Nuocytes represent a new innate effector leukocyte that mediates type-2 immunity.

Innate immunity provides the first line of defence against invading pathogens and provides important cues for the development of adaptive immunity. Type-2 immunity-responsible for protective immune responses to helminth parasites and the underlying cause of the pathogenesis of allergic asthma-consists of responses dominated by the cardinal type-2 cytokines interleukin (IL)4, IL5 and IL13 (ref. 5). T cells are an important source of these cytokines in adaptive immune responses, but the innate cell sources remain to be comprehensively determined. Here, through the use of novel Il13-eGFP reporter mice, we present the identification and functional characterization of a new innate type-2 immune effector leukocyte that we have named the nuocyte. Nuocytes expand in vivo in response to the type-2-inducing cytokines IL25 and IL33, and represent the predominant early source of IL13 during helminth infection with Nippostrongylus brasiliensis. In the combined absence of IL25 and IL33 signalling, nuocytes fail to expand, resulting in a severe defect in worm expulsion that is rescued by the adoptive transfer of in vitro cultured wild-type, but not IL13-deficient, nuocytes. Thus, nuocytes represent a critically important innate effector cell in type-2 immunity.

IL-33 is more potent than IL-25 in provoking IL-13-producing nuocytes (type 2 innate lymphoid cells) and airway contraction.

BACKGROUND: IL-25 and IL-33 belong to distinct cytokine families, but experimental mouse studies suggest their immunologic functions in type 2 immunity are almost entirely overlapping. However, only polymorphisms in the IL-33 pathway (IL1RL1 and IL33) have been significantly associated with asthma in large-cohort genome-wide association studies. OBJECTIVE: We sought to identify distinct pathways for IL-25 and IL-33 in the lung that might provide insight into their roles in asthma pathogenesis and potential for therapeutic intervention. METHODS: IL-25 receptor-deficient (Il17rb(-/-)), IL-33 receptor-deficient (ST2, Il1rl1(-/-)), and double-deficient (Il17rb(-/-)Il1rl1(-/-)) mice were analyzed in models of allergic asthma. Microarrays, an ex vivo lung slice airway contraction model, and Il13(+/eGFP) mice were then used to identify specific effects of IL-25 and IL-33 administration. RESULTS: Comparison of IL-25 and IL-33 pathway-deficient mice demonstrates that IL-33 signaling plays a more important in vivo role in airways hyperreactivity than IL-25. Furthermore, methacholine-induced airway contraction ex vivo increases after treatment with IL-33 but not IL-25. This is dependent on expression of the IL-33 receptor and type 2 cytokines. Confocal studies with Il13(+/eGFP) mice show that IL-33 more potently induces expansion of IL-13-producing type 2 innate lymphoid cells, correlating with airway contraction. This predominance of IL-33 activity is enforced in vivo because IL-33 is more rapidly expressed and released in comparison with IL-25. CONCLUSION: Our data demonstrate that IL-33 plays a critical role in the rapid induction of airway contraction by stimulating the prompt expansion of IL-13-producing type 2 innate lymphoid cells, whereas IL-25-induced responses are slower and less potent.

Matching-adjusted indirect comparison of talquetamab vs selinexor-dexamethasone and vs belantamab mafodotin in patients with relapsed/refractory multiple myeloma.

OBJECTIVE: Talquetamab is the first GPRC5D-targeting bispecific antibody approved for the treatment of triple-class exposed (TCE) relapsed/refractory multiple myeloma (RRMM). This matching-adjusted indirect comparison (MAIC) study was conducted to compare the effectiveness of talquetamab vs selinexor-dexamethasone (sel-dex) and vs belantamab mafodotin (belamaf) in patients with TCE RRMM. METHODS: An unanchored MAIC was performed using individual patient-level data from patients treated with subcutaneous talquetamab 0.4 mg/kg weekly (QW) and 0.8 mg/kg every other week (Q2W) from MonumenTAL-1 (NCT03399799/NCT04636552) and published summary data for sel-dex from STORM (NCT02336815) and belamaf from DREAMM-2 (NCT0325678). Patients from MonumenTAL-1 who met key eligibility criteria for STORM and DREAMM-2 were included. Outcomes of interest were overall response rate (ORR), complete response or better (≥CR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS). RESULTS: After adjustment for cross-trial differences, patients treated with both dosing schedules of talquetamab showed significantly better ORR, ≥CR, and DOR vs sel-dex and significantly higher ORR and ≥ CR vs belamaf; DOR was relatively similar to belamaf. PFS was significantly improved with talquetamab Q2W and numerically in favor of talquetamab QW vs sel-dex and significantly improved with both dosing schedules of talquetamab vs belamaf. OS was significantly improved with both dosing schedules of talquetamab vs sel-dex and was numerically in favor of both dosing schedules of talquetamab vs belamaf. CONCLUSION: These analyses show superior effectiveness of both talquetamab dosing schedules vs sel-dex and vs belamaf for most outcomes and highlight talquetamab as an effective treatment option for patients with TCE RRMM.

GPRC5D as a novel target for the treatment of multiple myeloma: a narrative review.

Multiple myeloma is a genetically complex and heterogenous malignancy with a 5-year survival rate of approximately 60%. Despite advances in therapy, patients experience cycles of remission and relapse, with each successive line of therapy associated with poorer outcomes; therefore, therapies with different mechanisms of action against new myeloma antigens are needed. G protein-coupled receptor class C group 5 member D (GPRC5D) has emerged as a novel therapeutic target for the treatment of multiple myeloma. We review the biology and target validation of GPRC5D, and clinical data from early phase trials of GPRC5D-targeting bispecific antibodies, talquetamab and forimtamig, and chimeric antigen receptor T cell (CAR-T) therapies, MCARH109, OriCAR-017, and BMS-986393. In addition to adverse events (AEs) associated with T-cell-redirection therapies irrespective of target, a consistent pattern of dermatologic and oral AEs has been reported across several trials of GPRC5D-targeting bispecific antibodies, as well as rare cerebellar events with CAR-T therapy. Additional studies are needed to understand the underlying mechanisms involved in the development of skin- and oral-related toxicities. We review the strategies that have been used to manage these GPRC5D-related toxicities. Preliminary efficacy data showed overall response rates for GPRC5D-targeting T-cell-redirecting therapies were ≥64%; most responders achieved a very good partial response or better. Pharmacokinetics/pharmacodynamics showed that these therapies led to cytokine release and T-cell activation. In conclusion, results from early phase trials of GPRC5D-targeting T-cell-redirecting agents have shown promising efficacy and manageable safety profiles, including lower infection rates compared with B-cell maturation antigen- and Fc receptor-like protein 5-targeting bispecific antibodies. Further clinical trials, including those investigating GPRC5D-targeting T-cell-redirecting agents in combination with other anti-myeloma therapies and with different treatment modalities, may help to elucidate the future optimal treatment regimen and sequence for patients with multiple myeloma and improve survival outcomes. Video Summary.

Talquetamab Versus Real-World Physician's Choice Treatment: Comparative Effectiveness in Patients With Triple-Class Exposed Relapsed/Refractory Multiple Myeloma.

BACKGROUND: Talquetamab is approved for treatment of triple-class exposed (TCE) patients with relapsed/refractory multiple myeloma (RRMM). We evaluated the comparative effectiveness of talquetamab in the MonumenTAL-1 study versus real-world physician's choice (RW) treatment. MATERIALS AND METHODS: An external control arm for MonumenTAL-1 was created from patients in the Flatiron Health database who satisfied MonumenTAL-1 eligibility criteria (n = 629 with 1169 eligible lines of therapy). Patient-level data from MonumenTAL-1 were included for patients who received subcutaneous talquetamab 0.4 mg/kg QW (n = 143) and 0.8 mg/kg Q2W (n = 145). After adjusting for baseline covariate imbalances, comparative effectiveness was assessed for progression-free survival (PFS), time to next treatment (TTNT), and overall survival (OS). RESULTS: Baseline covariates were comparable across cohorts after adjustment. Talquetamab 0.4 mg/kg QW and 0.8 mg/kg Q2W cohorts, respectively, showed significant improvement in PFS (HR, 0.55 [95% CI, 0.44-0.69; P < .0001; median, 7.5 vs. 4.0 months] and 0.40 [95% CI, 0.31-0.53; P < .0001; median, 14.2 vs. 4.0 months]), TTNT (HR, 0.59 [95% CI, 0.47-0.74; P < .0001; median, 9.1 vs. 5.1 months] and 0.45 [95% CI, 0.35-0.59; P < .0001; median, 13.3 vs. 5.1 months]), and OS (HR, 0.56 [95% CI, 0.40-0.78; P = .0007; median, NR vs. 16.5 months] and 0.48 [95% CI, 0.33-0.70; P = 0.0002; median NR vs. 15.9 months]) versus RW treatment. CONCLUSION: Both talquetamab schedules demonstrated superior effectiveness over RW treatment for all outcomes assessed. These data suggest talquetamab as an effective immunotherapy option in patients with TCE RRMM.

Evaluation of Drug-Drug Interaction Potential of Talquetamab, a T-Cell-Redirecting GPRC5D × CD3 Bispecific Antibody, as a Result of Cytokine Release Syndrome in Patients with Relapsed/Refractory Multiple Myeloma in MonumenTAL-1, Using a Physiologically Based Pharmacokinetic Model.

BACKGROUND: Cytokine release syndrome, commonly associated with T-cell immunotherapies, was observed with talquetamab, a T-cell-redirecting bispecific antibody, in the phase I/II MonumenTAL-1 study, leading to elevated interleukin (IL)-6, which can suppress cytochrome P450 (CYP) enzyme activity. OBJECTIVE: We aimed to evaluate the potential impact of elevated IL-6 on the exposure of co-administered CYP450 substrates for two scenarios: (1) the observed median IL-6 profile and (2) a profile with the highest IL-6 maximum concentration following talquetamab treatment. METHODS: A physiologically based pharmacokinetic model was developed based on the literature and simulations performed using observed IL-6 profiles from patients in MonumenTAL-1 who received the subcutaneous recommended phase 2 doses (RP2Ds) of talquetamab: 0.4 mg/kg weekly (QW) and 0.8 mg/kg every other week (Q2W). RESULTS: Median IL-6 maximum concentration was 18.4 and 7.1 pg/mL, and maximum IL-6 maximum concentration was 213 and 3503 pg/mL for talquetamab QW and Q2W RP2Ds, respectively. For the median IL-6 profile, no interaction between IL-6 and studied CYP substrates was predicted at either RP2D. The maximum IL-6 profile predicted weak-to-moderate impact on exposure of CYP2C19, CYP3A4, and CYP3A5 substrates and minimal impact on exposure of CYP1A2 substrates at both RP2Ds. Impact on exposure of CYP2C9 substrates was predicted as minimal at QW and minimal-to-weak at Q2W RP2Ds. Time to return to 20% difference from baseline enzymatic activity was predicted as 7 and 9 days after start of cycle 1 for QW and Q2W RP2Ds, respectively. CONCLUSIONS: These modeling results suggest that IL-6 release due to talquetamab-induced cytokine release syndrome has limited impact on potential drug-drug interactions, with the highest likelihood of impact occurring from initiation of talquetamab step-up dosing up to 7 (QW) or 9 (Q2W) days after first treatment dose in cycle 1 and during and after cytokine release syndrome. Multiple myeloma can be treated with immunotherapies such as the bispecific antibody, talquetamab, which binds the novel antigen G protein-coupled receptor family C group 5 member D on multiple myeloma cells and CD3 on T cells and induces T-cell-mediated lysis of multiple myeloma cells. Following talquetamab treatment, many patients experience cytokine release syndrome, an inflammatory immune response where levels of proinflammatory cytokines, including interleukin (IL)-6, are increased. Interleukin-6 can suppress the activity of important enzymes in the body (cytochrome [CYP] P450s) that are involved in drug clearance. This study used a physiologically based pharmacokinetic computer model to investigate the potential impact of increased IL-6 levels on CYP450 enzymes to determine subsequent impact on drugs that are metabolized by CYP450 enzymes. The results showed no predicted interaction between median levels of IL-6 observed in patients and CYP substrates (such as caffeine and omeprazole) with talquetamab. In a simulation that assessed higher (maximum) IL-6 levels observed in patients, the predicted impact of IL-6 was minimal to weak for most of the CYP substrates assessed. The effect on CYP450 enzymatic activity was highest from initiation of talquetamab step-up dosing up to 7-9 days after the first treatment dose of talquetamab. These results suggest that, in this treatment time period, elevated IL-6 levels due to talquetamab-induced cytokine release syndrome have limited impact on drugs that are CYP substrates that may be used in conjunction with talquetamab, but that the concentration and toxicity of these drugs should be monitored and the dose of CYP substrate adjusted as required.

Clinical Management of Patients With Relapsed/Refractory Multiple Myeloma Treated With Talquetamab.

BACKGROUND: Talquetamab is a bispecific antibody targeting the multiple myeloma-associated antigen G protein-coupled receptor family C group 5 member D (GPRC5D). In the phase 1/2 MonumenTAL-1 trial (NCT03399799/NCT04634552), overall responses rates were > 71% in patients with triple-class exposed relapsed/refractory multiple myeloma (RRMM). Due to the distribution of the target antigen, a unique pattern of GPRC5D-associated adverse events (AEs) was observed, together with T-cell redirection-associated AEs. Management strategies for talquetamab-associated AEs are described. DISCUSSION: GPRC5D-associated AEs included dermatologic (rash, nonrash, and nail toxicities) and oral AEs (dysgeusia, dysphagia, and dry mouth). The incidence of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were consistent with other T-cell redirection therapies. The incidence of high-grade infections was lower than observed with B-cell maturation antigen-targeting bispecific antibodies, with less frequent use of intravenous immunoglobulin required. GPRC5D-associated AEs were mostly low grade and led to few discontinuations. Skin toxicities were managed with emollients, topical corticosteroids, and oral corticosteroids (for high-grade, persistent, or AEs that progress). Nail toxicities were commonly managed with emollients. Based on investigator experience, dose modification may be effective for controlling oral events. Observation for potential weight changes is required. Infections were managed per standard of care. CRS and ICANS were effectively managed, consistent with other trials of T-cell redirection therapies. CONCLUSION: Although talquetamab had a distinct safety profile, AEs were considered clinically manageable and mostly low grade. With appropriate education and support, health care practitioners can ensure patients with RRMM maintain quality of life and treatment adherence. VIDEO ABSTRACT.

Daratumumab Plus Atezolizumab in Previously Treated Advanced or Metastatic NSCLC: Brief Report on a Randomized, Open-Label, Phase 1b/2 Study (LUC2001 JNJ-54767414).

INTRODUCTION: The programmed death-ligand 1 inhibitor atezolizumab improves progression-free survival (PFS) and overall survival (OS) for patients with previously treated advanced NSCLC. Preclinical studies indicate that targeting CD38-positive cells with daratumumab may synergistically enhance atezolizumab's antitumor activity by increasing the effector T-cell activity. METHODS: This phase 1b-2 study included a safety run-in (one cycle of daratumumab plus atezolizumab) and randomized phases (daratumumab plus atezolizumab versus atezolizumab alone). The primary objective of the randomized phase was to compare overall response rates. The secondary objectives included evaluations of safety, clinical benefit rate (stable disease or better), PFS, OS, and pharmacokinetics. RESULTS: In total, 99 patients were enrolled (safety run-in, n = 7; randomized, n = 46 per arm). In the randomized phase, the overall response rate was 4.3% for daratumumab plus atezolizumab and 13.0% for atezolizumab alone (OR: 0.30; 95% confidence interval: 0.03-1.92). The respective clinical benefit rates were 52.2% and 43.5%. No improvements were observed in the median PFS or median OS for combination therapy. The study was terminated because of the limited efficacy of daratumumab plus atezolizumab. CONCLUSIONS: Daratumumab plus atezolizumab therapy did not improve efficacy versus atezolizumab monotherapy for patients with previously treated advanced NSCLC.

Review series on helminths, immune modulation and the hygiene hypothesis: mechanisms underlying helminth modulation of dendritic cell function.

Dendritic cells (DCs) play a central role in activating CD4 T (T helper, Th) cells. As a component of their response to pathogen-associated stimuli, DCs produce cytokines and express surface molecules that provide important cues to modulate the effector functions of responding Th cells. Much is known of how DCs respond to, and influence immune response outcome to, bacterial and viral pathogens. However, relatively little is understood about how DCs respond to helminth parasites. This is an area of considerable interest since it impacts our understanding of the initiation of Th2 responses, which are stereotypically associated with helminth infections, and the regulation of allergic and autoimmune pathologies which evidence suggests are less severe or absent in individuals infected with helminths. This review attempts to summarize our understanding of the effects of helminth products on dendritic cell biology.

Schistosoma mansoni egg antigen-mediated modulation of Toll-like receptor (TLR)-induced activation occurs independently of TLR2, TLR4, and MyD88.

Unlike most pathogens, helminth parasites and their products induce strong Th2 responses, and dendritic cells (DCs) and macrophages exposed to helminth antigens generally fail to produce interleukin-12. Rather, it has been shown that helminth products such as soluble egg antigens (SEA; a soluble extract from Schistosoma mansoni eggs) inhibit the activation of DCs in response to classical Toll-like receptor (TLR) ligands such as lipopolysaccharide or CpG. Nevertheless, recent work has suggested that TLR4 and/or TLR2 plays an important role in the recognition of helminth products by DCs and macrophages and in the development of Th2 responses. Using DCs derived from TLR4(-/-), TLR2(-/-), or MyD88(-/-) mice, we have demonstrated that the ability of SEA to modulate DC activation is MyD88 independent and requires neither TLR4 nor TLR2. Moreover, TLR2 and TLR4 are not required for SEA-pulsed DCs to induce Th2 responses in naïve mice.

Regulation of dendritic cell function by pathogen-derived molecules plays a key role in dictating the outcome of the adaptive immune response.

There is increasing awareness that dendritic cells (DCs) can interpret pathogen-inherent signals and play a pivotal role in polarizing Th cell differentiation. Polarized Th1 responses are induced by DCs, which respond to pathogen-derived TLR ligands to mature and produce IL-12 and related cytokines that are instrumental in Th1 cell outgrowth. In contrast, DCs exposed to SEA (soluble egg Ag from the helminth parasite Schistosoma mansoni) retain a (modified) immature phenotype and induce Th2 responses. In addition to providing positive signals for Th1 cell development, DCs activated to mature by TLR-engagement also provide a potent negative signal that prevents the development of Th2 cells. Production of this signal is dependent upon a MyD88-dependent signaling pathway in DCs. In contrast, exposure of DCs to SEA severely limits their ability to respond to inflammatory TLR ligands such as LPS and CpG. Thus as part of their pathogen-specific response programs, DC can exert negative as well as positive signals for Th response polarization. These effects may have powerful and systemic effects on disease outcome.

Fusion to a highly stable consensus albumin binding domain allows for tunable pharmacokinetics.

A number of classes of proteins have been engineered for high stability using consensus sequence design methods. Here we describe the engineering of a novel albumin binding domain (ABD) three-helix bundle protein. The resulting engineered ABD molecule, called ABDCon, is expressed at high levels in the soluble fraction of Escherichia coli and is highly stable, with a melting temperature of 81.5°C. ABDCon binds human, monkey and mouse serum albumins with affinity as high as 61 pM. The solution structure of ABDCon is consistent with the three-helix bundle design and epitope mapping studies enabled a precise definition of the albumin binding interface. Fusion of a 10 kDa scaffold protein to ABDCon results in a long terminal half-life of 60 h in mice and 182 h in cynomolgus monkeys. To explore the link between albumin affinity and in vivo exposure, mutations were designed at the albumin binding interface of ABDCon yielding variants that span an 11 000-fold range in affinity. The PK properties of five such variants were determined in mice in order to demonstrate the tunable nature of serum half-life, exposure and clearance with variations in albumin binding affinity.

Inhalation delivery of protein therapeutics.

Inhaled therapeutics are used routinely to treat a variety of pulmonary diseases including asthma, COPD and cystic fibrosis. In addition, biological therapies represent the fastest growing segment of approved pharmaceuticals. However, despite the increased availability of biological therapies, nearly all inhaled therapeutics are small molecule drugs with only a single inhaled protein therapeutic approved. There remains a significant unmet need for therapeutics in pulmonary diseases, and biological therapies with potential to alter disease progression represent a significant opportunity to treat these challenging diseases. This review provides a background into efforts to develop inhaled biological therapies and highlights some of the associated challenges. In addition, we speculate on the ideal properties of a biologic therapy for inhaled delivery.

Dendritic cell-intrinsic expression of NF-kappa B1 is required to promote optimal Th2 cell differentiation.

A number of receptors and signaling pathways can influence the ability of dendritic cells (DC) to promote CD4(+) Th type 1 (Th1) responses. In contrast, the regulatory pathways and signaling events that govern the ability of DC to instruct Th2 cell differentiation remain poorly defined. In this report, we demonstrate that NF-kappaB1 expression within DC is required to promote optimal Th2 responses following exposure to Schistosoma mansoni eggs, a potent and natural Th2-inducing stimulus. Although injection of S. mansoni eggs induced production of IL-4, IL-5, and IL-13 in the draining lymph node of wild-type (WT) mice, NF-kappaB1(-/-) hosts failed to express Th2 cytokines and developed a polarized Ag-specific IFN-gamma response. In an in vivo adoptive transfer model in which NF-kappaB-sufficient OVA-specific DO11.10 TCR transgenic T cells were injected into OVA-immunized WT or NF-kappaB1(-/-) hosts, NF-kappaB1(-/-) APCs efficiently promoted CD4(+) T cell proliferation and IFN-gamma responses, but failed to promote Ag-specific IL-4 production. Further, bone marrow-derived DC from NF-kappaB1(-/-) mice failed to promote OVA-specific Th2 cell differentiation in in vitro coculture studies. Last, S. mansoni egg Ag-pulsed NF-kappaB1(-/-) DC failed to prime for Th2 cytokine responses following injection into syngeneic WT hosts. Impaired Th2 priming by NF-kappaB1(-/-) DC was accompanied by a reduction in MAPK phosphorylation in Ag-pulsed DC. Taken together, these studies identify a novel requirement for DC-intrinsic expression of NF-kappaB1 in regulating the MAPK pathway and governing the competence of DC to instruct Th2 cell differentiation.

Cutting edge: dendritic cells copulsed with microbial and helminth antigens undergo modified maturation, segregate the antigens to distinct intracellular compartments, and concurrently induce microbe-specific Th1 and helminth-specific Th2 responses.

To examine the ability of dendritic cells (DC) to discriminate between helminth and microbial Ag and induce appropriately polarized Th responses, mouse DC were copulsed with the helminth Ag, schistosome egg Ag (SEA), along with the bacterium Proprionebacterium acnes, Pa, and transferred into wild-type mice. Strikingly, SEA/Pa-copulsed DC induced concurrent Pa-specific Th1 (but not Th2) responses and SEA-specific Th2 (but not Th1) responses. Although DC exposed to both Ag undergo many of the maturation-associated changes that accompany exposure to Pa alone, Pa-induced IL-12 production was inhibited by SEA. Examination of Ag uptake revealed that SEA and Pa are acquired via discrete pathways and enter nonoverlapping intracellular compartments. Data suggest that segregation of SEA and Pa into distinct compartments, coupled with SEA-induced modifications of the DC maturation pathway, are significant components of the ability of DC to interpret signals inherent to SEA and Pa and induce appropriately polarized Th responses.

MxiE regulates intracellular expression of factors secreted by the Shigella flexneri 2a type III secretion system.

The mxi-spa locus on the virulence plasmid of Shigella flexneri encodes components of the type III secretion system. mxiE, a gene within this locus, encodes a protein that is homologous to the AraC/XylS family of transcriptional regulators, but currently its role in pathogenesis remains undefined. We characterized the virulence phenotype of a nonpolar mxiE mutant and found that this mutant retained the ability to invade mammalian cells in tissue culture and secrete Ipas (type III effectors required for host cell invasion), although it was less efficient than wild-type Shigella at cell-to-cell spread. Despite its invasive properties in culture, the mxiE mutant was completely avirulent in an animal model. Potential targets for MxiE activation were identified by using promoter-green fluorescent protein fusions, and gene expression was examined under various growth conditions. Six MxiE-regulated genes were discovered: ospB, ospC1, ospE2, ospF, virA, and ipaH(9.8). Notably, activation of these genes only occurred within the intracellular environment of the host and not during growth at 37 degrees C in liquid culture. Interestingly, all of the MxiE-regulated proteins previously have been shown to be secreted through the type III secretion system and are putative virulence factors. Our findings suggest that some of these Osp proteins may be involved in postinvasion events related to virulence. Since bacterial pathogens adapt to multiple environments during the course of infecting a host, we propose that Shigella evolved a mechanism to take advantage of a unique intracellular cue, which is mediated through MxiE, to express proteins when the organism reaches the eukaryotic cytosol.

Th2 response polarization during infection with the helminth parasite Schistosoma mansoni.

T-helper 2 (Th2) cell responses play a critical role in protection against helminth infections. In the case of Schistosoma mansoni, an important helminth parasite of man, data from a mouse model of human disease have shown that Th2 responses are essential to allow host survival. In this infection, parasite eggs are the primary stimulus for Th2 response development. Recent work has shown that egg molecules exert multiple levels of control over the development of host interferon-gamma-associated inflammatory responses. Soluble egg antigen inhibits the ability of dendritic cells to make interleukin-12 and induces Th2-polarized adaptive immune responses that in combination with regulatory T-cell responses effectively limit Th1 response development. In this article, we discuss the factors influencing Th2 response polarization during infection with S. mansoni.

Helminth antigens modulate TLR-initiated dendritic cell activation.

There is increasing awareness that helminth infections can ameliorate proinflammatory conditions. In part, this is due to their inherent ability to induce Th2 and, perhaps, regulatory T cell responses. However, recent evidence indicates that helminths also have direct anti-inflammatory effects on innate immune responses. In this study, we address this issue and show that soluble molecules from the eggs of the helminth parasite Schistosoma mansoni (SEA) suppress LPS-induced activation of immature murine dendritic cells, including MHC class II, costimulatory molecule expression, and IL-12 production. SEA-augmented LPS-induced production of IL-10 is in part responsible for the observed reduction in LPS-induced IL-12 production. However, analyses of IL-10(-/-) DC revealed distinct IL-10-independent suppressive effects of SEA. IL-10-independent mechanisms are evident in the suppression of TLR ligand-induced MAPK and NF-kappaB signaling pathways. Microarray analyses demonstrate that SEA alone uniquely alters the expression of a small subset of genes that are not up-regulated during conventional TLR-induced DC maturation. In contrast, the effects of SEA on TLR ligand-induced DC activation were striking: when mixed with LPS, SEA significantly affects the expression of >100 LPS-regulated genes. These findings indicate that SEA exerts potent anti-inflammatory effects by directly regulating the ability of DC to respond to TLR ligands.