IC100, a humanized therapeutic monoclonal anti-ASC antibody alleviates oxygen-induced retinopathy in mice

BACKGROUND

Retinopathy of prematurity (ROP), which often presents with bronchopulmonary dysplasia (BPD), is among the most common morbidities affecting extremely premature infants and is a leading cause of severe vision impairment in children worldwide. Activations of the inflammasome cascade and microglia have been implicated in playing a role in the development of both ROP and BPD. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is pivotal in inflammasome assembly. Utilizing mouse models of both oxygen-induced retinopathy (OIR) and BPD, this study was designed to test the hypothesis that hyperoxia induces ASC speck formation, which leads to microglial activation and retinopathy, and that inhibition of ASC speck formation by a humanized monoclonal antibody, IC100, directed against ASC, will ameliorate microglial activation and abnormal retinal vascular formation.

METHODS

We first tested ASC speck formation in the retina of ASC-citrine reporter mice expressing ASC fusion protein with a C-terminal citrine (fluorescent GFP isoform) using a BPD model that causes both lung and eye injury by exposing newborn mice to room air (RA) or 85% O2 from postnatal day (P) 1 to P14. The retinas were dissected on P14 and retinal flat mounts were used to detect vascular endothelium with AF-594-conjugated isolectin B4 (IB4) and citrine-tagged ASC specks. To assess the effects of IC100 on an OIR model, newborn ASC citrine reporter mice and wildtype mice (C57BL/6 J) were exposed to RA from P1 to P6, then 75% O2 from P7 to P11, and then to RA from P12 to P18. At P12 mice were randomized to the following groups: RA with placebo PBS (RA-PBS), O2 with PBS (O2-PBS), O2 + IC100 intravitreal injection (O2-IC100-IVT), and O2 + IC100 intraperitoneal injection (O2-IC100-IP). Retinal vascularization was evaluated by flat mount staining with IB4. Microglial activation was detected by immunofluorescence staining for allograft inflammatory factor 1 (AIF-1) and CD206. Retinal structure was analyzed on H&E-stained sections, and function was analyzed by pattern electroretinography (PERG). RNA-sequencing (RNA-seq) of the retinas was performed to determine the transcriptional effects of IC100 treatment in OIR.

RESULTS

ASC specks were significantly increased in the retinas by hyperoxia exposure and colocalized with the abnormal vasculature in both BPD and OIR models, and this was associated with increased microglial activation. Treatment with IC100-IVT or IC100-IP significantly reduced vaso-obliteration and intravitreal neovascularization. IC100-IVT treatment also reduced retinal microglial activation, restored retinal structure, and improved retinal function. RNA-seq showed that IC100 treatment corrected the induction of genes associated with angiogenesis, leukocyte migration, and VEGF signaling caused by O2. IC100 also corrected the suppression of genes associated with cell junction assembly, neuron projection, and neuron recognition caused by O2.

CONCLUSION

These data demonstrate the crucial role of ASC in the pathogenesis of OIR and the efficacy of a humanized therapeutic anti-ASC antibody in treating OIR mice. Thus, this anti-ASC antibody may potentially be considered in diseases associated with oxygen stresses and retinopathy, such as ROP.

GSDMD gene knockout alleviates hyperoxia-induced hippocampal brain injury in neonatal mice

BACKGROUND

Neonatal hyperoxia exposure is associated with brain injury and poor neurodevelopment outcomes in preterm infants. Our previous studies in neonatal rodent models have shown that hyperoxia stimulates the brain's inflammasome pathway, leading to the activation of gasdermin D (GSDMD), a key executor of pyroptotic inflammatory cell death. Moreover, we found pharmacological inhibition of caspase-1, which blocks GSDMD activation, attenuates hyperoxia-induced brain injury in neonatal mice. We hypothesized that GSDMD plays a pathogenic role in hyperoxia-induced neonatal brain injury and that GSDMD gene knockout (KO) will alleviate hyperoxia-induced brain injury.

METHODS

Newborn GSDMD knockout mice and their wildtype (WT) littermates were randomized within 24 h after birth to be exposed to room air or hyperoxia (85% O2) from postnatal days 1 to 14. Hippocampal brain inflammatory injury was assessed in brain sections by immunohistology for allograft inflammatory factor 1 (AIF1) and CD68, markers of microglial activation. Cell proliferation was evaluated by Ki-67 staining, and cell death was determined by TUNEL assay. RNA sequencing of the hippocampus was performed to identify the transcriptional effects of hyperoxia and GSDMD-KO, and qRT-PCR was performed to confirm some of the significantly regulated genes.

RESULTS

Hyperoxia-exposed WT mice had increased microglia consistent with activation, which was associated with decreased cell proliferation and increased cell death in the hippocampal area. Conversely, hyperoxia-exposed GSDMD-KO mice exhibited considerable resistance to hyperoxia as O2 exposure did not increase AIF1 + , CD68 + , or TUNEL + cell numbers or decrease cell proliferation. Hyperoxia exposure differentially regulated 258 genes in WT and only 16 in GSDMD-KO mice compared to room air-exposed WT and GSDMD-KO, respectively. Gene set enrichment analysis showed that in the WT brain, hyperoxia differentially regulated genes associated with neuronal and vascular development and differentiation, axonogenesis, glial cell differentiation, hypoxia-induced factor 1 pathway, and neuronal growth factor pathways. These changes were prevented by GSDMD-KO.

CONCLUSIONS

GSDMD-KO alleviates hyperoxia-induced inflammatory injury, cell survival and death, and alterations of transcriptional gene expression of pathways involved in neuronal growth, development, and differentiation in the hippocampus of neonatal mice. This suggests that GSDMD plays a pathogenic role in preterm brain injury, and targeting GSDMD may be beneficial in preventing and treating brain injury and poor neurodevelopmental outcomes in preterm infants.

GSDMD gene knockout alleviates hyperoxia-induced hippocampal brain injury in neonatal mice

Background: Neonatal hyperoxia exposure is associated with brain injury and poor neurodevelopment outcomes in preterm infants. Our previous studies in neonatal rodent models have shown that hyperoxia stimulates the brain's inflammasome pathway, leading to the activation of gasdermin D (GSDMD), a key executor of pyroptotic inflammatory cell death. Moreover, we found inhibition of GSDMD activation attenuates hyperoxia-induced brain injury in neonatal mice. We hypothesized that GSDMD plays a pathogenic role in hyperoxia-induced neonatal brain injury and that GSDMD gene knockout (KO) will alleviate hyperoxia-induced brain injury. Methods: Newborn GSDMD knockout mice and their wildtype (WT) littermates were randomized within 24 h after birth to be exposed to room air or hyperoxia (85% O2) from postnatal day 1 to 14. Hippocampal brain inflammatory injury was assessed in brain sections by immunohistology for allograft inflammatory factor 1 (AIF1), a marker of microglial activation. Cell proliferation was evaluated by Ki-67 staining, and cell death was determined by TUNEL assay. RNA sequencing of the hippocampus was performed to identify the transcriptional effects of hyperoxia and GSDMD-KO, and qRT-PCR was performed to confirm some of the significantly regulated genes. Results: Hyperoxia-exposed WT mice had increased microglia consistent with activation, which was associated with decreased cell proliferation and increased cell death in the hippocampal area. Conversely, hyperoxia-exposed GSDMD-KO mice exhibited considerable resistance to hyperoxia as O2 exposure failed to increase either AIF1+ or TUNEL+ cell numbers, nor decrease cell proliferation. Hyperoxia exposure differentially regulated 258 genes in WT and only 16 in GSDMD-KO mice compared to room air- exposed WT and GSDMD-KO, respectively. Gene set enrichment analysis showed that in the WT brain, hyperoxia differentially regulated genes associated with neuronal and vascular development and differentiation, axonogenesis, glial cell differentiation, and core development pathways hypoxia-induced factor 1, and neuronal growth factor pathways. These changes were prevented by GSDMD-KO. Conclusion: GSDMD-KO alleviates hyperoxia-induced inflammatory injury, cell survival and death, and alterations of transcriptional gene expression of pathways involved in neuronal growth, development, and differentiation in the hippocampus of neonatal mice. This suggests that GSDMD plays a pathogenic role in preterm brain injury, and targeting GSDMD may be beneficial in preventing and treating brain injury and poor neurodevelopmental outcomes in preterm infants.

GSDMD deficiency ameliorates hyperoxia-induced BPD and ROP in neonatal mice

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are among the most common morbidities affecting extremely premature infants who receive oxygen therapy. Many clinical studies indicate that BPD is associated with advanced ROP. However, the mechanistic link between hyperoxia, BPD, and ROP remains to be explored. Gasdermin D (GSDMD) is a key executor of inflammasome-induced pyroptosis and inflammation. Inhibition of GSDMD has been shown to attenuate hyperoxia-induced BPD and brain injury in neonatal mice. The objective of this study was to further define the mechanistic roles of GSDMD in the pathogenesis of hyperoxia-induced BPD and ROP in mouse models. Here we show that global GSDMD knockout (GSDMD-KO) protects against hyperoxia-induced BPD by reducing macrophage infiltration, improving alveolarization and vascular development, and decreasing cell death. In addition, GSDMD deficiency prevented hyperoxia-induced ROP by reducing vasoobliteration and neovascularization, improving thinning of multiple retinal tissue layers, and decreasing microglial activation. RNA sequencing analyses of lungs and retinas showed that similar genes, including those from inflammatory, cell death, tissue remodeling, and tissue and vascular developmental signaling pathways, were induced by hyperoxia and impacted by GSDMD-KO in both models. These data highlight the importance of GSDMD in the pathogenesis of BPD and ROP and suggest that targeting GSDMD may be beneficial in preventing and treating BPD and ROP in premature infants.

Circulating extracellular vesicles activate the pyroptosis pathway in the brain following ventilation-induced lung injury

BACKGROUND

Mechanical ventilation of preterm newborns causes lung injury and is associated with poor neurodevelopmental outcomes. However, the mechanistic links between ventilation-induced lung injury (VILI) and brain injury is not well defined. Since circulating extracellular vesicles (EVs) are known to link distant organs by transferring their cargos, we hypothesized that EVs mediate inflammatory brain injury associated with VILI.

METHODS

Neonatal rats were mechanically ventilated with low (10 mL/kg) or high (25 mL/kg) tidal volume for 1 h on post-natal day 7 followed by recovery for 2 weeks. Exosomes were isolated from the plasma of these rats and adoptively transferred into normal newborn rats. We assessed the effect of mechanical ventilation or exosome transfer on brain inflammation and activation of the pyroptosis pathway by western blot and histology.

RESULTS

Injurious mechanical ventilation induced similar markers of inflammation and pyroptosis, such as increased IL-1β and activated caspase-1/gasdermin D (GSDMD) in both lung and brain, in addition to inducing microglial activation and cell death in the brain. Isolated EVs were enriched for the exosomal markers CD9 and CD81, suggesting enrichment for exosomes. EVs isolated from neonatal rats with VILI had increased caspase-1 but not GSDMD. Adoptive transfer of these EVs led to neuroinflammation with microglial activation and activation of caspase-1 and GSDMD in the brain similar to that observed in neonatal rats that were mechanically ventilated.

CONCLUSIONS

These findings suggest that circulating EVs can contribute to the brain injury and poor neurodevelopmental outcomes in preterm infants with VILI through activation of GSDMD.

Hyperoxia-activated circulating extracellular vesicles induce lung and brain injury in neonatal rats

Hyperoxia-induced lung injury plays a key role in the development of bronchopulmonary dysplasia (BPD), characterized by inflammatory injury and impaired lung development in preterm infants. Although BPD is a predictor of poor neurodevelopmental outcomes, currently it is uncertain how lung injury contributes to brain injury in preterm infants. Extracellular vesicles (EVs) are a heterogeneous group of cell-derived membranous structures that regulate intercellular and inter-organ communications. Gasdermin D (GSDMD) has emerged as a key executor of inflammasome-mediated cell death and inflammation. In this study, we utilized a neonatal rat model of BPD to assess if hyperoxia stimulates lung release of circulating EVs and if these EVs induce lung and brain injury. We found that hyperoxia-exposed rats had elevated numbers of plasma-derived EVs compared to rats maintained in room air. These EVs also had increased cargos of surfactant protein C, a marker of type II alveolar epithelial cells (AEC), and the active (p30) form of GSDMD. When these EVs were adoptively transferred into normal newborn rats via intravenous injection, they were taken up both by lung and brain tissues. Moreover, EVs from hyperoxic animals induced not only the pathological hallmarks of BPD, but also brain inflammatory injury in recipient rats, as well as inducing cell death in cultured pulmonary vascular endothelial cells and neural stem cells (NSC). Similarly, hyperoxia-exposed cultured AEC-like cells released EVs that also contained increased GSDMD-p30 and these EVs induced pyroptotic cell death in NSC. Overall, these data indicate that hyperoxia-activated circulating EVs mediate a lung to brain crosstalk resulting in brain injury and suggest a mechanism that links lung injury and neurodevelopmental impairment in BPD infants.

Riociguat prevents hyperoxia-induced lung injury and pulmonary hypertension in neonatal rats without effects on long bone growth

Bronchopulmonary dysplasia (BPD) remains the most common and serious chronic lung disease of premature infants. Severe BPD complicated with pulmonary hypertension (PH) increases the mortality of these infants. Riociguat is an allosteric soluble guanylate cyclase stimulator and is approved by the FDA for treating PH in adults. However, it has not been approved for use in neonates due to concern for adverse effects on long bone growth. To address this concern we investigated if administration of riociguat is beneficial in preventing hyperoxia-induced lung injury and PH without side effects on long bone growth in newborn rats. Newborn rats were randomized to normoxia (21% O₂) or hyperoxia (85% O₂) exposure groups within 24 hours of birth, and received riociguat or placebo by once daily intraperitoneal injections during continuous normoxia or hyperoxia exposure for 9 days. In the hyperoxia control group, radial alveolar count, mean linear intercept and vascular density were significantly decreased, the pathological hallmarks of BPD, and these were accompanied by an increased inflammatory response. There was also significantly elevated vascular muscularization of peripheral pulmonary vessels, right ventricular systolic pressure and right ventricular hypertrophy indicating PH. However, administration of riociguat significantly decreased lung inflammation, improved alveolar and vascular development, and decreased PH during hyperoxia by inducing cGMP production. Additionally, riociguat did not affect long bone growth or structure. These data indicate that riociguat is beneficial in preventing hyperoxia-induced lung injury and PH without affecting long bone growth and structure and hence, suggests riociguat may be a potential novel agent for preventing BPD and PH in neonates.

A connective tissue growth factor signaling receptor in corneal fibroblasts

PURPOSE

To biochemically characterize the receptor for connective tissue growth factor (CTGF) of human corneal fibroblasts (HCF).

METHODS

Radiolabeled recombinant human CTGF was used to determine the specificity and time course of binding to low-passage cultures of HCF. The affinity and number of receptors present were calculated by Scatchard and best-fit analyses. In vitro immunoprecipitation assays with radiolabeled CTGF and soluble mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF-2-R) alone, or with CTGF-related growth factors were conducted. Additionally, (125)I-CTGF-binding and CTGF-stimulated proliferation were measured in cultures of M6P/IGF-2-R knockout fibroblasts.

RESULTS

Binding of (125)I-CTGF to fibroblast cultures was significantly displaced by CTGF, but not by related growth factors. Scatchard plot analysis indicated the presence of both a high-affinity, low-abundance binding site, and a low-affinity, high-abundance binding site; whereas, the best-fit analysis suggests a single high-affinity, low-abundance binding site. A 280 kDa complex containing cross-linked (125)I-CTGF was immunoprecipitated by antibodies to CTGF or M6P/IGF-2-R. M6P/IGF-2-R knockout cells have a reduced proliferative response to TGF-β, and don't proliferate at all in response to CTGF.

CONCLUSIONS

CTGF binds to the M6P/IGF-2-R with high affinity, and the M6P/IGF-2-R is required for CTGF-stimulated proliferation in fibroblasts. These observations suggest that the M6P/IGF-2-R may be a new antifibrotic target.

Inhalation of sulfur mustard causes long-term T cell-dependent inflammation: possible role of Th17 cells in chronic lung pathology

Sulfur mustard (SM) is a highly toxic chemical warfare agent that remains a threat to human health. The immediate symptoms of pulmonary distress may develop into chronic lung injury characterized by progressive lung fibrosis, the major cause of morbidity among the surviving SM victims. Although SM has been intensely investigated, little is known about the mechanism(s) by which SM induces chronic lung pathology. Increasing evidence suggests that IL-17(+) cells are critical in fibrosis, including lung fibrotic diseases. In this study we exposed F344 rats and cynomolgus monkeys to SM via inhalation and determined the molecular and cellular milieu in their lungs at various times after SM exposure. In rats, SM induced a burst of pro-inflammatory cytokines/chemokines within 72 h, including IL-1β, TNF-α, IL-2, IL-6, CCL2, CCL3, CCL11, and CXCL1 that was associated with neutrophilic infiltration into the lung. At 2 wks and beyond (chronic phase), lymphocytic infiltration and continued elevated expression of cytokines/chemokines were sustained. TGF-β, which was undetectable in the acute phase, was strongly upregulated in the chronic phase; these conditions persisted until the animals were sacrificed. The chronic phase was also associated with myofibroblast proliferation, collagen deposition, and presence of IL-17(+) cells. At ≥30 days, SM inhalation promoted the accumulation of IL-17(+) cells in the inflamed areas of monkey lungs. Thus, SM inhalation causes acute and chronic inflammatory responses; the latter is characterized by the presence of TGF-β, fibrosis, and IL-17(+) cells in the lung. IL-17(+) cells likely play an important role in the pathogenesis of SM-induced lung injury.

ALK-5 mediates endogenous and TGF-beta1-induced expression of connective tissue growth factor in embryonic lung

Transforming growth factor-beta1 (TGF-beta1) has been implicated as a major negative regulator of lung branching morphogenesis. Since connective tissue growth factor (CTGF) is a downstream mediator of TGF-beta1 effects on mesenchymal cells, we hypothesized that TGF-beta1 induces CTGF expression in mouse embryonic lung explants and that CTGF mediates TGF-beta1 inhibition of branching morphogenesis. We show that addition of TGF-beta1 to the serum-free medium of embryonic day (E)12.5 lung explant cultures inhibited branching morphogenesis and induced CTGF mRNA expression in time- and dose-dependent manners. In contrast to basal endogenous CTGF protein, which was exclusively localized in the distal airway epithelium, TGF-beta1-induced CTGF protein was localized in both the epithelium and the mesenchyme. Addition of exogenous CTGF to culture medium directly inhibited branching morphogenesis. To identify the signal transduction pathway through which TGF-beta1 induces CTGF, we used SB431542, a specific inhibitor for TGF-beta type I receptor (TbetaRI)/ALK-5 to block TGF-beta1-induced Smad2/3 phosphorylation. Consequently, SB431542 stimulated normal branching morphogenesis and blocked TGF-beta1 inhibition of branching. Furthermore, SB-431542 blocked both endogenous and TGF-beta1-induced expression of CTGF mRNA and protein. These results demonstrate for the first time that TGF-beta1 induces CTGF expression in mouse embryonic lung explants, that CTGF inhibits branching morphogenesis, and that both endogenous and TGF-beta1-induced CTGF expression are mediated by the TbetaRI/ALK-5-dependent Smad2 signaling pathway.

Individual domains of connective tissue growth factor regulate fibroblast proliferation and myofibroblast differentiation

All members of the Ctgf, Cyr61, and Nov (CCN) family share a high degree of sequence homology and conservation of structural motifs and domains. Here, we present data about a structure function analysis of connective tissue growth factor (CTGF), a prototypic member of the CCN family, which has been shown to be a downstream mediator of transforming growth factor-beta activities on fibroblasts. Our findings demonstrate the two domains of CTGF function to mediate two distinct biological effects. The N-terminal domain of CTGF mediates myofibroblast differentiation and collagen synthesis. The C-terminal domain of CTGF mediates fibroblast proliferation. These data provide a molecular basis for the divergence of CTGF actions on connective tissue cell types and suggest a model for functional analysis of all of the CCN family gene products.

Combinatorial signaling pathways determine fibroblast proliferation and myofibroblast differentiation

Fibroblast proliferation, differentiation into myofibroblasts, and increased collagen synthesis are key events during both normal wound repair and fibrotic lesion formation. Here we report that these biological responses to TGF-beta by fibroblasts are regulated via a CTGF-dependent pathway in concert with either EGF or IGF-2. Our studies indicate these responses to TGF-beta are mutually exclusive, and cells that are proliferating do not express alpha-SMA or elevated levels of collagen synthesis. Cells expressing alpha-SMA do not exhibit DNA synthesis but do coexpress higher levels of types I and III collagen mRNA. Thus, fibroblast proliferation and differentiation are controlled by combinatorial signaling pathways involving not only components of the TGF-beta/CTGF pathway, but also signaling events induced by EGF and IGF-2-activated receptors. Collectively, our studies indicate TGF-beta functions as a classic embryonic inducer, initiating a cascade that is controlled by other factors in the cellular environment. We propose a model for this process with regard to wound repair and fibrotic lesion formation that is likely applicable to other instances of CTGF action during embryogenesis.

Etoricoxib in the treatment of chronic pain

For the many patients who suffer chronic pain, we seek the most effective anti-inflammatory drug with the least side-effect profile and the greatest long-term safety. Etoricoxib, a selective COX2 inhibitor, has been shown to be as effective as non-selective non-steroidal anti-inflammatory drugs in the management of chronic pain in rheumatoid arthritis and osteoarthritis, for periods of up to one year. Data on etoricoxib efficacy in chronic low back pain is beginning to emerge. The side-effect profile of etoricoxib suggests it is well tolerated with similar adverse effects to non-selective NSAIDs. Larger studies are awaited, to see whether superior gastrointestinal tolerability can be proven. Further work will be required to show that etoricoxib is safe in patients with pre-existing cardiovascular or gastrointestinal comorbidity, and the potentially confounding role of aspirin still needs to be elucidated. However, etoricoxib shows promise as a new and effective COX2 inhibitor in clinical practice.

Connective tissue growth factor expression and action in human corneal fibroblast cultures and rat corneas after photorefractive keratectomy

PURPOSE

Connective tissue growth factor (CTGF) has been linked to fibrosis in several tissues. In this study, the interactions between CTGF and transforming growth factor (TGF)-beta were assessed in human corneal fibroblasts, and the levels and location of CTGF protein and mRNA were measured during healing of excimer laser ablation wounds in rat corneas.

METHODS

Human corneal fibroblasts were incubated with TGF-beta1, -beta2, and -beta3 isoforms, and CTGF mRNA and protein were measured. CTGF was immunolocalized in the cultured fibroblasts by using a specific antibody. Regulation of collagen synthesis by TGF-beta and CTGF was assessed in human corneal fibroblasts with a neutralizing antibody and an antisense oligonucleotide to CTGF. CTGF mRNA and protein were measured in rat corneas up to day 21 after excimer ablation of the cornea. CTGF protein was immunolocalized in rat corneas after photorefractive keratectomy (PRK), and the presence of CTGF mRNA and protein in ex vivo rat corneal scrapings was established.

RESULTS

All three TGF-beta isoforms stimulated expression of CTGF in human corneal fibroblasts, and CTGF was immunolocalized in the cells. Both TGF-beta and CTGF increased collagen synthesis in corneal fibroblasts. Furthermore, CTGF antibody or antisense oligonucleotide blocked TGF-beta-stimulated collagen synthesis. CTGF protein and mRNA increased in rat corneas through day 21 after PRK. CTGF expression was also detected in ex vivo scrapings of rat corneas.

CONCLUSIONS

These data demonstrate that CTGF is expressed by corneal cells after stimulation by TGF-beta, that CTGF expression increases significantly during corneal wound healing, and that CTGF mediates the effects of TGF-beta induction of collagen synthesis by corneal fibroblasts. These data support the hypothesis that CTGF promotes corneal scar formation and imply that regulating CTGF synthesis and action may be an important goal for reducing corneal scarring.

Expression of connective tissue growth factor in intra-abdominal adhesions

PURPOSE

Connective tissue growth factor stimulates fibroblast proliferation and extracellular matrix deposition in many fibrotic disorders. The aim of our study was to determine the expression pattern of connective tissue growth factor in postoperative intra-abdominal adhesions.

METHODS

Adhesions were created in 46 Sprague-Dawley rats by complete dissection and resuturing of a peritoneal patch 2 cm in diameter, lateral from the midline incision. Animals were killed at postoperative Days 3, 6, 9, 12, 15, 18, and 21 and the adhesions scored on a scale of 0 to 5. Tissue samples from adhesion areas and from uninvolved peritoneum were evaluated by Northern and Western blotting for temporal connective tissue growth factor mRNA and protein expression, respectively. Immunohistochemical analysis was performed for connective tissue growth factor localization.

RESULTS

Adhesions formed in all animals after surgery and were confined to the peritoneal patches. Adhesion formation increased across time, with significant correlation between adhesion scores and postoperative days (r = 0.329, P = 0.026). Connective tissue growth factor mRNA concentrations were significantly elevated in adhesion tissue throughout the three-week period when compared with normal peritoneum (P = 0.012); peak levels occurred between Days 6 and 15. Western blots demonstrated connective tissue growth factor protein expression in adhesions from Days 6 to 21, in contrast to negligible bands in normal peritoneum. Fibroblasts within the adhesive tissue, but not in uninjured peritoneum, stained positive for connective tissue growth factor by immunohistochemistry.

CONCLUSIONS

We have demonstrated a specific temporal and spatial expression pattern for connective tissue growth factor in intra-abdominal adhesions during a three-week postoperative time course. According to what is known about the functional role of connective tissue growth factor in fibrogenesis, our findings warrant further investigations addressing a causal relationship between this growth factor and fibrous adhesion formation.

Connective tissue growth factor mediates transforming growth factor beta-induced collagen synthesis: down-regulation by cAMP

Connective tissue growth factor (CTGF) is a cysteine-rich peptide synthesized and secreted by fibroblastic cells after activation with transforming growth factor beta (TGF-beta) that acts as a downstream mediator of TGF-beta-induced fibroblast proliferation. We performed in vitro and in vivo studies to determine whether CTGF is also essential for TGF-beta-induced fibroblast collagen synthesis. In vitro studies with normal rat kidney (NRK) fibroblasts demonstrated CTGF potently induces collagen synthesis and transfection with an antisense CTGF gene blocked TGF-beta stimulated collagen synthesis. Moreover, TGF-beta-induced collagen synthesis in both NRK and human foreskin fibroblasts was effectively blocked with specific anti-CTGF antibodies and by suppressing TGF-beta-induced CTGF gene expression by elevating intracellular cAMP levels with either membrane-permeable 8-Br-cAMP or an adenylyl cyclase activator, cholera toxin (CTX). cAMP also inhibited collagen synthesis induced by CTGF itself, in contrast to its previously reported lack of effect on CTGF-induced DNA synthesis. In animal assays, CTX injected intradermally in transgenic mice suppressed TGF-beta activation of a human CTGF promoter/lacZ reporter transgene. Both 8-Br-cAMP and CTX blocked TGF-beta-induced collagen deposition in a wound chamber model of fibrosis in rats. CTX also reduced dermal granulation tissue fibroblast population increases induced by TGF-beta in neonatal mice, but not increases induced by CTGF or TGF-beta combined with CTGF. Our data indicate that CTGF mediates TGF-beta-induced fibroblast collagen synthesis and that in vivo blockade of CTGF synthesis or action reduces TGF-beta-induced granulation tissue formation by inhibiting both collagen synthesis and fibroblast accumulation.

Determining the capability of a drug product to be terminally sterilized: a case study involving a heat-sensitive, oxygen-sensitive drug product

A decision scheme for determining the capability of a finished product dosage form to be terminally sterilized was presented and followed for a heat-sensitive, oxygen-sensitive drug product (DP). Studies were conducted first in a laboratory steam sterilizer and then in a production unit. When a nonheat-sensitive steam sterilization cycle produced unfavorable loss of potency and increases in the amount of impurities, a new heat-sensitive steam sterilization cycle was investigated. An acceptable product was produced by reducing the headspace oxygen level and reducing the heat delivered to the product during terminal sterilization. The amount of sterilizing steam heat delivered to the product was reduced by reducing the allowable temperature range from set-point of the terminal steam sterilizer, and by developing a new heat-sensitive cycle. The heat-sensitive cycle, with a model based upon a known relationship of the biological indicator, product D value, and the environmental bioburden, can achieve a 10(-6) sterility assurance level when it delivers an F0 > or = 4 min. When the standard terminal sterilization model and cycle produced unacceptable levels of degradation, formulation/production changes, and terminal sterilization model and cycle modifications were explored, before the DP was directed to aseptic filling. Acceptable moist heat terminal sterilization the DP was then achieved.

Formulation of a stable parenteral product; Clonidine Hydrochloride Injection

Clonidine Hydrochloride Injection (Duraclon) is a clear, colorless, preservative-free, pyrogen free, aqueous solution of clonidine hydrochloride. The indication for this product is for use as an adjunct in pain management, administered epidurally, when opiates are insufficient. The drug formulation was evaluated under both normal and stress conditions in the preformulation/formulation studies. The list of studies conducted includes a light sensitivity study, an oxygen sensitivity study, a pH/stability study, a stopper compatibility evaluation, a freeze-thaw study, and a stability study. Samples from the light, oxygen, pH/stability, and stability studies were evaluated for color, visual clarity, pH, potency, and chromatographic purity. Samples from the freeze-thaw study were evaluated for all of the above except chromatographic purity. The results for these studies demonstrate the stability of the product as formulated. The pH of this unbuffered product was consistently within the acceptance criteria. The product remained clear and colorless for the duration of each study. The values obtained for the potency and chromatographic purity assays showed no evidence of degradation. The reasons for the lack of degradation can be found in the molecular structure of the drug substance and the formulation of the drug product. Since the molecular structure is that of a Schiff base, it is theoretically possible, although difficult, to cleave the molecule. A catalyst would be required, and none of the possible catalysts are present in the formulation. The molecule could also be cleaved upon exposure to light, and the evidence indicates that the molecule does interact with light. This interaction is not to the degree, however, that product stability is affected. The formulation contains only the active drug substance and sodium chloride in water for injection with a pH of approximately 6. Although the product is unbuffered, the influence of the stoppers and glass vials upon the formulation pH was minimal. In addition, the stopper compatibility of the product is enhanced by the absence of chelating agents, preservatives, acids, and bases. Since the dilute concentrations of both the active and excipient are well below their solubility limits, no solubility related issues would be expected upon freezing and subsequent thawing. Clonidine Hydrochloride Injection, as formulated, does not require protection from light, oxygen, or freezing. The product shows acceptable stability within the pH range, and the rubber closure is compatible with the product. Real time stability data combined with statistical projections support a 36-month expiration date.

Effect of social deprivation on disease severity and outcome in patients with rheumatoid arthritis

OBJECTIVE

Social deprivation is now recognised to have an important impact on morbidity and mortality. This study sought to ascertain the effect of deprivation, if any, on disease severity, functional disability, and outcome in rheumatoid patients in Glasgow.

METHODS

814 patients with rheumatoid arthritis (RA) were assessed for clinical, functional, and laboratory indices of disease activity. Deprivation categories for individual patients were determined using the Carstairs index. Five year follow up is available for 440 patients.

RESULTS

The study population of RA patients live largely in the most deprived areas. Patients from deprived areas have significantly poorer function at outset and at five years as defined by the Health Assessment Questionnaire (HAQ) score. This is not attributable to differences in disease duration in patients from the most deprived regions or compliance with treatment. Furthermore, these patients do not achieve over five years the initial functional level of those living in the most advantaged localities.

CONCLUSION

RA patients from deprived areas have poorer function, which is associated with greater need--medical, social, and paramedical. Strategies and resources for healthcare need to be adjusted according to this variation.

The use of antimalarials in combination with other disease modifying agents in RA--the British experience

Antimalarial drugs are effective disease modifying agents in RA with a low incidence of serious toxic effects. Recently, combinations of second-line agents have been used in RA in attempts to treat patients with no response to a number of single agents, or suboptimal response to a single agent. Combinations of drugs have been selected for maximum efficacy and minimum toxicity, but clinical trials are difficult to design and interpret. In particular, ensuring adequate power to detect small differences in response poses a major problem. Antimalarials are an attractive choice for combination therapy due to their efficacy, mechanisms of action and toxicity profile. In this review, the evidence for the use of antimalarials in combination in RA is examined. No advantage has been shown in combining antimalarials with gold, penicillamine or sulphasalazine compared with monotherapeutic regimens. There is some evidence to suggest a beneficial combination of antimalarials with methotrexate, but this is as yet inconclusive. Open non-randomised uncontrolled studies have shown that antimalarials combined with cytotoxic agents are effective but highly toxic. The authors conclude that there is little good evidence to support the introduction of combination second-line drug therapy for RA into widespread therapeutic use.

The use of antimalarials in combination with other disease modifying agents in RA – the British experience

Antimalarial drugs are effective disease modifying agents in RA with a low incidence of serious toxic effects. Recently, combinations of second-line agents have been used in RA in attempts to treat patients with no response to a number of single agents, or suboptimal response to a single agent.

Combinations of drugs have been selected for maximum efficacy and minimum toxicity, but clinical trials are difficult to design and interpret. In particular, ensuring adequate power to detect small differences in response poses a major problem. Antimalarials are an attractive choice for combination therapy due to their efficacy, mechanisms of action and toxicity profile.

In this review, the evidence for the use of antimalarials in combination in RA is examined. No advantage has been shown in combining antimalarials with gold, penicillamine or sulphasalazine compared with monotherapeutic regimens. There is some evidence to suggest a beneficial combination of antimalarials with methotrexate, but this is as yet inconclusive. Open non-randomised uncontrolled studies have shown that antimalarials combined with cytotoxic agents are effective but highly toxic.

The authors conclude that there is little good evidence to support the introduction of combination second-line drug therapy for RA into widespread therapeutic use.

Mononuclear cells isolated from fibrotic skin lesions in avian scleroderma constitutively produce fibroblast-activating cytokines and immunoglobulin M

University of California, Davis line 200 and 206 chickens develop an inherited autoimmune fibrotic disease associated with autoantibodies and other features similar to human scleroderma. Early in life, line 200/206 chickens develop mononuclear cell (MNC) infiltrates in the skin, followed by severe dermal fibrosis and vascular occlusions. Cultured fibroblasts derived from fibrotic skin lesions of line 200/206 chickens display an activated phenotype producing elevated quantities of collagen and glycosaminoglycan (GAG) compared to fibroblasts derived from normal chicken skin. To demonstrate a link between skin mononuclear cell infiltration and fibroblast activation, we cultured MNC isolated from developing fibrotic skin lesions, normal appearing skin, and peripheral blood of line 206 chickens for 24-72 h. Subsequent assay of MNC culture supernatants for effect on the collagen and GAG production of normal chicken skin fibroblasts demonstrated that only fibrotic lesion MNC supernatants contained significant collagen and GAG synthesis stimulatory activity. Both stimulatory activities were constitutively produced, undialyzable, heat and protease sensitive, and coeluted on gel filtration with a M(r) of 24-32 kD. Gel filtration also revealed that fibrotic lesion MNC secrete a protein > 250 kD, which we have identified as immunoglobulin (Ig) M by Western blot analysis. These results demonstrate that skin infiltrating MNC secrete both fibroblast-activating cytokines and IgM and thus they likely play an important role as effector cells in the development of dermal fibrosis and autoantibodies in this avian model of scleroderma.

Pentoxifylline, pentifylline, and interferons decrease type I and III procollagen mRNA levels in dermal fibroblasts: evidence for mediation by nuclear factor 1 down-regulation

Pentoxifylline (PTX) is a methylxanthine that exhibits multiple biologic activities, including the inhibition of collagen synthesis by dermal fibroblasts. Because some PTX activities have recently been linked to transcription factor-mediated regulation of gene transcription, we have investigated if PTX acts to inhibit collagen synthesis at a transcriptional locus by measuring procollagen mRNA levels by assaying for the presence of an activator of procollagen gene promoters, nuclear factor (NF)-1. The effects of another methylxanthine, pentifylline (PTF), shown herein to be a tenfold more potent inhibitor of collagen synthesis than PTX, and interferon-alpha, -beta, and -gamma were studied in parallel. Analysis of extracellular protein and RNA from 48-h-treated fibroblasts showed that PTX, PTF, and interferons decreased alpha 1(I), alpha 2(I), and alpha 1(III) procollagens by reducing the steady-state levels of the corresponding procollagen mRNA transcripts. Reduction of procollagen mRNA levels appeared to be dependent on new protein synthesis, as it was prevented by treatment with cycloheximide. Assay for the presence of nuclear NF-1 by gel mobility shift analysis showed that extracts from interferon, PTX, and PTF-treated fibroblasts lacked proteins recognizing the consensus DNA binding sequence for NF-1. Taken together, these observations suggest interferons and methylxanthines may inhibit fibroblast collagen synthesis by a common mechanism requiring new protein synthesis that suppresses procollagen gene transcription through down-regulation of NF-1.

Oncostatin M stimulates collagen and glycosaminoglycan production by cultured normal dermal fibroblasts: insensitivity of sclerodermal and keloidal fibroblasts

It is thought that normal fibrotic repair progresses to dermal fibrosis when fibroblasts are activated persistently by chronic exposure to cytokines such as transforming growth factor-beta. However, additional cytokines and mechanisms may play a role in the development of fibrosis. Thus, we examined a recently described T-lymphocyte/macrophage-derived cytokine, oncostatin M, for its effect on the production of collagen and glycosaminoglycan by microcultures of normal dermal, sclerodermal, and keloidal fibroblasts. Treatment with oncostatin M for 48 h induced dose-dependent (1-100 ng/ml) increases in the collagen and glycosaminoglycan production of nine normal fibroblast strains, which in the absence of fetal bovine serum at 100 ng/ml averaged 196% and 244%, respectively. Oncostatin M treatment increased both types I and III procollagens and their mRNA transcripts, as well as levels of hyaluronic acid, chondroitin-4/6 sulfates, and dermatan sulfate, but not fibronectin or general noncollagenous protein synthesis. In contrast, the collagen production of six of eight sclerodermal and keloidal fibroblast strains was essentially unresponsive to oncostatin M treatment, with 100 ng/ml inducing an average increase of only 34% for the eight fibrotic strains. Oncostatin M stimulation of fibrotic fibroblast glycosaminoglycan production was also hyporesponsive, as 100 ng/ml of oncostatin M induced an average increase of only 101%. These results indicate that oncostatin M could function as a stimulator of normal fibrotic repair via activation of fibroblast collagen and glycosaminoglycan synthesis and that the persistent activation of sclerodermal and keloidal fibroblasts is accompanied by a loss of sensitivity to oncostatin M stimulation.

Nonradioactive gel mobility shift assay using chemiluminescent detection

A nonradioactive gel mobility shift assay using chemiluminescent detection following semidry transfer to nylon membranes is described. The procedure utilizes digoxigenin-labeled oligonucleotides in conjunction with anti-digoxigenin antibody Fab fragments coupled to alkaline phosphatase. Detection of alkaline phosphatase is by autoradiography of the chemiluminescence produced during enzymatic dephosphorylation of a dioxetane substrate. This method offers similar sensitivity to radioactive methods while having the advantages of multiple exposures, faster processing, stability of labeled oligonucleotides and safety associated with nonradioactive methods of detection.

Cultured fibroblasts in avian scleroderma, an autoimmune fibrotic disease, display an activated phenotype

University of California, Davis, line 200 and 206 chickens spontaneously develop an autoimmune syndrome that has many features analogous to human scleroderma, including dermal fibrosis, antinuclear antibodies and antibodies to type II collagen. These birds also have thymic subcapsular epithelial defects and an abnormality in T cell calcium influx and proliferation in response to both T cell receptor-dependent and -independent activators. To determine whether fibroblast activation is a contributing factor to development of skin fibrosis in line 200/206 chickens, as it is in human scleroderma, we studied the collagen, non-collagenous protein and glycosaminoglycan (GAG) production of 34 separate fibroblast lines derived from the normal and fibrotic skin of line 200 and 206 chickens and from the skin of control chicken lines 058 and 254. The mean +/- SEM 24-h incorporation of 3H-proline or 3H-glucosamine into extracellular collagen, non-collagenous protein or GAG by first passage fibroblast lines derived from the fibrotic skin of diseased birds was 1,526 +/- 136, 859 +/- 82 and 25.7 +/- 1.3 dpm/10(3) cells, respectively, while fibroblast lines derived from the skin of control birds produced only 341 +/- 36, 343 +/- 42 and 15.2 +/- 1.4 dpm/10(3) cells. Similar differences in results were recorded for cell-associated production, and when collagen and non-collagenous protein production were assessed using non-radioactive electrophoretic methods. The activated phenotype of the fibroblast lines derived from the fibrotic skin of diseased birds persisted through 10 cell doublings in tissue culture. However, the ratio of type I:III collagen and the profile of GAG types produced were similar in all fibroblast lines studied. These results suggest that fibroblast activation is responsible for the skin fibrosis observed in this avian model of scleroderma.

Pentoxifylline inhibits certain constitutive and tumor necrosis factor-alpha-induced activities of human normal dermal fibroblasts

Pentoxifylline (PFN), analog of theobromine, which phenotypically and functionally alters various cell types including dermal fibroblasts, has been reported to inhibit tumor necrosis factor-alpha (TNF alpha) activation of neutrophils. We investigated the ability of PFN to alter constitutive and TNF alpha-induced biosynthetic activities of human normal dermal fibroblasts. The sixteenfold increase over constitutive intracellular 2'-5' oligo-adenylate synthetase (2'-5' A synthetase) activity induced by TNF alpha (400 U/ml) failed to occur when PFN (1 mg/ml) was added prior to cytokine treatment. This loss of biologic activity paralleled a reduction in 2'-5' A synthetase proteins and 2'-5' A synthetase-specific m-RNA. PFN failed to inhibit constitutive or TNF alpha-induced IL-6 hybridoma proliferative activity, IL-6 protein, or IL-6-specific m-RNA levels. The presence of PFN (1 mg/ml) in fibroblast cultures reduced constitutive synthesis of collagen and glycosaminoglycan (GAG) by 87% and 45%, respectively, and blocked induction of their synthesis by TNF alpha (10(4) U/ml). Total non-collagenous protein synthesis was not inhibited following PFN treatment (1 mg/ml). PFN did not inhibit TNF alpha induction of only those biosynthetic activities also susceptible to PFN in the constitutive state, with PFN failing to reduce constitutive collagenolytic activity but reducing TNF alpha-induced enhanced collagenolytic activity by 26% and collagenase m-RNA by 51%. Furthermore, PFN did inhibit, by 98%, TNF alpha-dependent murine and human fibroblast cytotoxicity. The selective nature of PFN inhibition of certain TNF alpha activities, the failure of PFN (1 mg/ml) to alter constitutive and TNF alpha-induced levels of type 1 and 2 TNF alpha receptor m-RNA, and the finding that PFN-treated fibroblasts express a similar number of receptors, of similar molecular weight and high affinity for TNF alpha as control, untreated cells, suggest that inhibitory activities of PFN are mediated at a locus other than receptors for TNF alpha.

Stimulation of collagen and glycosaminoglycan production in cultured human adult dermal fibroblasts by recombinant human interleukin 6

Interleukin (IL) 6 is a pleiotropic cytokine synthesized by fibroblasts in response to many stimuli, including IL-1 beta. To evaluate the possibility that previously observed stimulation of fibroblast biosynthetic functions by IL-1 beta may be mediated by autocrine IL-6, we investigated the effect of recombinant human (rh) IL-6 on the connective tissue-related biosynthetic functions of three lines of cultured human adult dermal fibroblasts. We found that rhIL-6 mimicked some of the activities of IL-1 beta, as 24-96-h treatment of confluent fibroblast cultures with rhIL-6 caused concentration (10 to 1000 ng/ml)-dependent increases in the production of collagen and the glycosaminoglycans (GAG), hyaluronic acid and chondroitin-4/6-sulfates, but had little effect on fibronectin or total protein production. Although the effective stimulating concentrations of IL-6 were within the range (approximately 100 ng/ml) we found produced by rhIL-1 beta-treated fibroblast cultures, rhIL-1 beta at 0.2-1.0 ng/ml induced significantly greater amounts of collagen and GAG than the maximum effective concentrations of IL-6. Moreover, an anti-rhIL-6 antibody, which effectively neutralized the fibroblast-stimulating activities of rhIL-6, only fractionally blocked the fibroblast-stimulating actions of rhIL-1 beta, suggesting autocrine IL-6 only partially mediates the effects of IL-1 beta on fibroblasts. Conversely, the fibroblast-stimulating effects of rhIL-6 are unlikely due to autocrine IL-1 beta, as an anti-rhIL-1 beta antibody had only minimal inhibitory action on rhIL-6-treated fibroblast cultures. Overall these results suggest that IL-6 could function as a paracrine/autocrine regulator of dermal fibrotic repair.

Regulation of the proliferation and biosynthetic activities of cultured human Peyronie's disease fibroblasts by interferons-alpha, -beta and -gamma

To determine the therapeutic potential of interferon (IFN) treatment for Peyronie's disease, we investigated the effect of human recombinant (hu-r) IFNs on cultured fibroblasts derived from a Peyronie's disease penile plaque. Treatment of cultured fibroblasts with hu-r-IFN-alpha2b, hu-r-IFN-beta-ser17 and hu-r-IFN gamma caused a concentration dependent inhibition of both fibroblast proliferation and collagen production, as well as an increase in collagenase production. Hu-r-IFN-alpha and beta had no effect on fibroblast glycosaminoglycan (GAG) or fibronectin production, while hu-r-IFN-gamma markedly increased both GAG and fibronectin production. These results demonstrate that IFNs, especially IFNs-alpha and beta, exhibit antifibrotic activity on Peyronie's disease fibroblasts and suggest a rationale for using IFNs to treat Peyronie's disease.

Pentoxifylline inhibits the proliferation of human fibroblasts derived from keloid, scleroderma and morphoea skin and their production of collagen, glycosaminoglycans and fibronectin

Pentoxifylline, an analogue of the methylxanthine theobromine, inhibits the proliferation and certain biosynthetic activities of fibroblasts derived from normal human skin. Fibroblasts from the skin of patients with keloids, scleroderma and morphoea were cultured in vitro in the presence and absence of pentoxifylline (100-1000 micrograms/ml) to determine whether it inhibits fibroblast proliferation and the production of collagen, glycosaminoglycans (GAG), fibronectin and collagenase activity. The exposure of subconfluent fibroblast cultures to pentoxifylline resulted in non-lethal, dose-dependent reductions in serum-driven fibroblast proliferation, with 1000 micrograms/ml pentoxifylline virtually negating the proliferative effect of serum on the cells. The fibroblasts assayed as confluent cultures produced reduced amounts, by up to 95%, of collagen and GAG, dependent on the concentration of pentoxifylline, both in the presence and absence of serum. Pentoxifylline similarly inhibited the fibronectin production by keloid and scleroderma fibroblasts, but had no effect on collagenase activity.

Urinary cytokines following photodynamic therapy for bladder cancer. A preliminary report

This preliminary study was undertaken to test for the presence of urinary cytokines whose detection would provide evidence in support of the theory that photodynamic therapy (PDT) produces an immunologic response in patients treated for bladder cancer. Gamma interferon, interleukin 1-beta, interleukin 2, and tumor necrosis factor-alpha were assayed for in the urine of 4 patients treated with photodynamic therapy for bladder cancer, in 7 control patients undergoing transurethral surgical procedures, and in 5 healthy control subjects. Quantifiable concentrations of all cytokines, except gamma interferon, were measured in urine samples from the PDT patients with the highest light energies, while no urinary cytokines were found in the PDT patient who received the lowest light energy nor in any of the control subjects. These findings suggest that a local immunologic response may occur following PDT for bladder cancer.

Short-term keloid treatment in vivo with human interferon alfa-2b results in a selective and persistent normalization of keloidal fibroblast collagen, glycosaminoglycan, and collagenase production in vitro

Two intralesional injections of interferon alfa-2b (1.5 million U per injection) into a progressively enlarging keloid resulted in a 41% reduction in its area. Fibroblasts cultured from the keloid before and 9 days after the initial injection were compared with fibroblasts cultured from the patient's normal skin with respect to proliferation and production of connective tissue matrix components and collagenase. There were no significant differences in the in vitro doubling times of keloidal fibroblasts before (p greater than 0.2) and after (p greater than 0.5) treatment with interferon alfa-2b, as well as of normal fibroblasts, in subconfluent cultures. Multiple passages of keloidal fibroblasts before interferon alfa-2b therapy assayed as confluent cultures produced more collagen (171%, 187%, and 204%), more glycosaminoglycans (153% and 141%), and less collagenase (26% and 31%) than the patient's own normal fibroblasts. In contrast, keloidal fibroblasts after interferon alfa-2b therapy persistently produced normal or subnormal amounts of collagen (107%, 73%, and 64%) and glycosaminoglycans (97% and 96%) and normalized levels of collagenase activity (96% and 86%). Normal amounts of fibronectin were produced by keloidal fibroblasts before and after treatment with interferon alfa-2b.

Differential regulation of collagen, glycosaminoglycan, fibronectin, and collagenase activity production in cultured human adult dermal fibroblasts by interleukin 1-alpha and beta and tumor necrosis factor-alpha and beta

In order to clarify the role played by immunologically derived cytokines in dermal connective tissue synthesis and degradation, we investigated the effect of human recombinant (hu-r) interleukin (IL) 1-alpha and beta, hu-r tumor necrosis factor (TNF)-alpha and beta, hu-r IL 2, and hu-r granulocyte-macrophage colony-stimulating factor (GM-CSF) on the production of collagen, glycosaminoglycan, fibronectin, and collagenase activity by three lines of cultured human adult dermal fibroblasts. Our results show that 24-72 h treatment of confluent fibroblast cultures with IL 1-alpha or beta or TNF-alpha or beta causes concentration (1 to 1 X 10(4) U/ml) dependent increases in collagen, glycosaminoglycan, and collagenase activity production, but decreases in fibronectin production. In contrast, treatment with IL 2 and GM-CSF had no effect on fibroblast functions. The data show that IL 1-alpha and beta and TNF-alpha and beta differentially regulate fibroblast functions, and that increases in catabolic functions like collagenase activity production are more than tenfold greater than increases in anabolic functions like collagen production. When these results are considered along with other reports, they suggest that IL 1 and TNF may play predominately a catabolic role in situ during dermal fibrotic responses by directly inhibiting fibronectin production and indirectly causing the degradation of collagen and glycosaminoglycan by significantly increasing dermal fibroblast elaboration of collagenase and proteoglycanase activities.

Pentoxifylline inhibits normal human dermal fibroblast in vitro proliferation, collagen, glycosaminoglycan, and fibronectin production, and increases collagenase activity

Fibroblasts from normal human adult skin were cultured in vitro in the presence and absence of different concentrations of pentoxifylline or a pentoxifylline analog, A81-3138 (10(-1)-10(3) micrograms/ml). Similar concentration dependent reductions in normal proliferation of fibroblasts in fetal calf serum-driven subconfluent cultures were detected following treatment with pentoxifylline or A81-3138. Fibroblasts assayed as confluent cultures produced sub-normal amounts of collagen, glycosaminoglycans (GAGs), and fibronectin in a fashion dependent upon the concentration of pentoxifylline. In contrast, fibroblasts exposed to pentoxifylline elaborated double the collagenase activity produced by normal, untreated fibroblasts. The reduced proliferation and reduced synthetic activities were not due to a lethal toxic effect on fibroblasts by pentoxifylline and A81-3138, nor was the reduction in collagen synthesis simply due to an inability to secrete newly synthesized intracellular collagen. Unlike pentoxifylline-induced inhibition of collagen and fibronectin production, which was detected only in cultures supplemented with serum, pentoxifylline inhibits, to a similar degree, both constitutive and serum-driven production of GAGs. The addition of IL1 beta (2.5 and 10.0 U/ml) to serum-driven fibroblast cultures resulted in greater proliferation, which was inhibitable by the presence of pentoxifylline and A81-3138 as anti-fibrotic agents in certain disorders of fibrosis.

Differential regulation of glycosaminoglycan, fibronectin, and collagenase production in cultured human dermal fibroblasts by interferon-alpha, -beta, and -gamma

In order to determine whether interferons (IFNs) play a universal role in terminating the fibrotic response by inhibiting other fibroblast functions in addition to growth and collagen production, we investigated the effect of human recombinant (hu-r) IFN-alpha, -beta, and -gamma on the glycosaminoglycan, fibronectin, and collagenase production of cultured human dermal fibroblasts. Our results show that short-term (48 h) treatment of confluent fibroblast cultures with hu-r-IFN-alpha 2 and hu-r-IFN-beta-ser17 causes a concentration (1 to 1 x 10(5) U/ml)-dependent inhibition of glycosaminoglycan production, has no effect on fibronectin production, and markedly increases collagenase production. In contrast, hu-r-IFN-gamma not only causes a concentration-dependent increase in collagenase production but also increases both glycosaminoglycan and fibronectin production. These results demonstrate that IFNs differently regulate fibroblast functions rather than universally inhibit all functions, and show that IFN-alpha and -beta exhibit a broader antifibrotic spectrum that IFN-gamma.

Stimulation of mono (ADP-ribosyl)ation by reduced extracellular calcium levels in human fibroblasts

Lowering extracellular calcium in cultures of human diploid fibroblast-like cells caused a rapid depletion of NAD pools. This loss of NAD was reversed by restoring extracellular Ca2+ and was inhibited by 3-aminobenzamide, an inhibitor of ADP-ribosyl transfer reactions. The concentrations of 3-aminobenzamide needed to inhibit the loss of NAD were consistent with those required to inhibit cellular mono(ADP-ribosyl) rather than poly(ADP-ribosyl) reactions. Calcium depletion did not inhibit the biosynthesis of NAD. These results suggest that mono(ADP-ribosyl)ation is involved in the regulation of cellular Ca2+ levels.

Persistence of a reduced-collagen-producing phenotype in cultured scleroderma fibroblasts after short-term exposure to interferons

Transient exposure to inflammation-associated, fibroblast-stimulatory factors appears to initiate fibrosis by inducing the persistently activated phenotypes displayed by fibroblast cultures derived from scleroderma skin and other fibrotic tissues. To determine whether one class of fibroblast-inhibitory factors, the interferons (IFNs), plays a role in terminating fibrosis by acting as persistent fibroblast deactivators, we inhibited (40-60%) the growth and collagen production of normal dermal fibroblasts and hypercollagen-producing scleroderma fibroblasts by short-term exposure to IFN-alpha, beta, or gamma. During subsequent subculture in the absence of IFNs, the growth and collagen production of normal fibroblasts and the growth of scleroderma fibroblasts increased to untreated control levels after two to three passages. In contrast, collagen production by scleroderma fibroblasts remained inhibited for at least five passages (18 cell doublings) and was not further suppressed by subsequent IFN exposure. These data suggest that IFNs may help terminate fibrosis by suppressing persistently activated fibroblast functions.

Gamma interferon is the lymphokine and beta interferon the monokine responsible for inhibition of fibroblast collagen production and late but not early fibroblast proliferation

Human peripheral blood mononuclear cells activated with concanavalin A (Con A) or lipopolysaccharide (LPS) produce, respectively, lymphokines (LK) of 50,000 Mr or monokines (MK) of 20,000 Mr that inhibit the growth and collagen production of cultured human dermal fibroblasts. Because antigenic typing of the antiviral activity of these LK and MK preparations revealed that LK contained mainly gamma interferon (IFN-gamma), and MK, primarily IFN-beta, we investigated if any of the fibroblast-inhibiting activities could be attributed to human IFN. Unlike LK and MK, which act within 24 h to inhibit the growth of subconfluent foreskin and adult dermal fibroblasts, samples of purified, natural derived IFN-alpha, -beta, and -gamma and recombinant DNA-derived IFN-alpha 2 and -gamma were ineffective inhibitors at 24 h and required 48-72 h to significantly inhibit growth. However, all IFN did mimic LK/MK action in causing concentration-dependent inhibition of collagen production by confluent fibroblast microcultures. Furthermore, the collagen production-inhibiting activity of Con A-induced LK supernatant and its 50,000 Mr fraction was completely suppressed by 10(3) neutralizing U/ml of either polyclonal or monoclonal antibody to IFN-gamma, while polyclonal antibodies to IFN-alpha and -beta had no effect. Similarly, the collagen production-inhibiting activity of LPS-induced MK supernatant and its 20,000 Mr fraction was suppressed by polyclonal anti-IFN-beta but not by anti-IFN-alpha or -gamma. Anti-IFN failed to reverse early-acting LK or MK growth-inhibiting activities. These data suggest collagen production-inhibiting LK and MK are IFN-gamma and IFN-beta, respectively, and that early acting, growth-inhibiting LK and MK are not IFN.

Interferon enhancement of HLA-DR antigen expression on epidermal Langerhans cells

Langerhans cells (LCs) are dendritic epidermal cells whose ability to function as accessory/stimulatory cells in initiating the immune response is, like that of macrophages, dependent on the expression of class II major histocompatibility antigens. In normal human skin approximately 50% of LCs identified by cell surface T6 antigenicity also express HLA-DR histocompability determinants. We report here that recombinant DNA-derived human interferon (IFN)-gamma, but not IFN-alpha 2, induces the expression of HLA-DR antigens by the population of human epidermal LCs on which such antigens normally are not detected. IFN-gamma effectively induced HLA-DR on both neonatal and adult epidermal LCs and such induction was blocked by neutralization with a murine monoclonal antibody to IFN-gamma. IFN-gamma induction of LC HLA-DR expression is inhibited by prostaglandin E2 (PGE2) and is mimicked by the presence of fatty acid cyclooxygenase inhibitors, known to reduce PGE2 production. These results suggest that IFN-gamma may play a role in regulating skin-associated immune responses through enhanced expression of HLA-DR antigens on LCs and that such enhancement may be mediated by alterations in arachidonic acid metabolism.

Lymphokine/monokine inhibition of fibroblast proliferation and collagen production: role in progressive systemic sclerosis (PSS)

A normal fibrotic response to inflammatory stimuli appears to be dependent on the balanced production of a number of stimulatory and inhibitory fibroblast-regulatory mediators by activated mononuclear cells (MNL). To investigate whether altered mediator production contributes to the fibrosis observed in progressive systemic sclerosis (PSS), we stimulated human peripheral blood MNL with concanavalin A (Con A) and lipopolysaccharide (LPS) to produce macromolecular mediators that inhibit the proliferation and the collagen production of cultured normal human fibroblasts. The two Con A-induced mediators were lymphokines (LK) as they were exclusively produced by activated T cells and they coeluted from a Sephacryl S-200 column with a Mr of 50,000. In contrast, the two LPS-induced mediators were monokines (MK) as they were exclusively produced by activated monocytes, and they coeluted in the Mr 20,000 range. Each pair of inhibitory LK and MK may also be distinct as inhibition of collagen production still occurred in proliferatively quiescent cultures. A quantitative comparison of the levels of fibroblast-inhibitory LK/MK produced by normal volunteers and long-term PSS patients revealed that although PSS MNL produced normal levels of both collagen production inhibitory mediators, they were aberrant producers of both proliferation inhibitory mediators, being hypo-producers (-49%) of the LK and hyper-producers (+196%) of the MK. These results suggest that reduced production of proliferation inhibitory LK may allow stimulatory mediators to induce the unrestricted fibroblast proliferation observed in early active PSS, which then may be stabilized in long-term PSS by the increased production of proliferation inhibitory MK.

Histone acetylation and deacetylation in senescent human diploid fibroblasts

We measured the kinetics of histone H4 hyperacetylation and kinetics of deacetylation for all core histones in young and senescent human diploid fibroblast-like cells. Both cell populations contained a fraction of histone H4 characterized by very rapid acetylation and deacetylation. The kinetics of these reactions were similar in young and senescent cells. The distribution of acetylated species of core histones was also similar in young and senescent human diploid fibroblast-like cells. These results indicated that previously-reported alterations in chromatin template activity in senescent cells were due to a mechanism other than histone acetylation.

Circulating immune complexes in childhood malignancies: a Pediatric Oncology Group study

Pretreatment serum samples obtained at diagnosis from 89 children with various pediatric malignancies were examined for circulating immune complexes (CIC) using the [125I]Clq binding assay. The study population consisted of 35 children with acute lymphocytic leukemia (ALL), 22 children with acute non-lymphocytic leukemia (ALL), 24 with neuroblastoma (NB), and eight with osteosarcoma (OS). Concomitant quantitation of immunoglobulins was performed in 55 patients, revealing normal values for age. Increased levels of CIC at diagnosis were found in 9%, 22%, 42%, and 50% of children with ALL, AML, NB, and OS, respectively. Except for a higher proportion of CIC-positive patients observed in stage IV NB (nine of 17) compared to stage I-III NB (one of seven), no correlation was observed between initial CIC level and presenting clinical features, response to treatment, prognosis, or presence of infection. Longitudinal sampling of six NB and two OS patients did not reveal a clear relationship between disease activity and quantity of CIC. For the pediatric malignancies studied, these data demonstrate minimal value in quantitating CIC as a means of assessing disease activity or predicting response to treatment and are in contrast to the apparently adverse effect of elevated pretreatment CIC on response to therapy and survival observed in adults with ALL, AML, and OS.

Kinetics of histone hyperacetylation and deacetylation in human diploid fibroblasts

We have utilized sodium butyrate-treated normal human diploid fibroblasts to study core histone hyperacetylation kinetics. We report a small, distinct population of core histone characterized by a very rapid rate of hyperacetylation (t1/2 approximately equal to 10-15 min for monoacetylated histone H4) compared to the slower rate (t1/2 approximately equal to 140-200 min for monoacetylated H4) observed for bulk histone. Two rates of core histone deacetylation were also detected and we demonstrated that the rapidly hypermodified histone H4 population was also rapidly deacetylated. The kinetics of histone H4 hyperacetylation and deacetylation in these cells were not significantly altered, regardless of whether cultures were exponentially growing, confluent or arrested in an essentially non-mitotic state.

The effects of histones, in vitro age, and culture state on the digestion of DNA by micrococcal nuclease and deoxyribonuclease I

Nuclei from confluent and mitotically arrested populations of human diploid fibroblast-like cells were subjected to digestion by micrococcal nuclease and deoxyribonuclease (DNase I) following the removal of various histone components by salt extraction. There was no age or culture state variation in the susceptibility of DNA to micrococcal nuclease digestion. There was an age related inhibition of DNA digestion by DNase I in nuclei from older confluent cells before and after the removal of H1 histone but not after the removal of core particle histones. This inhibition was not detected in older arrested populations. These results indicate that an age-related masking by nucleosome core histones may limit the accessibility of DNA to enzymatic activities in older confluent cells. Since this inhibition was absent in older arrested populations, the importance of limited DNA accessibility as a primary cause of cellular senescence is questionable.

Concanavalin A-induced human lymphocyte mitogenic factor: activity distinct from interleukin 1 and 2

Fresh human mononuclear cells (MNL) cultured in serum-free medium and stimulated with concanavalin A (Con A) produce a lymphokine functionally similar to the previously described antigen-induced lymphokine human lymphocyte mitogenic factor (LMF). T lymphocytes appear to be the source of Con A-induced LMF and the presence of adherent monocytes is required for maximal production. The proliferative response to LMF, assayed either as supernatant fluids in the presence of alpha-methyl-D-mannoside or as partially purified 27,000 to 35,000 m.w. fractions from Bio-Gel P-100 columns, indicates LMF is distinct from Con A. LMF acts almost exclusively on B lymphocyte-enriched (E rosette-negative) MNL while exhibiting only minimal activity on T lymphocytes and no activity on monocytes. LMF preparations induce both B cell proliferation and the maturation and proliferation of E rosette-negative T cell progenitors into E rosette-positive cells. Assay of interleukin 1 (IL 1) and interleukin 2 (IL 2) preparations for LMF activity implicate IL 2 as the T cell progenitor stimulating factor. Assay of the proliferation of human IL 2-dependent alloreactive T lymphocyte line/ATLL) indicates that LMF preparations contain IL 2, IL 2 activity, however, is completely removed by absorption of LMF preparations by ATLL cells, whereas LMF activity (B cell proliferation) is unabsorbable, thus distinguishing LMF from IL 2. These absorbed LMF preparations contain no IL 1 activity as assayed by murine thymocyte proliferation, nor does IL 1 have LMF activity. These results indicate that Con A-induced LMF contains a functionally distinct lymphokine with the ability to act as a B cell growth factor.

Concanavalin A-induced human lymphocyte mitogenic factor: activity distinct from interleukin 1 and 2

Fresh human mononuclear cells (MNL) cultured in serum-free medium and stimulated with concanavalin A (Con A) produce a lymphokine functionally similar to the previously described antigen-induced lymphokine human lymphocyte mitogenic factor (LMF). T lymphocytes appear to be the source of Con A-induced LMF and the presence of adherent monocytes is required for maximal production. The proliferative response to LMF, assayed either as supernatant fluids in the presence of alpha-methyl-D-mannoside or as partially purified 27,000 to 35,000 m.w. fractions from Bio-Gel P-100 columns, indicates LMF is distinct from Con A. LMF acts almost exclusively on B lymphocyte-enriched (E rosette-negative) MNL while exhibiting only minimal activity on T lymphocytes and no activity on monocytes. LMF preparations induce both B cell proliferation and the maturation and proliferation of E rosette-negative T cell progenitors into E rosette-positive cells. Assay of interleukin 1 (IL 1) and interleukin 2 (IL 2) preparations for LMF activity implicate IL 2 as the T cell progenitor stimulating factor. Assay of the proliferation of human IL 2-dependent alloreactive T lymphocyte line/ATLL) indicates that LMF preparations contain IL 2, IL 2 activity, however, is completely removed by absorption of LMF preparations by ATLL cells, whereas LMF activity (B cell proliferation) is unabsorbable, thus distinguishing LMF from IL 2. These absorbed LMF preparations contain no IL 1 activity as assayed by murine thymocyte proliferation, nor does IL 1 have LMF activity. These results indicate that Con A-induced LMF contains a functionally distinct lymphokine with the ability to act as a B cell growth factor.