Immunoreactive leukotrienes in nettle plants (Urtica urens)

Anti-inflammatory activities of arthropod peptides: a systematic review

Peptides obtained from different animal species have gained importance recently due to research that aims to develop biopharmaceuticals with therapeutic potential. In this sense, arthropod venoms have drawn attention, not only because of their toxicity but mainly for the search for molecules with various bioactivities, including anti-inflammatory activity. The purpose of the present study is to gather data available in the literature on new peptides derived from arthropod species with anti-inflammatory potential. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Studies on peptides from arthropods that display anti-inflammatory activity were retrieved from PubMed, Scopus, Web of Science, and Google Scholar databases. The bibliographic research started in 2020 and searched papers without a limit on the publication date. The articles were analyzed using a search string containing the following terms: "Peptides" and "Anti-inflammatory", in combinations such as "Ant", "Bee", "Wasp", "Crab", "Shrimp", "Scorpion", "Spider", "Tick" and "Centipedes". Besides, a search was carried out in the databases with the terms: "Peptides", "Antitumor", or "Anticancer", and "Arthropods". Articles that met the inclusion and exclusion criteria totalized 171, and these served for data extraction. Additionally, the present review included anti-inflammatory peptides with anticancer properties. Peptides with confirmed anti-inflammatory activity were from insects (ants, bees, and wasps), crustaceans (shrimp and crabs), arachnids (scorpions, spiders, and ticks), and centipedes. These arthropod peptides act mainly by decreasing pro-inflammatory cytokines as analyzed in vitro and in vivo. Some showed significant antineoplastic activity, working in essential cellular pathways against malignant neoplasms.

Distribution, Ecology, Chemistry and Toxicology of Plant Stinging Hairs

Plant stinging hairs have fascinated humans for time immemorial. True stinging hairs are highly specialized plant structures that are able to inject a physiologically active liquid into the skin and can be differentiated from irritant hairs (causing mechanical damage only). Stinging hairs can be classified into two basic types: Urtica-type stinging hairs with the classical "hypodermic syringe" mechanism expelling only liquid, and Tragia-type stinging hairs expelling a liquid together with a sharp crystal. In total, there are some 650 plant species with stinging hairs across five remotely related plant families (i.e., belonging to different plant orders). The family Urticaceae (order Rosales) includes a total of ca. 150 stinging representatives, amongst them the well-known stinging nettles (genus Urtica). There are also some 200 stinging species in Loasaceae (order Cornales), ca. 250 stinging species in Euphorbiaceae (order Malphigiales), a handful of species in Namaceae (order Boraginales), and one in Caricaceae (order Brassicales). Stinging hairs are commonly found on most aerial parts of the plants, especially the stem and leaves, but sometimes also on flowers and fruits. The ecological role of stinging hairs in plants seems to be essentially defense against mammalian herbivores, while they appear to be essentially inefficient against invertebrate pests. Stinging plants are therefore frequent pasture weeds across different taxa and geographical zones. Stinging hairs are usually combined with additional chemical and/or mechanical defenses in plants and are not a standalone mechanism. The physiological effects of stinging hairs on humans vary widely between stinging plants and range from a slight itch, skin rash (urticaria), and oedema to sharp pain and even serious neurological disorders such as neuropathy. Numerous studies have attempted to elucidate the chemical basis of the physiological effects. Since the middle of the 20th century, neurotransmitters (acetylcholine, histamine, serotonin) have been repeatedly detected in stinging hairs of Urticaceae, but recent analyses of Loasaceae stinging hair fluids revealed high variability in their composition and content of neurotransmitters. These substances can explain some of the physiological effects of stinging hairs, but fail to completely explain neuropathic effects, pointing to some yet unidentified neurotoxin. Inorganic ions (e.g., potassium) are detected in stinging hairs and could have synergistic effects. Very recently, ultrastable miniproteins dubbed "gympietides" have been reported from two species of Dendrocnide, arguably the most violently stinging plant. Gympietides are shown to be highly neurotoxic, providing a convincing explanation for Dendrocnide toxicity. For the roughly 648 remaining stinging plant species, similarly convincing data on toxicity are still lacking.

Patient consensus on mode of use of nettle sting for musculoskeletal pain

BACKGROUND

Many patients with musculoskeletal pain prefer topical treatments because they consider them safer than oral drugs. There is a long history of topical use of nettle sting for pain, but no standard method of application. Our objective was to develop a consensus of the experiences of nettle sting users.

METHODS

A consensus study was conducted using the expert panel method. Media articles resulted in 16 responses and nine users attended a meeting. Participants first responded to questions on how they chose the leaf and how they applied the nettle sting; then discussed their individual responses; and finally responded once more to the same questions. Consensus was defined as 70% agreement. Participants' consensus was developed from the responses and discussions, and modified in response to repeated feedback and to comments of seven other nettle users.

RESULTS

Consensus was present initially on three questions: 'Important to feel a good strong sting', 'Immediately sting the area again' and 'Sting once a day'. Opinions on the method and site of application, and format of a course of treatment varied. This range of advice was incorporated into a treatment consensus document acceptable to all users in the study.

CONCLUSIONS

The users' consensus document for the use of nettle sting for musculoskeletal pain is published for anyone who wishes to use this self-care approach to treating their pain. The user's consensus document represents an essential step in undertaking further research into the effectiveness of nettle sting as a treatment for musculoskeletal pain.

The role of multifunctional M1 metallopeptidases in cell cycle progression

BACKGROUND

Metallopeptidases of the M1 family are found in all phyla (except viruses) and are important in the cell cycle and normal growth and development. M1s often have spatiotemporal expression patterns which allow for strict regulation of activity. Mutations in the genes encoding M1s result in disease and are often lethal. This family of zinc metallopeptidases all share the catalytic region containing a signature amino acid exopeptidase (GXMXN) and a zinc binding (HEXXH[18X]E) motif. In addition, M1 aminopeptidases often also contain additional membrane association and/or protein interaction motifs. These protein interaction domains may function independently of M1 enzymatic activity and can contribute to multifunctionality of the proteins.

SCOPE

A brief review of M1 metalloproteases in plants and animals and their roles in the cell cycle is presented. In animals, human puromycin-sensitive aminopeptidase (PSA) acts during mitosis and perhaps meiosis, while the insect homologue puromycin-sensitive aminopeptidase (PAM-1) is required for meiotic and mitotic exit; the remaining human M1 family members appear to play a direct or indirect role in mitosis/cell proliferation. In plants, meiotic prophase aminopeptidase 1 (MPA1) is essential for the first steps in meiosis, and aminopeptidase M1 (APM1) appears to be important in mitosis and cell division.

CONCLUSIONS

M1 metalloprotease activity in the cell cycle is conserved across phyla. The activities of the multifunctional M1s, processing small peptides and peptide hormones and contributing to protein trafficking and signal transduction processes, either directly or indirectly impact on the cell cycle. Identification of peptide substrates and interacting protein partners is required to understand M1 function in fertility and normal growth and development in plants.

Urtica ferox neuropathy

A 21-year-old student developed an acute, symmetrical, predominantly motor polyneuropathy within 48 h of walking through a patch of nettles (Urtica ferox). Two companions had similar but less severe symptoms. Nerve conduction studies demonstrated markedly reduced compound muscle action potentials and prolonged distal motor latencies. Recovery occurred over a period of a few weeks. This case demonstrates that cutaneous exposure to Urtica ferox can cause an acute polyneuropathy and that its stinging hairs contain an unidentified neurotoxin.

Bioinformatic and enzymatic characterization of the MAPEG superfamily

The membrane associated proteins in eicosanoid and glutathione metabolism (MAPEG) superfamily includes structurally related membrane proteins with diverse functions of widespread origin. A total of 136 proteins belonging to the MAPEG superfamily were found in database and genome screenings. The members were found in prokaryotes and eukaryotes, but not in any archaeal organism. Multiple sequence alignments and calculations of evolutionary trees revealed a clear subdivision of the eukaryotic MAPEG members, corresponding to the six families of microsomal glutathione transferases (MGST) 1, 2 and 3, leukotriene C4 synthase (LTC4), 5-lipoxygenase activating protein (FLAP), and prostaglandin E synthase. Prokaryotes contain at least two distinct potential ancestral subfamilies, of which one is unique, whereas the other most closely resembles enzymes that belong to the MGST2/FLAP/LTC4 synthase families. The insect members are most similar to MGST1/prostaglandin E synthase. With the new data available, we observe that fish enzymes are present in all six families, showing an early origin for MAPEG family differentiation. Thus, the evolutionary origins and relationships of the MAPEG superfamily can be defined, including distinct sequence patterns characteristic for each of the subfamilies. We have further investigated and functionally characterized representative gene products from Escherichia coli, Synechocystis sp., Arabidopsis thaliana and Drosophila melanogaster, and the fish liver enzyme, purified from pike (Esox lucius). Protein overexpression and enzyme activity analysis demonstrated that all proteins catalyzed the conjugation of 1-chloro-2,4-dinitrobenzene with reduced glutathione. The E. coli protein displayed glutathione transferase activity of 0.11 micromol.min(-1).mg(-1) in the membrane fraction from bacteria overexpressing the protein. Partial purification of the Synechocystis sp. protein yielded an enzyme of the expected molecular mass and an N-terminal amino acid sequence that was at least 50% pure, with a specific activity towards 1-chloro-2,4-dinitrobenzene of 11 micromol.min(-1).mg(-1). Yeast microsomes expressing the Arabidopsis enzyme showed an activity of 0.02 micromol.min(-1).mg(-1), whereas the Drosophila enzyme expressed in E. coli was highly active at 3.6 micromol.min(-1).mg(-1). The purified pike enzyme is the most active MGST described so far with a specific activity of 285 micromol.min(-1).mg(-1). Drosophila and pike enzymes also displayed glutathione peroxidase activity towards cumene hydroperoxide (0.4 and 2.2 micromol.min(-1).mg(-1), respectively). Glutathione transferase activity can thus be regarded as a common denominator for a majority of MAPEG members throughout the kingdoms of life whereas glutathione peroxidase activity occurs in representatives from the MGST1, 2 and 3 and PGES subfamilies.

Histamine mediates the pro-inflammatory effect of latex of Calotropis procera in rats

INTRODUCTION

Calotropis procera is known to produce contact dermatitis and the latex of this plant produces intense inflammation when injected locally. However, the precise mode of its pro-inflammatory effect is not known. In present study we have pharmacologically characterized the inflammation induced by latex of C. procera in a rat paw edema model and determined the role of histamine in latex-induced inflammation.

METHODS

Inflammation was induced in the hind paw of rats by injecting different doses of dried latex (DL) of C. procera. The inhibitory effect of phenylbutazone, dexamethasone, celecoxib, cyproheptadine, chlorpheniramine and compound 48/80 on edema volume was evaluated and compared with that against carrageenan. The histamine content of DL was measured fluorometrically.

RESULTS

DL produced dose-dependent inflammation of the rat paw. Cyproheptadine and chlorpheniramine effectively inhibited DL-induced inflammation (90%; p < 0.01), while anti-inflammatory drugs phenylbutazone, dexamethasone and celecoxib were more effective against carrageenan-induced inflammation. Depletion of mast cell histamine by compound 48/80 produced a significant decrease in DL-induced inflammation as compared with carrageenan (500% versus 25%). DL was also found to contain about 6 microg/g of histamine.

CONCLUSIONS

Thus, our study shows that the biogenic amines play a significant role in C. procera latex-induced inflammation and antihistaminic drugs could be effectively used to inhibit inflammatory response elicited by exposure to latex.

Complementary and alternative medicine in children with asthma

BACKGROUND

The popularity of complementary and alternative medicine (CAM), particularly for chronic conditions such as asthma, is growing rapidly, but little is known about its use in asthmatic children.

OBJECTIVE

To evaluate the extent, characteristics, and possible predictors of CAM use in a group of Turkish children with asthma.

METHODS

The parents of asthmatic children were invited to participate in a questionnaire-based survey of 13 worldwide and 5 local methods of CAM. Current asthma treatment, asthma exacerbations, emergency admittances and hospitalizations due to exacerbations, and parental education levels were investigated as predictors that influenced the use of CAM.

RESULTS

Of the 304 asthmatic children (mean +/- SEM age, 10.5 +/- 0.2 years; range, 1-16 years), 49% (n = 150) had used some form of CAM previously, and 38% had used CAM within the previous year. The most popular forms of CAM were quail eggs (79%), herbal medicine (31%), Turkish wild honey (26%), speleotherapy (5%), and royal jelly (5%). The respondents learned about CAM through friends (61%), relatives (25%), the media (9%), and physicians (6%). Age, sex, and mother's and father's education levels were insignificant between the groups that used and did not use CAM (P = 0.40, P = 0.18, P = 0.15, and P = 0.09, respectively). The use of regular asthma treatment, the use of inhaled corticosteroids, asthma exacerbations, emergency admittances, and treatment score were significantly high in the CAM group (P = 0.006, P = 0.03, P = 0.008, P = 0.02, and P = 0.02, respectively). A significantly high percentage of respondents in the CAM group had considered using CAM for their child's asthma in the future (P = 0.001).

CONCLUSIONS

Asthmatic children in whom the disease is not well controlled are more likely to use CAM as complementary therapy.

Medium-chain dehydrogenases/reductases (MDR). Family characterizations including genome comparisons and active site modeling

Completed eukaryotic genomes were screened for medium-chain dehydrogenases/reductases (MDR). In the human genome, 23 MDR forms were found, a number that probably will increase, because the genome is not yet fully interpreted. Partial sequences already indicate that at least three further members exist. Within the MDR superfamily, at least eight families were distinguished. Three families are formed by dimeric alcohol dehydrogenases (ADH; originally detected in animals/plants), cinnamyl alcohol dehydrogenases (originally detected in plants) and tetrameric alcohol dehydrogenases (originally detected in yeast). Three further families are centred around forms initially detected as mitochondrial respiratory function proteins, acetyl-CoA reductases of fatty acid synthases, and leukotriene B4 dehydrogenases. The two remaining families with polyol dehydrogenases (originally detected as sorbitol dehydrogenase) and quinone reductases (originally detected as zeta-crystallin) are also distinct but with variable sequences. The most abundant families in the human genome are the dimeric ADH forms and the quinone oxidoreductases. The eukaryotic patterns are different from those of Escherichia coli. The different families were further evaluated by molecular modelling of their active sites as to geometry, hydrophobicity and volume of substrate-binding pockets. Finally, sequence patterns were derived that are diagnostic for the different families and can be used in genome annotations.

Eicosanoids: the molecules of evolution

The molecules of evolution constitute a response system linking the environment to the internal machinery of cells and are key factors in evolutionary disorders. They orchestrate such mechanisms of evolution as replication and reproduction, variation, inheritance, natural selection, heterochrony, neoteny, aging, recapitulation, metamorphosis, homology, paradox, and extinction. Eicosanoids fulfill these criteria.

Study of two plants used in traditional medicine in Zimbabwe for skin problems and rheumatism: Dioscorea sylvatica and Urginea altissima

Two plants used in Zimbabwean traditional medicine, Dioscorea sylvatica (Dioscoreaceae) and Urginea altissima (Liliaceae), produce mild inflammation and itching when rubbed on the skin. Investigations of the causes of these cutaneous reactions showed that raphides of calcium oxalate are, at least in part, responsible for the effects. Histamine could not be detected.

Randomized controlled trial of nettle sting for treatment of base-of-thumb pain

There are numerous published references to use of nettle sting for arthritis pain but no randomized controlled trials have been reported. We conducted a randomized controlled double-blind crossover study in 27 patients with osteoarthritic pain at the base of the thumb or index finger. Patients applied stinging nettle leaf (Urtica dioica) daily for one week to the painful area. The effect of this treatment was compared with that of placebo, white deadnettle leaf (Lamium album), for one week after a five-week washout period. Observations of pain and disability were recorded for the twelve weeks of the study. After one week's treatment with nettle sting, score reductions on both visual analogue scale (pain) and health assessment questionnaire (disability) were significantly greater than with placebo (P = 0.026 and P = 0.0027).

Nettle sting of Urtica dioica for joint pain--an exploratory study of this complementary therapy

This exploratory study aims to explore the present use of the common stinging nettle to treat joint pain. Eighteen self-selected patients using the nettle sting of Urtica dioica were interviewed. Information regarding patients' use of nettle therapy was elicited, in particular mode of application, dosage and effects. All except one respondent were sure that netles had been very helpful and several considered themselves cured. No observed side effects were reported, except a transient urticarial rash. This exploratory study suggests nettle sting is a useful, safe and cheap therapy which needs further study. A randomized controlled trial is planned in collaboration with a rheumatology specialist.