Broad-spectrum chemokine inhibition ameliorates experimental obliterative bronchiolitis

A Broad-Spectrum Chemokine Inhibitor Blocks Inflammation-Induced Myometrial Myocyte-Macrophage Crosstalk and Myometrial Contraction

Prophylactic administration of the broad-spectrum chemokine inhibitor (BSCI) FX125L has been shown to suppress uterine contraction, prevent preterm birth (PTB) induced by Group B Streptococcus in nonhuman primates, and inhibit uterine cytokine/chemokine expression in a murine model of bacterial endotoxin (LPS)-induced PTB. This study aimed to determine the mechanism(s) of BSCI action on human myometrial smooth muscle cells. We hypothesized that BSCI prevents infection-induced contraction of uterine myocytes by inhibiting the secretion of pro-inflammatory cytokines, the expression of contraction-associated proteins and disruption of myocyte interaction with tissue macrophages. Myometrial biopsies and peripheral blood were collected from women at term (not in labour) undergoing an elective caesarean section. Myocytes were isolated and treated with LPS with/out BSCI; conditioned media was collected; cytokine secretion was analyzed by ELISA; and protein expression was detected by immunoblotting and immunocytochemistry. Functional gap junction formation was assessed by parachute assay. Collagen lattices were used to examine myocyte contraction with/out blood-derived macrophages and BSCI. We found that BSCI inhibited (1) LPS-induced activation of transcription factor NF-kB; (2) secretion of chemokines (MCP-1/CCL2 and IL-8/CXCL8); (3) Connexin43-mediated intercellular connectivity, thereby preventing myocyte–macrophage crosstalk; and (4) myocyte contraction. BSCI represents novel therapeutics for prevention of inflammation-induced PTB in women.

Landscape of Preterm Birth Therapeutics and a Path Forward

Preterm birth (PTB) remains the leading cause of infant morbidity and mortality. Despite 50 years of research, therapeutic options are limited and many lack clear efficacy. Tocolytic agents are drugs that briefly delay PTB, typically to allow antenatal corticosteroid administration for accelerating fetal lung maturity or to transfer patients to high-level care facilities. Globally, there is an unmet need for better tocolytic agents, particularly in low- and middle-income countries. Although most tocolytics, such as betamimetics and indomethacin, suppress downstream mediators of the parturition pathway, newer therapeutics are being designed to selectively target inflammatory checkpoints with the goal of providing broader and more effective tocolysis. However, the relatively small market for new PTB therapeutics and formidable regulatory hurdles have led to minimal pharmaceutical interest and a stagnant drug pipeline. In this review, we present the current landscape of PTB therapeutics, assessing the history of drug development, mechanisms of action, adverse effects, and the updated literature on drug efficacy. We also review the regulatory hurdles and other obstacles impairing novel tocolytic development. Ultimately, we present possible steps to expedite drug development and meet the growing need for effective preterm birth therapeutics.

A Broad Spectrum Chemokine Inhibitor Prevents Preterm Labor but Not Microbial Invasion of the Amniotic Cavity or Neonatal Morbidity in a Non-human Primate Model

Leukocyte activation within the chorioamniotic membranes is strongly associated with inflammation and preterm labor (PTL). We hypothesized that prophylaxis with a broad-spectrum chemokine inhibitor (BSCI) would downregulate the inflammatory microenvironment induced by Group B Streptococcus (GBS, Streptococcus agalactiae) to suppress PTL and microbial invasion of the amniotic cavity (MIAC). To correlate BSCI administration with PTL and MIAC, we used a unique chronically catheterized non-human primate model of Group B Streptococcus (GBS)-induced PTL. In the early third trimester (128–138 days gestation; ~29–32 weeks human pregnancy), animals received choriodecidual inoculations of either: (1) saline (N = 6), (2) GBS, 1–5 × 10⁸ colony forming units (CFU)/ml; N = 5), or (3) pre-treatment and daily infusions of a BSCI (10 mg/kg intravenous and intra-amniotic) with GBS (1–5 × 10⁸ CFU/ml; N = 4). We measured amniotic cavity pressure (uterine contraction strength) and sampled amniotic fluid (AF) and maternal blood serially and cord blood at delivery. Cesarean section was performed 3 days post-inoculation or earlier for PTL. Data analysis used Fisher's exact test, Wilcoxon rank sum and one-way ANOVA with Bonferroni correction. Saline inoculation did not induce PTL or infectious sequelae. In contrast, GBS inoculation typically induced PTL (4/5, 80%), MIAC and fetal bacteremia (3/5; 60%). Remarkably, PTL did not occur in the BSCI+GBS group (0/4, 0%; p = 0.02 vs. GBS), despite MIAC and fetal bacteremia in all cases (4/4; 100%). Compared to the GBS group, BSCI prophylaxis was associated with significantly lower cytokine levels including lower IL-8 in amniotic fluid (p = 0.03), TNF-α in fetal plasma (p < 0.05), IFN-α and IL-7 in the fetal lung (p = 0.02) and IL-18, IL-2, and IL-7 in the fetal brain (p = 0.03). Neutrophilic chorioamnionitis was common in the BSCI and GBS groups, but was more severe in the BSCI+GBS group with greater myeloperoxidase staining (granulocyte marker) in the amnion and chorion (p < 0.05 vs. GBS). Collectively, these observations indicate that blocking the chemokine response to infection powerfully suppressed uterine contractility, PTL and the cytokine response, but did not prevent MIAC and fetal pneumonia. Development of PTL immunotherapies should occur in tandem with evaluation for AF microbes and consideration for antibiotic therapy.

The broad-spectrum chemokine inhibitor NR58-3.14.3 modulates macrophage-mediated inflammation in the diseased retina

Background

The activity of macrophages is implicated in the progression of retinal pathologies such as atrophic age-related macular degeneration (AMD), where they accumulate among the photoreceptor layer and subretinal space. This process is aided by the local expression of chemokines, which furnish these cells with directional cues that augment their migration to areas of retinal injury. While these qualities make chemokines a potential therapeutic target in curtailing damaging retinal inflammation, their wide variety and signalling redundancy pose challenges in broadly modulating their activity. Here, we examine the efficacy of the broad-spectrum chemokine inhibitor NR58-3.14.3—a suppressor of Ccl- and Cxcl- chemokine pathways—in suppressing macrophage activity and photoreceptor death, using a light-induced model of outer retinal atrophy and inflammation.

Methods

Photo-oxidative damage was induced in SD rats via exposure to 1000 lux of light for 24 h, after which animals were euthanized at 0- or 7-day post-exposure time points. Prior to damage, NR58-3.14.3 was injected intravitreally. Retinas were harvested and evaluated for the effect of NR58-3.14.3 on subretinal macrophage accumulation and cytokine expression profile, as well as photoreceptor degeneration.

Results

We report that intravitreal administration of NR58-3.14.3 reduces the accumulation of macrophages in the outer retina following exposure to light damage, at both 0- and 7-day post-exposure time points. Injection of NR58-3.14.3 also reduced the up-regulation of inflammatory markers including of Il6, Ccl3, and Ccl4 in infiltrating macrophages, which are promoters of their pathogenic activity in the retina. Finally, NR58-3.14.3-injected retinas displayed markedly reduced photoreceptor death following light damage, at both 0 and 7 days post-exposure.

Conclusions

Our findings indicate that NR58-3.14.3 is effective in inhibiting subretinal macrophage accumulation in light-induced retinal degeneration and illustrate the potential of broad-spectrum chemokine inhibitors as novel therapeutic agents in thwarting retinal inflammation. Although broad-spectrum chemokine inhibitors may not be appropriate for all retinal inflammatory conditions, our results suggest that they may be beneficial for retinal dystrophies in which chemokine expression and subretinal macrophage accumulation are implicated, such as advanced AMD.

Inhibition of infection-mediated preterm birth by administration of broad spectrum chemokine inhibitor in mice

Preterm birth (PTB) is the single most important cause of perinatal and infant mortality worldwide. Maternal infection can result in PTB. We investigated the ability of a Broad Spectrum Chemokine Inhibitor (BSCI) to prevent infection-induced PTB in mice. PTB was initiated in pregnant mice by intraperitoneal injection of lipopolysaccharide (LPS; 50 μg). Half the mice received BSCI (10 mg/kg) 24 hrs prior to and immediately before LPS administration. The impact of LPS alone or LPS plus BSCI was assessed on (i) injection-to-delivery interval, foetal survival rate, placental and neonates' weight; (ii) amniotic fluid and maternal plasma cytokine levels (by Luminex assay); foetal and maternal tissue cytokine gene expression levels (by Real-Time RT-PCR); (iii) immune cells infiltration into the uterine tissue (by stereological immunohistochemistry). Pre-treatment with BSCI (i) decreased LPS-induced PTB (64% versus 100%, P < 0.05); (ii) significantly attenuated cytokine/chemokine expression in maternal tissues (plasma, liver, myometrium, decidua); (iii) significantly decreased neutrophil infiltration in the mouse myometrium. BSCI-treated mice in which PTB was delayed till term had live foetuses with normal placental and foetal weight. BSCI represents a promising new class of therapeutics for PTB. In a mouse model of preterm labour, BCSI suppresses systemic inflammation in maternal tissues which resulted in the reduced incidence of LPS-mediated PTB. These data provide support for efforts to target inflammatory responses as a means of preventing PTB.

Plasma membrane signaling in HIV-1 infection

Plasma membrane is a multifunctional structure that acts as the initial barrier against infection by intracellular pathogens. The productive HIV-1 infection depends upon the initial interaction of virus and host plasma membrane. Immune cells such as CD4+ T cells and macrophages contain essential cell surface receptors and molecules such as CD4, CXCR4, CCR5 and lipid raft components that facilitate HIV-1 entry. From plasma membrane HIV-1 activates signaling pathways that prepare the grounds for viral replication. Through viral proteins HIV-1 hijacks host plasma membrane receptors such as Fas, TNFRs and DR4/DR5, which results in immune evasion and apoptosis both in infected and uninfected bystander cells. These events are hallmark in HIV-1 pathogenesis that leads towards AIDS. The interplay between HIV-1 and plasma membrane signaling has much to offer in terms of viral fitness and pathogenicity, and a better understanding of this interplay may lead to development of new therapeutic approaches. This article is part of a Special Issue entitled: Viral Membrane Proteins - Channels for Cellular Networking.

Preventive usage of broad spectrum chemokine inhibitor NR58-3.14.3 reduces the severity of pulmonary and hepatic graft-versus-host disease

Pulmonary graft-versus-host disease (pGVHD) is a major complication after allogeneic bone marrow transplantation (BMT), which involves donor leukocyte migration into the lung along chemokine gradients, leading to pulmonary dysfunction and respiratory insufficiency. As broad spectrum chemokine inhibitor (BSCI) NR58-3.14.3 suppresses leukocyte migration in response to various chemokines, including CCL2, CCL3, CCL5, we investigated the effects of NR58-3.14.3 on the evolution of pGVHD. Lethally irradiated B6D2F1 mice received BMT from syngeneic (B6D2F1) or allogeneic (C57BL/6) donors, and animals were treated with either NR58-3.14.3 or vehicle control from day -1 to day +14. At week 6, in allogeneic recipients that received BSCI, inflammatory cell infiltrates in the lung were decreased, and reduced histopathologic changes translated into improved pulmonary function when compared to allo-controls. Acute GVHD of the liver was also diminished, whereas no differences were seen in the gut. Alloantigen-dependent splenic T cell expansion and systemic TNF-alpha and IFN-gamma levels were comparable in NR58-3.14.3-treated animals and allo-controls. No suppressive effect of NR58-3.14.3 on CTL cytotoxicity was found, and diminished cellular infiltrates in lung and liver were most likely due to decreased migration of mononuclear cells. Therefore, novel approaches involving BSCIs may provide a promising tool in the management of pGVHD.

The broad-spectrum chemokine inhibitor NR58-3.14.3 suppresses the implantation and survival of human endometrial implants in the nude mice endometriosis model

Many chemokines likely contribute to the pathogenesis of endometriosis. The authors hypothesize that the broad-spectrum chemokine inhibitor NR58-3.14.3 may prevent ectopic human endometrium implantation and growth. After placing human endometrium fragments into the peritoneal cavity, ovariectomized athymic nude mice (n = 31) receiving intramuscular estradiol valerate were randomly assigned to daily intraperitoneal injections of either phosphate-buffered saline or NR58-3.14.3. Fourteen days later, the implant number and volume, proliferating cell nuclear antigen (PCNA) and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) index, and MTT cell viability were assessed in the implants. NR58-3.14.3 reduced the total number (45%) and total volume (81%) of endometriotic lesions (P < .05) and revealed a lower PCNA and higher TUNEL index in ectopic implants compared with controls (P < .05). NR58-3.14.3 treatment did not affect endometrial cell proliferation in vitro. NR58-3.14.3, by possibly regulating cell survival, can reduce the number and size of ectopic implants in vivo, supporting the potential use of chemokine inhibitors in novel therapies for endometriosis.

Inhibition of chemokines prevents intraperitoneal adhesions in mice

BACKGROUND

The present study evaluates the efficacy of a broad-spectrum chemokine inhibitor, NR58-3.14.3, in the prevention of adhesion formation after i.p. surgery in mice.

METHODS

A total of 110 eight week old female Balb/c mice underwent laparotomy. Forty animals were randomly assigned to receive daily i.p. injections of either vehicle (control) or NR58-3.14.3. Time-course of adhesion formation was assessed. A titration of NR58-3.14.3 was conducted for i.p. and s.c. administrations. The effectiveness of a single intra-operative dose of NR58-3.14.3 was evaluated. Number, extent, location and type of adhesions were recorded. Immunohistochemistry of adhesions was done with leukocyte common antigen, CD45.

RESULTS

Adhesion scores peaked on post-operative days 6-8. On both days 6 and 8, there were smaller adhesion size and lower cumulative adhesion scores in NR58-3.14.3-treated group. Moreover, on day 8, there were significantly fewer adhesions in NR58-3.14.3-treated group compared to controls. The least effective dose for i.p. administration of NR58-3.14.3 was 0.45 mg/animal. Subcutaneous and single intra-operative i.p. administrations were also effective in the prevention of i.p. adhesions. Although NR58-3.14.3 decreased the number of CD45+ inflammatory cells in the adhesions by 22.5% compared to control group, this was not significant.

CONCLUSIONS

Our results show that this broad-spectrum chemokine inhibitor prevents post-operative adhesions in mice and may have a potential clinical use.

Obliterative airway disease in rat tracheal allografts requires tumor necrosis factor alpha

Obliterative bronchiolitis is the major complication affecting long-term lung transplant survivors. Tumor necrosis factor-alpha (TNF-alpha) promotes inflammation and fibrosis in chronic lung injury models. These experiments defined the role of TNF-alpha in an established model of obliterative airway disease (OAD). Rat tracheas were transplanted from Brown-Norway donors into Lewis recipients, and explanted on days 7 and 14. Treated groups received either anti-TNF-alpha antibodies or a novel TNF-alpha translational inhibitor, RDP-58, beginning either immediately or on post-transplant day 7. Morphometry assessed epithelial loss and luminal obliteration, while separate tracheas were processed for TNF-alpha mRNA expression by RQRT-PCR or protein localization/expression by immunohistochemistry. EMSAs evaluated NFkappaB activation. 14-day control allografts averaged 58% occlusion and 98% epithelial loss. These parameters were significantly improved with TNF-alpha inhibition, averaging 32% luminal obliteration and 37% epithelial preservation. TNF-alpha mRNA expression increased at 14-days relative to native tracheas, and was unchanged by RDP-58 treatment. However, TNF-alpha protein expression, localized to the mucosa/submucosa, was markedly reduced with RDP-58, and resulted in diminished global NFkappaB activation in allografts. Delayed RDP treatment reduced disease progression during the second week, as luminal occlusion increased from 26% to only 35%, while respiratory epithelium persisted at 21%. TNF-alpha promotes the development of OAD in tracheal allografts via an NFkappaB-dependent mechanism, and its inhibition may prove beneficial clinically.

Identification of 3-(Acylamino)azepan-2-ones as Stable Broad-Spectrum Chemokine Inhibitors Resistant to Metabolism in Vivo

3-(acylamino)glutarimides, a class of broad spectrum chemokine inhibitors, are rapidly hydrolyzed in serum, despite being stable in aqueous solution. Synthesis and high-performance liquid chromatography analysis of the proposed N-acyl-glutamate and -glutamine metabolites establish the enzyme-catalyzed breakdown pathways. In vitro assays suggest that despite their short half-life in vivo, the parent acylamino-glutarimides, not the ring-opened hydrolysis products, are the source of the antiinflammatory activity. Identification of this metabolic pathway has led to the development of 3-(acylamino)azepan-2-ones that are also broad spectrum chemokine inhibitors and act as stable, orally available powerful antiinflammatory agents in vivo with doses of 1 mg/kg.

FR167653 reduces obliterative airway disease in rats

BACKGROUND

Obliterative bronchiolitis (OB) is the main cause of late mortality among long-term survivors of lung transplantation. Although p38 kinase is functional in multiple acute inflammatory injury models, its role in chronic lung rejection is undefined. p38 regulates the expression of the cytokines tumor necrosis (TNF)-alpha and interleukin (IL)-1beta, 2 mediators involved in the development of OB in a tracheal transplant model. These studies assessed whether specific inhibition of p38 with FR167653 (FR) protects against the development of OB in rat tracheal allografts.

METHODS

Rat airways were heterotopically transplanted from Brown-Norway donors into Lewis recipients, and animals were sacrificed on day 14 (6 per group). Treated animals received 10 mg/kg daily of FR intraperitoneally beginning either immediately or at day 7 after transplant. Allografts were assessed by computerized morphometry, and tracheas were processed for TNF-alpha mRNA and protein expression by quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry, respectively. Electrophoretic mobility shift assays evaluated nuclear factor kappa beta (NFkappaB) transactivation.

RESULTS

Control allografts averaged 61% occlusion and 98% loss of epithelium at 14 days, whereas FR administration reduced luminal occlusion to 28% (p < 0.001) and epithelial loss to 71% (p < 0.001). Delayed treatment beginning on day 7 slowed progression of disease, as tracheal occlusion averaged 44% and epithelial loss averaged 80%, both of which were significant (p < 0.05) improvements relative to 14-day controls. NFkappa transactivation (p < 0.004) and TNF-alpha mRNA and protein expression were reduced dramatically by FR at 14 days.

CONCLUSIONS

A specific p38 inhibitor, FR 167653, ameliorates obliterative airway disease in rat tracheal allografts via attenuated NFkappaB transactivation, which ultimately results in diminished TNF-alpha mRNA and protein expression.

Poly (ADP) ribose synthetase inhibition reduces obliterative airway disease in rat tracheal allografts

BACKGROUND

Obliterative bronchiolitis (OB) is the major long-term complication affecting lung transplant recipients, and is characterized pathologically by chronic inflammatory and fibroproliferative airway disease. Based on studies revealing anti-inflammatory and anti-apoptotic properties of poly (ADP)-ribose synthetase (PARS) inhibitors, we hypothesized that their administration would be protective in a heterotopic model of experimental OB.

METHODS

We transplanted rat tracheas from Brown-Norway donors into Lewis recipients, and treated 2 groups with a novel PARS inhibitor, INO-1001. One group received 14 days of treatment, whereas a second received delayed treatment beginning on Day 7 post-transplant. Tracheas were analyzed by light microscopy and computerized morphometry. Effects on cytokine transcription, nuclear transcription factor activation and cellular death were assessed by in situ hybridization for tumor necrosis factor-alpha (TNF-alpha), electromobility shift assays for nuclear factor-kappaB (NF-kappaB) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays, respectively.

RESULTS

PARS inhibition significantly decreased luminal obstruction (p < 0.001) and enhanced preservation of epithelial lining (p < 0.001) at 14 days post-transplant. Day 7 controls confirmed the development of an obstructive lesion in the lumen, averaging 28% occlusion. Delayed treatment (beginning on Day 7) arrested (p < 0.001) progression of the established lesion. Allograft airways treated with INO-1001 demonstrated attenuated NF-kappaB nuclear translocation, reduced transcription of TNF-alpha mRNA, and decreased cellular death on TUNEL and caspase 3 staining.

CONCLUSIONS

PARS inhibition is anti-inflammatory, protects against experimental OB, and is associated with enhanced preservation of respiratory epithelium and decreased cellular death. Delayed treatment with INO-1001 arrests progression of the lesion developed by Day 7. These studies suggest that activation of PARS plays a critical role in the development of airway obliterative disease.