Targeting B-Raf inhibitor resistant melanoma with novel cell penetrating peptide disrupters of PDE8A - C-Raf

Background

Recent advances in the treatment of melanoma that involve immunotherapy and B-Raf inhibition have revolutionised cancer care for this disease. However, an un-met clinical need remains in B-Raf inhibitor resistant patients where first-generation B-Raf inhibitors provide only short-term disease control. In these cases, B-Raf inhibition leads to paradoxical activation of the C-Raf – MEK – ERK signalling pathway, followed by metastasis. PDE8A has been shown to directly interact with and modulate the cAMP microdomain in the vicinity of C-Raf. This interaction promotes C-Raf activation by attenuating the PKA-mediated inhibitory phosphorylation of the kinase.

Methods

We have used a novel cell-penetrating peptide agent (PPL-008) that inhibits the PDE8A – C-Raf complex in a human malignant MM415 melanoma cell line and MM415 melanoma xenograft mouse model to investigate ERK MAP kinase signalling.

Results

We have demonstrated that the PDE8A – C-Raf complex disruptor PPL-008 increased inhibitory C-Raf-S259 phosphorylation and significantly reduced phospho-ERK signalling. We have also discovered that the ability of PPL-008 to dampen ERK signalling can be used to counter B-Raf inhibitor-driven paradoxical activation of phospho-ERK in MM415 cells treated with PLX4032 (Vemurafenib). PPL-008 treatment also significantly retarded the growth of these cells. When applied to a MM415 melanoma xenograft mouse model, PPL-008C penetrated tumour tissue and significantly reduced phospho-ERK signalling in that domain.

Conclusion

Our data suggests that the PDE8A-C-Raf complex is a promising therapeutic treatment for B-Raf inhibitor resistant melanoma.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5489-4) contains supplementary material, which is available to authorized users.

Anti-inflammatory Activity of MTL-CEBPA, a Small Activating RNA Drug, in LPS-Stimulated Monocytes and Humanized Mice

Excessive or inappropriate inflammatory responses can cause serious and even fatal diseases. The CCAAT/enhancer-binding protein alpha (CEBPA) gene encodes C/EBPα, a transcription factor that plays a fundamental role in controlling maturation of the myeloid lineage and is also expressed during the late phase of inflammatory responses when signs of inflammation are decreasing. MTL-CEBPA, a small activating RNA targeting for upregulation of C/EBPα, is currently being evaluated in a phase 1b trial for treatment of hepatocellular carcinoma. After dosing, subjects had reduced levels of pro-inflammatory cytokines, and we therefore hypothesized that MTL-CEBPA has anti-inflammatory potential. The current study was conducted to determine the effects of C/EBPα saRNA - CEBPA-51 - on inflammation in vitro and in vivo after endotoxin challenge. CEBPA-51 led to increased expression of the C/EBPα gene and inhibition of pro-inflammatory cytokines in THP-1 monocytes previously stimulated by E. coli-derived lipopolysaccharide (LPS). Treatment with MTL-CEBPA in an LPS-challenged humanized mouse model upregulated C/EBPα mRNA, increased neutrophils, and attenuated production of several key pro-inflammatory cytokines, including TNF-α, IL-6, IL-1β, and IFN-γ. In addition, a Luminex analysis of mouse serum revealed that MTL-CEBPA reduced pro-inflammatory cytokines and increased the anti-inflammatory cytokine IL-10. Collectively, the data support further investigation of MTL-CEBPA in acute and chronic inflammatory diseases where this mechanism has pathogenic importance.

Create a translational medicine knowledge repository--research downsizing, mergers and increased outsourcing have reduced the depth of in-house translational medicine expertise and institutional memory at many pharmaceutical and biotech companies: how will they avoid relearning old lessons?

Pharmaceutical industry consolidation and overall research downsizing threatens the ability of companies to benefit from their previous investments in translational research as key leaders with the most knowledge of the successful use of biomarkers and translational pharmacology models are laid off or accept their severance packages. Two recently published books may help to preserve this type of knowledge but much of this type of information is not in the public domain. Here we propose the creation of a translational medicine knowledge repository where companies can submit their translational research data and access similar data from other companies in a precompetitive environment. This searchable repository would become an invaluable resource for translational scientists and drug developers that could speed and reduce the cost of new drug development.

Translational strategies to implement personalized medicine: rheumatoid arthritis examples

Advances in the molecular definition of disease, biomarker technologies and informatics have brought us to the threshold of a new way to individualize treatment for patients - personalized medicine. However, while the clinical translation of drug metabolism and cancer-related genomics data has resulted in accepted individualized treatment paradigms, this has not occurred as frequently or efficiently for patients with common chronic diseases such as rheumatoid arthritis. This gap between the rapidly increasing amount of disease-related genomic information and its clinical translation can be addressed through the creation and testing of personalized medicine treatment hypotheses using the same strategies that translational medicine scientists utilize to achieve proof-of-concept for drugs with novel targets. This is illustrated with three testable personalized medicine hypotheses for rheumatoid arthritis where known genetic markers in patients can potentially be used to select the most appropriate treatments and dose. Incentives resulting from changes in government and regulatory agency policies, investments in sample and data repositories, acceptance of new economic models by pharmaceutical companies and third party payers as well as more training, research support and academic opportunities for translational medicine scientists are all needed to speed up the implementation of personalized medicine for patients with rheumatoid arthritis and other common chronic diseases.

What's next in translational medicine?

Translational medicine is the integrated application of innovative pharmacology tools, biomarkers, clinical methods, clinical technologies and study designs to improve disease understanding, confidence in human drug targets and increase confidence in drug candidates, understand the therapeutic index in humans, enhance cost-effective decision making in exploratory development and increase phase II success. Translational research is one of the most important activities of translational medicine as it supports predictions about probable drug activities across species and is especially important when compounds with unprecedented drug targets are brought to humans for the first time. Translational research has the potential to deliver many practical benefits for patients and justify the extensive investments placed by the private and public sector in biomedical research. Translational research encompasses a complexity of scientific, financial, ethical, regulatory, legislative and practical hurdles that need to be addressed at several levels to make the process efficient. Several have resisted the idea of supporting translational research because of its high costs and the fear that it may re-direct funds from other biomedical disciplines. Resistance also comes from those more familiar with traditional clinical research methods. In this review, we argue that translational research should be seen as enabled by ongoing efforts in basic and clinical research and not competing with them. Translational research provides the knowledge necessary to draw important conclusions from clinical testing regarding disease and the viability of novel drug mechanisms. Advancing translational research requires education and new sources of funding. This could be achieved through public and congressional education by a joint coalition of patients' advocacy groups, academia, drug regulatory agencies and industry.

Experiences with dose finding in patients in early drug development: the use of biomarkers in early decision making

With the increasing cost and complexity of drug development, biomarkers will play an increasing role in the early phases. Biomarkers can be classified into target, mechanistic, or outcome with varying degrees of linkage to disease or treatment effect. They can be used to determine proof of concept by characterising the efficacy or safety profiles, or determining differentiation from any competitor drugs. PK/PD modelling of biomarker data for novel and marketed compounds can be used to predict outpatient dose response. Subsequent simulations may replace or reduce the size and cost of larger phase 2b outpatient studies. Two examples of biomarkers and PK/PD modelling used to characterise dose response are presented. Penile plethysmography (RigiScan Plus) in male erectile dysfunction and phenylephrine challenge urethral pressure in benign prostatic hyperplasia are used to reduce time and cost to reach major exploratory development decision points in these indications.

The ultimate model organism: progress in experimental medicine

Experimental medicine is the use of innovative measurements, models and designs in studying human subjects for establishing proof of mechanism and concept of new drugs, for exploring the potential for market differentiation for successful drug candidates, and for efficiently terminating the development of unsuccessful ones. Humans are the ultimate 'model' because of the uncertain validity and efficacy of novel targets and drug candidates that emerge from genomics, combinatorial chemistry and high-throughput screening and the use of poorly predictive preclinical models. The in-depth investigation of the effects of drugs and the nature of disease progression is becoming ever more feasible because of advances in clinical biomarkers.

Prevention of organ allograft rejection by a specific Janus kinase 3 inhibitor

Because of its requirement for signaling by multiple cytokines, Janus kinase 3 (JAK3) is an excellent target for clinical immunosuppression. We report the development of a specific, orally active inhibitor of JAK3, CP-690,550, that significantly prolonged survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants. CP-690,550 treatment was not associated with hypertension, hyperlipidemia, or lymphoproliferative disease. On the basis of these preclinical results, we believe JAK3 blockade by CP-690,550 has potential for therapeutically desirable immunosuppression in human organ transplantation and in other clinical settings.

Mapping of local renal blood flow with PET and H(2)(15)O

We developed a noninvasive method for the mapping of regional renal blood flow in humans using PET and H(2)(15)O.

METHODS

Fifteen subjects participated in the study, 5 with normal renal function and 10 with renal disease. The protocol used a whole-body PET scanner, intravenous bolus injection of 1,110-1,850 MBq H(2)(15)O and sequential imaging at 3 s per frame. (131)I-Iodohippuran was used to independently assess effective renal plasma flow in each subject. Hippuran clearance and renal blood flow (RBF) were measured twice, before and after treatment with probenecid, to verify that RBF is not affected. Flow analysis was based on the Kety model, according to the operational equation: C(t) = F integral C(a)(u)du - k integral C(u)du, where F is the RBF, k is the tissue-to-blood clearance rate, C is the PET concentration, and C(a) is the tracer concentration in the abdominal aorta. F and k were estimated by linear least squares on a pixel-by-pixel basis to produce quantitative maps (parametric images) of RBF. The flow maps were analyzed by regions of interest (largely excluding the medulla and collecting system) for each kidney on each slice and pooled to yield mean RBF.

RESULTS

In the 5 healthy subjects, mean RBF was 3.4 +/- 0.4 mL/min/g. There was no difference in flow between kidneys (t = -0.59; n = 11; P > 0.95). Before treatment with probenecid, RBF was linearly related to hippuran clearance (r(2) = 0.92). Probenecid treatment significantly reduced hippuran clearance (P < 0.003), but RBF was unchanged (P > 0.17). Compared with healthy control subjects, RBF was significantly decreased in patients with renal disease (P < 0.002). Flow maps were of good quality in all subjects, exhibiting characteristic patterns, with higher values in regions composed largely of renal cortex.

CONCLUSION

Parametric mapping of RBF with PET and H(2)(15)O provides a straightforward, noninvasive method for quantitative mapping of RBF, which may prove useful in research applications and in the management of patients whose therapy alters renal tubular transport.

Analysis of changes in acute-phase plasma proteins in an acute inflammatory response and in rheumatoid arthritis using two-dimensional gel electrophoresis

Two-dimensional (2-D) gel analysis was used to examine differences in the levels of 19 plasma proteins: before and after an acute inflammatory reaction (parenteral typhoid vaccination) in normal subjects, between rheumatoid arthritis (RA) patients and normals and in RA patients treated with tenidap (120 mg) and piroxicam (20 mg). Typhoid vaccination increased levels of SAA, haptoglobin alpha1, haptoglobin alpha2, haptoglobin beta and alpha1-anti-chymotrypsin but decreased transthyretin and apolipoprotein E. In RA patients, serum amyloid A (SAA), haptoglobin alpha2, haptoglobin beta, alpha1-antichymotrypsin and C3 proactivator levels were elevated while apolipoprotein A-I, apolipoprotein A-IV, transthyretin, Gc-globulin, alpha2-HS glycoprotein, alpha2-macroglobulin and alpha1-B glycoprotein levels were decreased, compared to normals. Compared to piroxicam, tenidap lowered levels of alpha1-antiprotease and SAA but raised the levels of transthyretin, Gc-globulin, alpha2-HS-glycoprotein and alpha2-macroglobulin in RA patients. C-reactive protein (CRP) could not be quantified on 2-D gels but, when measured by rate nephelometry, levels were reduced after treatment with tenidap compared to piroxicam. The general pattern of the acute phase protein response to an acute inflammatory response to typhoid vaccination is similar to that in the chronic inflammatory condition, RA. The impact of tenidap on both positive and negative acute-phase proteins in RA patients could clearly be distinguished from that of piroxicam.

Steroid sparing activity of tenidap in patients with polymyalgia rheumatica: a multicenter double blind randomized placebo controlled study

OBJECTIVE

To determine whether tenidap treatment would allow reduction or replacement of systemic corticosteroid treatment in patients with polymyalgia rheumatica (PMR).

METHODS

A 15-week double blind, randomized, multicenter, placebo-controlled study of tenidap sodium (120 mg/day) in patients with symptomatically controlled PMR receiving 10 mg/day prednisone was conducted. After receiving study drug for 3 weeks, prednisone dose was reduced by 2.5 mg/day every 3 weeks. The lowest clinically effective dose of prednisone was recorded as 10, 7.5, 5, 2.5 or 0 mg/day.

RESULTS

Thirty-two patients were randomized to tenidap or placebo. As prednisone was reduced more placebo patients experienced an exacerbation of PMR symptoms, elevation of erythrocyte sedimentation rate and increased serum C-reactive protein. Twice as many placebo patients (10 of 16) as tenidap patients (5 of 16) discontinued due to lack of efficacy. The lowest effective dose of prednisone could be determined in 27 of the 32 patients, 11 receiving tenidap and 16 placebo. A significantly (p = 0.027) greater proportion of patients receiving tenidap (5 of 11) than placebo (1 of 16) were able to discontinue prednisone without experiencing a symptomatic flare.

CONCLUSION

As prednisone was reduced, symptoms of PMR were controlled better by tenidap than by placebo. Forty-five percent of evaluable patients receiving tenidap were able to discontinue prednisone without a disease flare compared to 6% for placebo.

Rheumatoid arthritis treated with tenidap and piroxicam. Clinical associations with cytokine modulation by tenidap

OBJECTIVE

To compare the effects of tenidap and piroxicam on acute-phase protein and cytokine levels in the blood of rheumatoid arthritis (RA) patients and to explore their associations with clinical disease activity.

METHODS

A double-blind, randomized, crossover trial in 49 patients with active RA compared 6 weeks of treatment with tenidap (120 mg/day) versus 6 weeks of treatment with piroxicam (20 mg/day).

RESULTS

Median values for C-reactive protein (CRP), Westergren erythrocyte sedimentation rate (ESR), serum amyloid A (SAA) protein, and interleukin-6 (IL-6) were significantly lower after tenidap treatment compared with piroxicam treatment, even in the presence of stable background treatment with prednisone, methotrexate, or prednisone plus methotrexate. The median within-patient treatment differences (after tenidap minus after piroxicam) in the CRP, ESR, SAA, and IL-6 values were -1.7 mg/dl, -10.0 mm/hour, -22.0 micrograms/ml, and -3.7 pg/ml, respectively, and represent -60.4%, -17.7%, -35.5%, and -26.1% of the respective baseline levels. IL-6 levels were positively correlated with CRP and SAA. Plasma IL-1 beta was generally below the level of detection. Tumor necrosis factor alpha levels were similar after tenidap and after piroxicam. Treatment differences for 4 of 7 clinical parameters favored tenidap, but did not reach statistical significance. IL-6, CRP, and ESR were significantly correlated with clinical treatment differences. Tenidap and piroxicam toleration were similar, although tenidap-treated patients exhibited a reversible increase in urinary protein excretion.

CONCLUSION

Tenidap was differentiated from piroxicam by lower levels of acute-phase proteins, ESR, and IL-6 after tenidap treatment. These treatment differences were significantly correlated with clinical parameters.

Gene expression (collagenase, tissue inhibitor of metalloproteinases, complement, and HLA-DR) in rheumatoid arthritis and osteoarthritis synovium. Quantitative analysis and effect of intraarticular corticosteroids

In situ hybridization was used to localize and quantify gene expression in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissue. Collagenase, tissue inhibitor of metalloproteinases (TIMP), HLA-DR, and complement (C2 and C3) gene expression was studied in synovial tissue from 23 patients with RA, OA, or other inflammatory arthropathies. Gene expression was highly compartmentalized: Collagenase, TIMP, and C2 messenger RNA (mRNA) were localized primarily to the synovial lining layer; HLA-DR mRNA was prominent in the lining and in some sublining lymphoid aggregates; the C3 probe hybridized only to sublining lymphoid aggregates. Relative mRNA levels were quantified using computer-assisted image analysis. There was significantly more collagenase, C2, C3, and HLA-DR mRNA in RA compared with OA patients. However, TIMP mRNA levels were similar in RA and OA. Expression of collagenase, TIMP, C2, C3, and HLA-DR genes correlated with the degree of synovial inflammation. The effect of intraarticular corticosteroid injection on synovial tissue gene expression was studied using serial percutaneous synovial biopsy samples from the knees of 3 RA patients. Joints were biopsied, injected with triamcinolone, and rebiopsied 1-2 weeks later. Histologic inflammation scores were lower in posttreatment synovia. Collagenase and TIMP mRNA, although abundant in presteroid samples, were nearly undetectable in post-steroid tissues. HLA-DR mRNA levels also were significantly decreased. C2 and C3 hybridization significantly decreased in 2 of 3 patients and 1 of 3 patients, respectively. Hence, clinical response to intraarticular steroid therapy was accompanied by histologic improvement and decreased expression of genes that play a role in articular destruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of gold sodium thiomalate and tenidap sodium (CP-66,248-2) on a model of macrophage differentiation using HL-60 cells

We studied the effects of gold sodium thiomalate (GST) and a new antirheumatic drug, tenidap sodium ([Z]-5-chloro-2,3-dihydro-3-[hydroxy-2-thienylmethylene]-2-oxo-1H- indole-1-carboxamide, sodium salt), previously known as CP-66,248-2, in a model system of macrophage differentiation using a myelomonocytic cell line. HL-60 cells can be stimulated by vitamin D3 to differentiate along a monocytic pathway. Monocytic HL-60 cells express CD14 (Leu-M3), a macrophage surface marker, and develop the capacity to produce the second complement component (C2) in response to stimulation with cytokines such as gamma-interferon. The effects of GST and tenidap sodium were compared with the effects of dexamethasone and a variety of nonsteroidal antiinflammatory drugs in this model system. We found that GST inhibited the capacity of HL-60 cells to produce C2 but did not inhibit the expression of CD14. Tenidap sodium inhibited C2 production as well as CD14 expression, and it partially reversed the decrease in 3H-thymidine incorporation by HL-60 cells, which accompanies monocytic differentiation. At concentrations that inhibited C2 production by HL-60 cells, tenidap sodium did not inhibit C2 production by monocytes. Neither dexamethasone nor the other nonsteroidal antiinflammatory drugs tested possessed these activities. Thus, both GST and tenidap inhibit markers of monocytic differentiation in HL-60 cells, and this activity may relate to their antirheumatic activities.

Linear scleroderma: a response to neurologic injury? Report and literature review

A 28-year-old white man presented with neurologic symptoms and skin changes. Subsequent evaluation led to the diagnosis of transverse myelitis of the cervical spine (C8) and linear scleroderma. The progression of neurologic abnormalities prompted treatment with corticosteroids. Neurologic symptoms diminished and the progression of linear skin lesions halted. A review of the literature uncovered considerable evidence for underlying abnormalities of the spine and spinal cord in many patents with linear scleroderma and a paucity of immunologic abnormalities characteristic of progressive systemic sclerosis. Patients presenting with new onset linear scleroderma should be evaluated for underlying neurologic causes.

Regulation of monocyte/macrophage C2 production and HLA-DR expression by IL-4 (BSF-1) and IFN-gamma

IL-4 was originally described on the basis of its ability to co-stimulate the proliferation of resting B cells treated with anti-IgM. Recently, this cytokine has been shown to have other effects on mast cells, T cells, B cells, and macrophages. We studied the ability of IL-4 to regulate the production of C2 by human monocytes and monocytic cell lines and compared this with stimulation of HLA-DR expression, another recently described activity of IL-4. Responses to IL-4 were compared to IFN-gamma, a cytokine with both activities. IL-4 up-regulated C2 production by human monocytes and this effect was not inhibited by neutralizing anti-IFN-gamma antibody. IL-4 also stimulated C2 production by HL-60 cells that had been pre-treated with vitamin D3 to induce monocytic differentiation. IL-4 did not stimulate C2 production by U937 cells. IFN-gamma, in contrast to IL-4, stimulates C2 production by all three cell types. Although IL-4 increased C2 production by HL-60 cells we could not detect C2 mRNA by Northern blotting. However, co-stimulation of these cells with IL-4 and low concentrations of IFN-gamma resulted in an additive effect on C2 production and a greater increase in C2 mRNA than was seen with IFN-gamma alone. As reported by others, IL-4-stimulated HLA-DR expression by monocytes. In contrast to our findings regarding C2 production, stimulation of HLA-DR expression was inhibited by neutralizing anti-IFN-gamma mAb and IL-4 did not stimulate HLA-DR expression by U937 or HL-60 cells. IFN-gamma stimulated HLA-DR expression by all three cell types. These results identify IL-4 as an additional cytokine able to directly stimulate C2 production by human monocytes and by a monocytic cell line whereas IL-4 stimulation of HLA-DR expression by monocytes appears to be IFN-gamma dependent.

Regulation of monocyte/macrophage C2 production and HLA-DR expression by IL-4 (BSF-1) and IFN-gamma

IL-4 was originally described on the basis of its ability to co-stimulate the proliferation of resting B cells treated with anti-IgM. Recently, this cytokine has been shown to have other effects on mast cells, T cells, B cells, and macrophages. We studied the ability of IL-4 to regulate the production of C2 by human monocytes and monocytic cell lines and compared this with stimulation of HLA-DR expression, another recently described activity of IL-4. Responses to IL-4 were compared to IFN-gamma, a cytokine with both activities. IL-4 up-regulated C2 production by human monocytes and this effect was not inhibited by neutralizing anti-IFN-gamma antibody. IL-4 also stimulated C2 production by HL-60 cells that had been pre-treated with vitamin D3 to induce monocytic differentiation. IL-4 did not stimulate C2 production by U937 cells. IFN-gamma, in contrast to IL-4, stimulates C2 production by all three cell types. Although IL-4 increased C2 production by HL-60 cells we could not detect C2 mRNA by Northern blotting. However, co-stimulation of these cells with IL-4 and low concentrations of IFN-gamma resulted in an additive effect on C2 production and a greater increase in C2 mRNA than was seen with IFN-gamma alone. As reported by others, IL-4-stimulated HLA-DR expression by monocytes. In contrast to our findings regarding C2 production, stimulation of HLA-DR expression was inhibited by neutralizing anti-IFN-gamma mAb and IL-4 did not stimulate HLA-DR expression by U937 or HL-60 cells. IFN-gamma stimulated HLA-DR expression by all three cell types. These results identify IL-4 as an additional cytokine able to directly stimulate C2 production by human monocytes and by a monocytic cell line whereas IL-4 stimulation of HLA-DR expression by monocytes appears to be IFN-gamma dependent.

Effects of vitamin D3 and IFN-gamma on the synthesis of the second complement component, C2, by a human myeloid leukemia (HL-60) cell line

HL-60 cells, a human promyelocytic cell line, can be induced to differentiate along either monocytic or granulocytic pathways. The production of the second complement component, C2, is a marker of monocytic differentiation and can be up-regulated by cytokine stimulation. We studied the effects of IFN-gamma and vitamin D3, two factors previously shown to induce monocytic differentiation of HL-60 cells, on C2 production and C2 mRNA content. We found that HL-60 cells produce little if any C2 but can be induced to synthesize C2 by IFN-gamma. Vitamin D3 pretreatment followed by IFN-gamma stimulation resulted in earlier and greater production of C2. HL-60 cells did not contain detectable amounts of C2 mRNA unless they were stimulated with IFN-gamma. Pretreatment with vitamin D3 followed by IFN-gamma stimulation resulted in a 147% increase in C2 mRNA content compared with IFN-gamma stimulation alone. These results indicate that the up-regulation of C2 production by IFN-gamma and vitamin D3 is pretranslational although additional posttranslational effects were not excluded. C2 production by these cells is a useful marker of monocytic differentiation.

Effects of vitamin D3 and IFN-gamma on the synthesis of the second complement component, C2, by a human myeloid leukemia (HL-60) cell line

HL-60 cells, a human promyelocytic cell line, can be induced to differentiate along either monocytic or granulocytic pathways. The production of the second complement component, C2, is a marker of monocytic differentiation and can be up-regulated by cytokine stimulation. We studied the effects of IFN-gamma and vitamin D3, two factors previously shown to induce monocytic differentiation of HL-60 cells, on C2 production and C2 mRNA content. We found that HL-60 cells produce little if any C2 but can be induced to synthesize C2 by IFN-gamma. Vitamin D3 pretreatment followed by IFN-gamma stimulation resulted in earlier and greater production of C2. HL-60 cells did not contain detectable amounts of C2 mRNA unless they were stimulated with IFN-gamma. Pretreatment with vitamin D3 followed by IFN-gamma stimulation resulted in a 147% increase in C2 mRNA content compared with IFN-gamma stimulation alone. These results indicate that the up-regulation of C2 production by IFN-gamma and vitamin D3 is pretranslational although additional posttranslational effects were not excluded. C2 production by these cells is a useful marker of monocytic differentiation.

Effects of gold sodium thiomalate on interferon stimulation of C2 synthesis and HLA-DR expression by human monocytes

Gamma-interferon (gamma-IFN) is a T cell-derived lymphokine that has potent macrophage-activating properties. It increases Fc receptor density, increases the formation and release of reactive oxygen intermediates, increases the synthesis and release of complement cascade proteins, especially C2 and factor B, and increases class II (HLA-DR) antigen expression. These effects may play a role in the potentiation of inflammation in rheumatoid arthritis. We examined the possibility that gold sodium thiomalate (GST), an effective treatment for rheumatoid arthritis, would inhibit gamma-IFN-mediated stimulation of monocyte/macrophages. GST in concentrations attainable in vivo was shown to inhibit both spontaneous and gamma-IFN-stimulated C2 production up to 50%. GST inhibition could be only partially overcome with increasing concentrations of gamma-IFN. In addition, GST inhibited gamma-IFN-stimulated HLA-DR expression at the highest concentrations tested (20-50 micrograms/ml). GST alone in low concentrations (0.1-5 micrograms/ml) was found to increase HLA-DR antigen expression as quantitated by several methods, including flow cytometry, cell surface enzyme-linked immunosorbent assay, and Western blotting. This GST-stimulated increase in HLA-DR antigen expression paralleled an increased ability of monocytes to present antigen. The mechanism by which low concentrations of GST stimulate HLA-DR antigen expression is unclear, but was shown by 35S-methionine cell labeling not to involve increased HLA-DR protein synthesis.

Correlation of immunoglobulin and C reactive protein levels in ankylosing spondylitis and rheumatoid arthritis

Serum C reactive protein (CRP), IgG, and IgA levels were measured in 22 patients with ankylosing spondylitis (AS) and in 20 patients with rheumatoid arthritis (RA) to study the regulation of these proteins in inflammatory disease states. In both RA and AS the mean CRP, IgG, and IgA levels were raised above normal values. Although IgA and CRP levels showed a significant positive correlation in RA (r = 0.53, p = 0.02), there was no correlation between these values in AS (r = 0.24, p = 0.29). The difference in correlation coefficients between the AS and RA groups was significant at a p = 0.05 level. In RA the raised IgA levels may be another manifestation of the acute phase response, as shown by the good correlation between IgA and CRP in that disease. In AS, however, the IgA levels, although raised, do not correlate with CRP levels, suggesting that the mechanism of increase of IgA in the two diseases is different. Gut mediated immune stimulation has been proposed as a cause of raised IgA levels in AS.

Lymphokine stimulation of human macrophage C2 production is partially due to interferon-gamma

Monocyte complement stimulator (MCS), a product of T lymphocytes, is defined by its ability to stimulate the synthesis and secretion of the second complement component (C2) by monocytes. Most macrophage-activating factor (MAF) activity present in lymphokine-rich culture supernatants has recently been found to be due to interferon-gamma (IFN-gamma). We therefore hypothesized that IFN-gamma may have MCS activity as well. We tested recombinant, E. coli-derived, human IFN-gamma (rIFN-gamma) for its effects on C2 production by adherent peripheral blood monocytes and U937 cells, a human monocytic cell line. Recombinant IFN-gamma in concentrations ranging from 0.1 to 300 U/ml (0.003 to 8.8 ng/ml) stimulates C2 production by both cell populations. Exposure of responding cells for at least 24 hr is required for maximal stimulation. To determine the contribution of IFN-gamma toward total MCS activity in crude lymphokine-rich supernatants, we employed a solid-phase immunoabsorption technique with the use of a monoclonal anti-IFN-gamma antibody. This technique removed all IFN-gamma detectable by a sensitive ELISA, but MCS activity was decreased by only 40 to 50%. Additionally, MCS activity of these supernatants did not correlate with IFN-gamma content as determined by ELISA. By using another method to eliminate IFN-gamma activity, acid dialysis destroyed all rIFN-gamma activity, as measured by stimulation of U937 C2 synthesis, but eliminated only 30 to 67% of MCS activity from crude lymphokine preparations. Thus IFN-gamma stimulates C2 production by monocytes and U937 cells and apparently accounts for some, but not all, MCS activity present in lymphokine-rich supernatants. Other lymphokines are present in such supernatants that also possess this activity.

Lymphokine stimulation of human macrophage C2 production is partially due to interferon-gamma

Monocyte complement stimulator (MCS), a product of T lymphocytes, is defined by its ability to stimulate the synthesis and secretion of the second complement component (C2) by monocytes. Most macrophage-activating factor (MAF) activity present in lymphokine-rich culture supernatants has recently been found to be due to interferon-gamma (IFN-gamma). We therefore hypothesized that IFN-gamma may have MCS activity as well. We tested recombinant, E. coli-derived, human IFN-gamma (rIFN-gamma) for its effects on C2 production by adherent peripheral blood monocytes and U937 cells, a human monocytic cell line. Recombinant IFN-gamma in concentrations ranging from 0.1 to 300 U/ml (0.003 to 8.8 ng/ml) stimulates C2 production by both cell populations. Exposure of responding cells for at least 24 hr is required for maximal stimulation. To determine the contribution of IFN-gamma toward total MCS activity in crude lymphokine-rich supernatants, we employed a solid-phase immunoabsorption technique with the use of a monoclonal anti-IFN-gamma antibody. This technique removed all IFN-gamma detectable by a sensitive ELISA, but MCS activity was decreased by only 40 to 50%. Additionally, MCS activity of these supernatants did not correlate with IFN-gamma content as determined by ELISA. By using another method to eliminate IFN-gamma activity, acid dialysis destroyed all rIFN-gamma activity, as measured by stimulation of U937 C2 synthesis, but eliminated only 30 to 67% of MCS activity from crude lymphokine preparations. Thus IFN-gamma stimulates C2 production by monocytes and U937 cells and apparently accounts for some, but not all, MCS activity present in lymphokine-rich supernatants. Other lymphokines are present in such supernatants that also possess this activity.

Effects of gold sodium thiomalate on functional correlates of human monocyte maturation

The mechanism of action of gold salts in the treatment of rheumatoid arthritis is unknown. Effects of gold on monocyte-macrophage function could be due to inhibition of maturation and differentiation. We found that 3 markers of monocyte differentiation, loss of peroxidase activity, spontaneous synthesis of C2, and spontaneous cytotoxicity for chicken erythrocytes, were all inhibited by gold treatment. This was not a general toxic effect since phorbol myristate acetate could still induce gold-treated monocytes to lyse chicken erythrocytes. Also, phorbol myristate acetate-stimulated superoxide production, a monocyte function not requiring further differentiation, was not inhibited by incubation with gold. Lymphokine-stimulated cytotoxicity for nucleated target cells, another function of monocytes, was inhibited only partially for certain target cells and not at all for others. These data suggest that gold has the capacity to selectively inhibit some monocyte functions which are associated with macrophage differentiation.

The fibrinogenolytic activity of purified tryptase from human lung mast cells

The capacity of purified tryptase from human lung mast cells to metabolize human fibrinogen, fibrin, and plasminogen was evaluated. Tryptase (5 micrograms/ml) inactivated the thrombin-induced clotting activity of fibrinogen (100 micrograms/ml) with essentially similar t 1/2 values of 4.6 min in the absence of heparin and 5.8 min in the presence of heparin (20 micrograms/ml) that were not appreciably different than with lysine-Sepharose-purified plasmin (5 micrograms/ml). Fibrinogen treated with tryptase together with heparin lost all detectable clotting activity by 4 hr at 37 degrees C, whereas fibrinogen treated with tryptase alone resulted in destruction of only 80% of fibrinogen clotting equivalents after 16 hr. Tryptase alone was observed to cleave only the alpha-chains of fibrinogen by electrophoresis of tryptase-treated, denatured, and reduced fibrinogen in polyacrylamide gradient gels. Tryptase together with heparin cleaved first the alpha-chain and then the beta-chain, the latter cleavage corresponding to complete loss of fibrinogen clotting activity by 4 hr. No fibrinogen fragments with anticoagulant activity were generated by tryptase. In contrast, plasmin left no residual clotting activity after 4 hr of incubation and generated fibrinogen fragments with anticoagulant activity. Plasmin sequentially cleaved the alpha, beta, and gamma subunits of fibrinogen. Tryptase alone (6 micrograms/ml) or together with heparin (20 micrograms/ml) failed to activate plasminogen (0.6 mg/ml) after a 60-min incubation at 37 degrees C. Addition of urokinase to tryptase-treated or untreated plasminogen resulted in essentially identical plasmin activities (0.32 and 0.34 U/ml, respectively), indicating that tryptase neither activates nor destroys plasminogen. Tryptase (700 ng) also failed to substantially solubilize cross-linked fibrin (2.6 micrograms) or the corresponding amount of fibrinogen bound to plastic microtiter plates with or without heparin. The failure to solubilize fibrinogen and, possibly, fibrin is consistent with the observation that the apparent m.w. by SDS polyacrylamide gel electrophoresis of unreduced fibrinogen is not appreciably altered by prior treatment with tryptase, even though cleavage of alpha-and beta-chains is revealed after reduction. Fibrinogenolysis by tryptase complements other mast cell mediators with anticoagulant properties such as heparin and suggests a significant prevention of coagulation by activated mast cells.

The fibrinogenolytic activity of purified tryptase from human lung mast cells

The capacity of purified tryptase from human lung mast cells to metabolize human fibrinogen, fibrin, and plasminogen was evaluated. Tryptase (5 micrograms/ml) inactivated the thrombin-induced clotting activity of fibrinogen (100 micrograms/ml) with essentially similar t 1/2 values of 4.6 min in the absence of heparin and 5.8 min in the presence of heparin (20 micrograms/ml) that were not appreciably different than with lysine-Sepharose-purified plasmin (5 micrograms/ml). Fibrinogen treated with tryptase together with heparin lost all detectable clotting activity by 4 hr at 37 degrees C, whereas fibrinogen treated with tryptase alone resulted in destruction of only 80% of fibrinogen clotting equivalents after 16 hr. Tryptase alone was observed to cleave only the alpha-chains of fibrinogen by electrophoresis of tryptase-treated, denatured, and reduced fibrinogen in polyacrylamide gradient gels. Tryptase together with heparin cleaved first the alpha-chain and then the beta-chain, the latter cleavage corresponding to complete loss of fibrinogen clotting activity by 4 hr. No fibrinogen fragments with anticoagulant activity were generated by tryptase. In contrast, plasmin left no residual clotting activity after 4 hr of incubation and generated fibrinogen fragments with anticoagulant activity. Plasmin sequentially cleaved the alpha, beta, and gamma subunits of fibrinogen. Tryptase alone (6 micrograms/ml) or together with heparin (20 micrograms/ml) failed to activate plasminogen (0.6 mg/ml) after a 60-min incubation at 37 degrees C. Addition of urokinase to tryptase-treated or untreated plasminogen resulted in essentially identical plasmin activities (0.32 and 0.34 U/ml, respectively), indicating that tryptase neither activates nor destroys plasminogen. Tryptase (700 ng) also failed to substantially solubilize cross-linked fibrin (2.6 micrograms) or the corresponding amount of fibrinogen bound to plastic microtiter plates with or without heparin. The failure to solubilize fibrinogen and, possibly, fibrin is consistent with the observation that the apparent m.w. by SDS polyacrylamide gel electrophoresis of unreduced fibrinogen is not appreciably altered by prior treatment with tryptase, even though cleavage of alpha-and beta-chains is revealed after reduction. Fibrinogenolysis by tryptase complements other mast cell mediators with anticoagulant properties such as heparin and suggests a significant prevention of coagulation by activated mast cells.

Monoclonal lupus autoantibody secretion by human-human hybridomas. Selection of hybrids by conventional and novel techniques

Autoantibody-secreting hybridomas were produced by somatic cell fusion of B lymphocytes from a patient with systemic lupus erythematosus with two different human myeloma lines. Selection of hybrids formed from one of these cell lines was performed by using aminopterine-containing culture medium as this cell line was deficient in hypoxanthine-guanine-phosphoribosyl transferase (HGPRT). The second myeloma line was not HGPRT-deficient but instead was treated with diethylpyrocarbonate, which assured death of unfused myeloma cells. This novel technique has wide applicability. Hybridomas were found to secrete antibodies to native DNA and to extractable nuclear antigen. The binding specificities of one IgM anti-DNA antibody was characterized and found to be specific for double-stranded DNA and had particular binding affinity for poly(dG) . poly(dC).

Lymphokine and phorbol (PMA) regulation of complement (C2) synthesis using U937

Human monocytes synthesize large amounts of the second complement component (C2) after incubation with a T-lymphocyte product called monocyte complement stimulator (MCS). The human monocyte-like cell line, U937, also synthesizes C2 and can be stimulated to increase this synthesis by lymphokine-rich culture supernates. Additionally, phorbol myristate acetate (PMA), an agent which induces maturational changes in other macrophage-like cell lines, also stimulates C2 synthesis by U937 cells. Lymphokine and PMA stimulation of C2 secretion by U937 are both reversibly inhibitable by cycloheximide. At optimal concentrations for stimulation of C2 synthesis, PMA inhibits [3H]thymidine incorporation by U937 indicating that increased C2 is not due to increased numbers of U937 cells.

Gold inhibition of the production of the second complement component by lymphokine-stimulated human monocytes

The ability of gold sodium thiomalate to inhibit production of the second complement component (C2) by monocytes stimulated by a lymphokine (monocyte complement stimulator is demonstrated. This gold salt inhibits C2 production irreversibly if monocytes are incubated with it before or during lymphokine stimulation. Thiomalic acid is not inhibitory. Monocytes already stimulated by lymphokine are resistant to inhibition of C2 production by gold sodium thiomalate. Gold salts do not reduce monocyte viability, phagocytic ability (latex heads) accessory cell function (as measured by the ability to present antigen to autologous lymphocytes), or capacity to act as stimulating cells in mixed leukocyte culture. Gold sodium thiomalate's inhibition of monocyte responsiveness to lymphokine may be significant in explaining the therapeutic benefit of gold salts in rheumatoid arthritis.

Monocyte Complement Stimulator (M.C.S.): A T Lymphocyte Product Capable of Stimulating Production of the Second Complement Component (C2)

We have previously reported that the production of the second complement component (C2) by human monocytes can be stimulated by co-culture with lymphocytes and antigen or with lymphokine-rich culture supernates. Using lymphocyte subpopulations separated on the basis of rosetting with sheep erythrocytes (T-lymphocytes), we now report that only cultures composed of antigen-stimulated monocytes and T lymphocytes could produce this lymphokine activity. Macrophage migration inhibitory factor (M.I.F.) was also present in this supernate. Although antigen-stimulated B lymphocytes (rosette-negative lymphocytes), B lymphocytes with monocytes, monocytes only, and T lymphocytes only could not produce this lymphokine activity, supernate of antigen-stimulated B lymphocytes and monocytes did contain M.I.F., indicating that molecules with this activity are not necessarily identical with those responsible for stimulating C2 synthesis by monocytes.

Further, Sephadex G-100 gel filtration of supernates from antigen-stimulated lymphocyte cultures resulted in fractions also capable of stimulating monocytes to increase their C2 production.

Ibuprofen-induced meningitis in systemic lupus erythematosus

A patient with systemic lupus erythematosus had chills, fever, and headache on four separate occasions after ibuprofen ingestion. One such episode was accompanied by cerebrospinal fluid findings compatible with meningitis. Drug rechallenge under controlled conditions established the relationship between ibuprofen ingestion and meningitis.

Production of the second component of complement by human monocytes: stimulation by antigen-activated lymphocytes or lymphokines

Human peripheral blood mononuclear cells cultured in the presence of antigen produced hemolytically active second complement component earlier and in larger amounts than did control cultures of the same cells without antigen. The increased amount of C2 in culture supernates came primarily from the adherent cell population and was due to increased synthesis as demonstrated by inhibition with 10(-4) M cycloheximide. Purified adherent monocytes produced more C2 when exposed to lymphokine-rich supernates from antigen-stimulated lymphocytes than when exposed to control supernates from unstimulated lymphocyte cultures. The increased synthesis of C2, which appeared to be mediated by a lymphokine, was partially inhibited specifically by 0.025 M alpha-L(-) fucose, a sugar which has previously been shown in inhibit the response of macrophages to migration inhibitory factor.