Search

Mammalian zinc ectopeptidases have significant functions in deactivating neurological and hormonal peptide signals on the cell surface. The identification of Opiorphin, a physiological inhibitor of zinc ectopeptidases that inactivate enkephalin, has revealed its strong analgesic effects in both chemical and mechanical pain models. Opiorphin achieves this by increasing the transmission of endogenous opioids, which are dependent on the body's own opioid system. The function of opiorphin is closely linked to the rat sialorphin peptide, which inhibits pain perception by enhancing the activity of naturally occurring enkephalinergic pathways that depend on μ- and δ-opioid receptors. Opiorphin is highly intriguing in terms of its physiological implications within the endogenous opioidergic pathways, particularly in its ability to regulate mood-related states and pain perception. Opiorphin can induce antidepressant-like effects by influencing the levels of naturally occurring enkephalin, which are released in response to specific physical and/or psychological stimuli. This effect is achieved through the modulation of delta-opioid receptor-dependent pathways. Furthermore, research has demonstrated that opiorphin's impact on the cardiovascular system is facilitated by the renin–angiotensin system (RAS), sympathetic ganglia, and adrenal medulla, rather than the opioid system. Hence, opiorphin shows great potential as a solitary candidate for the treatment of several illnesses such as neurodegeneration, pain, and mood disorders. [ABSTRACT FROM AUTHOR]

Objective: Opiorphin is a pentapeptide secreted in saliva and has a strong analgesic effect. Salivary opiorphin has been shown to increase in orofacial pain and may act as a pain reliever in pain caused by denture‐related ulcers. The current study aimed to evaluate the salivary opiorphin levels in traumatic ulcers caused by ill‐fitting dentures and demonstrate whether there is any correlation between trauma‐related pain levels and salivary opiorphin levels. Materials and Methods: Twenty‐two individuals with new full dentures and a complaint of pain due to ill‐fitting were included in this study. Patients were asked to rate their level of pain on a visual analog scale (VAS). Then, saliva specimens were collected at the first visit with the complaint of pain and 7 days following the denture adjustment. Results: The average saliva opiorphin level before and after denture adjustment were 19.29 ± 5.44 and 15.78 ± 3.95 ng/mL, respectively. A dependent (paired) t‐test determined that the mean salivary opiorphin level differed statistically significantly before and after the adjustment of the dentures. Conclusions: The findings show that salivary opiorphin levels increase in pain associated with denture‐related traumatic ulcers. Adjusting the dentures resulted in pain relief and a statistically significant reduction in opiorphin levels. [ABSTRACT FROM AUTHOR]

Objectives: Opiorphin is an analgesic peptide released by salivary glands and capsaicin an agonist of TRPV1 receptors eliciting burning sensations. The primary objective of this study was to assess opiorphin release after stimulation of the tongue by capsaicin (STC). The secondary objectives were to compare opiorphin release after STC in 3 groups of subjects [healthy (CTRL), Burning Mouth Syndrome (BMS), painful Temporomandibular disorders (TMDp)] and pain evoked by STC in these 3 groups. Materials and methods: Salivary opiorphin was assessed with high-performance liquid chromatography at 3 different time points (baseline, after 5 min and 20 min of STC). Pain was self-reported on a (0–10) numeric rating scale. Results: Three groups (N = 16) of adults were recruited at the Clinical Hospital Centre and School of Dental Medicine in Zagreb. Opiorphin levels were higher (1) in TMDp compared to CTRL in 1st (2.23 ± 1.72 pg/ul vs. 0.67 ± 0.44 pg/ul, p = 0.002) and 3rd sampling (2.44 ± 2.01 pg/ul vs. 0.74 ± 0.52 pg/ul, p = 0.020) and (2) within BMS group at 3rd sampling vs. baseline (p < 0.025). Pain scores were higher in BMS compared to TMDp (p < 0.025) and CTRL (p < 0.025). Conclusion: This study evidenced (1) a differential basal amount of opiorphin in two pain conditions and control subjects (2) a differential kinetic of release of opiorphin after STC in CTRL, BMS and TMDp (3) a differential pain perception after STC in BMS and TMDp vs. CTRL, which can provide a readout for animal models. Clinical relevance: The specific regulation of opiorphin release in patients with orofacial painful conditions provides valuable insights for clinicians and researchers in physiology and pathology and encourages further research in this area. Trial registration: ClinicalTrials.gov NCT04694274. Registered on 01/05/2021. [ABSTRACT FROM AUTHOR]

Cancer still represents one of the biggest challenges in current medical practice. Among different types of cancer, oral cancer has a huge impact on patients due to its great visibility, which is more likely to create social stigma and increased anxiety. New early diagnose methods are still needed to improve treatment efficiency and patients' life quality. Raman/SERS (Surface Enhanced Raman Spectroscopy) spectroscopy has a unique and powerful potential for detecting specific molecules that can become priceless biomarkers in different pathologies, such as oral cancer. In this study, a batch of saliva samples obtained from a group of 17 patients with oro-maxillofacial pathologies compared with saliva samples from 18 healthy donors using the aforementioned methods were evaluated. At the same time, opiorphin, potassium thiocyanate and uric acid were evaluated as potential specific biomarkers for oro-maxillofacial pathologies using multivariate analysis. A careful examination of SERS spectra collected on saliva samples showed that the spectra are dominated by the vibrational bands of opiorphin, potassium thiocyanate and uric acid. Given the fact that all these small molecules are found in very small amounts, we filtrated all the samples to get rid of large molecules and to improve our analysis. By using solid plasmonic substrates, we were able to gain information about molecular concentration and geometry of interaction. On the other hand, the multivariate analysis of the salivary spectra contributed to developing a new detection method for oral cancer. [ABSTRACT FROM AUTHOR]

Plain English summary The orofacial region is affected by various inflammatory and autoimmune conditions, which might translate into general and regional changes. Saliva is one of the biological fluids where biomarkers of the aforementioned conditions, including sensitivity to pain, could be detected. It is also noteworthy that anorexia nervosa (AN) and malnutrition may change the saliva's analgesic or immune content, but this scientific area is still not satisfactorily explored. The present work related to analgesic (opiorphin peptide) and anti-infectious agents (immunoglobulins Ig A, IgG, IgM) in said body fluid among 83 adolescent patients with severe AN compared to 79 healthy controls. In addition, oral hygiene levels were assessed in the oral cavity via the Plaque Control Record index (PCR). In the AN group, the concentration of opiorphin was significantly higher as compared to the control group, in contrast to IgM, which was significantly lower than in the control group. There were no notable differences in the levels of IgA and IgG between groups, despite a slightly higher concentrations of IgA in the AN group. A correlation was found between opiorphin and all immunoglobulins. A similar correlation was found between PCR index and all immunoglobulins.The present work shows how analgesic opiorphin depends on the oral inflammatory status. This might be a direction for further investigating the immune alterations in patients with AN-related malnutrition. Inclusion of AN patients in intensive oral hygiene care may also be considered.

The work aimed to explore the clinical hypothesis on the possible alternative to Opiorphin and its stable analogues for treating fibromyalgia pain. Fibromyalgia is a condition characterized by chronic pain triggered by an interplay of biological and psychosocial variables, although the exact pathogenesis is still controversial. Standard therapy for low threshold tender point pain includes NSAIDs and opioid analgesics, both of which have serious adverse profiles after long-term exposure, highlighting the need for an intermediate compound capable of bridging the gap between NSAIDs and opioid analgesics. Opiorphin is an anti-nociceptive modulator which inhibits the enzyme responsible for the degradation of natural endogenous opioid neuropeptides. This paper hypothesizes and concludes that Opiorphin and its stable analogues (Sialorphine, STR-324) can be an alternative for the treatment of chronic long-standing low-threshold tender point pain associated with fibromyalgia. [ABSTRACT FROM AUTHOR]

Background and Aims: Atypical facial pain (AFP) is a chronic disease associated with local pain in the craniofacial area. A wide range of treatments including drug therapy, psychiatric methods and open surgery are used for its treatment. Opiorphin is a pentapeptide that can block pain and also has proven antidepressant effects. The aim of this study was conducted to investigate the opiorphin concentration in AFP patients and to compare it with healthy people. Materials and Methods: This study was performed on 30 AFP patients and 40 healthy individuals. Unstimulated saliva was collected from both groups by spitting method. HAD-A (Hamilton Anxiety Test) and HAD-D (Hamilton Depression Test) questionnaires were completed for all patients and controls. Psychological interview with the patients and psychological analysis were performed to determine anxiety and depression scores. Data analysis was done using SPSS (ver.24) statistical software Results: The subjects of two groups were homogeneous in terms of age and sex. The mean salivary opiorphin concentrations in the case and control groups were 1.8050±0.2923 and 1.8032±0.3682 ng/ml, respectively. According to the results of t-Test, no significant difference was observed in the mean opiorphin concentration between the AFP group and control group (P=1.000). According to the Pearson's test, no significant relationship was found between the opiorphin levels and the age, sex, and anxiety or depression score in the patient and control groups (P>0.05). Also, there was no remarkable correlation between initial VAS, duration of pain and previous treatments with opiorphin levels in the AFP patients (P>0.05). No significant correlation was found between the opiorphin concentration and menopausal period in the case and control women (P>0.05). Conclusion: The results showed that most AFP patients had some degree of anxiety and depression. However, salivary opiorphin concentration did not significantly increase in the AFP patients.

Copyright of Journal of Dental Medicine is the property of Tehran University of Medical Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Patients who suffer from anorexia nervosa (AN) are characterized by exceedingly lower body weight, micro- and macro-nutrient deficiencies, and hyposalivation as compared to healthy subjects. In addition, AN may predispose to difficulties in oral health maintenance. However, little is known about the relationship between stress-dependent salivary neuro/immunopeptidergic biomarkers such as opiorphin and immunoglobulins (Ig) and AN.The aim of this case–control study was to evaluate salivary opiorphin and immunoglobulins in female children and adolescents diagnosed with AN compared to healthy controls. Methods: Adolescent patients with clinically-confirmed severe restrictive subtype AN (Body Mass Index BMI < 15 kg/m2, mean age 15.0 ± 1.8, n = 83) were examined in the first week of hospital admission and compared to healthy matched controls (n = 79). Measurements of salivary opiorphin, IgA, IgG, IgM (ELISA technique), and oral hygiene levels (Plaque Control Record index—PCR) were performed. Results: In the AN group, a significantly higher concentration of opiorphin was evidenced (3.1 ± 4.1 ng/ml) compared to the control group (1.1 ± 1.2 ng/ml), (p < 0.001), contrary to IgM, which was significantly lower (311.0 ± 185.3 ng/ml) than in the control group (421.2 ± 168.1 ng/ml), (p < 0.001). There were no significant differences in the levels of IgA and IgG, despite a higher concentration of IgA in the AN group vs. controls (p = 0.14). Spearman analysis revealed a correlation between opiorphin and age (p < 0.05), but also with all immunoglobulins IgA, IgG, IgM (p = 0.006, p < 0.001, p < 0.001). Similarly a correlation was found between PCR index and immunoglobulins IgG, IgM (respectively p = 0.028, p < 0.001), and between body mass, BMI, IBW% and IgA, IgM (all p < 0.05). Conclusions: In the acute phase of AN, salivary changes in opiorphin and immunoglobulins related to dental plaque suggest an essential role in oral health balance. Changes related to AN may affect the anti-inflammatory and analgesic components of saliva and suggest their use as neurobiological markers in severe malnutrition. Plain English summary: The orofacial region is affected by various inflammatory and autoimmune conditions, which might translate into general and regional changes. Saliva is one of the biological fluids where biomarkers of the aforementioned conditions, including sensitivity to pain, could be detected. It is also noteworthy that anorexia nervosa (AN) and malnutrition may change the saliva's analgesic or immune content, but this scientific area is still not satisfactorily explored. The present work related to analgesic (opiorphin peptide) and anti-infectious agents (immunoglobulins Ig A, IgG, IgM) in said body fluid among 83 adolescent patients with severe AN compared to 79 healthy controls. In addition, oral hygiene levels were assessed in the oral cavity via the Plaque Control Record index (PCR). In the AN group, the concentration of opiorphin was significantly higher as compared to the control group, in contrast to IgM, which was significantly lower than in the control group. There were no notable differences in the levels of IgA and IgG between groups, despite a slightly higher concentrations of IgA in the AN group. A correlation was found between opiorphin and all immunoglobulins. A similar correlation was found between PCR index and all immunoglobulins.The present work shows how analgesic opiorphin depends on the oral inflammatory status. This might be a direction for further investigating the immune alterations in patients with AN-related malnutrition. Inclusion of AN patients in intensive oral hygiene care may also be considered. [ABSTRACT FROM AUTHOR]

Various opinions have been suggested regarding non suicidal self-injury (NSSI) and pain relationship. Opiorphin is a recently found peptide that inhibits enkephaline-catabolizing enzymes. Analgesia caused by opiorphine has been demonstrated in animal experiments. No studies have examined the relationship between opiorphin and pain sensation until today. We aimed to investigate opiorphine and pain threshold among self-injuring adolescents. Adolescents aged 14–18 years were included in the study. The NSSI group consisted of 37 adolescents diagnosed with NSSI according to DSM-V Section 3, and the non-NSSI group consisted of 36 adolescents without any psychiatric disorder. We measured pain threshold with a pressure sensitive algometer device and analyzed saliva opiorphin levels by ELISA method. Mediation analysis was performed using Process Macro developed by Hayes. NSSI group had statistically significantly higher pain threshold and opiorphin levels than the non-NSSI group. There was a positive correlation between pain threshold values and opiorphin levels in the NSSI group. Also, a positive correlation between opiorphin levels and total cutting episode number was found. We searched for a probable relationship of pain threshold with episode number of each type of NSSI act. Accordingly, a positive correlation with two major act and a negative correlation with two minor act was shown. The opiorphine was found to be a mediator variable in the relationship between the pain threshold and the cutting number. The relationship between opiorphin, pain threshold and cutting number and their mediating effects with each other may highlight the pain-based biological origins of NSSI. • Adolescents with NSSI have higher pain threshold than non-NSSI adolescents. • Adolescents with NSSI have higher saliva opiorphin levels than non-NSSI adolescents. • There is positive correlation between pain threshold and saliva opiorphin levels. • There is positive correlation between pain threshold and self-cutting episodes. • There is positive correlation between self-cutting episodes and opiorphin levels. [ABSTRACT FROM AUTHOR]

Opiorphin (Oph) is a naturally produced endogenous peptide with a strong analgesic effect, superior to that of morphine, and without the severe side effects that morphine and morphine-like drugs exert. However, despite its strong therapeutic potential, the short duration of action, probably due to its low chemical stability and rapid degradation by the peptidases in the bloodstream, represents a serious obstacle to the Oph use into clinical practice. In this work a novel approach to construct Oph-loaded particles as a platform for its delivery has been developed. Gel beads loaded with Oph were synthesized from alginate, a naturally occurring biodegradable anionic polysaccharide, and coated with polyelectrolyte multilayers (from natural polyelectrolytes (chitosan and hyaluronic acid) and synthetic polyelectrolytes (poly(allylamine hydrochloride) and poly(styrene sulfonate)) or hybrid polyelectrolyte-graphene oxide multilayers. All coated Oph-loaded alginate beads show prolonged drug release compared to the non-coated ones, but the extent of the prolongation depends on the type of the coating. We expect that the successful encapsulation of opiorphin in biodegradable particles will provide an opportunity for the development of adequate drug delivery system with effective and prolonged analgesic activity and will offer a new alternative for pain management.;;

Background: We describe the first studies investigating a role for opiorphin genes (PROL1, SMR3A and SMR3B) in prostate cancer (PrCa). Materials & methods: Databases and PrCa tissue arrays were screened for opiorphin expression. Xenografted tumor growth of human PrCa cells overexpressing PROL1 was compared with controls in nude mice. Modulated gene expression by overexpression of PROL1 was determined by RNA sequencing. Results: PrCa is associated with overexpression of opiorphin genes. Xenografted androgen-sensitive PrCa cells overexpressing PROL1 developed into tumors in castrated male mice (in contrast to parental cells). PROL1 overexpression modulates expression of genes in angiogenesis, steroid and hypoxic response pathways. Conclusions: Opiorphins promote the development of androgen-insensitive PrCa and activate pathways that potentially overcome the hypoxic barrier generated during tumor growth. [ABSTRACT FROM AUTHOR]

Opiorphin (Oph) is a naturally produced endogenous peptide with a strong analgesic effect, superior to that of morphine, and without the severe side effects that morphine and morphine-like drugs exert. However, despite its strong therapeutic potential, the short duration of action, probably due to its low chemical stability and rapid degradation by the peptidases in the bloodstream, represents a serious obstacle to the Oph use into clinical practice. In this work a novel approach to construct Oph-loaded particles as a platform for its delivery has been developed. Gel beads loaded with Oph were synthesized from alginate, a naturally occurring biodegradable anionic polysaccharide, and coated with polyelectrolyte multilayers (from natural polyelectrolytes (chitosan and hyaluronic acid) and synthetic polyelectrolytes (poly(allylamine hydrochloride) and poly(styrene sulfonate)) or hybrid polyelectrolyte-graphene oxide multilayers. All coated Oph-loaded alginate beads show prolonged drug release compared to the non-coated ones, but the extent of the prolongation depends on the type of the coating. We expect that the successful encapsulation of opiorphin in biodegradable particles will provide an opportunity for the development of adequate drug delivery system with effective and prolonged analgesic activity and will offer a new alternative for pain management. [ABSTRACT FROM AUTHOR]

Background and objective: A growing body of literature suggests modulated expression of members of the opiorphin family of genes (PROL1, SMR3A and SMR3B) is associated with cancer. Recently, overexpression of PROL1 was shown to be associated with prostate cancer, with evidence of a role in overcoming the hypoxic barrier that develops as tumors grow. The primary goal of the present studies was to support and expand evidence for a role of PROL1 in the development and progression of prostate cancer. Material and methods: We engineered knock-out of the opiorphin gene, PROL1, in LNCaP, an androgen-sensitive, human prostate cancer derived, cell-line. Using xenograft assays, we compared the ability of injected LNCaP PROL1 knock-out cell-lines to develop tumors in both castrated and intact male mice with the parental LNCaP and LNCaP PROL1 overexpressing cell-lines. We used RNAseq to compare global gene expression between the parental and LNCaP PROL1 knock-out cell-lines. Wound closure and 3D spheroid invasion assays were used to compare cell motility and migration between parental LNCaP cells and LNCaP cells overexpressing of PROL1. Results: The present studies demonstrate that LNCaP cell-lines with consisitutive knock-out of PROL1 fail to develop tumors when injected into both castrated and intact male mice. Using RNAseq to compare global gene expression between the parental and LNCaP PROL1 knock-out cell-lines, we confirmed a role for PROL1 in regulating molecular pathways associated with angiogenesis and tumor blood supply, and also identified a potential role in pathways related to cell motility and migration. Through the use of wound closure and 3D spheroid invasion assays, we confirmed that overexpression of PROL1 in LNCaP cells leads to greater cell motility and migration compared to parental cells, suggesting that PROL1 overexpression results in a more invasive phenotype. Conclusion: Overall, our studies add to the growing body of evidence that opiorphin-encoding genes play a role in cancer development and progression. PROL1 is essential for establishment and growth of tumors in mice injected with LNCaP cells, and we provide evidence that PROL1 has a possible role in progression towards a more invasive, metastatic and castration resistant prostate cancer (PrCa).

Abstract Background The objective of this study was to compare the changes in the electroencephalogram (EEG) in response to noxious stimuli with tail flick and hot plate responses of rats administered opiorphin. Methods Female Sprague -Dawley rats (n = 8 per group) randomly received intravenous (IV) injection of morphine (1 mg/kg,) or opiorphin (2 mg/kg,) or saline (0.5 ml,) in each of the three testing methods (EEG, tail flick and hot plate). Each type of test (n = 24 per test) was conducted in different population of rats on separate occasions. The tail flick and hot plate latencies were recorded until 5 min after test drug administration to conscious rats. The EEG was recorded in anaesthetised rats subjected to noxious thermal and electrical stimuli after test drug administration. At the end of 5 min in each of the testing methods rats were administered naloxone subcutaneously (SC) (1 mg/kg) and the test procedure was repeated. Results There was no significant increase in the median frequency and spectral edge frequency (F50 & F95) of EEG, indicators of nociception, of morphine and opiorphin groups after noxious stimulation. Noxious stimuli caused a significant increase in both F50 and F95 of the saline group. An injection of naloxone significantly increased the F50, thus blocking the action of both opiorphin and morphine. There was a significant increase in the tail flick latency after administration of opiorphin and morphine as compared to the baseline values. Rats of morphine group spent significantly longer on the hot plate when compared to those of the opiorphin and saline groups. There was no significant difference in the hot plate latencies of opiorphin and saline groups. Conclusion The results of this study suggest that the analgesic effect of opiorphin occurs at the spinal level and it is not as effective as morphine at supraspinal level. It may be due to rapid degradation of opiorphin or limited ability of opiorphin to cross the blood brain barrier or a higher dose of opiorphin is required for its action in the brain. Pharmacokinetic/pharmacodynamics studies along with in vivo penetration of opiorphin in the cerebrospinal fluid are required for further evaluation of opiorphin analgesia.

Objectives: Opiorphin is a physiological inhibitor of peptidases inactivating endogenous opioids displaying strong analgesic properties without undesirable side effects, antidepressant properties or hormonal dependency. It might therefore play an important role in patients with painful diseases related to neuro-hormonal dysregulation of the nervous system, affecting saliva secretion and composition such as anorexia nervosa (AN). The main objective aim of this study was to compare the level of opiorphin in saliva of patients with AN to matched subjects free of eating disorders. Methods: A case–control clinical trial was conducted in 68 AN patients and 43 healthy matched control subjects. Depression symptoms were assessed with the self-scored questionnaire Beck Depression Inventory (BDI) and salivary samples were taken during the acute stage of AN (BMI <15 kg/m2) for measuring opiorphin. Opiorphin levels were measured with a quantitative assay using a commercial immunoenzymatic Elisa kit (cat no. EH1927, Wuchan, Hubei, China). Results: No statistically significant difference was found in salivary opiorphin levels between the AN and control groups, (P = 0.499, Mann–Whitney U-test). Positive correlations to duration of the disease, BDI and bodyweight in AN patients were evidenced. Conclusions: Measurement of salivary opiorphin levels cannot be used as a marker of AN but may allow new perspectives in monitoring AN in its early stages. [ABSTRACT FROM AUTHOR]

Objectives: Opiorphin is a salivary peptide with analgesic and antidepressant properties. Its relationship with the hypothalamic-pituitary-adrenal, autonomic nervous and immune systems may provide understanding of chronic stress, especially in anorexia nervosa (AN). This study investigated a possible correlation between opiorphin and stress/immune biomarkers, cortisol, salivary alpha-amylase (sAA) and secretory immunoglobulin A (sIgA), in saliva of patients with restrictive-type AN. Methods: A case–control clinical trial was conducted in 92 AN patients (+75 healthy controls). Unstimulated salivary samples were taken during the acute stage of AN, measurements of cortisol, sAA, sIgA and opiorphin were performed with a quantitative assay (enzyme-linked immunosorbent assay, P < 0.05). Results: AN patients displayed an increase in cortisol (P < 0.001) and sIgA (P < 0.001) but not in sAA (P = 0.279) levels. Distinct correlation between these two parameters and body-weight indexes were observed. Opiorphin levels were neither correlated to stress and immune biomarkers, nor to salivary flow rate. Conclusions: The effect of stress responses can be reliably assessed in saliva in AN patients. The difference between sIgA and cortisol indicate that they can both be used for mental stress assessment in saliva. Modulation of opiorphin by chronic stress was not confirmed. Unchanged sAA indicates a partial adaptation of human organism to severe condition during malnutrition. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the mucoadhesive and regenerative properties of a novel lubricating multimolecular ophthalmic solution (GlicoPro®) extracted from snail mucus and its potential anti-inflammatory and analgesic role in the management of dry eye disease (DED). GlicoPro bio-adhesive efficacy was assessed using a lectin-based assay, and its regenerative properties were studied in a human corneal epithelial cell line. In vitro DED was induced in human corneal tissues; the histology and mRNA expression of selected genes of inflammatory and corneal damage biomarkers were analyzed in DED tissues treated with GlicoPro. A higher percentage of bio-adhesivity was observed in corneal cells treated with GlicoPro than with sodium hyaluronate-based compounds. In the scratch test GlicoPro improved in vitro corneal wound healing. Histo-morphological analysis revealed restoration of cellular organization of the corneal epithelium, microvilli, and mucin network in DED corneal tissues treated with GlicoPro. A significant reduction in inflammatory and ocular damage biomarkers was observed. High-performance liquid chromatography-mass spectrometry analysis identified an endogenous opioid, opiorphin, in the peptide fraction of GlicoPro. In conclusion, GlicoPro induced regeneration and bio-adhesivity in corneal cells; moreover, considering its anti-inflammatory and analgesic properties, this novel ophthalmic lubricating solution may be an innovative approach for the management of DED.

Background: Opiorphin has been reported to show a stronger analgesic effect than morphine without causing side effects brought about by morphine-like drugs. Functional opiorphin analogs have been created to enhance its metabolic stability and preserve its potent analgesic effect., Objective: We conducted a systematic review to summarize all opiorphin analogs and identify those with the strongest metabolic stability and antinociceptive effect., Methods: From a total of 122 articles, 11 made it to the quantitative synthesis phase. The included articles were categorized into the type of modifications used to improve the metabolic stability of the peptide, metabolism and toxicity profile, drug absorption and in vitro cytotoxicity, anti-nociceptive effect, the opiorphin analogs' administration in animals or humans, and the type of the test used to test the antinociceptive effect., Results: The substitution of natural amino acid with a non-natural amino acid, side-chain modifications, or D-aminoacid substitution were the most used type of peptide modification to create opiorphin analogs. STR-324 and PEGylated liposomes loaded with opiorphin showed the best metabolism and toxicity performance. [C]-[(CH 2 ) 6 ]-QRF-[S-O-(CH 2 ) 8 ]-R showed high stability in human plasma and stronger inhibitory potency. YQRFSR and PEGylated liposomes loaded with opiorphin showed a stronger antinociceptive effect than the parent opiorphin or morphine, with an analgesic effect of PEGylated liposomes lasting more than 50%. Intravenous administration was the preferred method of opiorphin analog administration, and different tests were used to test the antinociceptive effect., Conclusion: This paper presents the first systematic review discussing opiorphin and opiorphin analogs and identifies the most promising candidates for future research., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Highlights • The relationship between salivary opiorphin and orofacial pains is not fully understood. • Salivary opiorphin levels were investigated in irreversible pulpitis and apical periodontitis related dental pain. • Opiorphin levels found to be higher in the presence of dental pain. • Opiorphin levels found to be higher in irreversible pulpitis compared to apical periodontitis. • A strong correlation was observed between the reported level of pain and salivary opiorphin level. Abstract Objectives Opiorphin is a recently discovered peptide shown to inhibit the enkephalin-degrading enzymes and prolong the effects of enkephalins. Although opiorphin is found in high concentrations in saliva, the relationship between salivary opiorphin and orofacial pains is not yet fully understood. We aimed to determine salivary opiorphin concentrations in dental pain related to symptomatic irreversible pulpitis (SIP), and symptomatic apical periodontitis (SAP). Design 39 patients participated in this study. The participants were categorized into SIP and SAP based on their diagnosis. All the patients were treated with root canal treatment. Saliva specimens were collected, and pain levels were recorded at pre-treatment, 7 days post-treatment and 30 days post-treatment. Saliva opiorphin levels were measured using a commercially available ELISA kit. Pre-treatment and post-treatment opiorphin levels were evaluated using repeated measures ANOVA. Correlations between VAS scores, opiorphin levels and age were evaluated using Spearman's Rank Correlation. Results The average saliva opiorphin level pre-treatment, 7 days post-treatment and 30 days post-treatment were 31.28 ± 7.10 ng/ml, 20.41 ± 2.67 ng/ml and 18.61 ± 2.05 ng/ml respectively. Significantly higher pre-treatment opiorphin levels were observed in the SIP group compared to the SAP group. A strong correlation was observed between the pre-treatment pain levels and the saliva opiorphin concentrations. Conclusions Our findings indicate that saliva opiorphin levels increase in inflammation related dental pain. The level of salivary opiorphin is strongly correlated with the reported level of pain. The extent of the inflammation (pulpal vs. periodontal) also affects the opiorphin level. [ABSTRACT FROM AUTHOR]

Background: the pharmacological treatment and/or maintenance of remission in inflammatory bowel diseases (IBDs) is currently one of the biggest challenges in the field of gastroenterology. Method: our aim was the synthesis of homo- and heterodimers of natural enkephalinase inhibitors (opiorphin; sialorphin; spinorphin) and the in vitro characterization of their effect on the degradation of enkephalin by neutral endopeptidase (NEP) and stability in human plasma. We investigated the in vivo heterodimer of Cys containing analogs of sialorphin and spinorphin (peptide X) in a mouse model of colitis. The extent of inflammation was evaluated based on the microscopic score; macroscopic score; ulcer score, colonic wall thickness, colon length and quantification of myeloperoxidase activity. Results: we showed that the homo- and heterodimerization of analogs of sialorphin, spinorphin and opiorphin containing Cys residue at the N-terminal position resulted in dimeric forms which in vitro exhibited higher inhibitory activity against NEP than their parent and monomeric forms. We showed that peptide X was more stable in human plasma than sialorphin and spinorphin. Peptide X exerts potent anti-inflammatory effect in the mouse model of colitis. Conclusion: we suggest that peptide X has the potential to become a valuable template for anti-inflammatory therapeutics for the treatment of gastrointestinal (GI) tract inflammation.

Enkephalins are involved in a number of physiological processes. However, these peptides are quickly degraded by peptidases, e.g. the neutral endopeptidase (NEP). Inhibition of the enzymatic degradation of enkephalins is one of the possible approaches to prolong their activity. Selective inhibitor of NEP, sialorphin, is the attractive lead compound for enkephalins degradation studies. In this work, an alanine scan of sialorphin and a series of its hybrids with opiorphin, synthesised by the solid phase method, were performed. The effect of the peptides on degradation of Met-enkephalin by NEP in vitro was investigated. Molecular modelling technique was used to identify residues responsible for protein-ligand interactions. We showed that substitution of amino acids Gln1, Pro4 and Arg5 of sialorphin for Ala significantly reduced the half-life of Met-enkephalin in the presence of NEP. [Ala3]sialorphin displayed a higher inhibitory potency against NEP than sialorphin. Substitution of His2 for Ala led to a compound which was as active as lead compound. Sialorphin has a structure which hardly tolerates substitution in its sequence at positions 1, 4 and 5. The conversion of His2 for alanine in sialorphin is tolerated very well. The higher inhibitory potency of [Ala3]sialorphin than sialorphin against NEP is caused by removal of the hydrophilic residue (Asn) and a better fit of the peptide to the enzyme-binding pocket. The role of side chains of sialorphin in degradation of enkephalin by NEP has been explored. This study also provides an important SAR information essential for further drug design. [ABSTRACT FROM AUTHOR]

Objectives The NCBI gene database and human-transcriptome database for alternative splicing were used to determine the expression of mRNAs for P-B (SMR3B) and variant form of P-B. The translational product from the former mRNA was identified as the protein named P-B, whereas that from the latter has not yet been elucidated. In the present study, we investigated the expression of P-B and its variant form at the protein level. Design To identify the variant protein of P-B, (1) cationic proteins with a higher isoelectric point in human pooled whole saliva were purified by a two dimensional liquid chromatography; (2) the peptide fragments generated from the in-solution of all proteins digested with trypsin separated and analyzed by MALDI-TOF-MS; and (3) the presence or absence of P-B in individual saliva was examined by 15% SDS-PAGE. Results The peptide sequences (I 37 PPPYSCTPNMNNCSR 52 , C 53 HHHHKRHHYPCNYCFCYPK 72 , R 59 HHYPCNYCFCYPK 72 and H 60 HYPCNYCFCYPK 72 ) present in the variant protein of P-B were identified. The peptide sequence (G 6 PYPPGPLAPPQPFGPGFVPPPPPPPYGPGR 36 ) in P-B (or the variant) and sequence (I 37 PPPPPAPYGPGIFPPPPPQP 57 ) in P-B were identified. The sum of the sequences identified indicated a 91.23% sequence identity for P-B and 79.76% for the variant. There were cases in which P-B existed in individual saliva, but there were cases in which it did not exist in individual saliva. Conclusions The variant protein is produced by excising a non-canonical intron (CC-AC pair) from the 3′-noncoding sequence of the PBII gene. Both P-B and the variant are subject to proteolysis in the oral cavity. [ABSTRACT FROM AUTHOR]

Previous studies proved the effectiveness of an intravenous PEGylated liposomal formulation of opiorphin (1 mg/mL) in protecting the drug from enzymatic degradation, and improving intensity and duration of its painkilling effect. Therefore, considering the advantages of nasal administration, the aim of this work was the development of a liposomal mucoadhesive thermo-sensitive in situ gel for the extended nasal delivery of opiorphin. With this purpose, the potential of a series of combinations of different polymers (i.e. chitosan, hydroxypropylmethylcellulose, Poloxamer, Carbopol) in forming solutions able to rapidly gel at the nasal cavity temperature (34 °C) has been investigated. The best formulations were further characterized for gel strength and mucoadhesion properties. The selected formulation, composed by Poloxamer 407 (26.5%) and Carbopol 934P (1%), showed short gelation time at 34 °C (10 s) and suitable mucoadhesion duration (5.5 h) and strength (27 g/cm 2 ). Due to the low volume administrable via the nasal route, a concentrated liposomal formulation of the peptide (16.5 mg/mL) was developed and loaded in the selected in situ gel formulation. Ex-vivo permeation studies, by excised nasal porcine mucosa, showed that the liposomal hydrogel formulation enabled a sustained and controlled delivery of opiorphin over more than 5 h, and highlighted the role of the liposomal carrier in enhancing up to 6 times permeability coefficient and permeation rate of the peptide through the lipophilic nasal mucosa compared to a free peptide-loaded gel. [ABSTRACT FROM AUTHOR]

Reported results have shown that the pentapeptide opiorphin inhibits oligopeptidases that degrade brain neuropeptides, and has analgesic and antidepressant effects in experimental animals, without either tolerance or dependency after chronic administration. In a previous study we showed that opiorphin has a panicolytic-like effect in the dorsal periaqueductal gray (dPAG) electrical stimulation test (EST), mediated by the μ-opioid receptor (MOR). This study further analyzes the mechanism of opiorphin panicolytic action, using the EST and drug injection inside the dPAG. The obtained results showed that blockade of the 5-HT 1A receptors with WAY-100635 did not change the escape-impairing effect of opiorphin, and combined injection of sub-effective doses of opiorphin and the 5-HT 1A -agonist 8-OH-DPAT did not have a significant anti-escape effect. In contrast, the anti-escape effect of opiorphin was antagonized by pretreatment with the kinin B2 receptor blocker HOE-140, and association of sub-effective doses of opiorphin and bradykinin caused a significant anti-escape effect. The anti-escape effect of bradykinin was not affected by previous administration of WAY-100635. Therefore, the anti-escape effect of opiorphin in the dPAG seems to be mediated by endogenous bradykinin, acting on kinin B2 receptors, which previous results have shown to interact synergistically with MOR in the dPAG to restrain escape in two animal models of panic. Chemical compounds: Opiorphin (PubChem CID: 25195667); WAY100635 maleate salt (PubChem CID: 11957721); 8-OH-DPAT hydrobromide (PubChem CID: 6917794); Bradykinin (PubChem CID: 439201); HOE-140 (Icatibant) (PubChem CID: 6918173). [ABSTRACT FROM AUTHOR]

Objectives: Opiorphin is a pentapeptide isolated from human saliva that suppresses pain from chemically induced inflammation and acute physical pain. Burning mouth syndrome (BMS) is a chronic condition of a burning sensation in the mouth, where no underlying dental or medical cause can be identified. We aimed to measure the level of opiorphin in whole unstimulated (UWS) and stimulated (SWS) saliva of patients with BMS. Materials and methods: Originally developed and validated LC-MS/MS method was used for opiorphin quantification. Samples were obtained from 29 BMS patients and 29 age- and sex-matched controls. Results: The average concentration of opiorphin in UWS and SWS in the BMS group was 8.13 ± 6.45 and 5.82 ± 3.59 ng/ml, respectively. Opiorphin in BMS patients' UWS was significantly higher, compared to the control group ( t = 2.5898; p = 0.0122). SWS opiorphin levels were higher, but not significantly, in BMS patients than in controls. Conclusions: Our results indicate that higher quantities of salivary opiorphin in BMS may be a consequence of chronic pain, but we cannot exclude that they occur as a result of emotional and behavioral imbalances possibly associated with BMS. To our knowledge, this is the first original article measuring opiorphin in a pain disorder. Clinical relevance: Opiorphin may be a measurable biomarker for chronic pain, which could help in objectifying otherwise exclusively a subjective experience. Increased opiorphin could serve as a universal objective indicator of painful conditions. Since opiorphin may also reflect emotional and socio-relational imbalances occurring with BMS, it could as well represent a biomarker for BMS. Knowledge on opiorphin's involvement in pain pathways could contribute to developing new clinical diagnostic methods for BMS. [ABSTRACT FROM AUTHOR]

Objectives: Idiopathic Burning mouth syndrome (iBMS) is a poorly understood affection characterized by persistent pain in the oral cavity without any clinical or biological abnormality. Opiorphin is a natural inhibitor of enkephalin-inactivating ectopeptidases, mainly produced by salivary glands, that has demonstrated analgesic properties. The objective of the present case-control study was to test the hypothesis of a decrease in opiorphin levels in iBMS patients. Materials and methods: Twenty-one iBMS patients and 21 matched controls subjects were included between 2011 and 2013. Submandibular and sublingual salivary, blood, and urinary opiorphin levels of iBMS patients were compared to controls. Results: Results are expressed as mean values ± SD and compared using the Wilcoxon Signed Rank test. Correlations were analyzed with Spearman coefficient. The level of significance was fixed at p < 0.05. Opiorphin levels in iBMS and controls were respectively (in ng/ml) in basal saliva: 37.8 ± 42.5 and 67.6 ± 188.9 ( p = NS); stimulated saliva: 28.8 ± 25.3 and 31.1 ± 29.1 ( p = NS); blood: 4.6 ± 5.4 and 1.9 ± 1.4 ( p < 0.05); and urines: 68.5 ± 259.8 and 8.9 ± 6.2 ( p = NS). Clinical relevance: In conclusion, the lack of significative difference in salivary opiorphin levels between iBMS and controls does not favor a direct local role for opiorphin in the etiopathogeny of iBMS. However, higher blood opiorphin levels may reflect a systemic dysregulation in iBMS. Trial registration NCT02686359 [ABSTRACT FROM AUTHOR]

This is the study on the effect of opiorphin, sialorphin and their analogs on antitumor activity. We demonstrated that conjugation of opiorphin and sialorphin with a proapoptotic, antimicrobial peptide klak (klaklakklaklak) led to compounds (opio-klak and sialo-klak) that were cytotoxic against cancer cells (LN18, PC3, A549, HCT116 and B10-F16) in the MTT test. The conjugated analogs were designed to increase the effectiveness of the peptide. The opio-klak derivative was the most effective in the in vitro assays and led to a decrease in viability of cancer cells over time as compared with that of untreated controls. In contrast, treatment with either the untargeted klak peptide or opiorphin as a negative control led to a negligible loss in viability. Antitumor effect of the opio-klak was also observed in vivo in murine melanoma tumor-bearing mice. Cessation of peptide administration resulted in tumor regrowth. Our results are seemingly valuable for the development of opiorphin analogs with potential clinical applications. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Reported evidence indicates that endogenous opioid peptides regulate the expression of escape behavior in rats, a panic-related defensive response, through μ-opioid receptors (MORs) in the dorsal periaqueductal gray (dPAG). These peptides are rapidly catabolized by degrading enzymes, including neutral endopeptidase (NEP) and aminopeptidase N (APN). Opiorphin is a peptide inhibitor of both NEP and APN and potentiates the action of endogenous enkephalins. This study evaluated the effects of intravenous and intra-dPAG administration of opiorphin on escape responses in the elevated T-maze and in a dPAG electrical stimulation test in rats. We also evaluated the involvement of MORs in the effects of opiorphin using the selective MOR antagonist CTOP. A dose of 2.0 mg/kg, i.v., of opiorphin impaired escape performance in both tests. Similar effects were observed with intra-dPAG administration of 5.0 nmol of opiorphin. Local pretreatment with 1.0 nmol CTOP antagonized the anti-escape effects of intra-dPAG opiorphin in both tests, as well as the effect of systemically administered opiorphin (2.0 mg/kg, i.v.) in the electrical stimulation test. These results indicate that opiorphin has an antipanic-like effect that is mediated by MORs in the dPAG. They may open new perspectives for the development of opiorphin analogues with greater bioavailability and physicochemical characteristics in the pursuit of new medications for the treatment of panic disorder. [ABSTRACT FROM AUTHOR]

Opioid peptides are potent analgesics with therapeutic potential in the treatment of acute and chronic pain. Their efficacy is limited by peptidases (enkephalinases). Opiorphin pentapeptide (QRFSR) is the first characterized human endogenous inhibitor of enkephalinases. The peptide is able to increase the binding and affinity of endogenous opiates to mu opioid receptors; thus, the mechanism of opiorphin may provide a new therapeutic approach in pain management. The analgesic effect of opiorphin was proven in several earlier published in vitro and in vivo studies. Our aim was to test the transfer of opiorphin through a blood-brain barrier model for the first time. The flux of opiorphin was tested on a blood-brain barrier culture model consisting of rat brain endothelial, glial and pericyte cells. Brain endothelial cells in this triple co-culture model form tight monolayers characterized by transendothelial electrical resistance measurement. Relative quantity of the peptide was estimated by mass spectrometry. The transfer of opiorphin through the blood-brain barrier model was estimated to be ∼3%, whereas the permeability coefficient was 0.53 ± 1.36 × 10 −6 cm/s ( n = 4). We also observed rapid conversion of N-terminal glutamine into pyroglutamic acid during the transfer experiments. Our results indicate that opiorphin crosses cultured brain endothelial cells in the absence of serum factors in a significant amount. This is in agreement with previous in vivo data showing potentiation of enkephalin-mediated antinociception. We suggest that opiorphin may have a potential as a centrally acting novel drug to treat pain. [ABSTRACT FROM AUTHOR]

Highlights: [•] Opiorphin induced an increase of mean arterial pressure in conscious rats. [•] Opiorphin evaluated the level of angiotensin II in serum. [•] Hypertension induced by opiorphin was inhibited by valsartan or captopril. [•] Opiorphin reversed hypotension induced by hypoxia. [Copyright &y& Elsevier]

Background: In dentistry, needles are the most feared and anxiety-causing tool, making anesthetic injection a worrying practice for patients., Aim: To evaluate the effect of intraosseous anesthesia (IOA) and needle-free dental anesthesia (NFA) on pain levels in systemically healthy 8-10-year-old patients., Patients and Methods: Twenty patients aged 8-10 years were included in this cross-over study. Specifically, the pain was measured by Wong Baker, pulse rate (PR), and salivary opiorphin levels (SOL). In addition, the Frankl Behavioral scale was used to measure behaviors and face, legs, activity, cry, consolability (FLACC) was utilized to measure pain and discomfort. To determine the patients' anxiety levels Spielberger State-Trait Anxiety Scale (SSAS-SAAS) was used. The Friedman and Wilcoxon signed-rank tests were used. P < 0.05 was considered significant., Results: According to FLACC scores, IOA and NFA exhibited significantly pain alteration patterns in during local and topical anesthesia, respectively (p = 0.004, 0.001; P < 0.01). Also, only NFA showed significantly decreased SOL values in 5- and 10-min after local anesthesia periods compared to the before levels (p = 0.004, P = 0.001; P < 0.01)., Conclusion: Patients feel similar pain perceptions during local anesthesia application in both injection systems. According to the SOL values, NFA may provide more higher anesthetic efficiency than IOA., Competing Interests: None