Anti-inflammatory effect of Natterins, the major toxins from the Thalassophryne nattereri fish venom is dependent on TLR4/MyD88/PI3K signaling pathway

Inflammatory role of S100A8/A9 in the central nervous system non-neoplastic diseases

S100A8 (MRP8) and S100A9 (MRP14) are critical mediators of the inflammatory response; they are usually present as heterodimers because of the instability of homodimers. Studies have demonstrated that S100A8/A9 expression is significantly upregulated in several central nervous system (CNS) diseases. S100A8/A9 is actively released by neutrophils and monocytes; it plays a key role in regulating the inflammatory response by stimulating leukocyte recruitment and inducing cytokine secretion during inflammation. Additionally, S100A8/A9 can be used as a diagnostic biomarker for several CNS diseases and as a predictor of therapeutic response to inflammation-related diseases. In this work, we reviewed our current understanding of S100A8/A9 overexpression in inflammation and its importance in the development and progression of CNS inflammatory diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and stroke, and the functional roles and therapeutic applications of S100A8/A9 in these diseases. Finally, we discussed the current barriers and future research directions of S100A8/A9 in CNS diseases.

Combination of Merocel sponge with Lipopolysaccharide to establish rat rhinosinusitis model

OBJECTIVE

The study aimed to investigate the feasibility of establishing rhinosinusitis model in rats combinated with Lipopolysaccharide (LPS) and merocel sponge.

METHODS

SD (Sprague Dawley) rats that underwent nasal obstruction using Merocel sponge packing, rats with LPS instillation alone, and rats with both nasal obstruction and LPS instillation were used to establish rat models of rhinosinusitis. After the models were established, the nasal symptoms of rats were recorded, the histopathological examination and Transmission Electron Microscopy (TME) of the sinus tissue were performed and the levels of Tumor Necrosis Factor-α (TNF-α), Interleukin-6 (IL-6) in the blood were also analyzed. The expressions of Aquaporin-5 (AQP5), Occludin, Toll-Like Receptor-4 (TLR4), Medullary differentiation factor 88 (MyD88) and phosphorylated (p)-p65 protein were detected by Western blot to evaluate the effect and mechanism of the experimental models.

RESULTS

We found that compared with the control group and LPS group, the sinusitis symptom scores in the Merocel sponge combined with LPS group were significantly increased; the respiratory epithelia of the maxillary sinus were degenerated, cilia were detached, and even inflammatory cell infiltration occurred; the levels of TNF-α and IL-6 were increased; the expression of AQP5 and Occludin protein was decreased; and the expressions of TLR4, MyD88, and p-p65 protein were increased.

CONCLUSION

For the first time, we successfully established a rat rhinosinusitis model using Merocel sponge with LPS and explored the possible mechanism of LPS action.

Molecular Characterization and Functional Analysis of the Nattectin-like Toxin from the Venomous Fish Thalassophryne maculosa

TmC4-47.2 is a toxin with myotoxic activity found in the venom of Thalassophryne maculosa, a venomous fish commonly found in Latin America whose envenomation produces an injury characterized by delayed neutrophil migration, production of major pro-inflammatory cytokines, and necrosis at the wound site, as well as a specific systemic immune response. However, there are few studies on the protein structure and functions associated with it. Here, the toxin was identified from the crude venom by chromatography and protein purification systems. TmC4-47.2 shows high homology with the Nattectin from Thalassophryne nattereri venom, with 6 cysteines and QPD domain for binding to galactose. We confirm its hemagglutinating and microbicide abilities independent of carbohydrate binding, supporting its classification as a nattectin-like lectin. After performing the characterization of TmC4-47.2, we verified its ability to induce an increase in the rolling and adherence of leukocytes in cremaster post-capillary venules dependent on the α5β1 integrin. Finally, we could observe the inflammatory activity of TmC4-47.2 through the production of IL-6 and eotaxin in the peritoneal cavity with sustained recruitment of eosinophils and neutrophils up to 24 h. Together, our study characterized a nattectin-like protein from T. maculosa, pointing to its role as a molecule involved in the carbohydrate-independent agglutination response and modulation of eosinophilic and neutrophilic inflammation.

Identification of immune-related proteins of Dreissena polymorpha hemocytes and plasma involved in host-microbe interactions by differential proteomics

Biological responses of zebra mussel Dreissena polymorpha are investigated to assess the impact of contaminants on aquatic organisms and ecosystems. In addition to concentrate chemical contaminants in their tissues, zebra mussels accumulate several microorganisms such as viruses, protozoa and bacteria. In order to understand the molecular mechanisms involved in the defence against microorganisms this study aims at identifying immune proteins from D. polymorpha hemolymph involved in defence against protozoa and viruses. For this purpose, hemolymph were exposed ex vivo to Cryptosporidium parvum and RNA poly I:C. Differential proteomics on both hemocytes and plasma revealed immune proteins modulated under exposures. Different patterns of response were observed after C. parvum and RNA poly I:C exposures. The number of modulated proteins per hemolymphatic compartments suggest that C. parvum is managed in cells while RNA poly I:C is managed in plasma after 4 h exposure. BLAST annotation and GO terms enrichment analysis revealed further characteristics of immune mechanisms. Results showed that many proteins involved in the recognition and destruction of microorganisms were modulated in both exposure conditions, while proteins related to phagocytosis and apoptosis were exclusively modulated by C. parvum. This differential proteomic analysis highlights in zebra mussels modulated proteins involved in the response to microorganisms, which reflect a broad range of immune mechanisms such as recognition, internalization and destruction of microorganisms. This study paves the way for the identification of new markers of immune processes that can be used to assess the impact of both chemical and biological contaminations on the health status of aquatic organisms.

Heparin-Binding Protein Release Is Strongly Induced by Leptospira Species and Is a Candidate for an Early Diagnostic Marker of Human Leptospirosis

BACKGROUND

Leptospirosis, caused by spirochetes of the genus Leptospira, is one of the most widespread zoonoses worldwide. Efficient diagnostic methods for early diagnosis of leptospirosis are still lacking, and acute disease presents with nonspecific symptomatology and is often misdiagnosed. The leptospires pathogenic processes and virulence mechanisms remain virtually unknown. In severe infections, hemostatic impairment is frequently observed, and pathophysiological complications often develop when the host response is modulated by the pathogen. The neutrophil heparin-binding protein (HBP) is an inflammatory mediator and potent inducer of vascular leakage.

RESULTS

In this study, we found that leptospires and their secreted products induce the release of HBP from stimulated neutrophils through a controlled degranulation mechanism. We acknowledged 2 leptospiral proteins as able to induce HBP degranulation. These findings have clinical implications, as high levels of HBP were detected in serum from patients with leptospirosis, especially at the early phase of the disease.

CONCLUSION

In conclusion, we describe a new mechanism by which the leptospirosis pathophysiological complications may arise, such as vascular leakage and edema formation. We also propose HBP as a new early screening biomarker for human leptospirosis.

Biotoxins in muscle regeneration research

Skeletal muscles are characterized by their unique regenerative capacity following injury due to the presence of muscle precursor cells, satellite cells. This characteristic allows researchers to study muscle regeneration using experimental injury models. These injury models should be stable and reproducible. Variety of injury models have been used, among which the intramuscular injection of myotoxic biotoxins is considered the most common and widespread method in muscle regeneration research. By using isolated biotoxins, researchers could induce acute muscle damage and regeneration in a controlled and reproducible manner. Therefore, it is considered an easy method for inducing muscle injury in order to understand the different mechanisms involved in muscle injuries and tissue response following injury. However, different toxins and venoms have different compositions and subsequently the possible effects of these toxins on skeletal muscle vary according to their composition. Moreover, regeneration of injured muscle by venoms and toxins varies according to the target of toxin or venom. Therefore, it is essential for researcher to be aware of the mechanism and possible target of toxin-induced injury. The current paper provides an overview of the biotoxins used in skeletal muscle research.

DM9 Domain Containing Protein Functions As a Pattern Recognition Receptor with Broad Microbial Recognition Spectrum

DM9 domain was first identified in Drosophila melanogaster, and it was subsequently found to integrate with or without other protein domains across a wide range of invertebrates and vertebrates. In the present study, a member of DM9 domain containing protein (DM9CP) family from marine invertebrate Crassostrea gigas (designated CgDM9CP-1), which was only composed of two DM9 domains, was taken as a protein model to study the biological functions of DM9 domain and its molecular determinants. CgDM9CP-1 was found to exhibit high binding specificity and avidity toward d-mannose residue. It served as a pattern recognition receptor (PRR) with a broad range of recognition spectrum to various pathogen-associated molecular patterns, including lipopolysaccharide, peptidylglycan, mannan, and β-1, 3-glucan in a d-mannose-dependent manner, as well as bacteria and fungi. In order to reveal the molecular mechanism underlying its pattern recognition activity, the crystal structures of wild-type and loss-of-function mutants were solved, and Asp22 and Lys43 were found to be the critical residues for ligand recognition. Moreover, CgDM9CP-1 protein was found to mainly distribute on the surface of C. gigas hemocytes, and it could be translocated into cytoplasm and colocalized with the engulfed microbes during hemocyte phagocytosis. The present result clearly indicated that CgDM9CP-1 was a PRR, and it provided an important clue for the better understanding of DM9CP function.

Neuropeptide Kyotorphin Impacts on Lipopolysaccharide-Induced Glucocorticoid-Mediated Inflammatory Response. A Molecular Link to Nociception, Neuroprotection, and Anti-Inflammatory Action

Neuropeptide kyotorphin (KTP) is a potent analgesic if administered directly into the brain. In contrast, KTP-amide (KTP-NH₂) is analgesic, neuroprotective, and anti-inflammatory following systemic administration, albeit its mechanism of action is unknown. The aim of this study was to shed light on the mechanism of action of KTP-NH₂ at the molecular level. KTP-NH₂ does not inhibit the enkephalinases angiotensin-converting-enzyme and dipeptidyl-peptidase 3. Intravital microscopy showed that KTP-NH₂ decreased the number of rolling leukocytes in a mouse model of inflammation induced by lipopolysaccharide (LPS). Pretreatment with metyrapone abrogated the action of KTP-NH₂. Interestingly, stimulating rolling leukocytes using CXCL-1 is also counteracted by the KTP-NH₂, but this effect is not abrogated by metyrapone. We conclude that KTP-NH₂ has dual action: a glucocorticoid-mediated action, which is dominant in the full-fledged LPS-induced inflammation model, and a glucocorticoid-independent mechanism, which is predominant in models in which leukocyte rolling is stimulated but inflammation is not totally developed.

Anticonvulsant Effects of Fractions Isolated from Dinoponera quadriceps (Kempt) Ant Venom (Formicidae: Ponerinae)

Natural products, sources of new pharmacological substances, have large chemical diversity and architectural complexity. In this context, some toxins obtained from invertebrate venoms have anticonvulsant effects. Epilepsy is a neurological disorder that affects about 65 million people worldwide, and approximately 30% of cases are resistant to pharmacological treatment. Previous studies from our group show that the denatured venom of the ant Dinoponera quadriceps (Kempt) protects mice against bicuculline (BIC)-induced seizures and death. The aim of this study was to investigate the anticonvulsant activity of compounds isolated from D. quadriceps venom against seizures induced by BIC in mice. Crude venom was fractionated by high-performance liquid chromatography (HPLC) resulting in six fractions referred to as DqTx1-DqTx6. A liquid chromatography-mass spectrometry (LC/MS) analysis revealed a major 431 Da compound in fractions DqTx1 and DqTx2. Fractions DqTx3 and DqTx4 showed a compound of 2451 Da and DqTx5 revealed a 2436 Da compound. Furthermore, the DqTx6 fraction exhibited a major component with a molecular weight of 13,196 Da. Each fraction (1 mg/mL) was microinjected into the lateral ventricle of mice, and the animals were observed in an open field. We did not observe behavioral alterations when the fractions were given alone. Conversely, when the fractions were microinjected 20 min prior to the administration of BIC (21.6 nM), DqTx1, DqTx4, and DqTx6 fractions increased the latency for onset of tonic-clonic seizures. Moreover, all fractions, except DqTx5, increased latency to death. The more relevant result was obtained with the DqTx6 fraction, which protected 62.5% of the animals against tonic-clonic seizures. Furthermore, this fraction protected 100% of the animals from seizure episodes followed by death. Taken together, these findings indicate that compounds from ant venom might be a potential source of new anticonvulsants molecules.

Bioactive components in fish venoms

Animal venoms are widely recognized excellent resources for the discovery of novel drug leads and physiological tools. Most are comprised of a large number of components, of which the enzymes, small peptides, and proteins are studied for their important bioactivities. However, in spite of there being over 2000 venomous fish species, piscine venoms have been relatively underrepresented in the literature thus far. Most studies have explored whole or partially fractioned venom, revealing broad pharmacology, which includes cardiovascular, neuromuscular, cytotoxic, inflammatory, and nociceptive activities. Several large proteinaceous toxins, such as stonustoxin, verrucotoxin, and Sp-CTx, have been isolated from scorpaenoid fish. These form pores in cell membranes, resulting in cell death and creating a cascade of reactions that result in many, but not all, of the physiological symptoms observed from envenomation. Additionally, Natterins, a novel family of toxins possessing kininogenase activity have been found in toadfish venom. A variety of smaller protein toxins, as well as a small number of peptides, enzymes, and non-proteinaceous molecules have also been isolated from a range of fish venoms, but most remain poorly characterized. Many other bioactive fish venom components remain to be discovered and investigated. These represent an untapped treasure of potentially useful molecules.

Thalassophryne nattereri fish venom: from the envenoming to the understanding of the immune system

Thalassophryne nattereri (niquim) is a venomous fish found off North and Northeast coast of Brazil, where it is known by the severity of the accidents involving humans. This review article is divided into four topics. The first one provides a brief description of the animal biology and its distribution off Brazilian coastal waters, the venom apparatus, signs and symptoms observed in envenomated humans and also describes envenomation in mice. The second topic describes the use of modern genetic approach and mass spectrometry for identification of highly expressed genes in its venom glands and the sequence of major toxins. The third chapter offers a detailed study of tissue injury induced by the venom and reveals the role of toxins that impair inflammation reduction. Finally, the fourth section expands the understanding of many extrinsic and intrinsic essential factors in maintaining survival of memory B cell compartment. Our results demonstrate the wide possibilities for research in the area of toxinology, also the necessity of interconnection among biochemistry, pharmacology and immunology areas for the expansion of knowledge and for generation of innovation.