Neutrophil priming occurs in a sequential manner and can be visualized in living animals by monitoring IL-1ß promoter activation.

Rapid enhancement of phagocyte functionality is a hallmark of neutrophil priming. GeneChip analyses unveiled elevated CD54, dectin-2, and IL-1ß mRNA expression by neutrophils isolated from inflammatory sites. In fact, CD54 and dectin-2 protein expression was detected on neutrophils recovered from skin, peritoneal, and lung inflammation lesions but not on those in bone marrow or peripheral blood. Neutrophils increased CD54 and dectin-2 mRNA during migration in Boyden chambers and acquired CD54 and dectin-2 surface expression after subsequent exposure to GM-CSF. Neutrophils purified from IL-1ß promoter-driven DsRed-transgenic mice acquired DsRed signals during cell migration or exposure to GM-CSF. CD54 and dectin-2 were expressed by DsRed(+) (but not DsRed(-)) neutrophils in GM-CSF-supplemented cultures, and neutrophils recovered from inflammatory sites exhibited strong DsRed signals. The dynamic process of neutrophil priming was studied in chemically induced inflammatory skin lesions by monitoring DsRed expression using confocal microscopy. A majority (>80%) of Ly6G(+) neutrophils expressed DsRed, and those DsRed(+)/Ly6G(+) cells exhibited crawling motion with a higher velocity compared with their DsRed(-)/Ly6G(+) counterparts. This report unveils motile behaviors of primed neutrophils in living animals. We propose that neutrophil priming occurs in a sequential manner with rapid enhancement of phagocyte functionality, followed by CD54 and dectin-2 mRNA and protein expression, IL-1ß promoter activation, and accelerated motility. Not only do these findings provide a new conceptual framework for our understanding of the process of neutrophil priming, they also unveil new insights into the pathophysiology of many inflammatory disorders that are characterized by neutrophil infiltration.

Neutrophil differentiation into a unique hybrid population exhibiting dual phenotype and functionality of neutrophils and dendritic cells.

Neutrophils have been reported to acquire surface expression of MHC class II and co-stimulatory molecules as well as T-cell stimulatory activities when cultured with selected cytokines. However, cellular identity of those unusual neutrophils showing antigen presenting cell (APC)-like features still remains elusive. Here we show that both immature and mature neutrophils purified from mouse bone marrow differentiate into a previously unrecognized "hybrid" population showing dual properties of both neutrophils and dendritic cells (DCs) when cultured with granulocyte macrophage-colony-stimulating factor but not with other tested growth factors. The resulting hybrid cells express markers of both neutrophils (Ly6G, CXCR2, and 7/4) and DCs (CD11c, MHC II, CD80, and CD86). They also exhibit several properties typically reserved for DCs, including dendritic morphology, probing motion, podosome formation, production of interleukin-12 and other cytokines, and presentation of various forms of foreign protein antigens to naïve CD4 T cells. Importantly, they retain intrinsic abilities of neutrophils to capture exogenous material, extrude neutrophil extracellular traps, and kill bacteria via cathelicidin production. Not only do our results reinforce the notion that neutrophils can acquire APC-like properties, they also unveil a unique differentiation pathway of neutrophils into neutrophil-DC hybrids that can participate in both innate and adaptive immune responses.

Emergence, origin, and function of neutrophil-dendritic cell hybrids in experimentally induced inflammatory lesions in mice.

Although unusual neutrophils expressing major histocompatibility complex class II (MHC II) and costimulatory molecules have been detected at inflammatory sites in mice and humans, their identity, origin, and function remain unclear. We have demonstrated that, when cultured with granulocyte macrophage-colony-stimulating factor, neutrophils can give rise to a unique hybrid population exhibiting dual phenotypic and functionality of neutrophils and dendritic cells (DCs). Here we report that hybrid cells expressing surface markers of neutrophils (Ly6G, L-selectin, CXC chemokines receptor 2, and 7/4) and DCs (CD11c, MHC II, CD80, and CD86) become detectable in the peritoneal cavity, skin, lung, and lymph nodes under inflammatory conditions. Importantly, 20% to 30% of the adoptively transferred neutrophils acquired CD11c and MHC II expression when recovered from inflammatory lesions, demonstrating neutrophil → hybrid conversion in living animals. Using Escherichia coli strains expressing green fluorescent protein and ovalbumin, we further show hybrids play dual protective roles by rapidly clearing bacteria and presenting bacterial antigens to CD4 T cells. These results indicate that some of the neutrophils recruited to inflammatory lesions can differentiate into neutrophil-DC hybrids, thus challenging the classic view of neutrophils as terminally differentiated leukocytes destined to die or to participate primarily in host innate immunity.

Neutrophil-derived IL-1ß is sufficient for abscess formation in immunity against Staphylococcus aureus in mice.

Neutrophil abscess formation is critical in innate immunity against many pathogens. Here, the mechanism of neutrophil abscess formation was investigated using a mouse model of Staphylococcus aureus cutaneous infection. Gene expression analysis and in vivo multispectral noninvasive imaging during the S. aureus infection revealed a strong functional and temporal association between neutrophil recruitment and IL-1ß/IL-1R activation. Unexpectedly, neutrophils but not monocytes/macrophages or other MHCII-expressing antigen presenting cells were the predominant source of IL-1ß at the site of infection. Furthermore, neutrophil-derived IL-1ß was essential for host defense since adoptive transfer of IL-1ß-expressing neutrophils was sufficient to restore the impaired neutrophil abscess formation in S. aureus-infected IL-1ß-deficient mice. S. aureus-induced IL-1ß production by neutrophils required TLR2, NOD2, FPR1 and the ASC/NLRP3 inflammasome in an α-toxin-dependent mechanism. Taken together, IL-1ß and neutrophil abscess formation during an infection are functionally, temporally and spatially linked as a consequence of direct IL-1ß production by neutrophils.

Long-Term Safety, Efficacy, and Patient-Centered Outcomes of Filgotinib in the Treatment of Rheumatoid Arthritis: Current Perspectives.

Filgotinib is an orally administered, preferential Janus kinase (JAK) inhibitor indicated for the treatment of moderate-to-severe rheumatoid arthritis (RA). The short-term safety, efficacy, and patient-reported outcomes (PROs) with filgotinib from Phase 2b/3 clinical trials (DARWIN 1 and 2; FINCH 1, 2, and 3) are described in patients who inadequately responded to methotrexate (MTX) and biologic disease-modifying antirheumatic drugs or who were naïve to MTX. This article reviews the safety and efficacy from the long-term extension (LTE) trials, DARWIN 3 (N=739) and FINCH 4 (N=2731), and PROs across the filgotinib development program in RA. Overall, in the DARWIN clinical trials (conducted from 2013-2023), patients received their LTE treatment for ≤8 years, while in the FINCH trials (ongoing from 2016-2025), patients received filgotinib treatment for ≤6 years in the LTE. The longer-term safety profile and consistent, sustained efficacy (American College of Rheumatology 20/50/70, Clinical Disease Activity Index, and Disease Activity Scale in 28 joints with C-reactive protein response rates) of filgotinib were largely similar to those observed in the shorter-term parent trials ≤52 weeks. PRO results from the parent trials showed improvements in patients' quality of life with filgotinib treatment, which compared to or exceeded improvements seen with placebo and active comparators (adalimumab, MTX). Filgotinib has a higher specificity for JAK1 compared with other therapeutic treatments, leading to reduced inhibition of JAK2/3-dependent pathways, potentially providing a distinct safety profile. Filgotinib is approved in Europe and Japan for treatment of people with moderate-to-severe RA, though it has not been approved by the US Food and Drug Administration, due to concerns around the benefit/risk profile of the filgotinib 200-mg dosage and the potential impact on semen parameters.

Filgotinib Modulates Inflammation-Associated Peripheral Blood Protein Biomarkers in Adults with Active Rheumatoid Arthritis and Prior Inadequate Response to Methotrexate.

INTRODUCTION: Our aim was to evaluate protein biomarker changes related to the administration of filgotinib, a Janus kinase (JAK) 1 preferential inhibitor, in patients with moderately to severely active rheumatoid arthritis (RA) with inadequate response to methotrexate. METHODS: Plasma and serum samples were collected from patients enrolled in FINCH 1 (NCT02889796), a Phase 3 trial. Patients with stable backgrounds of methotrexate were randomly assigned once-daily oral filgotinib 200 or 100 mg, subcutaneous adalimumab 40 mg every 2 weeks (W), or placebo. Up to 35 biomarkers were analyzed at baseline, W4, and W12 with enzyme-linked immunosorbent assays and chemiluminescence and electrochemiluminescence assays. RESULTS: At baseline, four distinct biomarker clusters were identified. The strongest intragroup correlations were in bone-cartilage resorption/inflammation and JAK/signal transducer and activator of transcription (STAT) signaling activity. At baseline, significant positive correlations were identified for cytokines with patient-reported pain and with patient measures of fatigue. Filgotinib reduced levels of cytokines associated with inflammation and cell migration as early as W4 and through W12. Compared to adalimumab, filgotinib induced significant reductions in bone-related turnover biomarkers, N-telopeptide of type 1 collagen and C-telopeptide 1, as well as biomarkers associated with baseline disease activity. No baseline predictors of therapeutic response to filgotinib were identified. CONCLUSIONS: Filgotinib reduced peripheral protein biomarkers associated with JAK/STAT signaling, inflammatory signaling, immune cell migration, and bone resorption as soon as W4 in FINCH 1. Effects were dose-dependent and consistent with the clinical efficacy of filgotinib observed in FINCH 1. The changes in peripheral biomarkers associated with filgotinib treatment in methotrexate-experienced patients are consistent with changes observed in both methotrexate-naïve and biologic disease-modifying antirheumatic drug-experienced RA populations. These data demonstrate dose-dependent effects of preferential JAK1 inhibition by filgotinib on peripheral blood protein biomarkers in methotrexate-experienced patients with RA. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02889796.

Identification of crassin acetate as a new immunosuppressant triggering heme oxygenase-1 expression in dendritic cells.

By screening 720 natural compounds in a standard 2-way allogeneic mixed leukocyte reaction assay, we identified a potent immunosuppressive capacity of crassin acetate (CRA), a coral-derived cembrane diterpenoid. CRA efficiently inhibited allogeneic mixed leukocyte reaction as well as antigen-specific activation of CD4 T cells by bone marrow-derived dendritic cells (DCs). With regard to cellular targets, CRA suppressed not only mitogen-triggered T-cell activation, but also lipopolysaccharide-induced DC maturation, indicating dual functionality. Treatment with CRA at nontoxic doses induced heme oxygenase-1 (HO-1) mRNA/protein expression and HO-1 enzymatic activity in DCs, suggesting a unique mechanism of action. In fact, lipopolysaccharide-induced DC maturation was also inhibited by structurally unrelated compounds known to induce HO-1 expression or carbon monoxide (CO) release. Allergic contact hypersensitivity response to oxazolone and oxazolone-induced Langerhans cell migration from epidermis were both prevented almost completely by systemic administration of CRA. Not only do our results support the recent concept that HO-1/CO system negatively regulates immune responses, they also form both conceptual and technical frameworks for a more systematic, large-scale drug discovery effort to identify HO-1/CO-targeted immunosuppressants with dual target specificity.

IL-33 promotes DC development in BM culture by triggering GM-CSF production.

Short-term DC cultures generated with GM-CSF and other cytokines have markedly improved our ability to study the immunobiology of DC. Here, we tested 65 cytokines individually for their potential to promote the generation of CD11c+ cells in a murine BM culture system. In addition to several cytokines known to promote DC survival and/or growth, IL-33 was found to augment DC development time- and dose-dependently. Although the resulting CD11c+ cells generated in the presence of IL-33 exhibited a typical dendritic morphology, they expressed MHC class II molecules only at modest levels, showed negligible responses to TLR ligands, produced no detectable IL-12 p70, displayed PD-L1 and PD-L2 on the surface, and failed to activate immunologically naïve T cells efficiently. IL-33-induced expansion of CD11c+ cells was completely blocked by anti-GM-CSF mAb, and GM-CSF mRNA and protein expression in BM culture was markedly elevated by added IL-33, indicating that IL-33 promotes in vitro DC generation indirectly by a GM-CSF-dependent manner. With regard to the cellular source, IL-33-dependent GM-CSF production was observed exclusively within the CD45+/FcepsilonRI+ BM population. Not only do our results reinforce the notion that GM-CSF serves as a primary DC growth factor, but they also reveal a previously unrecognized mechanism supporting DC development.

A sustainable wood biorefinery for low-carbon footprint chemicals production.

The profitability and sustainability of future biorefineries are dependent on efficient feedstock use. Therefore, it is essential to valorize lignin when using wood. We have developed an integrated biorefinery that converts 78 weight % (wt %) of birch into xylochemicals. Reductive catalytic fractionation of the wood produces a carbohydrate pulp amenable to bioethanol production and a lignin oil. After extraction of the lignin oil, the crude, unseparated mixture of phenolic monomers is catalytically funneled into 20 wt % of phenol and 9 wt % of propylene (on the basis of lignin weight) by gas-phase hydroprocessing and dealkylation; the residual phenolic oligomers (30 wt %) are used in printing ink as replacements for controversial para-nonylphenol. A techno-economic analysis predicts an economically competitive production process, and a life-cycle assessment estimates a lower carbon dioxide footprint relative to that of fossil-based production.

Identification of novel pharmacological activities of an antifungal agent, nystatin, to promote dendritic cell maturation.

As an unbiased functional screen to identify agents activating dendritic cells (DCs), we recently developed a DC-based biosensor system, in which a stable murine DC line XS106 was engineered to express the yellow fluorescent protein (YFP) gene under the control of the IL-1beta promoter. Here we report that nystatin (NYT), an antifungal drug of the family of polyene macrolide antibiotics, elevated YFP expression by the resulting XS106-pIL1-YFP DC biosensor clone in a dose-dependent fashion. With respect to the underlying mechanisms, NYT activated the NFkappaB p65 and c-Rel subunits in the parental XS106 DC line. Moreover, NYT dose-dependently increased the surface expression of major histocompatibility complex (MHC) class II (MHC II), CD40, CD54, CD80, and CD86 by murine bone marrow-derived DCs and triggered their robust production of IL-1beta, IL-6, IL-12, tumor necrosis factor alpha, and macrophage inflammatory protein-1alpha. Our results document previously unrecognized pharmacological activities of the most commonly used antifungal drug to promote DC maturation.

Generation of a large number of connective tissue type mast cells by culture of murine fetal skin cells.

We describe a novel culture system for generating large numbers of murine skin-associated mast cells and distinguish their characteristics from bone marrow-derived cultured mast cells. Culture of day 16 fetal skin single cell suspensions in the presence of interleukin-3 and stem cell factor allowed expansion and maturation of mast cells in the presence of stromal cells. The average yield of mast cells after 2 wk was 7.3 million cells per fetus at a purity of 96%. These fetal skin-derived cultured mast cells increased their histamine content in a time-dependent manner to 3.6 pg per cell after 2 wk and 6.7 pg per cell after 4 wk. Phenotypic analyses revealed much greater expression of CD49b and CD81 and lesser expression of CD77 and CD102 on fetal skin-derived cultured mast cells as compared with bone marrow-derived cultured mast cells. These findings suggest a close similarity between fetal skin-derived cultured mast cells and freshly isolated cutaneous mast cells. Connective tissue mast cell characteristics of fetal skin-derived cultured mast cells were evidenced by: (1) their greater histamine content than bone marrow-derived cultured mast cells; (2) the presence of heparin; and (3) their degranulation in response to compound 48/80 and substance P. Importantly, fetal skin-derived cultured mast cells secreted greater amounts of interleukin-13 but much less MIP-1beta and interleukin-6 than bone marrow-derived cultured mast cells in response to ionomycin. Thus fetal skin-derived cultured mast cells have many characteristics distinct from bone marrow-derived cultured mast cells and can be used as a model of cutaneous mast cells to discern their functions.

Localization of the laminin alpha4 chain in the skin and identification of a heparin-dependent cell adhesion site within the laminin alpha4 chain C-terminal LG4 module.

The laminin alpha4 chain, a component of laminin-8/9, is expressed in basement membranes of endothelial cells, the peripheral nerves, and muscle fibers. The localization and functions of laminin alpha4 chain in the skin have not been elucidated. By immunostaining with specific antibodies, we demonstrate here that the alpha4 chain is located in the basement membrane zones of blood vessels and is also associated with fibroblast-like cells in the dermis. Western blot showed that cultured fibroblasts secreted a laminin trimer containing the alpha4 chain. We have also focused on the cell adhesion activities of the human laminin alpha4 LG4 module since the corresponding LG4 module of laminin alpha3 was previously identified as active for cell adhesion. Recombinant human alpha4 LG4 was active for heparin-dependent fibroblast adhesion. Screening assays with 19 synthetic peptides covering the entire alpha4 LG4 module identified three peptides (HA4G82: TLFLAHGRLVYM; HA4G83: LVYMFNVGHKKL; and HA4G90: TEATWKIKGPIYL) as active sites for heparin- and heparan sulfate-dependent cell adhesion. Serine-substituted peptides demonstrated that two basic residues, His and Arg, within HA4G82 were essential for cell adhesion activity. The cell surface heparan sulfate proteoglycans (HSPGs), syndecan-2, -4, and glypican-1, were stably expressed in 293T cells to estimate whether they function as cell adhesion receptors. 293T cells overexpressing syndecan-2 or -4 bound to recombinant alpha4 LG4 and to HA4G82, but parental or glypican-1-overexpressing 293T cells did not. Therefore, syndecan-2 and -4 could mediate cell adhesion to the laminin alpha4 LG4 module. Our study suggests that the laminin alpha4 LG4 module may play an important role in cell adhesion and/or vessel wall formation in the skin by interacting with syndecan-2 and/or -4.

Skin scratching switches immune responses from Th2 to Th1 type in epicutaneously immunized mice.

BACKGROUND: The balance between Th1 and Th2 subsets is important with respects to susceptibility and resistance to particular infection or autoimmune diseases. However, the mechanism controlling Th1/Th2 balance remains unclear, although several factors have been reported to induce Th1/Th2 differentiation. Atopic Dermatitis (AD) that is a chronic skin disorder has been known as Th2 biased nature characterized by high expression of IgE in the serum. In contrast, the chronic skin lesions express IFNgamma and some patients don't show IgE in the serum. Thus, the pathology is also complicated now. OBJECTIVE: We focused on skin scratching that is common feature in the patients. In this study, we investigated in order to determine whether skin scratching regulates immune responses in murine epicutaneous sensitization model. METHODS: The scratched mice on abdominal skin using wire brush were applied with keyhole limpet hemocyanin (KLH) on the skin using occlusive patch. We examined the immune responses including delayed type hypersensitivity (DTH) reaction, antigen-specific serum immunoglobulin formation, and cytokine expressions on the local skin in comparison with mice without scratching. RESULTS: We found that the epicutaneously sensitized mice with KLH on abdominal skin showed Th2 biased immune response including expression of antigen-specific IgE in the serum and IL-13 in the local skin. Surprisingly, scratching on local abdominal skin using wire brush exchanged the immune response from Th2 dominance to Th1, because the mice displayed DTH reaction and significant level of antigen-specific IgG2a and IgG2b but not IgE in the serum. Furthermore, the abdominal skin showed significant level of IFNgamma but not IL-13. CONCLUSION: These data demonstrate that skin scratching switches immune response from Th2 biased response to Th1. This suggests that skin scratching play critical roles as one of exogenous immune modulator. This murine sensitization model may help to understand natures of several allergic disorders including AD.

Levofloxacin alone efficiently treated a cutaneous mycobacterium fortuitum infection.

Cutaneous infections with Mycobacterium (M.) fortuitum are rare, and some cases resist treatment. We report two cases of cutaneous M. fortuitum infection successfully treated with levofloxacin alone.

Reciprocal regulation of development of neutrophil-dendritic cell hybrids in mice by IL-4 and interferon-gamma.

Neutrophils contribute to innate host immunity by functioning as professional phagocytes, whereas dendritic cells (DCs) are prototypic antigen presenting cells (APCs) responsible for the induction of adaptive immune responses. We have demonstrated recently that neutrophils trans-differentiate into a unique population, termed "neutrophil-DC hybrids," expressing surface markers of both neutrophils and DCs and exhibiting dual functionality of both phagocytes and APCs. Although the hybrid cells emerged in significant numbers in murine bone marrow (BM) culture in the presence of GM-CSF, mechanisms regulating their development remained mostly unknown. In this study, we tested a total of 61 cytokines for their potentials to regulate neutrophil-DC hybrid formation using a newly developed BM micro-culture system combined with semi-automated FACS analysis. Several cytokines including GM-CSF were found to promote the generation of neutrophil-DC hybrids defined by the phenotype of CD11c(+)/MHC II(+)/Ly6G(+). When tested in the presence of GM-CSF, hybrid cell development was enhanced by IL-4 and suppressed by interferon-γ (IFNγ) in dose-dependent fashions. We next determined in vivo impacts of IL-4 and IFNγ on the development of neutrophil-DC hybrids in thioglycollate-induced peritonitis lesions. Intraperitoneal administrations of IL-4/anti-IL-4 antibody complex (IL-4C) significantly increased the number of hybrids recovered from the lesions. By contract, recovery of hybrids was reduced by recombinant IFNγ. With regard to function, those hybrid cells recovered from IL-4C-treated mice and IFNγ-treated mice showed potent abilities to capture E.coli. These observations imply that emergence of neutrophil-DC hybrids in inflammatory sites is tightly regulated by local cytokine milieus.

Real-time visualization of macromolecule uptake by epidermal Langerhans cells in living animals.

As a skin-resident member of the dendritic cell family, Langerhans cells (LCs) are generally regarded to function as professional antigen-presenting cells. Here we report a simple method to visualize the endocytotic activity of LCs in living animals. BALB/c mice received subcutaneous injection of FITC-conjugated dextran (DX) probes into the ear skin and were then examined under confocal microscopy. Large numbers of FITC(+) epidermal cells became detectable 12-24 hours after injection as background fluorescence signals began to disappear. Most (>90%) of the FITC(+) epidermal cells expressed Langerin, and >95% of Langerin(+) epidermal cells exhibited significant FITC signals. To assess intracellular localization, Alexa Fluor 546-conjugated DX probes were locally injected into IAß-enhanced green fluorescent protein (EGFP) knock-in mice and Langerin-EGFP-diphtheria toxin receptor mice--three dimensional rotation images showed close association of most of the internalized DX probes with major histocompatibility complex (MHC) class II molecules, but not with Langerin molecules. These observations support the current view that LCs constantly sample surrounding materials, including harmful and innocuous antigens, at the environmental interface. Our data also validate the potential utility of the newly developed imaging approach to monitor LC function in wild-type animals.

Bidirectional homing of Tregs between the skin and lymph nodes.

Although several homing receptors are known to be differentially expressed by Tregs in lymphoid tissues compared with those found in peripheral tissues, it remains unclear whether these cells traffic between the two locations. In this issue of the JCI, Tomura et al. report steady-state Treg migration from the skin to draining LNs in mice. Furthermore, they report that not only does skin inflammation exacerbate LN-directed Treg homing, it also triggers reverse circulation of Tregs from LNs to skin, whereby these cells contribute to regulation of the immune response. These results now form a new framework for our understanding of Treg homing.

Intravital imaging of IL-1beta production in skin.

IL-1 is a prototypic inflammatory cytokine that has pathogenic roles in various skin disorders. Although Langerhans cells (LCs) have been reported to express IL-1beta mRNA upon application of contact sensitizers, it remains unclear whether other cell types produce IL-1beta in skin. Thus, we sought to directly identify IL-1beta-producing cells in living animals by construction of transgenic mice expressing DsRed fluorescence protein gene under the control of IL-1beta promoter. Little DsRed fluorescence signal was detected in skin under steady-state conditions. Striking increases in DsRed signal were observed after topical application of a contact sensitizer, oxazolone, which also induced markedly elevated IL-1beta mRNA and protein expression. DsRed signal was expressed primarily by CD45(+)/CD11b(+) myeloid leukocytes in both epidermal and dermal compartments and was detected only in small fractions of epidermal LCs. Interestingly, DsRed(+) cells emerged preferentially as clusters around hair follicles. Intravital confocal imaging experiments revealed highly motile potentials of DsRed(+) cells-they constantly crawled around hair follicles via amoeba-like movements with a mean velocity of 1.0+/-0.4 microm min(-1) (epidermis) or 2.7+/-1.4 microm min(-1) (dermis). The newly developed in vivo imaging system represents a useful tool for studying spatial regulation of IL-1beta production in skin.