CCL17 in Inflammation and Pain

Epigenetic control of inflammation in Atopic Dermatitis

Atopic dermatitis (AD), also known as atopic eczema, is a common but also complex chronic, itchy skin condition with underlying inflammation of the skin. This skin ailment is prevalent worldwide and affects people of all ages, particularly children below five years of age. The itching and resulting rashes in AD patients are often the result of inflammatory signals, thus necessitating a closer look at the inflammation-regulating mechanisms for putative relief, care and therapy. Several chemical- as well as genetically-induced animal models have established the importance of targeting pro-inflammatory AD microenvironment. Epigenetic mechanisms are gaining attention towards a better understanding of the onset as well as the progression of inflammation. Several physiological processes with implications in pathophysiology of AD, such as, barrier dysfunction either due to reduced filaggrin / human β-defensins or altered microbiome, reprograming of Fc receptors with resulting overexpression of high affinity IgE receptors, elevated eosinophil numbers or the elevated IL-22 production by CD4 + T cells have underlying epigenetic mechanisms that include differential promoter methylation and/or regulation by non-coding RNAs. Reversing these epigenetic changes has been verified to reduce inflammatory burden through altered secretion of cytokines IL-6, IL-4, IL-13, IL-17, IL-22 etc, with benefit against AD progression in experimental models. A thorough understanding of epigenetic remodeling of inflammation in AD has the potential of opening avenues for novel diagnostic, prognostic and therapeutic options.

Cytokine and Chemokine Production in Mice Inoculated with NVX-CoV2373 (Nuvaxovid®) in Comparison with Omicron BA.4/5 Bivalent BNT162b2 (Comirnaty®)

A recombinant SARS-CoV-2 spike protein vaccine (NVX-CoV2373) has been licensed and has a lesser incidence of adverse events. To know the immunological mechanisms of adverse events, the production of cytokines and chemokines was investigated in mice inoculated with NVX-CoV2373. Serum IL-6 was detected on Day 1 of the first and second doses and the IFN-γ, IL-4, IL-10, TNF-α, and IL-6 levels increased on Day 1 of the second dose at the inoculation site. The enhanced production of the inflammatory chemokines (CCL2), homeostatic chemokine (CXCL13), and Th2 chemokine (CCL17) was observed at the inoculation site on Day 1 of the second dose. These findings were compared with data obtained following inoculation with BNT162b2 bivalent vaccine containing omicron BA.4/5. Significantly lower levels of inflammatory chemokines were detected on Day 1 after the first dose of NVX-CoV2373 in sera and inoculation site than those following inoculation with bivalent BNT162b2 (p < 0.01), reflecting a lower incidence of adverse events after immunization with NVX-CoV2373 in humans. NVX-CoV2373 induced significantly higher concentrations of IFN-γ, TNF-α, and IL-10 at the inoculation site obtained on Day 1 of the second dose (p < 0.05). Significant higher levels of Th2 chemokines, CCL11 and CCL17, were induced at the inoculation site on Day 1 of the second dose (p < 0.01) and they explain the booster IgG EIA antibody response after the second dose of NVX-CoV2373.

Epigenetic and transcriptional regulation of CCL17 production by glucocorticoids in arthritis

Glucocorticoids (GCs) are potent anti-inflammatory agents and are broadly used in treating rheumatoid arthritis (RA) patients, albeit with adverse side effects associated with long-term usage. The negative consequences of GC therapy provide an impetus for research into gaining insights into the molecular mechanisms of GC action. We have previously reported that granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced CCL17 has a non-redundant role in inflammatory arthritis. Here, we provide molecular evidence that GCs can suppress GM-CSF-mediated upregulation of IRF4 and CCL17 expression via downregulating JMJD3 expression and activity. In mouse models of inflammatory arthritis, GC treatment inhibited CCL17 expression and ameliorated arthritic pain-like behavior and disease. Significantly, GC treatment of RA patient peripheral blood mononuclear cells ex vivo resulted in decreased CCL17 production. This delineated pathway potentially provides new therapeutic options for the treatment of many inflammatory conditions, where GCs are used as an anti-inflammatory drug but without the associated adverse side effects.

The GM-CSF/CCL17 pathway in obesity-associated osteoarthritic pain and disease in mice

OBJECTIVES

We have previously identified a granulocyte macrophage-colony stimulating factor (GM-CSF)/C-C motif ligand 17 (CCL17) pathway in monocytes/macrophages, in which GM-CSF regulates the formation of CCL17, and it is important for an experimental osteoarthritis (OA) model. We explore here additional OA models, including in the presence of obesity, such as a requirement for this pathway.

DESIGN

The roles of GM-CSF, CCL17, CCR4, and CCL22 in various experimental OA models, including those incorporating obesity (eight-week high-fat diet), were investigated using gene-deficient male mice. Pain-like behavior and arthritis were assessed by relative static weight distribution and histology, respectively. Cell populations (flow cytometry) and cytokine messenger RNA (mRNA) expression (qPCR) in knee infrapatellar fat pad were analyzed. Human OA sera were collected for circulating CCL17 levels (ELISA) and OA knee synovial tissue for gene expression (qPCR).

RESULTS

We present evidence that: i) GM-CSF, CCL17, and CCR4, but not CCL22, are required for the development of pain-like behavior and optimal disease in three experimental OA models, as well as for exacerbated OA development due to obesity, ii) obesity alone leads to spontaneous knee joint damage in a GM-CSF- and CCL17-dependent manner, and iii) in knee OA patients, early indications are that BMI correlates with a lower Oxford Knee Score (r = -0.458 and p = 0.0096), with elevated circulating CCL17 levels (r = 0.2108 and p = 0.0153) and with elevated GM-CSF and CCL17 gene expression in OA synovial tissue.

CONCLUSIONS

The above findings indicate that GM-CSF, CCL17, and CCR4 are involved in obesity-associated OA development, broadening their potential as targets for possible treatments for OA.

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype and is associated with increased survival in cancer patients with high tumor macrophage content

Background

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that can either induce cell death or activate survival pathways after binding to death receptors (DRs) DR4 or DR5. TRAIL is investigated as a therapeutic agent in clinical trials due to its selective toxicity to transformed cells. Macrophages can be polarized into pro-inflammatory/tumor-fighting M1 macrophages or anti-inflammatory/tumor-supportive M2 macrophages and an imbalance between M1 and M2 macrophages can promote diseases. Therefore, identifying modulators that regulate macrophage polarization is important to design effective macrophage-targeted immunotherapies. The impact of TRAIL on macrophage polarization is not known.

Methods

Primary human monocyte-derived macrophages were pre-treated with either TRAIL or with DR4 or DR5-specific ligands and then polarized into M1, M2a, or M2c phenotypes in vitro. The expression of M1 and M2 markers in macrophage subtypes was analyzed by RNA sequencing, qPCR, ELISA, and flow cytometry. Furthermore, the cytotoxicity of the macrophages against U937 AML tumor targets was assessed by flow cytometry. TCGA datasets were also analyzed to correlate TRAIL with M1/M2 markers, and the overall survival of cancer patients.

Results

TRAIL increased the expression of M1 markers at both mRNA and protein levels while decreasing the expression of M2 markers at the mRNA level in human macrophages. TRAIL also shifted M2 macrophages towards an M1 phenotype. Our data showed that both DR4 and DR5 death receptors play a role in macrophage polarization. Furthermore, TRAIL enhanced the cytotoxicity of macrophages against the AML cancer cells in vitro. Finally, TRAIL expression was positively correlated with increased expression of M1 markers in the tumors from ovarian and sarcoma cancer patients and longer overall survival in cases with high, but not low, tumor macrophage content.

Conclusions

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype via both DR4 and DR5. Our study defines TRAIL as a new regulator of macrophage polarization and suggests that targeting DRs can enhance the anti-tumorigenic response of macrophages in the tumor microenvironment by increasing M1 polarization.

Plasma proteomic profiles of pain subtypes in adolescents and young adults with endometriosis

STUDY QUESTION

What are the similarities and differences in the systemic proteomic profiles by endometriosis-associated pain subtypes among adolescents and young adults with endometriosis?

SUMMARY ANSWER

Endometriosis-associated pain subtypes exhibited distinct plasma proteomic profiles.

WHAT IS KNOWN ALREADY

Endometriosis patients, especially those diagnosed in adolescents and young adults, are often plagued by various pain symptoms. However, it is not clear what biological processes underlie this heterogeneity.

STUDY DESIGN, SIZE, DURATION

We conducted a cross-sectional analysis using data and plasma samples from 142 adolescent or young adult participants of the Women's Health Study: From Adolescence to Adulthood cohort with laparoscopically confirmed endometriosis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We measured 1305 plasma protein levels by SomaScan. We classified self-reported endometriosis-associated pain into subtypes of dysmenorrhea, acyclic pelvic pain, life impacting pelvic pain, bladder pain, bowel pain, and widespread pain phenotype. We used logistic regression to calculate the odds ratios and 95% confidence intervals for differentially expressed proteins, adjusting for age, BMI, fasting status, and hormone use at blood draw. Ingenuity Pathway Analysis identified enriched biological pathways.

MAIN RESULTS AND THE ROLE OF CHANCE

Our study population consisted mainly of adolescents and young adults (mean age at blood draw = 18 years), with nearly all (97%) scored as rASRM stage I/II at laparoscopic diagnosis of endometriosis, which is a common clinical presentation of endometriosis diagnosed at a younger age. Pain subtypes exhibited distinct plasma proteomic profiles. Multiple cell movement pathways were downregulated in cases with severe dysmenorrhea and life impacting pelvic pain compared to those without (P < 7.5×10-15). Endometriosis cases with acyclic pelvic pain had upregulation of immune cell adhesion pathways (P < 9.0×10-9), while those with bladder pain had upregulation of immune cell migration (P < 3.7×10-8) and those with bowel pain had downregulation (P < 6.5×10-7) of the immune cell migration pathways compared to those without. Having a wide-spread pain phenotype involved downregulation of multiple immune pathways (P < 8.0×10-10).

LIMITATIONS, REASONS FOR CAUTION

Our study was limited by the lack of an independent validation cohort. We were also only able to explore any presence of a pain subtype and could not evaluate multiple combinations by pain subtypes. Further mechanistic studies are warranted to elucidate the differences in pathophysiology by endometriosis-pain subtype.

WIDER IMPLICATIONS OF THE FINDINGS

The observed variation in plasma protein profiles by pain subtypes suggests different underlying molecular mechanisms, highlighting the need for potential consideration of pain subtypes for effectively treating endometriosis patients presenting with various pain symptoms.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Department of Defense W81XWH1910318 and the 2017 Boston Center for Endometriosis Trainee Award. Financial support for establishment of and data collection within the A2A cohort were provided by the J. Willard and Alice S. Marriott Foundation. N.S., A.F.V., S.A.M., and K.L.T. have received funding from the Marriott Family Foundation. C.B.S. is funded by an R35 MIRA Award from NIGMS (5R35GM142676). S.A.M. and K.L.T. are supported by NICHD R01HD094842. S.A.M. reports serving as an advisory board member for AbbVie and Roche, Field Chief Editor for Frontiers in Reproductive Health, personal fees from Abbott for roundtable participation; none of these are related to this study. Other authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

CC chemokines and receptors in osteoarthritis: new insights and potential targets

Osteoarthritis (OA) is a prevalent degenerative disease accompanied by the activation of innate and adaptive immune systems-associated inflammatory responses. Due to the local inflammation, the expression of various cytokines was altered in affected joints, including CC motif chemokine ligands (CCLs) and their receptors (CCRs). As essential members of chemokines, CCLs and CCRs played an important role in the pathogenesis and treatment of OA. The bindings between CCLs and CCRs on the chondrocyte membrane promoted chondrocyte apoptosis and the release of multiple matrix-degrading enzymes, which resulted in cartilage degradation. In addition, CCLs and CCRs had chemoattractant functions to attract various immune cells to osteoarthritic joints, further leading to the aggravation of local inflammation. Furthermore, in the nerve endings of joints, CCLs and CCRs, along with several cellular factors, contributed to pain hypersensitivity by releasing neurotransmitters in the spinal cord. Given this family's diverse and complex functions, targeting the functional network of CCLs and CCRs is a promising strategy for the prognosis and treatment of OA in the future.

Hydrogen-Rich Saline Attenuates Chronic Allodynia after Bone Fractures via Reducing Spinal CXCL1/CXCR2-Mediated Iron Accumulation in Mice

PURPOSE

Neuroinflammation often initiates iron overload in the pathogenesis of neurological disorders. Chemokine-driven neuroinflammation is required for central sensitization and chronic allodynia following fractures, but specific molecular modulations are elusive. This present study explored whether hydrogen-rich saline, as one potent anti-inflammatory pharmaceutical, could alleviate fracture-caused allodynia by suppressing chemokine CXCL1 expression and iron overload.

METHODS

A mouse model of tibial fracture with intramedullary pinning was employed for establishing chronic allodynia. Three applications of hydrogen-rich saline (1, 5 or 10 mL/kg) were administrated intraperitoneally on a daily basis from days 4 to 6 following fractures. Spinal CXCL1 and its receptor CXCR2 levels, transferrin receptor 1 (TfR1) expression and iron concentration were examined. Recombinant CXCL1, a selective CXCR2 antagonist and an iron chelator were used for verification of mechanisms.

RESULTS

Repetitive injections of hydrogen-rich saline (5 and 10 mL/kg but not 1 mL/kg) prevent fracture-caused mechanical allodynia and cold allodynia in a dose-dependent manner. Single exposure to hydrogen-rich saline (10 mL/kg) on day 14 after orthopedic surgeries controls the established persistent fracture allodynia. Furthermore, hydrogen-rich saline therapy reduces spinal CXCL1/CXCR2 over-expression and TfR1-mediated iron accumulation in fracture mice. Spinal CXCR2 antagonism impairs allodynia and iron overload following fracture surgery. Intrathecal delivery of recombinant CXCL1 induces acute allodynia and spinal iron overload, which is reversed by hydrogen-rich saline. Moreover, iron chelation alleviates exogenous CXCL1-induced acute pain behaviors.

CONCLUSIONS

These findings identify that hydrogen-rich saline confers protection against fracture-caused chronic allodynia via spinal down-modulation of CXCL1-dependent TfR1-mediated iron accumulation in mice.

Macrophages alter inflammatory and fibrotic gene expression in human vocal fold fibroblasts

Macrophage phenotypes are simplistically classified as pro-inflammatory (M1) or anti-inflammatory/pro-fibrotic (M2). Phenotypically different macrophages are putatively involved in vocal fold (VF) fibrosis. The current study investigated interactions between macrophages and VF fibroblasts. THP-1 monocyte-derived macrophages were treated with interferon-gamma (IFN-γ), lipopolysaccharide (LPS)/IFN-γ, interleukin-10 (IL10), transforming growth factor-β1 (TGF-β), or interleukin-4 (IL4) for 24 h (M(IFN), M(IFN/LPS), M(IL10), M(TGF), and M(IL4), respectively; M(-) denotes untreated macrophages). Differentially activated macrophages and human VF fibroblasts were co-cultured ± direct contact. Expression of CXCL10, CCN2, ACTA2, FN1, TGM2, and LOX was quantified by real-time polymerase chain reaction. Type I collagen and smooth muscle actin (SMA) were observed by immunofluorescence. CXCL10 and PTGS2 were upregulated in fibroblasts indirectly co-cultured with M(IFN) and M(IFN/LPS). M(TGF) stimulated CCN2, ACTA2, and FN1 in fibroblasts. Enzymes involved in extracellular matrix crosslinking (TGM2, LOX) were increased in monocultured M(IL4) compared to M(-). Direct co-culture with all macrophages increased type I collagen and SMA in fibroblasts. Macrophage phenotypic shift was consistent with stimulation and had downstream differential effects on VF fibroblasts. Direct contact with macrophages, regardless of phenotype, stimulated a pro-fibrotic response in VF fibroblasts. Collectively, these data suggest meaningful interactions between macrophages and fibroblasts mediate fibrosis.

Different Roles of Dendritic Cells for Chronic Rhinosinusitis Treatment According to Phenotype

Dendritic cells (DCs) are antigen-presenting cells derived from the bone marrow that play an important role in the association between the innate and adaptive immune responses. The onset and development of chronic rhinosinusitis (CRS) involve a serious imbalance in immune regulation and mechanical dysfunction caused by an abnormal remodeling process. Recent studies have shown that an increase in DCs in CRS and their function of shaping the nasal mucosal immune response may play an important role in the pathogenesis of CRS. In this review, we discuss DC subsets in mice and humans, as well as the function of DCs in the nasal sinus mucosa. In addition, the mechanism by which DCs can be used as targets for therapeutic intervention for CRS and potential future research directions are also discussed.

The role of interleukin (IL)-23 in regulating pain in arthritis

Current understanding of IL-23 biology, with its link to other pro-inflammatory cytokines, for example, IL-17 and granulocyte macrophage-colony stimulating factor (GM-CSF), is primarily focused on T lymphocyte-mediated inflammation/autoimmunity. Pain is a significant symptom associated with many musculoskeletal conditions leading to functional impairment and poor quality of life. While the role of IL-23 in arthritis has been studied in mouse models of adaptive immune-mediated arthritis using targeted approaches (e.g., monoclonal antibody (mAb) neutralization), the literature on IL-23 and arthritis pain is limited. Encouragingly, the anti-IL-23p19 mAb, guselkumab, reduces pain in psoriatic arthritis patients. Recent evidence has suggested a new biology for IL-23, whereby IL-23 is required in models of innate immune-mediated arthritis and its associated pain with its action being linked to a GM-CSF-dependent pathway (the so-called GM-CSF➔CCL17 pathway). This Commentary discusses the current understanding of potential cytokine networks involving IL-23 in arthritis pain and provides a rationale for future clinical studies targeting IL-23p19 in arthritis pain.

Macrophage-Specific MCPIP1/Regnase-1 Attenuates Kidney Ischemia-Reperfusion Injury by Shaping the Local Inflammatory Response and Tissue Regeneration

Sterile inflammation either resolves the initial insult or leads to tissue damage. Kidney ischemia/reperfusion injury (IRI) is associated with neutrophilic infiltration, enhanced production of inflammatory mediators, accumulation of necrotic cells and tissue remodeling. Macrophage-dependent microenvironmental changes orchestrate many features of the immune response and tissue regeneration. The activation status of macrophages is influenced by extracellular signals, the duration and intensity of the stimulation, as well as various regulatory molecules. The role of macrophage-derived monocyte chemoattractant protein-induced protein 1 (MCPIP1), also known as Regnase-1, in kidney ischemia-reperfusion injury (IRI) and recovery from sterile inflammation remains unresolved. In this study, we showed that macrophage-specific Mcpip1 deletion significantly affects the kidney phenotype. Macrophage-specific Mcpip1 transgenic mice displayed enhanced inflammation and loss of the tubular compartment upon IRI. We showed that MCPIP1 modulates sterile inflammation by negative regulation of Irf4 expression and accumulation of IRF4+ cells in the tissue and, consequently, suppresses the post-ischemic kidney immune response. Thus, we identified MCPIP1 as an important molecular sentinel of immune homeostasis in experimental acute kidney injury (AKI) and renal fibrosis.

Deoxynivalenol and zearalenone: Different mycotoxins with different toxic effects in donkey (Equus asinus) endometrial epithelial cells

Deoxynivalenol (DON) and zearalenone (ZEA), which are commonly found in feed products, exhibit serious negative effects on the reproductive systems of domestic animals. However, the toxicity of mycotoxins on the uterine function of donkey (Equus asinus) remains unclear. This study investigated the biological effects of DON and ZEA exposure on donkey endometrial epithelial cells (EECs). It was administered 10 μM and 30 μM DON and ZEA to cells cultured in vitro. The results showed that 10 μM DON exposure markedly changed the expression levels of pyroptosis-associated genes and that 30 μM ZEA exposure changed the expression levels of inflammation-associated genes in EECs. The mRNA expression of cancer-promoting genes was markedly upregulated in cells exposed to DON and 30 μM ZEA; in particular, 10 μM and 30 μM DON and ZEA markedly disturbed the expression of androgen and estrogen secretion-related genes. Furthermore, Q-PCR, Western blot, and immunofluorescence analyses verified the different expression patterns of related genes in DON- and ZEA-exposed EECs. Collectively, these results illustrated the impact of exposure to different toxins and concrete toxicity on the mRNA expression of EECs from donkey in vitro.

Targeting GM-CSF in inflammatory and autoimmune disorders

Granulocyte macrophage-colony stimulating factor (GM-CSF) was originally identified as a growth factor for its ability to promote the proliferation and differentiation in vitro of bone marrow progenitor cells into granulocytes and macrophages. Many preclinical studies, using GM-CSF deletion or depletion approaches, have demonstrated that GM-CSF has a wide range of biological functions, including the mediation of inflammation and pain, indicating that it can be a potential target in many inflammatory and autoimmune conditions. This review provides a brief overview of GM-CSF biology and signaling, and summarizes the findings from preclinical models of a range of inflammatory and autoimmune disorders and the latest clinical trials targeting GM-CSF or its receptor in these disorders.

The progress of chemokines and chemokine receptors in autism spectrum disorders

Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders and the main symptoms of ASD are impairments in social communication and abnormal behavioral patterns. Studies have shown that immune dysfunction and neuroinflammation play a key role in ASD patients and experimental models. Chemokines are groups of small proteins that regulate cell migration and mediate inflammation responses via binding to chemokine receptors. Thus, chemokines/chemokine receptors may be involved in neurodevelopmental disorders and associated with ASD. In this review, we summarize the research progress of chemokine aberrations in ASD and also review the recent progress of clinical treatment of ASD and pharmacological research related to chemokines/chemokine receptors. This review highlights the possible connection between chemokines/chemokine receptors and ASD, and provides novel potential targets for drug discovery of ASD.

Effects of external low intensity focused ultrasound on inflammatory markers in neuropathic pain

BACKGROUND

Changes in inflammatory cytokine levels contribute to the induction and maintenance of neuropathic pain. We have shown that external low intensity focused ultrasound (liFUS) reduces allodynia in a common peroneal nerve injury (CPNI). Here, we investigate an underlying mechanism of action for this treatment and measure the effect of liFUS on inflammatory markers.

METHODS

Male rats were divided into four groups: CPNI/liFUS, CPNI/shamliFUS, shamCPNI/liFUS, and shamCPNI/shamliFUS. Mechanical nociceptive thresholds were measured using Von Frey filaments (VFF) to confirm the absence/presence of allodynia at baseline, after CPNI, and after liFUS. Commercial microarray and ELISA assays were used to assess cytokine expression in the treated L5 dorsal root ganglion (DRG) and dorsal horn (DH) tissue 24 and 72 h after liFUS.

RESULTS

VFF thresholds were significantly reduced following CPNI in both groups that received the injury (p < 0.001). After liFUS, only the CPNI/liFUS cohort showed a significant increase in mechanical thresholds (p < 0.001). CPNI significantly increased TNFa, IL6, CNTF, IL1b (p < 0.05 for all) levels in the DRG and DH, compared to baseline, consistent with previous work in sciatic nerve injury. LiFUS in CPNI rats resulted in a decrease in these cytokines in DRG 72 h post-therapy (TNFa, IL6, CNTF and IL1b, p < 0.001). In the DH, IL1b, CNTF, and TNFa (p < 0.05 for all) decreased 72 h after liFUS.

CONCLUSION

We have demonstrated that liFUS modifies inflammatory cytokines in both DRG and DH in CPNI rats. These data provide evidence that liFUS, reverses the allodynic phenotype, in part, by altering inflammatory cytokine pathways.

Repeated exposure of house dust mite induces progressive airway inflammation in mice: Differential roles of CCL17 and IL-13

We conducted a systematic evaluation of lung inflammation indued by repeated intranasal exposure (for 10 consecutive days) to a human aeroallergen, house dust mite (HDM) in BALB/c mice. Peak influx of neutrophils, monocytes/lymphocytes, and eosinophils was observed in bronchoalveolar lavage (BAL) on days 1, 7 and 11, respectively, and normalized to baseline by day 21. Peak elevations of Th2, myeloid-derived cytokines/chemokines and serum IgE were seen both in BAL and lung tissue homogenates between days 7 and 11, and declined thereafter; however, IL-33 levels remained elevated from day 7 to day 21. Airway hyperreactivity to inhaled methacholine was significantly increased by day 11 and decreased to baseline by day 21. The lung tissue showed perivascular and peribronchial cuffing, epithelial hypertrophy and hyperplasia and goblet cell formation in airways by day 11, and resolution by day 21. Levels of soluble collagen and tissue inhibitors of metalloproteinases (TIMP) also increased reflecting tissue remodeling in the lung. Microarray analysis demonstrated a significant time-dependent up-regulation of several genes including IL-33, CLCA3, CCL17, CD4, CD10, CD27, IL-13, Foxa3, IL-4, IL-10, and CD19, in BAL cells as well as the lung. Pre-treatment of HDM challenged mice with CCL17 and IL-13 antibodies reduced BAL cellularity, airway hyper-responsiveness (AHR), and histopathological changes. Notably, anti-IL-13, but not anti-CCL17 monoclonal antibodies (mAbs) reduced BAL neutrophilia while both mAbs attenuated eosinophilia. These results suggest that CCL17 has an overlapping, yet distinct profile versus IL-13 in the HDM model of pulmonary inflammation and potential for CCL17-based therapeutics in treating Th2 inflammation.

GM-CSF: A Promising Target in Inflammation and Autoimmunity

The cytokine, granulocyte macrophage-colony stimulating factor (GM-CSF), was firstly identified as being able to induce in vitro the proliferation and differentiation of bone marrow progenitors into granulocytes and macrophages. Much preclinical data have indicated that GM-CSF has a wide range of functions across different tissues in its action on myeloid cells, and GM-CSF deletion/depletion approaches indicate its potential as an important therapeutic target in several inflammatory and autoimmune disorders, for example, rheumatoid arthritis. In this review, we discuss briefly the biology of GM-CSF, raise some current issues and questions pertaining to this biology, summarize the results from preclinical models of a range of inflammatory and autoimmune disorders and list the latest clinical trials evaluating GM-CSF blockade in such disorders.