleavage product after LLO treatment. Contrasting recent reports with another pore-forming toxin, this pathway did not aid cell survival as caspase 1-deficient cells were equally sensitive to lysis by LLO. Key lipogenesis enzymes were suppressed in IFN-beta-treated cells, which may exacerbate the membrane damage caused by LLO.

Stimulation of inducible nitric oxide synthase expression by beta interferon increases necrotic death of macrophages upon Listeria monocytogenes infection.

Murine macrophage death upon infection with Listeria monocytogenes was previously shown to be increased by beta interferon, produced by the infected cells. We saw that interferon-upregulated caspase activation or other interferon-inducible, death-associated proteins, including TRAIL, protein kinase R, and p53, were not necessary for cell death. Macrophage death was reduced when inducible nitric oxide synthase (iNOS) was inhibited during infection, and iNOS-deficient macrophages were less susceptible to death upon infection than wild-type cells. The production of nitric oxide correlated with increased death, while no role was seen for iNOS in control of Listeria numbers during infection of resting macrophages. This indicates that the induction of iNOS by beta interferon in cells infected with L. monocytogenes contributes to cell death. Based on morphology, the maintenance of mitochondrial membrane potential, and a lack of dependence on caspase 1, we characterize the type of cell death occurring and show that infected macrophages die by interferon-upregulated necrosis.

Type I IFN are host modulators of strain-specific Listeria monocytogenes virulence.

Type I IFN (IFN-I) increase the sensitivity of cells and mice to lethal infection with Listeria monocytogenes. Therefore the amount of IFN-I produced during infection might be an important factor determining Listeria virulence. Two commonly used strains of L. monocytogenes, EGD and LO28, were identified as, respectively, low and high inducers of IFN-I synthesis in infected macrophages. Increased IFN-I production resulted from the stronger ability of the LO28 strain to trigger the IRF3 signalling pathway and correlated with an increased sensitization of macrophages to lethal infection. In contrast, stimulation of NFkappaB, MAPK, or inflammasome signalling by the LO28 and EGD strains did not differ significantly. The LO28 strain was more virulent in wild-type (wt) C57/BL6 mice than the EGD strain whereas both strains were similarly virulent in IFN-I receptor-deficient C57/BL6 mice. Together our data suggest that isolates of wt L. monocytogenes differ in their ability to trigger the IRF3 signalling pathway and IFN-I production, and that the amount of IFN-I produced during infection is an important determinant of Listeria virulence.

Nod1 and Nod2 induce CCL5/RANTES through the NF-kappaB pathway.

The Nod-like receptor proteins Nod1 and Nod2 participate in innate immune responses against bacteria through intracellular detection of peptidoglycan, a component of bacterial cell wall. Recent evidence has demonstrated that Nod1 stimulates the release of chemokines that attract neutrophils at the site of infection, such as CXCL8/IL-8 in humans, and CXCL1/keratinocyte-derived chemokine and CXCL2/MIP-2 in mice. We aimed to determine whether Nod proteins could trigger the release of CCL5/RANTES, a chemokine known to attract a number of immune cells, but not neutrophils. Our results demonstrate that activation of both Nod1 and Nod2 results in substantial secretion of CCL5 by murine macrophages. Moreover, in vivo, the intraperitoneal injection of murine Nod1 or Nod2 agonists resulted in a rapid secretion of CCL5 into the bloodstream. We also observed that Nod-dependent secretion of CCL5 did not correlate with the induction of the interferon-beta pathway, a major signaling cascade for the activation of CCL5 by viruses. In contrast, we identified a key role of the NF-kappaB pathway in Nod-dependent stimulation of the CCL5 promoter. Together, these results identify a novel target downstream of Nod1 and Nod2, which is likely to play a key role in orchestrating the global Nod-dependent immune defense during bacterial infections.