Targeting the EGFR-ERK axis using the compatible solute ectoine to stabilize CFTR mutant F508del

Mutations in the CFTR gene lead to cystic fibrosis, a genetic disease associated with chronic infection and inflammation and ultimately respiratory failure. The most common CF-causing mutation is F508del and CFTR modulators (correctors and potentiators) are being developed to rescue its trafficking and activity defects. However, there are currently no modulators that stabilize the rescued membrane F508del-CFTR which is endocytosed and quickly degraded resulting in a shorter half-life than wild-type (WT). We previously reported that the extracellular signal-regulated kinase (ERK) MAPK pathway is involved in CFTR degradation upon cigarette smoke exposure. Interestingly, we found that ERK phosphorylation was increased in CF human bronchial epithelial (HBE) cells (CF-HBE41o- and primary CF-HBE) compared to non-CF controls, and this was likely due to signaling by the epidermal growth factor receptor (EGFR). EGFR can be activated by several ligands, and we provide evidence that amphiregulin (AREG) is important for activating this signaling axis in CF. The natural osmolyte ectoine stabilizes membrane macromolecules. We show that ectoine decreases ERK phosphorylation, increases the half-life of rescued CFTR, and increases CFTR-mediated chloride transport in combination with the CFTR corrector VX-661. Additionally, ectoine reduces production of AREG and interleukin-8 by CF primary bronchial epithelial cells. In conclusion, EGFR-ERK signaling negatively regulates CFTR and is hyperactive in CF, and targeting this axis with ectoine may prove beneficial for CF patients.

Ectoine in the Treatment of Irritations and Inflammations of the Eye Surface

The ocular surface is facing various unspecific stress factors resulting in irritation and inflammation of the epithelia, causing discomfort to the patients. Ectoine is a bacteria-derived extremolyte with the ability to protect proteins and biological membranes from damage caused by extreme environmental conditions like heat, UV-light, high osmolarity, or dryness. Evidence from preclinical and clinical studies attest its effectiveness in treating several epithelium-associated inflammatory diseases, including the eye surface. In this review, we analysed 16 recent clinical trials investigating ectoine eye drops in patients with allergic conjunctivitis or with other unspecific ocular inflammations caused by e.g. ophthalmic surgery. Findings from these studies were reviewed in context with other published work on ectoine. In summary, patients with irritations and unspecific inflammations of the ocular surface have been treated successfully with ectoine-containing eye drops. In these patients, significant improvement was observed in ocular symptoms of allergic rhinoconjunctivitis, postoperative secondary dry eye syndrome, or ocular reepithelisation after surgery. Using ectoine as an add-on therapy to antihistamines, in allergy patients accelerated symptom relief by days, and its use as an add-on to antibiotics resulted in faster wound closure. Ectoine is a natural substance with an excellent tolerability and safety profile thus representing a helpful alternative for patients with inflammatory irritation of the ocular surface, who wish to avoid local reactions and side effects associated with pharmacological therapies or wish to increase the efficacy of standard treatment regimen.

Dencichine ameliorates renal injury by improving oxidative stress, apoptosis and fibrosis in diabetic rats

OBJECTIVE

To investigate protective efficacies and mechanisms of dencichine on diabetic kidney injury via in vitro and in vivo assays.

METHODS

Effects of dencichine on hydrogen peroxide (H₂O₂) induced oxidative damage in HK-2 renal cells were assessed by CCK-8 method. Forty streptozotocin (STZ)-induced diabetic rats with kidney injury were randomly divided into negative control group, three doses of dencichine (40, 80 and 160 mg/kg) groups. Blood biochemical and kidney related indexes as well adrenal morphological changes, apoptosis and autophagy related markers of diabetic rats were measured.

RESULTS

Cell viability of HK-2 cells with oxidative damage induced by H₂O₂ was significantly improved by dencichine with 160 μg/mL for 43.7% and 320 μg/mL for 52.9% compared with control. Moreover, the decreased reactive oxygen species (ROS), and increased intracellular antioxidant enzymes including GPX1, SOD2 and GSH were showed in dencichine groups. In addition, incubation of dencichine in HK-2 cells promoted the increase of p-AMPK, BCL2, LC3, decreased activation of p-mTOR, BAX and Caspase 3. Chronic treatment of dencichine improved the STZ-induced diabetic characteristics of model rats. Further histopathological examination of renal tissues revealed 12-week treatment of dencichine effectively improved the morphology of nephropathy in diabetic rats. Moreover, dencichine also ameliorated excessive oxidation stress, down-regulated renal cell apoptosis and fibrosis related proteins, thereby protected renal tissues in diabetic rats.

CONCLUSION

Dencichine ameliorated STZ-induced kidney injury mainly through inhibiting oxidative stress, reducing renal fibrosis, increasing autophagy, and reducing the renal cell apoptosis related proteins to protect nephrocytes and decrease renal tissue damage.

Ectoine lozenges in the treatment of acute viral pharyngitis: a prospective, active-controlled clinical study

PURPOSE

Acute pharyngitis is an uncomfortable disorder mostly caused by viruses and for which antibiotics are unwarranted. This study compared lozenges containing ectoine, a natural extremolyte, with hyaluronic acid lozenges and hypertonic saline gargle for symptomatic treatment of acute viral pharyngitis.

METHODS

This prospective, controlled clinical study, recruited 90 patients with moderate-to-severe pharyngitis symptoms who chose to use either ectoine (n = 35), hyaluronic acid (n = 35), or saline gargle (n = 20). Patients applied their 7-day treatment from the inclusion visit (V1) until the end-of-study visit (V2). Patients' pharyngitis symptoms, general health, general treatment effectiveness and tolerability, and patient compliance were assessed by investigators and patients.

RESULTS

The sum score for three primary symptoms (pain on swallowing, urge to cough, and hoarseness) decreased by 79.5% (ectoine), 72.2% (hyaluronic acid), and 44.8% (saline gargle). Both lozenges were significantly superior to saline gargle (P < 0.05). Regarding general health improvement, ectoine was significantly superior to saline gargle (72.5% vs. 45.2%, P < 0.05), but hyaluronic acid (63.3%) was not. At V2, 65.7% of patients receiving ectoine reported "very good" general health vs. 48.6% of those receiving hyaluronic acid and 20.0% using saline gargle. Ectoine was significantly superior (P < 0.05) to both hyaluronic acid and saline gargle in terms of tolerability and patient compliance. No patients taking ectoine reported unpleasant sensations while applying their treatment, whereas almost half of patients using hyaluronic acid lozenges and saline gargle did.

CONCLUSION

Treatment with ectoine lozenges significantly relieves moderate-to-severe symptoms of acute viral pharyngitis and is more effective and tolerable than treatments with hyaluronic acid lozenges and hypertonic saline gargle.

ASSESSMENT OF FUNCTIONAL CHANGES TEAR PRODUCTION UNDER THE ACTION OF THE EYE DROPS ON THE BASE OF NATURAL MOLECULE OF ECTOINE AND ARTIFICIAL TEARS IN PATIENTS WITH DRY EYE SYNDROME ON THE BACKGROUND OF ENDOCRINE OPHTHALMOPATHY

Conducted a comparative analysis of functional changes in tear production in patients with dry eye syndrome and endocrine ophthalmopathy in the conditions of the long-term acting of preservative free medications based on natural substances. A total of 30 people, aged 35 to 53 years old with clinical manifestations of DES on the background of EO were divided on two groups. In I group eye drops of ectoine and in II - artificial tears were administered. The examination included general and specific methods. The term of follow up - 30 days. It was found that long-term use of preservative free eye drops based on ectoine leads to more expressive positive changes in the condition of the anterior surface of the eye and the secretion and quality of the tear.

A prospective, controlled study of SNS01 (ectoine nasal spray) compared to BNO-101 (phytotherapeutic dragées) in patients with acute rhinosinusitis

OBJECTIVES

In this observational study, data on the efficacy, effects on quality of life and tolerability of the topical formulation SNS01 (Ectoin Rhinitis nasal spray) were compared to those of BNO-101 (Sinupret forte dragées) in patients with acute rhinosinusitis in the ear, nose, and throat (ENT) clinical setting.

DESIGN AND METHODS

Patients with the diagnosis of acute rhinosinusitis were included in this non-interventional study with a treatment duration of 14-16 days. They received either a herbal phytotherapeutic dragée (control) or an ectoine-based nasal spray (investigational product), each to be taken according to the instructions for use (IFU) and summary of product characteristics (SPC). At each visit, the physician performed a nasal endoscopy, recorded the Sinusitis Symptom Score and checked for adverse events. During the entire treatment period, patients recorded the Sinusitis Symptom Score in patient diaries. In addition, patients receiving the nasal spray filled out a questionnaire to assess the tolerability of the treatment. To investigate effects on quality of life patients were asked to fill out the German version of a sinusitis-specific HRQL (health related quality of life) questionnaire.

CLINICAL TRIAL REGISTRATION

NCT01684540.

RESULTS

Patient diary entries, the assessment of the Sinusitis Symptom Score and the HRQL questionnaire demonstrated that the ectoine nasal spray was as effective as the phytotherapeutic dragées in treating acute rhinosinusitis. After two weeks of treatment, the assessments of both the patients' diaries and physicians' record forms indicated statistically significant improvement (p ≤ 0.001) in the symptom scores of the two groups (57.8% improvement for ectoine and 49.3% improvement for the phytotherapeutic dragées compared to baseline). Also, overall scores of 80 in the sensory questionnaire confirmed the good tolerability of the nasal spray. Correspondingly, HRQL improved significantly over the course of the treatment in both groups.

CONCLUSION

SNS01 and BNO-101 demonstrated comparable effects in the treatment of acute rhinosinusitis.

LIMITATIONS

Following German regulations, this trial was set up as an observational 'non-interventional' study, which does not allow for a placebo group or randomization of patients. Although the grade of evidence delivered by the study data is thus reduced from Ib to IIa, it does, however, reflect a realistic view of the most common clinical practice.

[Treatment with antisense oligonucleotides in Duchenne's disease]

In this paper I review the results of the treatments directed to modify the mRNA of dystrophin with the goal of converting the severe Duchenne type to the milder Becker muscular dystrophy. Antisense oligomers potential to modify Duchenne muscular dystrophy (DMD) gene expression and therapeutic strategies to induce ribosomal read-through of nonsense mutations (PTC124) are described. They are an important advance in the treatment of DMD, so far unspecific. Significant expression of new dystrophin is observed in biopsies of peripheral muscle, although the functional improvement is not so encouraging. New modification of chemistries are expected to improve the liberation, broad distribution in muscles, as well as their efficacy and safety enough to allow a positive chronic treatment of DMD.

[Experimental study of the anti-inflammatory and analgesic effects of diethyl 1,3-dicyclohexyl- 1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylate]

OBJECTIVE

To study the anti-inflammatory and analgesic activities of diethyl 1,3-dicyclohexyl-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylate (ZL-5010) in vivo and in vitro.

METHODS

The analgesic effect of ZL-5010 was evaluated by acetic acid-induced writhing response in mice, and the anti-inflammatory effects was assessed in mice with xylene-induced ear edema and in rats with carrageenan-induced paw edema. Mouse peritoneal exudate cells activated by bacterial lipopolysaccharides (LPS) were used to evaluate the anti-inflammatory effect of ZL-5010 in vitro. The levels of interleukin-1β (IL -1β) and tumor necrosis factor-α (TNF-α) in the cell culture supernatant were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

At the doses of 0.25 and 0.5 mmol/kg, ZL-5010 administered by gavage once daily for 3 days significantly reduced acetic acid-induced writhing frequency and suppressed xylene-induced ear edema in mice, and alleviated paw edema induced by carrageenan in rats (P<0.05). The agent also inhibited the production of the pro-inflammatory cytokines IL-1β and TNF-α by LPS-induced mouse peritoneal exudate cells in vitro, with the statistically significant minimum effective concentrations of 10 and 20 µmol/L, respectively (P<0.05).

CONCLUSION

ZL-5010 administered by gavage has anti-inflammatory and analgesic effects in mice and rats, and in mouse peritoneal exudate cell cultures, the agent also inhibits the production of the pro-inflammatory cytokines IL-1β and TNF-α.

[Therapeutic readthrough strategy for suppression of nonsense mutations in duchenne muscular dystrophy]

Effective treatment for Duchenne muscular dystrophy (DMD) is currently unavailable. Readthrough of disease-causing premature termination codons might alleviate the symptoms of genetic diseases caused by nonsense mutations. Several ribosome-binding compounds, including selective antibiotics and synthetic novel small molecules, induce translational readthrough, restoring full-length functional proteins. Here in this innovative therapeutic strategy has been summarized with a focus on DMD. We have previously reported that negamycin restored dystrophin expression with less toxicity than gentamicin in mdx mice. To explore more potent readthrough inducers, we established the transgenic mouse called READ (readthrough evaluation and assessment by dural receptor) for readthrough-specific detection. Using READ mice, we discovered drug candidates, including sterically negamycin-like small molecules and aminoglycoside derivatives. The newly developed small molecules induced dose-dependent readthrough with greater potency than ataluren in vitro and promoted the expression of dystrophin and reduction in serum creatine kinase activity in mdx mice. Moreover, the aminoglycoside derivative restored both dystrophin protein and contractile function of mdx skeletal muscles with appreciably higher readthrough activity and lower toxicity than that of gentamicin. Furthermore, we confirmed the efficacy of a thioglycolate-based depilatory agent to enhance the topical delivery of skin-impermeable drugs, including aminoglycosides. These promising new chemotherapeutic agents with beneficial effects on readthrough action, lower toxicity, and transdermal delivery may have significant value in treating or preventing genetic diseases caused by nonsense mutations.

In vivo assessment of Ectoin: a randomized, vehicle-controlled clinical trial

The aim of the study was to assess an Ectoin formulation with regard to the antiageing properties. The study was designed as a monocentric, randomized, double-blind application test, in order to ensure the compatibility and the efficacy of Ectoin in comparison to a vehicle emulsion. A total of 104 voluntary healthy female test subjects were included in the study. Moisturizing properties as well as other parameters of skin ageing, like skin surface structure and skin elasticity, were determined for treatment A (vehicle) and treatment B (with 2% Ectoin) versus an untreated control. Statistical evaluations according to the Wilcoxon rank-sum test indicate a general preference for the Ectoin treatment by the test subjects in both the application and the efficacy tests. None of the participating test subjects had any side effects throughout the study. In terms of antiageing properties, previous in vitro studies could be confirmed by this clinical trial, clarifying that the natural cell protection concept of Ectoin is transferable to skin care with manifold benefits.

Ectoine alters subcellular localization of inclusions and reduces apoptotic cell death induced by the truncated Machado–Joseph disease gene product with an expanded polyglutamine stretch

Protein misfolding is considered a key event in the pathogenesis of polyglutamine disease such as Machado-Joseph disease (MJD). Overexpression of chaperone proteins and the application of chemical chaperones are reported to suppress polyglutamine induced cytotoxicity in vitro and in vivo. The effects of compatible solutes, which are osmoprotectants in bacteria and possess the action in stabilizing proteins under stress, have not, to our knowledge, been studied. We explored the protective effects of the compatible solutes ectoine, hydroxyectoine, and betaine on apoptotic cell death produced by the truncated MJD gene product with an expanded polyglutamine tract in cultured neuro2a cells. Ectoine, but not hydroxyectoine or betaine, decreased large cytoplasmic inclusions and increased the frequency of nuclear inclusions. Immunoblot analysis showed that ectoine reduced the total amount of aggregates. Despite the presence of nuclear inclusions, apoptotic features were less frequently observed after ectoine application. Our findings suggest that ectoine, a natural osmoprotectant in bacteria, may function as a novel molecule protecting cells from polyglutamine-induced toxicity.

Ectoin: an effective natural substance to prevent UVA-induced premature photoaging

With the help of a new 'UVA stress model', it was shown that Ectoin protects the skin from the effects of UVA-induced cell damage in a number of different ways. Using cell cultures, high-performance thin-layer chromatography, gel electrophoresis mobility shift assays, reverse transcriptase polymerase chain reaction, ion exchange chromatography and UV spectroscopy, it was demonstrated that the UVA-induced second messenger release, transcription factor AP-2 activation, intercellular adhesion molecule-1 expression and mitochondrial DNA mutation could be prevented. The results obtained clearly demonstrate that Ectoin counteracts the effects of UVA-induced and accelerated skin aging at different cell levels.

[Possible chemotherapy of muscular dystrophy caused by nonsense mutation]

Gentamicin, an aminoglycoside antibiotic which causes read-through of premature termination codon during translation, has been used to rescue genetic diseases caused by nonsense mutation. Its strong side effects, however, has always threaten patients. In order to utilize other antibiotics with less side effects than gentamicin, we have shown that negamycin, a dipeptide antibiotic with read-through activity in prokaryotes, restored dystrophin in skeletal and cardiac muscles of mdx mouse, an animal model for Duchenne type muscular dystrophy caused by nonsense mutation. To avoid miscoding and emerging resistant bacteria for these read-through antibiotics, further drug design and high throughput screening of gentamicin- or negamycin-related molecules will be needed.

Negamycin restores dystrophin expression in skeletal and cardiac muscles of mdx mice

The ability of aminoglycoside antibiotics to promote read-through of nonsense mutations has attracted interest in these drugs as potential therapeutic agents in genetic diseases. However, the toxicity of aminoglycoside antibiotics may result in severe side effects during long-term treatment. In this paper, we report that negamycin, a dipeptide antibiotic, also restores dystrophin expression in skeletal and cardiac muscles of the mdx mouse, an animal model of Duchenne muscular dystrophy (DMD) with a nonsense mutation in the dystrophin gene, and in cultured mdx myotubes. Dystrophin expression was confirmed by immunohistochemistry and immunoblotting. We also compared the toxicity of negamycin and gentamicin, and found negamycin to be less toxic. Furthermore, we demonstrate that negamycin binds to a partial sequence of the eukaryotic rRNA-decoding A-site. We conclude that negamycin is a promising new therapeutic candidate for DMD and other genetic diseases caused by nonsense mutations.

Aerosolized soluble nitric oxide donor improves oxygenation and pulmonary hypertension in acute lung injury

Acute respiratory distress syndrome (ARDS) is a major cause of morbidity and mortality in critically ill patients. The associated ventilation/perfusion mismatch and pulmonary hypertension are amenable to treatment with inhaled nitric oxide (NO) gas. Compounds formed by reacting NO with various nucleophiles (NONOates) release NO spontaneously and induce vasodilation. Intratracheally administered NONOates result in selective reduction in pulmonary hypertension. We hypothesized that a nebulized NONOate would improve oxygenation and reduce pulmonary vascular resistance in oleic acid-induced acute lung injury and pulmonary hypertension. Pigs underwent catheterization of the pulmonary artery, left atrium, and right atrium, and a flow probe was positioned around the pulmonary artery. Acute lung injury and pulmonary hypertension were induced with intravenous oleic acid. Animals were randomly assigned to receive either nebulized saline or the NONOate 2-(dimethylamino)ethylputreanine/NO (DMAEP/NO). Hemodynamic, gas exchange, pulmonary function, methemoglobin, and nitrite/nitrate measurements were obtained for 60 min. Animals in the DMAEP/NO group had improvement in PaO2 as compared with control animals (from 139 +/- 19 mm Hg to 180 +/- 19 mm Hg in the DMAEP/NO group [n = 6]; and from 144 +/- 6 mm Hg to 150 +/- 9 mm Hg in the saline group [n = 6], p < 0.05). After aerosol treatment, animals in the DMAEP/NO group had a greater reduction in pulmonary vascular resistance index (PVRI) than did control animals (from 81 +/- 17 dyne. s/cm5/kg to 34 +/- 8 dyne. s/cm5/kg; and from 104 +/- 16 dyne. s/cm5/kg to 64 +/- 11 dyne. sec/cm5/ kg in the saline group at 60 min, p < 0.05). There were no differences between the groups in systemic vascular resistance index (SVRI), cardiac index (CI), methemoglobin, nitrite/nitrate, or lung pathology scores. We conclude that DMAEP/NO improves oxygenation and has selective pulmonary vasodilating properties without causing significant systemic toxicity in this porcine model of acute lung injury.

Aerosolization of novel nitric oxide donors selectively reduce pulmonary hypertension

OBJECTIVES

Inhaled nitric oxide (NO) reduces pulmonary hypertension in acute respiratory failure. Soluble nitric oxide donors (NO/nucleophile adducts-NONOates) are less cumbersome to deliver and may offer clinical advantage compared with inhaled NO. The objective of this study was to examine the pulmonary and systemic hemodynamic effects of tracheal aerosolization of a new class of NONOates in a porcine model of experimentally induced pulmonary hypertension.

DESIGN

Prospective, randomized, controlled study.

SETTING

Research laboratory.

SUBJECTS

Yorkshire pigs (n = 18), weighing 11.4 to 16.4 kg.

INTERVENTIONS

In anesthetized, mechanically ventilated, instrumented pigs, steady-state pulmonary hypertension (SSPH) was induced using a thromboxane agonist (U46619). Control animals received tracheal aerosolization of saline (n = 6); EP/NO animals received tracheal aerosolization of ethylputreanine NONOate (EP/ NO, n = 6); and DMAEP/NO animals received aerosolized 2-(dimethylamino) ethylputreanine NONOate (DMAEP/NO, n = 6).

MEASUREMENTS AND MAIN RESULTS

Mean pulmonary (MPAP) and mean systemic arterial pressures (MAP), atrial pressures, cardiac output, and arterial blood gases were measured following drug instillation. DMAEP/NO animals had significant reductions in pulmonary vascular resistance index (PVRI) and MPAP at all time points compared with SSPH and control animals (p < .05), while systemic vascular resistance index did not change. EP/NO animals had a significant reduction in PVRI and MPAP at some time points compared with SSPH and control animals. For both NONOate-treated animal groups, MAP and cardiac index did not change significantly compared with SSPH and control animals (p < .05).

CONCLUSIONS

In this porcine model of pulmonary hypertension, intratracheal aerosolization of soluble NO donors results in sustained reduction of pulmonary hypertension without reducing systemic arterial pressure. Intermittent aerosolization of NONOates may be an alternative to continuously inhaled NO in the treatment of acute pulmonary hypertension.

Activation of tumoricidal properties in macrophages and inhibition of experimentally-induced murine metastases by a new synthetic acyltripeptide, FK-565

The effect of FK-565, a novel low molecular weight (MW) acyltripeptide, on tumoricidal properties of murine macrophages is reported here. Peritoneal macrophages (PMs) harvested from C57BL/6 mice and beige mice were rendered cytotoxic to syngeneic B16 melanoma cells following their interaction in vitro with FK-565. Maximal and reproducible activation of tumoricidal properties in PM were obtained by interaction in vitro with 25 micrograms/ml of FK-565 for a 24 h period, and as little as 0.5 microgram/ml of FK-565 was sufficient to induce significant cytotoxicity. Murine PMs activated by FK-565 in vitro were cytotoxic to syngeneic and xenogeneic tumor cells, but did not affect allogeneic nontumor cells. The PMs were also activated to kill B16 melanoma cells by intraperitoneal injections of FK-565 (10 mg/kg). Multiple injections of FK-565 into mice also slightly but significantly inhibited lung metastases. These results suggest that FK-565 has potential as an effective immunopotentiator in immunotherapy.

Immunoactive peptides, FK-156 and FK-565. III. Enhancement of host defense mechanisms against infection

We investigated the effect of immunoactive peptides, FK-156 and FK-565 on host defense mechanisms against microbial invasion. It was shown that these drugs given to normal mice increased the counts of phagocytes in both peripheral blood and peritoneal cavity, and enhanced the chemotactic, phagocytic and killing activities of peritoneal macrophages and polymorphonuclear leukocytes, and stimulated the phagocytic function of the reticuloendothelial system. Enhanced host resistance to microbial infection by these immunoactive peptides might be induced by both increase in counts and enhancement of functions of phagocytes. FK-156 restored decreased counts and functions of phagocytes in mice immunosuppressed by cyclophosphamide, hydrocortisone or tumor. These findings suggest that these immunoactive peptides could be applied to prevent intractable infection in immunocompromised hosts.

Immunoactive peptides, FK-156 and FK-565. I. Enhancement of host resistance to microbial infection in mice

The protective effect of an immunoactive peptide, D-lactoyl-L-alanyl-gamma-D-glutamyl-(L)-meso-diaminopimelyl-(L)-glycine (FK-156) and a related compound, heptanoyl-gamma-D-glutamyl-(L)-meso-diaminopimelyl-(D)-alanine (FK-565) was determined in mice with various kinds of microbial infections. FK-156 and FK-565 were given to mice either subcutaneously or orally before challenge. The drugs enhanced significantly the defense of mice against acute systemic infections induced by various extracellular and facultative intracellular organisms, and subcutaneous abscess by Staphylococcus aureus. The protective effect of these drugs against Escherichia coli infection differed considerably depending on the route of administration; FK-156 was only effective by the parenteral route; however, FK-565 was effective by both parenteral and oral routes. After subcutaneous dosing with FK-156, the enhancement of host defense of mice against E. coli infection was more rapid than against Listeria infection. The enhancing effects of FK-156 and FK-565 on host defense of mice against pseudomonal infection was more potent than other immunoactive drugs.

Immunoactive peptides, FK-156 and FK-565. II. Restoration of host resistance to microbial infection in immunosuppressed mice

The immunoactive peptides, FK-156 and its analogue, FK-565 were evaluated in various models of mice immunosuppressed with cyclophosphamide, hydrocortisone, mitomycin C, carrageenan and tumor cells. Treatment with FK-156 (subcutaneous) and FK-565 (oral) markedly restored host defense ability against microbial infection. The therapeutic effect of ticarcillin or gentamicin alone against pseudomonal infection in cyclophosphamide- and hydrocortisone-treated mice and tumor-bearing mice was much lower than in normal mice. The therapeutic effect of these antibiotics against pseudomonal infection in immunosuppressed mice was enhanced markedly by combined use with FK-156. The killing ability of macrophages and polymorphonuclear leukocytes of the immunosuppressed mice was also markedly enhanced by dosing with FK-156.

Antitumor effects of novel immunoactive peptides, FK-156 and its synthetic derivatives

Effects produced by intratumor or systemic application of FK-156 and its synthetic derivatives on the syngeneic P388-DBA/2 mouse system were investigated. Among 21 compounds tested, FK-156, FK-565, FR-46758, FR-48217, FR-46091 and FR-47920 substantially suppressed tumor growth when directly injected into a tumor mass and further experiments showed that FK-156, FK-565 and FR-46758 were effective even when administered subcutaneously into site remote from tumor. The mechanisms of growth inhibition are strongly suggested to be host mediated, because these three compounds have remarkably low cytotoxicity against P388 cells in vitro. A single dose of FK-565, however, markedly decreased body weight in healthy DBA/2 mice, whereas FK-156 and FR-46758 did not. These results indicate the superiority of FK-156 and FR-46758 as immunotherapeutic agents over FK-565 with respect to their safety for treatment of cancer. Although significant life-span prolongation could not be seen in the two-injection regimen of six compounds in either system, systemic multiple injections of FK-156 and FR-46758 provided a statistically significant increase in the median survival time of P388 tumor bearing mice.