The role of serpins in vertebrate immunity

Insights into the molecular mechanisms of pesticide tolerance in the Aporrectodea caliginosa earthworm

Diffuse pollution of the environment by pesticides has become a major soil threat to non-target organisms, such as earthworms for which declines have been reported. However some endogeic species are still abundant and persist in intensively cultivated fields, suggesting they become tolerant to long-term anthropogenic pressure. We thus considered the working hypothesis that populations of Aporrectodea caliginosa earthworms from conventionally managed fields developed a tolerance to pesticides compared with those from organically managed fields. To investigate this hypothesis, we studied earthworm populations of the same genetic lineage from soils that were either lowly or highly contaminated by pesticides to detect any constitutive expression of differentially expressed molecular pathways between these populations. Earthworm populations were then experimentally exposed to a fungicide-epoxiconazole-in the laboratory to identify different molecular responses when newly exposed to a pesticide. State-of-the-art omics technology (RNA sequencing) and bioinformatics were used to characterize molecular mechanisms of tolerance in a non-targeted way. Additional physiological traits (respirometry, growth, bioaccumulation) were monitored to assess tolerance at higher levels of biological organization. In the present study, we generated the de novo assembly transcriptome of A. caliginosa consisting of 64,556 contigs with N50 = 2862 pb. In total, 43,569 Gene Ontology terms were identified for 21,593 annotated sequences under the three main ontologies (biological processes, cellular components and molecular functions). Overall, we revealed that two same lineage populations of A. caliginosa earthworms, inhabiting similar pedo-climatic environment, have distinct gene expression pathways after they long-lived in differently managed agricultural soils with a contrasted pesticide exposure history for more than 22 years. The main difference was observed regarding metabolism, with upregulated pathways linked to proteolytic activities and the mitochondrial respiratory chain in the highly exposed population. This study improves our understanding of the long-term impact of chronic exposure of soil engineers to pesticide residues.

The proteome of hand eczema assessed by tape stripping

Hand eczema (HE) is a prevalent skin disease. However, classification of HE into different subtypes remains challenging. Limited number of prior studies have employed invasive biopsy-based strategies; yet, studies of the HE proteome using non-invasive tape stripping methodology have not been reported. In this study, we wanted to assess whether global proteomic analysis of skin tape strip samples can be used for sub-classification of HE patients. Tape strips were collected from patients with HE and healthy skin. Liquid chromatography-mass spectrometry (LC/MS) proteomics was performed, and the global protein expression was analyzed. We identified 2,919 proteins in stratum corneum-derived skin cells from tape strip samples. Compared to healthy skin, the lesional samples from HE patients exhibited increased expression of immune-related markers and a decreased expression of structural barrier proteins. The difference between HE subtypes was restricted to the lesional skin areas, and included an increased expression of skin barrier-related proteins independently of the concurrent AD. In conclusion we found, that the non-invasive tape strip method used in combination with LC/MS proteomics can be used for analysis of skin protein expression in HE patients. Thus, the method shows potential for assessing the proteomic differences between subtypes of HE, and biomarker discovery.

SERPINB3, Adult-Onset Immunodeficiency, and Generalized Pustular Psoriasis

BACKGROUND

Generalized pustular psoriasis (GPP; MIM 614204) is a rare and severe pustular autoinflammatory skin disease in which acute generalized erythema and scaling develop with numerous sterile pustules. GPP shares skin manifestations, especially pustular skin reaction, with adult-onset immunodeficiency (AOID) with anti-interferon-γ autoantibodies, an autoimmune disease.

METHODS

Clinical examinations and whole-exome sequencing (WES) were performed on 32 patients with pustular psoriasis phenotypes and 21 patients with AOID with pustular skin reaction. Immunohistochemical and histopathological studies were performed.

RESULTS

WES identified three Thai patients presenting with similar pustular phenotypes-two with a diagnosis of AOID and the other with GPP. A heterozygous missense variant chr18:g.61325778C>A NM_006919.2: c.438G>T; NP_008850.1: p.Lys146Asn; rs193238900 in SERPINB3 was identified in two patients: one with GPP and the other with AOID. The other patient who had AOID carried a heterozygous missense variant chr18:g.61323147T>C NM_006919.2: c.917A>G; NP_008850.1: p.Asp306Gly in SERPINB3. Immunohistochemical studies showed overexpression of SERPINA1 and SERPINB3, a hallmark of psoriatic skin lesions.

CONCLUSIONS

Genetic variants in SERPINB3 are associated with GPP and AOID with pustular skin reaction. The skin of patients with GPP and AOID carrying SERPINB3 mutations showed overexpression of SERPINB3 and SERPINA1. Clinically and genetically, GPP and AOID appear to share pathogenetic mechanisms.

Native and activated antithrombin inhibits TMPRSS2 activity and SARS-CoV-2 infection

Host cell proteases such as TMPRSS2 are critical determinants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tropism and pathogenesis. Here, we show that antithrombin (AT), an endogenous serine protease inhibitor regulating coagulation, is a broad-spectrum inhibitor of coronavirus infection. Molecular docking and enzyme activity assays demonstrate that AT binds and inhibits TMPRSS2, a serine protease that primes the Spike proteins of coronaviruses for subsequent fusion. Consequently, AT blocks entry driven by the Spikes of SARS-CoV, MERS-CoV, hCoV-229E, SARS-CoV-2 and its variants of concern including Omicron, and suppresses lung cell infection with genuine SARS-CoV-2. Thus, AT is an endogenous inhibitor of SARS-CoV-2 that may be involved in COVID-19 pathogenesis. We further demonstrate that activation of AT by anticoagulants, such as heparin or fondaparinux, increases the anti-TMPRSS2 and anti-SARS-CoV-2 activity of AT, suggesting that repurposing of native and activated AT for COVID-19 treatment should be explored.

Grass carp SERPINA1 inhibits GCRV infection through degrading CF2

SERPINA1, a member of the serine protease inhibitor family, plays a role in viral infection and inflammation by regulating the activities of serine and cysteine proteases. To date, there have been no reports on the immune function of SERPINA1 in fishes. In this study, we first cloned the serpina1 gene of grass carp (Ctenopharyngodon idellus) and found that it could respond rapidly to the infection of Grass carp reovirus (GCRV), and overexpression of serpina1 could enhance the antiviral response of CIK cells. A polyclonal antibody of SERPINA1 was prepared, and the protein interacting with SERPINA1 was screened by CoIP/MS in grass carp hepatopancreas tissue. It was found that SERPINA1 interacted with coagulation factor 2 (CF2) and could degrade it in a dose-dependent manner. In addition, overexpression of cf2 contributed to the infection of GCRV in CIK cells, whereas co-expression of serpina1 and cf2 in grass carp reduced the copy number of GCRV in cells. The results showed that grass carp SERPINA1 could inhibit GCRV infection by degrading CF2. This study proposes that SERPINA1 can inhibit viral infection through interaction with the coagulation factor, providing new insights into the molecular mechanism of SERPINA1’s antiviral function.

Characterization and perturbation of CTCF-mediated chromatin interactions for enhancing myogenic transdifferentiation

Expression of key transcription factors can induce transdifferentiation in somatic cells; however, this conversion is usually incomplete due to undefined intrinsic barriers. Here, we employ MyoD-induced transdifferentiation of fibroblasts as a model to illustrate the chromatin structures that impede the cell-fate transition. Focusing on the three-dimensional (3D) chromatin interactions, we show that MyoD directly establishes chromatin loops to activate myogenic transcriptional program. Similarly, dynamic changes of CTCF-mediated chromatin interactions are favorable for fibroblast-to-myoblast conversion. However, a substantial portion of CTCF-mediated chromatin interactions remain stable, and the associated genes are steady in expression and enriched for fibroblast function that may restrict cell-identity transformation. Temporal CTCF depletion can interrupt the resistant chromatin loops to enhance myogenic transdifferentiation in mice, pig, and chicken fibroblasts. Therefore, during induced transdifferentiation, the transcription factor can directly reorganize the 3D chromatin interactions, and perturbation of CTCF-mediated genome topology may resolve the limitations of cell fate transitions.

Genetic characterization of potential venom resistance proteins in California ground squirrels ( Otospermophilus beecheyi ) using transcriptome analyses

Understanding the molecular basis of adaptations in coevolving species requires identifying the genes that underlie reciprocally selected phenotypes, such as those involved in venom in snakes and resistance to the venom in their prey. In this regard, California ground squirrels (CGS; Otospermophilus beecheyi) are eaten by northern Pacific rattlesnakes (Crotalus oreganus oreganus), but individual squirrels may still show substantial resistance to venom and survive bites. A recent study using proteomics identified venom interactive proteins (VIPs) in the blood serum of CGS. These VIPs represent possible resistance proteins, but the sequences of genes encoding them are unknown despite the value of such data to molecular studies of coevolution. To address this issue, we analyzed a de novo assembled transcriptome from CGS liver tissue-where many plasma proteins are synthesized-and other tissues from this species. We then examined VIP sequences in terms of three characteristics that identify them as possible resistance proteins: evidence for positive selection, high liver expression, and nonsynonymous variation across CGS populations. Based on these characteristics, we identified five VIPs (i.e., α-2-macroglobulin, α-1-antitrypsin-like protein GS55-LT, apolipoprotein A-II, hibernation-associated plasma protein HP-20, and hibernation-associated plasma protein HP-27) as the most likely candidates for resistance proteins among VIPs identified to date. Four of these proteins have been previously implicated in conferring resistance to the venom in mammals, validating our approach. When combined with the detailed information available for rattlesnake venom proteins, these results set the stage for future work focused on understanding coevolutionary interactions at the molecular level between these species.

Serpins in Tick Physiology and Tick-Host Interaction

Tick saliva has been extensively studied in the context of tick-host interactions because it is involved in host homeostasis modulation and microbial pathogen transmission to the host. Accumulated knowledge about the tick saliva composition at the molecular level has revealed that serine protease inhibitors play a key role in the tick-host interaction. Serpins are one highly expressed group of protease inhibitors in tick salivary glands, their expression can be induced during tick blood-feeding, and they have many biological functions at the tick-host interface. Indeed, tick serpins have an important role in inhibiting host hemostatic processes and in the modulation of the innate and adaptive immune responses of their vertebrate hosts. Tick serpins have also been studied as potential candidates for therapeutic use and vaccine development. In this review, we critically summarize the current state of knowledge about the biological role of tick serpins in shaping tick-host interactions with emphasis on the mechanisms by which they modulate host immunity. Their potential use in drug and vaccine development is also discussed.

A fingerprint of plasma proteome alteration after local tissue damage induced by Bothrops leucurus snake venom in mice

Bothrops spp. is responsible for about 70% of snakebites in Brazil, causing a diverse and complex pathophysiological condition. Bothrops leucurus is the main species of medical relevance found in the Atlantic coast in the Brazilian Northeast region. The pathophysiological effects involved B. leucurus snakebite as well as the organism's reaction in response to this envenoming, it has not been explored yet. Thus, edema was induced in mice paw using 1.2, 2.5, and 5.0 μg of B. leucurus venom, the percentage of edema was measured 30 min after injection and the blood plasma was collected and analyzed by shotgun proteomic strategy. We identified 80 common plasma proteins with differential abundance among the experimental groups and we can understand the early aspects of this snake envenomation, regardless of the suggestive severity of an ophidian accident. The results showed B. leucurus venom triggers a thromboinflammation scenario where family's proteins of the Serpins, Apolipoproteins, Complement factors and Component subunits, Cathepsins, Kinases, Oxidoreductases, Proteases inhibitors, Proteases, Collagens, Growth factors are related to inflammation, complement and coagulation systems, modulators platelets and neutrophils, lipid and retinoid metabolism, oxidative stress and tissue repair. Our findings set precedents for future studies in the area of early diagnosis and/or treatment of snakebites. SIGNIFICANCE: The physiopathological effects that the snake venoms can cause have been investigated through classical and reductionist tools, which allowed, so far, the identification of action mechanisms of individual components associated with specific tissue damage. The currently incomplete limitations of this knowledge must be expanded through new approaches, such as proteomics, which may represent a big leap in understanding the venom-modulated pathological process. The exploration of the complete protein set that suffer modifications by the simultaneous action of multiple toxins, provides a map of the establishment of physiopathological phenotypes, which favors the identification of multiple toxin targets, that may or may not act in synergy, as well as favoring the discovery of biomarkers and therapeutic targets for manifestations that are not neutralized by the antivenom.

Mice heterozygous for the Serpinb6a null mutation show deficits in central auditory function after acoustic trauma

OBJECTIVES

Complete deficiency of the serine protease inhibitor gene, SERPINB6, is responsible for autosomal-recessive, nonsyndromic sensorineural hearing loss in humans. A mouse model of this deafness gene identifies Serpinb6a expression in the neurosensory epithelium and fibrocytes of the cochlea. Homozygous Serpinb6a mutant mice display an exaggerated hearing loss after exposure to moderate acoustic trauma. It is unknown if and how heterozygous Serpinb6a mice show increased vulnerability to acoustic trauma.

METHODS

We exposed Serpinb6a+/- and Serpinb6a+/+ mice to acoustic trauma and measured their hearing function prior to, 3 and 14 days postexposure, analysing shifts in hearing threshold and amplitudes of Wave I and II of the auditory brainstem-evoked response (ABR) to 4, 8, 16 and 32 kHz tones.

RESULTS

Shifts in hearing threshold and Wave I amplitude of Serpinb6a+/- mice were not significantly different from Serpinb6a+/+ mice at both time points and all frequencies tested (P > 0.05, Mann-Whitney test). However, Wave II amplitudes at 16 and 32 kHz tones, were more severely diminished in Serpinb6a+/- mice (P < 0.05). To exclude any effects of ageing on auditory function in Serpinb6a+/- mice, hearing function of unexposed Serpinb6a+/- mice was measured at start and end of the experimental period. The shift in Wave II amplitude of exposed Serpinb6a+/- mice was significantly lower than unexposed Serpinb6a+/- mice only at 16 and 32 kHz (P < 0.01), confirming acoustic trauma as the main cause of hearing deficits in Serpinb6a+/- mice.

CONCLUSION

These results suggest that heterozygous Serpinb6a humans may be vulnerable to noise.

Priming With Toll-Like Receptor 3 Agonist Poly(I:C) Enhances Content of Innate Immune Defense Proteins but Not MicroRNAs in Human Mesenchymal Stem Cell-Derived Extracellular Vesicles

Mesenchymal stem cells (MSCs) help fight infection by promoting direct bacterial killing or indirectly by modulating the acute phase response, thereby decreasing tissue injury. Recent evidence suggests that extracellular vesicles (EVs) released from MSCs retain antimicrobial characteristics that may be enhanced by pretreatment of parent MSCs with the toll-like receptor 3 (TLR3) agonist poly(I:C). Our aim was to determine whether poly(I:C) priming can modify EV content of miRNAs and/or proteins to gain insight into the molecular mechanisms of their enhanced antimicrobial function. Human bone marrow-derived MSCs were cultured with or without 1 μg/ml poly(I:C) for 1 h and then conditioned media was collected after 64 h of culture in EV-depleted media. Mass spectrometry and small RNA next-generation sequencing were performed to compare proteomic and miRNA profiles. Poly(I:C) priming resulted in 49 upregulated EV proteins, with 21 known to be important in host defense and innate immunity. In contrast, EV miRNA content was not significantly altered. Functional annotation clustering analysis revealed enrichment in biological processes and pathways including negative regulation of endopeptidase activity, acute phase, complement and coagulation cascades, innate immunity, immune response, and Staphylococcus aureus infection. Several antimicrobial peptides identified in EVs remained unaltered by poly(I:C) priming, including dermcidin, lactoferrin, lipocalin 1, lysozyme C, neutrophil defensin 1, S100A7 (psoriasin), S100A8/A9 (calprotectin), and histone H4. Although TLR3 activation of MSCs improves the proteomic profile of EVs, further investigation is needed to determine the relative importance of particular functional EV proteins and their activated signaling pathways following EV interaction with immune cells.

Direct Tumor Killing and Immunotherapy through Anti-SerpinB9 Therapy

Cancer therapies kill tumors either directly or indirectly by evoking immune responses and have been combined with varying levels of success. Here, we describe a paradigm to control cancer growth that is based on both direct tumor killing and the triggering of protective immunity. Genetic ablation of serine protease inhibitor SerpinB9 (Sb9) results in the death of tumor cells in a granzyme B (GrB)-dependent manner. Sb9-deficient mice exhibited protective T cell-based host immunity to tumors in association with a decline in GrB-expressing immunosuppressive cells within the tumor microenvironment (TME). Maximal protection against tumor development was observed when the tumor and host were deficient in Sb9. The therapeutic utility of Sb9 inhibition was demonstrated by the control of tumor growth, resulting in increased survival times in mice. Our studies describe a molecular target that permits a combination of tumor ablation, interference within the TME, and immunotherapy in one potential modality.

Serpins in cartilage and osteoarthritis: what do we know?

Serpins (serine proteinase inhibitors) are an ancient superfamily of structurally similar proteins, the majority of which use an elegant suicide inhibition mechanism to target serine proteinases. Despite likely evolving from a single common ancestor, the 36 human serpins have established roles regulating diverse biological processes, such as blood coagulation, embryonic development and extracellular matrix (ECM) turnover. Genetic mutations in serpin genes underpin a host of monogenic disorders — collectively termed the ‘serpinopathies’ — but serpin dysregulation has also been shown to drive pathological mechanisms in many common diseases. Osteoarthritis is a degenerative joint disorder, characterised by the progressive destruction of articular cartilage. This breakdown of the cartilage is driven by the metalloproteinases, and it has long been established that an imbalance of metalloproteinases to their inhibitors is of critical importance. More recently, a role for serine proteinases in cartilage destruction is emerging; including the activation of latent matrix metalloproteinases and cell-surface receptors, or direct proteolysis of the ECM. Serpins likely regulate these processes, as well as having roles beyond serine proteinase inhibition. Indeed, serpins are routinely observed to be highly modulated in osteoarthritic tissues and fluids by ‘omic analysis, but despite this, they are largely ignored. Confusing nomenclature and an underappreciation for the role of serine proteinases in osteoarthritis (OA) being the likely causes. In this narrative review, serpin structure, biochemistry and nomenclature are introduced, and for the first time, their putative importance in maintaining joint tissues — as well as their dysregulation in OA — are explored.

Differential immune gene expression associated with contemporary range expansion in two invasive rodents in Senegal

Biological invasions are major anthropogenic changes associated with threats to biodiversity and health. However, what determines the successful establishment and spread of introduced populations remains unclear. Here, we explore several hypotheses linking invasion success and immune phenotype traits, including those based on the evolution of increased competitive ability concept. We compared gene expression profiles between anciently and recently established populations of two major invading species, the house mouse Mus musculus domesticus and the black rat Rattus rattus, in Senegal (West Africa). Transcriptome analyses identified differential expression between anciently and recently established populations for 364 mouse genes and 83 rat genes. All immune-related genes displaying differential expression along the mouse invasion route were overexpressed at three of the four recently invaded sites studied. Complement activation pathway genes were overrepresented among these genes. By contrast, no particular immunological process was found to be overrepresented among the differentially expressed genes of black rat. Changes in transcriptome profiles were thus observed along invasion routes, but with different specific patterns between the two invasive species. These changes may be driven by increases in infection risks at sites recently invaded by the house mouse, and by stochastic events associated with colonization history for the black rat. These results constitute a first step toward the identification of immune eco-evolutionary processes potentially involved in the invasion success of these two rodent species.

Dual Host-Intracellular Parasite Transcriptome of Enucleated Cells Hosting Leishmania amazonensis: Control of Half-Life of Host Cell Transcripts by the Parasite

Enucleated cells or cytoplasts (cells whose nucleus is removed in vitro) represent an unexplored biological model for intracellular infection studies due to the abrupt interruption of nuclear processing and new RNA synthesis by the host cell in response to pathogen entry. Using enucleated fibroblasts hosting the protozoan parasite Leishmania amazonensis, we demonstrate that parasite multiplication and biogenesis of large parasitophorous vacuoles in which parasites multiply are independent of the host cell nucleus. Dual RNA sequencing of both host cytoplast and intracellular parasite transcripts identified host transcripts that are more preserved or degraded upon interaction with parasites and also parasite genes that are differentially expressed when hosted by nucleated or enucleated cells. Cytoplasts are suitable host cells, which persist in culture for more than 72 h and display functional enrichment of transcripts related to mitochondrial functions and mRNA translation. Crosstalk between nucleated host de novo gene expression in response to intracellular parasitism and the parasite gene expression to counteract or benefit from these host responses induces a parasite transcriptional profile favoring parasite multiplication and aerobic respiration, and a host-parasite transcriptional landscape enriched in host cell metabolic functions related to NAD, fatty acid, and glycolytic metabolism. Conversely, interruption of host nucleus-parasite cross talk by infection of enucleated cells generates a host-parasite transcriptional landscape in which cytoplast transcripts are enriched in phagolysosome-related pathway, prosurvival, and SerpinB-mediated immunomodulation. In addition, predictive in silico analyses indicated that parasite transcript products secreted within cytoplasts interact with host transcript products conserving the host V-ATPase proton translocation function and glutamine/proline metabolism. The collective evidence indicates parasite-mediated control of host cell transcripts half-life that is beneficial to parasite intracellular multiplication and escape from host immune responses. These findings will contribute to improved drug targeting and serve as database for L. amazonensis-host cell interactions.

Serpin-type serine protease inhibitor mediates coelomocyte apoptosis in Apostichopus japonicus

Serine protease inhibitors (SPIs, serpins) are a protein superfamily involved in almost all physiological processes in all organisms. In this study, a novel serpin was identified from Apostichopus japonicus (Ajserpin) by using high-throughput sequencing and RACE approaches. The full-length cDNA of Ajserpin was 1893 bp with a 5'-untranslated region (UTR) of 130 bp, a 3'-UTR of 587 bp, and an open reading frame of 1176 bp encoding a polypeptide of 391 amino acids with a deduced molecular weight of 43.8 kDa. Ajserpin shares the standard structure of SPI, including three β-sheets and eight α-helices. The deduced amino acid sequences of Ajserpin had no nuclear location signal and signal peptide structure. The phylogenetic tree and immunofluorescence showed that Ajserpin belonged to the clade B subfamily and was mainly located in the cytoplasm and nucleus. Sequence comparison and protein inhibition experiments showed that the active site (P1-P1' site) of Ajserpin was Arginine and Serine, which displayed inhibitory activity toward trypsin in a dose-dependent manner. Tissue distribution analysis showed that Ajserpin transcripts were constitutively expressed in all examined tissues with the peak in the body wall. Ajserpin mRNA transcripts could be induced in Vibrio splendidus-challenged sea cucumber or lipopolysaccharide-exposed coelomocytes. Furthermore, Ajserpin knockdown by small interfering RNAs could inhibit coelomocytes apoptosis. All our results revealed that Ajserpin might serve as an immune regulator in sea cucumber.

The molecular basis of venom resistance in a rattlesnake-squirrel predator-prey system

Understanding how interspecific interactions mould the molecular basis of adaptations in coevolving species is a long-sought goal of evolutionary biology. Venom in predators and venom resistance proteins in prey are coevolving molecular phenotypes, and while venoms are highly complex mixtures it is unclear if prey respond with equally complex resistance traits. Here, we use a novel molecular methodology based on protein affinity columns to capture and identify candidate blood serum resistance proteins ("venom interactive proteins" [VIPs]) in California Ground Squirrels (Otospermophilus beecheyi) that interact with venom proteins from their main predator, Northern Pacific Rattlesnakes (Crotalus o. oreganus). This assay showed that serum-based resistance is both population- and species-specific, with serum proteins from ground squirrels showing higher binding affinities for venom proteins of local snakes compared to allopatric individuals. Venom protein specificity assays identified numerous and diverse candidate prey resistance VIPs but also potential targets of venom in prey tissues. Many specific VIPs bind to multiple snake venom proteins and, conversely, single venom proteins bind multiple VIPs, demonstrating that a portion of the squirrel blood serum "resistome" involves broad-based inhibition of nonself proteins and suggests that resistance involves a toxin scavenging mechanism. Analyses of rates of evolution of VIP protein homologues in related mammals show that most of these proteins evolve under purifying selection possibly due to molecular constraints that limit the evolutionary responses of prey to rapidly evolving snake venom proteins. Our method represents a general approach to identify specific proteins involved in co-evolutionary interactions between species at the molecular level.

Evaluation of immune response to Bacillus subtilis spores expressing Clonorchis sinensis serpin3

Clonorchis sinensis (C. sinensis) is one of the most serious food-borne parasites, which can lead to liver fibrosis or cholangiocarcinoma. Effective measures for clonorchiasis prevention are still urgently needed. Bacillus subtilis (B. subtilis) is an effective antigen delivery platform for oral vaccines. Chonorchis sinensis serpin (CsSerpin) was proved to be potential vaccine candidates. In this study, CsSerpin3 was displayed on the surface of B. subtilis spore and recombinant spores were orally administrated to BALB/C mice. CsSerpin3-specific IgA levels in faecal, bile and intestinal mucous increased at 4-8 weeks after the first administration compared with those in control groups. The mucus production and the number of goblet cells in intestinal mucosa elevated in B.s-CotC-CsSerpin3 (CotC, coat protein of B. subtilis spore) spores treated group compared to those in blank control. No significant difference in the activities of glutamic-pyruvic transaminase/ alanine aminotransferase and glutamic oxalacetic transaminase/aspartate aminotransferase were observed between groups. There was no side effect inflammation and observable pathological damage in the liver tissue of mice after administration. Moreover, collagen deposition and Ishak score were statistically reduced in B.s-CotC-CsSerpin3 spores treated mice. In conclusion, B. subtilis spores displaying CsSerpin3 could be investigated further as an oral vaccine against clonorchiasis.

Molecular cloning and characterization of serine protease inhibitor from food-borne nematode, Gnathostoma spinigerum

Gnathostoma spinigerum is a causative agent of human gnathostomiasis and infects people residing in endemic areas as well as travelers. Cutaneous and visceral larval migrants cause clinical manifestations, resulting in severe morbidity and mortality. To survive in hosts, these parasites have evolved various immune evasion mechanisms, including the release of regulatory molecules. Serine protease inhibitors (serpins) that are present in many parasitic helminths are proteins suspected of suppressing host serine protease-related digestion and immune responses. In this study, the serpin secreted by G. spinigerum (GsSerp) was characterized using bioinformatics and molecular biology techniques. The bioinformatics revealed that GsSerp contains 9 helices, 3 β-sheets, and a reactive central loop, which are conserved structures of the serpin superfamily. Recombinant GsSerp (rGsSerp) was expressed in E. coli (molecular weight, 39 kDa) and could inhibit chymotrypsin. Mouse polyclonal antibody against GsSerp could detect the native GsSerp in crude worm antigen but not the excretory-secretory product (ES) of infective-stage larva (aL3Gs). Moreover, the expression of GsSerp in the aL3Gs tissue was located in the hemolymph and intestinal tissue, indicating its role in parasite homeostasis. Our findings may help develop effective strategies for preventing and controlling gnathostomiasis.

The role of serpin protein on the natural immune defense against pathogen infection in Lampetra japonica

Serine protease inhibitors (serpins) are a large protein family that is involved in various physiological processes and is known to regulate innate immunity pathways. However, research for the functional study of serpins in lamprey is limited. In the present study, a serpin gene was cloned and characterized from Lampetra japonica at molecular, protein and cellular levels, named L-serpin which belongs to family F serine protease inhibitors (serpin family). The L-serpin includes a serpin domain in the N-terminus. The mRNA transcript of L-serpin was extensively expressed in kidney, supraneural body, intestine, liver, heart, gill and the highest expression in leukocytes. The mRNA expression level of L-serpin increased significantly after Vibrio anguillarum, Staphylocccus aureus and Poly I:C stimulation and dramatically peak at 8 h. It is demonstrated that the L-serpin protected cells from lethal Gram-negative endotoxemia through associating with inhibition of lipopolysaccharide (LPS)-triggered cell death and inflammatory factors expression. Surface plasmon resonance (SPR) and the microbe binding assay were used to determine that L-serpin interacts directly with LPS (KD = 6.14 × 10^-7 M). Furthermore, we confirmed L-serpin is a major inhibitor of complement activation by inactivating lamprey-C1q protein (KD = 2.06 × 10^-6 M). Taken together, these findings suggest that L-serpin is a endogenous anti-inflammatory factor to defend against Gram-negative bacterial challenge and involved in lamprey innate immunity.

Functional characterization of the clade B serine protease inhibitor SerpinB3 in the pacific white shrimp Litopenaeus vannamei

The clade B serpins contain predominantly intracellular proteins and were reported to be involved in multiple biological functions, especially in inflammation and immune system function. However, studies about the role of the invertebrate intracellular serpins in immune responses were still deficient. Therefore, this paper focused on the functional characterization of LvserpinB3 in white shrimp Litopenaeus vannamei. The pAc5.1-LvserpinB3-EGFP vector was transfected into Drosophila Schneider 2 (S2) cells to analyze the subcellular localization of LvserpinB3, and fluorescent imaging showed that LvserpinB3 were mainly localized to the mitochondria. Knockdown LvserpinB3 significantly increased the mRNA expression of LvSpätzle4 (LvSpz4) and LvPenaeidin4 (LvPen4) upon Vibrio anguillarum infection. Moreover, GST-Pull down analysis showed that LvserpinB3 could interact with serine protease 1 (LvSP1). The recombinant LvserpinB3 (rLvserpinB3) protein exhibited inhibitory roles on the proteolytic activity of trypsin, whereas, mutation at the P1 residue led to the disfunction of the inhibitor. Furthermore, the LvserpinB3 and trypsin mixture were incubated with Anti-SERPINB3 antibodies, and a peptide band with an apparent molecular weight of 30 kDa were detected by western blot analysis. These findings might be valuable in understanding the potential role for LvserpinB3 in inhibiting the target proteases during shrimp immune defences.

A pro-survival role for the intracellular granzyme B inhibitor Serpinb9 in natural killer cells during poxvirus infection

Intracellular serpins are proposed to inactivate proteases released from lysosome-related organelles into the host cell interior, preventing cell death. Serpinb9 opposes the immune cytotoxic protease, granzyme B, and in a number of settings protects cells against granzyme B-mediated cell death. Using a knockout mouse line engineered to express green fluorescent protein under the serpbinb9 promoter, we demonstrate that serpinb9 is vital for host survival during Ectromelia virus infection by maintaining both mature natural killer NK) cells, and activated CD8⁺ T cells. Serpinb9 expression parallels granzyme B expression within both populations during infection. Maturing serpinb9-null NK cells exhibit higher levels of granzyme B-mediated apoptosis during infection; hence there are fewer mature NK cells, and these cells also have lower cytotoxic potential. Thus the serpinb9-granzyme B axis is important for homeostasis of both major cytotoxic effector cell populations.

Characterization and expression analysis of serpinB3, the first clade B serine protease inhibitor in Pacific white shrimp, Litopenaeus vannamei

Currently, about nine serpin clades (A-I) were preferentially observed in higher animals and clustered on the basis of function. Of these, eight clades contain extracellular proteins, while clade B contains predominantly intracellular proteins. In the present study, the first clade B serpin (named LvserpinB3) was identified from the Pacific white shrimp Litopenaeus vannamei. LvserpinB3 encoded a 412-amino acid protein with a 19-amino acid signal peptide and a serpin domain. Moreover, a transmembrane helix (TMHs) was predicted to be located on the N-terminal of LvserpinB3. Alignment with the cDNA sequence indicated that the genomic LvserpinB3 gene contains 2 exons and 1 intron. The P1-P1' scissile bond of the core feature reactive center loop (RCL) represented for Arginine-Isoleucine (RI), which was in accordance with PmserpinB3, Msserpin-4, -5 and -7. The highest mRNA expression level of LvserpinB3 was detected in hepatopancreas. A significant decrease of LvserpinB3 was detected in hepatopancreas at 6 h post Vibrio anguillarum injection, and later on, the expression of LvserpinB3 was remarkably elevated at 24 h post bacterial challenge. Suppression of LvserpinB3 in vivo by double-stranded RNA (dsRNA) mediated RNA interference (RNAi) led to a significant increase in the transcripts of LvSP1 (Serine protease 1), LvPPAE2 (Prophenoloxidase-activating Enzyme 2) and cumulative mortality. Furthermore, rLvserpinB3 protein was expressed and purified in vitro for the prophenoloxidase inhibition assay. The rLvserpinB3 protein can strongly impede the extent of proPO cascade. All above imply that LvserpinB3 might be an inhibitor for prophenoloxidase-activating system.

Comparative transcriptomics of genetically divergent lines of chickens in response to Marek's disease virus challenge at cytolytic phase

Marek's disease (MD), caused by Marek's disease virus (MDV), remains an economically significant threat to the poultry industry worldwide. Genetic resistance to MD is a promising alternative strategy to augment current control measures (vaccination and management). However, only a few functional genes reportedly conferring MD resistance have been identified. Here, we performed a comparative transcriptomics analysis of two highly inbred yet genetically divergent lines of chickens (line 63 and 72) that are resistant and susceptible to MD, respectively, in response to a very virulent plus strain of MDV (vv+MDV) challenge at cytolytic phase. A total of 203 DEGs in response to MDV challenge were identified in the two lines. Of these, 96 DEGs were in common for both lines, in addition to 36 and 71 DEGs that were specific for line 63 and 72, respectively. Functional enrichment analysis results showed the DEGs were significantly enriched in GO terms and pathways associated with immune response. Especially, the four DEGs, FGA, ALB, FN1, and F13A1 that reportedly facilitate virus invasion or immunosuppression, were found to be significantly up-regulated in the susceptible line 72 but down-regulated in the resistant line 63 birds. These results provide new resources for future studies to further elucidate the genetic mechanism conferring MD resistance.

Inhibitors and Antibody Fragments as Potential Anti-Inflammatory Therapeutics Targeting Neutrophil Proteinase 3 in Human Disease

Proteinase 3 (PR3) has received great scientific attention after its identification as the essential antigenic target of antineutrophil cytoplasm antibodies in Wegener's granulomatosis (now called granulomatosis with polyangiitis). Despite many structural and functional similarities between neutrophil elastase (NE) and PR3 during biosynthesis, storage, and extracellular release, unique properties and pathobiological functions have emerged from detailed studies in recent years. The development of highly sensitive substrates and inhibitors of human PR3 and the creation of PR3-selective single knockout mice led to the identification of nonredundant roles of PR3 in cell death induction via procaspase-3 activation in cell cultures and in mouse models. According to a study in knockout mice, PR3 shortens the lifespan of infiltrating neutrophils in tissues and accelerates the clearance of aged neutrophils in mice. Membrane exposure of active human PR3 on apoptotic neutrophils reprograms the response of macrophages to phagocytosed neutrophils, triggers secretion of proinflammatory cytokines, and undermines immune silencing and tissue regeneration. PR3-induced disruption of the anti-inflammatory effect of efferocytosis may be relevant for not only granulomatosis with polyangiitis but also for other autoimmune diseases with high neutrophil turnover. Inhibition of membrane-bound PR3 by endogenous inhibitors such as the α-1-protease inhibitor is comparatively weaker than that of NE, suggesting that the adverse effects of unopposed PR3 activity resurface earlier than those of NE in individuals with α-1-protease inhibitor deficiency. Effective coverage of PR3 by anti-inflammatory tools and simultaneous inhibition of both PR3 and NE should be most promising in the future.

Genital Injury Signatures and Microbiome Alterations Associated With Depot Medroxyprogesterone Acetate Usage and Intravaginal Drying Practices

Background

Increasing evidence suggests depot medroxyprogesterone acetate (DMPA) and intravaginal practices may be associated with human immunodeficiency virus (HIV-1) infection risk; however, the mechanisms are not fully understood. This study evaluated the effect of DMPA and intravaginal practices on the genital proteome and microbiome to gain mechanistic insights.

Methods

Cervicovaginal secretions from 86 Kenyan women, including self-reported DMPA users (n = 23), nonhormonal contraceptive users (n = 63), and women who practice vaginal drying (n = 46), were analyzed using tandem-mass spectrometry.

Results

We identified 473 human and 486 bacterial proteins from 18 different genera. Depot medroxyprogesterone acetate use associated with increased hemoglobin and immune activation (HBD, HBB, IL36G), and decreased epithelial repair proteins (TFF3, F11R). Vaginal drying associated with increased hemoglobin and decreased phagocytosis factors (AZU1, MYH9, PLAUR). Injury signatures were exacerbated in DMPA users who also practiced vaginal drying. More diverse (H index: 0.71 vs 0.45; P = .009) bacterial communities containing Gardnerella vaginalis associated with vaginal drying, whereas DMPA showed no significant association with community composition or diversity.

Conclusions

These findings provide new insights into the impact of DMPA and vaginal drying on mucosal barriers. Future investigations are needed to confirm their relationship with HIV risk in women.

Analysis of the spleen proteome of chickens infected with reticuloendotheliosis virus

Infection with reticuloendotheliosis virus (REV), a gammaretrovirus in the family Retroviridae, can result in immunosuppression and subsequent increased susceptibility to secondary infections. In the present study, we identified differentially expressed proteins in the spleens of chickens infected with the REV-A HLJ07I strain, using two-dimensional gel electrophoresis on samples from time points coinciding with different phases of the REV life cycle. Differentially expressed proteins were identified using one-dimensional liquid chromatography electrospray ionization tandem mass spectrometry (1D LC ESI MS/MS). Comparative analysis of multiple gels revealed that the majority of changes occurred at early stages of infection. In total, 60 protein spots representing 28 host proteins were detected as either quantitatively (false discovery rate [FDR] ≤0.05 and fold change ≥2) or qualitatively differentially expressed at least once during different sampling points. The differentially expressed proteins identified in this study included antioxidants, molecular chaperones, cellular metabolism, formation of the cytoskeleton, signal transduction, cell proliferation and cellar aging. The present findings provide a basis for further studies to elucidate the role of these proteins in REV-host interactions. This could lead to a better understanding of REV infection mechanisms that cause immune suppression.

The secretome of MUSE cells contains factors that may play a role in regulation of stemness, apoptosis and immunomodulation

Mesenchymal stromal cells (MSCs) are a heterogeneous population, which contain several cell phenotypes: mesenchymal stem cells, progenitor cells, fibroblasts and other type of cells. Previously, we identified unique stem cells that we named multilineage-differentiating stress enduring (Muse) cells as one to several percent of MSCs of the bone marrow, adipose tissue and dermis. Among different cell populations in MSCs, Muse cells, positive for pluripotent surface marker SSEA-3, may represent cells responsible for pluripotent-like property of MSCs, since they express pluripotency genes, able to differentiated into triploblastic cells from a single cells and are self-renewable. MSCs release biologically active factors that have profound effects on local cellular dynamics. A thorough examination of MSC secretome seems essential for understanding the physiological functions exerted by these cells in our organism and also for rational cellular therapy design. In this setting, studies on secretome of Muse cells may shed light on pathways that are associated with their specific features. Our findings evidenced that secretomes of MSCs and Muse cells contain factors that regulate extracellular matrix remodeling, ox-redox activities and immune system. Muse cells appear to secrete factors that may preserve their stem cell features, allow survival under stress conditions and may contribute to their immunomodulation capacity. In detail, the proteins belonging to protein kinase A signaling, FXR/RXR activation and LXR/RXR activation pathways may play a role in regulation of Muse stem cell features. These last 2 pathways together with proteins associated with antigen presentation pathway and coagulation system may play a role in immunomodulation.

Three novel clade B serine protease inhibitors from disk abalone, Haliotis discus discus: Molecular perspectives and responses to immune challenges and tissue injury

Serine protease inhibitors (SERPINs) control cellular protease activity in order to maintain cellular homeostasis. The immune and inflammatory responses of invertebrate clade B SERPINs have not been widely reported. In the present study, three proteins with high similarity to clade B SERPINs, referred to as AbSERPIN-1, AbSERPIN-2 and AbSERPIN-3, were identified from disk abalone (Haliotis discus discus). While AbSERPIN-1 (399 aa) was of a typical size for this protein class, AbSERPIN-2 (506 aa) and AbSERPIN-3 (532 aa) were relatively larger. Bioinformatic analysis revealed the characteristic SERPIN domain in each AbSERPIN. In addition, the N-terminal region of both AbSERPIN-2 and AbSERPIN-3 contained a predicted low complexity region (LCR) and a signal peptide, suggesting that these proteins are secretory proteins and are, thus, novel peptides. Tertiary structural models of the AbSERPINs highlighted their structural and functional conservation. Ubiquitous expression of AbSERPIN transcripts was evaluated by quantitative real time PCR (qPCR) analysis in seven tissue types. AbSERPIN-1, AbSERPIN-2, and AbSERPIN-3 transcript levels were highest in mantle, hemocytes, and muscles, respectively. Temporal expression analysis revealed that AbSERPINs were significantly (P < 0.05) elevated in hemocytes during the early/middle stages following the injection of a bacterial pathogen (Vibrio parahaemolyticus or Listeria monocytogenes) or an immuno-stimulant (lipopolysaccharide). Moreover, mantle tissue injury led to significant changes in the temporal expression of AbSERPIN mRNA. Specifically, transcription of AbSERPIN-1 and AbSERPIN-3 was considerably up-regulated, while expression of AbSERPIN-2 was suppressed. These results suggest a potential role of AbSERPINs in response to pathogen invasion and tissue injury in disk abalone.

The serpin superfamily in channel catfish: identification, phylogenetic analysis and expression profiling in mucosal tissues after bacterial infections

The superfamily of serine protease inhibitors (serpins) are broadly distributed in all kingdoms of life. Serpins play critical roles in an array of fundamental biological processes. In this study, we identified a complete set of 25 serpin genes from channel catfish genome by comprehensive data mining of existing genomic resources. Phylogenetic analysis verified their identities and supported the classification of serpins into six families as in mammals. Extensive comparative genomic analyses suggested that most serpins were conserved among vertebrates, while some were lineage-specific. Analysis of serpin gene expression in mucosal tissues after bacterial infections indicated that serpin genes were regulated in a tissue-specific and time-dependent manner. Distinct expression patterns between infections of the two pathogens were observed, indicating that much more rapid host responses of serpin expression were initiated after ESC infection than after columnaris infection. These studies set the foundation for future studies of host-pathogen interactions.

Recombinant expression and characterization of a serine protease inhibitor (Lvserpin7) from the Pacific white shrimp, Litopenaeus vannamei

Serine protease inhibitors (serpins) are widely known to its inhibitory role on proteases involved in the immune responses. Herein, a novel serine protease inhibitor (Lvserpin7), encoding for 411 amino acids with calculated molecular mass of 46.29 kDa and isoelectric point of 6.98 was characterized from the Pacific white shrimp Litopenaeus vannamei. Lvserpin7 shared 92.9% identities to Penaeus monodon serpin7. Among the tested tissues, Lvserpin7 was mainly expressed in hemocytes and gill. The expression profiles analysis indicated that Lvserpin7 was significantly up-regulated in the early stage upon Vibrio anguillarum, Micrococcus lysodeikticus or White Spot Syndrome Virus (WSSV) infection. Fusion protein expression was induced by IPTG, and the purified recombinant Lvserpin7 protein (rLvserpin7) binds to both the Gram-positive and Gram-negative bacteria. Also rLvserpin7 exhibited inhibitory activity against the proteases secreted by Bacillus subtilis. Moreover, rLvserpin7 showed inhibition role on prophenoloxidase activation. To recap, we proposed that Lvserpin7 was implicated in the shrimp immunity via the inhibition of bacterial proteases and proteases involved in prophenoloxidase system.

Involvement of a Serpin serine protease inhibitor (OoSerpin) from mollusc Octopus ocellatus in antibacterial response

Serpin is an important member of serine protease inhibitors (SPIs), which is capable of regulating proteolytic events and involving in a variety of physiological processes. In present study, a Serpin homolog was identified from Octopus ocellatus (designated as OoSerpin). Full-length cDNA of OoSerpin was of 1735 bp, containing a 5' untranslated region of 214 bp, a 3' UTR of 282 bp, and an open reading frame of 1239 bp. The open reading frame encoded a polypeptide of 412 amino acids which has a predicted molecular weight of 46.5 kDa and an isoelectric point of 8.52. The OoSerpin protein shares 37% sequence identity with other Serpins from Mus musculus (NP_941373) and Ixodes scapularis (XP_002407493). The existence of a conserved SERPIN domain strongly suggested that OoSerpin was a member of the Serpin subfamily. Expression patterns of OoSerpin, both in tissues and towards bacterial stimulation, were then characterized. The mRNA of OoSerpin was constitutively expressed at different levels in all tested tissues of untreated O. ocellatus, including mantle (lowest), muscle, renal sac, gill, hemocyte, gonad, systemic heart, and hepatopancreas (highest). The transcriptional level of OoSerpin was significantly up-regulated (P<0.01) in O. ocellatus upon bacterial challenges with Vibrio anguillarum and Micrococcus luteus, indicating its involvement in the antibacterial immune response. Furthermore, rOoSerpin, the recombinant protein of OoSerpin, exhibited strong abilities to inhibit proteinase activities of trypsin and chymotrypsin as well as the growth of Escherichia coli. Our results demonstrate that OoSerpin is a potential antibacterial factor involved in the immune response of O. ocellatus against bacterial infection.

Domain 2 of a Kazal serine proteinase inhibitor SPIPm2 from Penaeus monodon possesses antiviral activity against WSSV

A 5-domain Kazal type serine proteinase inhibitor SPIPm2 from Penaeus monodon is involved in innate immune defense against white spot syndrome virus (WSSV). To test which domains were involved, the 5 domains of SPIPm2 were over-expressed and tested against WSSV infection. By using hemocyte primary cell culture treated with each recombinant SPIPm2 domain along with WSSV, the expression of WSSV early genes ie1, WSV477 and late gene VP28 were substantially reduced as compared to other domains when the recombinant domain 2, rSPIPm2D2, was used. Injecting the WSSV along with rSPIPm2D2 but not with other domains caused delay in mortality rate of the infected shrimp. The results indicate that the SPIPm2D2 possesses strong antiviral activity and, hence, contributes predominantly to the antiviral activity of SPIPm2.

PtSerpin from the swimming crab Portunus trituberculatus, a putative regulator of prophenoloxidase activation with antibacterial activity

Serpin or serine protease inhibitor is the largest family of protease inhibitors involved in many innate immune pathways, particularly the prophenoloxidase (proPO) activating system in arthropod. Here, we report the molecular and functional characterization of PtSerpin identified from the swimming crab Portunus trituberculatus. The genomic sequence encoding mature peptide of PtSerpin gene contained two exons of 84 and 1098 bp separated by one intron of 111 bp. The recombinant PtSerpin (rPtSerpin) with a predicted size of 44 kDa was expressed in Escherichia coli system, purified and assayed for its activities. The rPtSerpin exhibited inhibitory activity against trypsin in a dose-dependent manner, but did not affect chymotrypsin, which could define a role for PtSerpin as a trypsin inhibitor. The rPtSerpin could inhibit the growth of Gram-negative bacterium Vibrio alginolyticus, but not the tested Gram-positive bacterium and fungus. Further phenoloxidase (PO) assay showed PO activity was dramatically increased in hemocyte lysate supernatant of P. trituberculatus upon bacterial challenge. The rPtSerpin could depress the crab proPO system activation in vitro, and it could lead to 100% inhibition of PO activity under the concentration of 8.62 μM. Moreover, the rPtSerpin was able to inhibit the PO activity induced by rPtcSP and rPtSPH1. These results together indicate that PtSerpin is a potential trypsin inhibitor and may participate in crab innate immunity by the inhibition of bacterial growth and the regulation of proPO system.

A comparative proteomic analysis of the soluble immune factor environment of rectal and oral mucosa

Objective

Sexual transmission of HIV occurs across a mucosal surface, which contains many soluble immune factors important for HIV immunity. Although the composition of mucosal fluids in the vaginal and oral compartments has been studied extensively, the knowledge of the expression of these factors in the rectal mucosa has been understudied and is very limited. This has particular relevance given that the highest rates of HIV acquisition occur via the rectal tract. To further our understanding of rectal mucosa, this study uses a proteomics approach to characterize immune factor components of rectal fluid, using saliva as a comparison, and evaluates its antiviral activity against HIV.

Methods

Paired salivary fluid (n = 10) and rectal lavage fluid (n = 10) samples were collected from healthy, HIV seronegative individuals. Samples were analyzed by label-free tandem mass spectrometry to comprehensively identify and quantify mucosal immune protein abundance differences between saliva and rectal fluids. The HIV inhibitory capacity of these fluids was further assessed using a TZM-bl reporter cell line.

Results

Of the 315 proteins identified in rectal lavage fluid, 72 had known immune functions, many of which have described anti-HIV activity, including cathelicidin, serpins, cystatins and antileukoproteinase. The majority of immune factors were similarly expressed between fluids, with only 21 differentially abundant (p<0.05, multiple comparison corrected). Notably, rectal mucosa had a high abundance of mucosal immunoglobulins and antiproteases relative to saliva, Rectal lavage limited HIV infection by 40–50% in vitro (p<0.05), which is lower than the potent anti-HIV effect of oral mucosal fluid (70–80% inhibition, p<0.005).

Conclusions

This study reveals that rectal mucosa contains many innate immune factors important for host immunity to HIV and can limit viral replication in vitro. This indicates an important role for this fluid as the first line of defense against HIV.

Increased Serpin A5 levels in the cervicovaginal fluid of HIV-1 exposed seronegatives suggest that a subtle balance between serine proteases and their inhibitors may determine susceptibility to HIV-1 infection

HIV-exposed seronegative individuals (HESNs) are persons who remain seronegative despite repeated exposure to HIV, suggesting an in vivo resistance mechanism to HIV. Elucidation of endogenous factors responsible for this phenomenon may aid in the development of new classes of microbicides and therapeutics. We compared cervicovaginal protein abundance profiles between high-risk HESN and two control groups: low-risk HESN and HIV-positives. Four iTRAQ-based quantitative experiments were performed using samples classified based on presence/absence of particular gynaecological conditions. After statistical analysis, two proteins were shown to be differentially abundant between high-risk HESNs and control groups. Serpin A5, a serine proteinase inhibitor and Myeloblastin, a serine protease, were up- and downregulated, respectively. Commercially available ELISA assays were used to confirm differential Serpin A5 levels. These results suggest that HIV resistance in CVF of HESNs is the result of a delicate balance between two complementary mechanisms: downregulation of serine proteinases and upregulation of their inhibitors.

Serpins, immunity and autoimmunity: old molecules, new functions

Serine protease inhibitors (serpins) are evolutionary old, structurally conserved molecules which encompass nearly all branches of life. More than 1,000 serpins were characterized to date which are subdivided into 16 subgroups (A-P) according to their common ancestry; among them, 37 are found in humans. Serpins were termed after their capability to inhibit serine proteases, but mounting evidence suggests that they may achieve a greater deal of functions, ranging from embryological growth to synaptic plasticity, development of both myeloid and lymphoid immune cells, and modulation of apoptosis. Serpins are mainly extracellular molecules, although some of them (namely, ov-serpins or clade B serpins) mostly act inside the cells, being either ubiquitously or tissue-specifically expressed. Among newly characterized serpin functions, regulation of cellular proliferation through apoptosis modulation and proteasome disturbance seems to play a major role. Accordingly, several serpins were found to be hyperexpressed in tumor cells. Indeed, apoptosis dysregulation is likely to be a cornerstone in both tumorigenesis and autoimmunity, since uncontrolled cellular viability results in tumor proliferation, while inefficient disposal of apoptotic debris may favor the rescue of autoreactive immune cells. Such a process was widely documented in systemic lupus erythematosus (SLE). Interestingly, alterations in the expression of some serpins, e.g., the ov-serpin SERPINB3, are being unraveled in patients affected with SLE and other autoimmune disorders, suggesting that a failure in serpin function might affect immune homeostasis and self-tolerance, thereby contributing to autoimmunity. Here, we provide an overview of serpin origin, function, and dysfunction, focusing on human serpins and ov-serpins, with a hub on SERPINB3.

Identification, characterization and functional analysis of a serine protease inhibitor (Lvserpin) from the Pacific white shrimp, Litopenaeus vannamei

As important arthropod immune responses, prophenoloxidase (proPO) activation and Toll pathway initiation are mediated by serine proteinase cascades and regulated by serpins. Herein, a serine protease inhibitor (Lvserpin), encoding for 415 amino acids with calculated molecular weight of 46,639 Da and isoelectric point of 7.03 was characterized from the Pacific white shrimp Litopenaeus vannamei. Multiple sequence alignment revealed that Lvserpin shared the highest similarity with Penaeus monodon serpin6 (87%). Quantitative real-time PCR (qRT-PCR) results showed that the transcripts of Lvserpin were detected in all the examined tissues and most highly expressed in gill. The expression profiles of Lvserpin were greatly fluctuated upon infection of Vibrio anguillarum, Micrococcus lysoleikticus or White Spot Syndrome Virus (WSSV). Double stranded RNA-mediated suppression of Lvserpin resulted in a significant increase in the transcripts of two clip-domain serine proteinases (PPAE and PPAF), prophenoloxidase (proPO), anti-lipopolysaccharide factor (ALF), Crustin and penaeidin3 (Pens3) and also increased the high cumulative mortality post V. anguillarum injection. Besides, the recombinant Lvserpin protein (rLvserpin) was purified and exhibited inhibitory activity against trypsin. Also the rLvserpin showed inhibition on prophenoloxidase activation and bacterial growth. Hence, we proposed that the Lvserpin played important role in the shrimp innate immunity.

Are all granzymes cytotoxic in vivo?

Granzymes are serine proteases mainly found in cytotoxic lymphocytes. The most-studied member of this group is granzyme B, which is a potent cytotoxin that has set the paradigm that all granzymes are cyototoxic. In the last 5 years, this paradigm has become controversial. On one hand, there is a plethora of sometimes contradictory publications showing mainly caspase-independent cytotoxic effects of granzyme A and the so-called orphan granzymes in vitro. On the other hand, there are increasing numbers of reports of granzymes failing to induce cell death in vitro unless very high (potentially supra-physiological) concentrations are used. Furthermore, experiments with granzyme A or granzyme M knock-out mice reveal little or no deficit in their cytotoxic lymphocytes’ killing ability ex vivo, but indicate impairment in the inflammatory response. These findings of non-cytotoxic effects of granzymes challenge dogma, and thus require alternative or additional explanations to be developed of the role of granzymes in defeating pathogens. Here we review evidence for granzyme cytotoxicity, give an overview of their non-cytotoxic functions, and suggest technical improvements for future investigations.

Proteome changes in the intestinal mucosa of broiler (Gallus gallus) activated by probiotic Enterococcus faecium

Probiotics are supplemented to animal diet to support a well-balanced gut microbiota, finally contributing to improved health. The molecular mechanism of probiotics in animal intestine improvement is yet unclear. We investigated the production parameters, gut morphology and microbiota, and mucosal proteome of Arbor Acres broilers (Gallus gallus) supplemented with Enterococcus faecium by performing denaturing gradient gel electrophoresis, quantitative real-time PCR, two-dimensional fluorescence difference gel electrophoresis, and mass spectrometry. E. faecium supplementation promoted the development of immune organs and gut microvilli and enlarged the gut microbial diversity and population. However, it had no effects on daily weight gain and feed intake, and slightly enhanced feed conversion ratio. A total of 42 intestinal mucosal proteins were found to be differentially abundant. Four of them are related to intestinal structure and may extend the absorptive surface area. Of 17 differential proteins related to immune and antioxidant systems, only six are abundant in the broilers fed E. faecium, indicating that these chickens employ less nutrients and energy to deal with immune and antioxidant stresses. These findings have important implications for understanding the probiotic mechanisms of E. faecium on broiler intestine.

BIOLOGICAL SIGNIFICANCE

Probiotic supplementation to animal diet is closely related with improved health. The objective of this study is to determine the molecular mechanisms of probiotic E. faecium achieving its biological mission in the gut of Arbor Acres broilers (G. gallus). E. faecium supplementation did not improve daily weight gain and feed intake; however, it had effects on immune organ and gut microvillus development, and gut microbial diversity and population. Quantitative proteomic analysis of the intestinal mucosa of broilers treated with E. faecium identified 42 intestinal mucosal proteins related to substance metabolism, immune and antioxidant systems, and cell structure. This study identified the E. faecium derived probiotic mechanism on the proteome level.

An insight into the changes in human plasma proteome on adaptation to hypobaric hypoxia

Adaptation to hypobaric hypoxia is required by animals and human in several physiological and pathological situations. Hypobaric hypoxia is a pathophysiological condition triggering redox status disturbances of cell organization leading, via oxidative stress, to proteins, lipids, and DNA damage. Identifying the molecular variables playing key roles in this process would be of paramount importance to shed light on the mechanisms known to counteract the negative effects of oxygen lack. To obtain a molecular signature, changes in the plasma proteome were studied by using proteomic approach. To enrich the low-abundance proteins in human plasma, two highly abundant proteins, albumin and IgG, were first removed. By comparing the plasma proteins of high altitude natives with those of a normal control group, several proteins with a significant alteration were found. The up-regulated proteins were identified as vitamin D-binding protein, hemopexin, alpha-1-antitrypsin, haptoglobin β-chain, apolipoprotein A1, transthyretin and hemoglobin beta chain. The down-regulated proteins were transferrin, complement C3, serum amyloid, complement component 4A and plasma retinol binding protein. Among these proteins, the alterations of transthyretin and transferrin were further confirmed by ELISA and Western blotting analysis. Since all the up- and down- regulated proteins identified above are well-known inflammation inhibitors and play a positive anti-inflammatory role, these results show that there is some adaptive mechanism that sustains the inflammation balance in high altitude natives exposed to hypobaric hypoxia.

A systems biology examination of the human female genital tract shows compartmentalization of immune factor expression

Many mucosal factors in the female genital tract (FGT) have been associated with HIV susceptibility, but little is known about their anatomical distribution in the FGT compartments. This study comprehensively characterized global immune factor expression in different tissue sites of the lower and upper FGT by using a systems biology approach. Tissue sections from the ectocervix, endocervix, and endometrium from seven women who underwent hysterectomy were analyzed by a combination of quantitative mass spectrometry and immunohistochemical staining. Of the >1,000 proteins identified, 281 were found to be differentially abundant in different tissue sites. Hierarchical clustering identified four major functional pathways distinguishing compartments, including innate immune pathways (acute-phase response, LXR/RXR) and development (RhoA signaling, gluconeogenesis), which were enriched in the ectocervix/endocervix and endometrium, respectively. Immune factors important for HIV susceptibility, including antiproteases, immunoglobulins, complement components, and antimicrobial factors, were most abundant in the ectocervix/endocervix, while the endometrium had a greater abundance of certain factors that promote HIV replication. Immune factor abundance is heterogeneous throughout the FGT and shows unique immune microenvironments for HIV based on the exposure site. This may have important implications for early events in HIV transmission and site-specific susceptibility to HIV in the FGT.

Cholesteatoma growth and proliferation: relevance with serpin B3

OBJECTIVES/HYPOTHESIS

The mechanisms of cholesteatoma proliferation and growth remain unclear. The objective of this study is to discover the potential mechanisms of the proliferation and growth of cholesteatoma by direct experimental assessments on cholesteatoma tissues from patients.

STUDY DESIGN

Retrospective study by the comparisons between cholesteatoma tissues and retroauricular skin tissues from the patients.

METHODS

Two-dimensional gel electrophoresis, LC-MS/MS analysis and immunohistochemistry were performed to investigate specific protein expression in cholesteatoma tissues compared with retroauricular skin tissues collected from the patients. Western blotting analysis was conducted to verify the regulation of specific proteins found by 2-DE, and to determine the changes of associated potential modulators in cholesteatoma proliferation and growth.

RESULTS

Twelve serpin B3 isoforms were found by 2-DE and identified by LC-MS/MS analysis, which is coherent with the results exhibited by immunohistochemistry and western blot. Up-regulation of STAT3 and down-regulations of cathepsin K and cathepsin L were represented using western blot.

CONCLUSIONS

The data in this study suggested serpin B3, STAT3, cathepsin K, and cathepsin L are associated with the proliferation and growth of cholesteatoma, and these proteins may be influential factors in cholesteatoma growth.

Bovine neonatal pancytopenia--comparative proteomic characterization of two BVD vaccines and the producer cell surface proteome (MDBK)

Background

Bovine neonatal pancytopenia (BNP) is a disease syndrome in newborn calves of up to four weeks of age, first observed in southern Germany in 2006. By now, cases have been reported in several countries around the globe. Many affected calves die within days due to multiple haemorrhages, thrombocytopenia, leukocytopenia and bone marrow depletion. A certain vaccine directed against Bovine Virus Diarrhoea Virus (BVDV) was recently shown to be associated with BNP pathogenesis. Immunized cows develop alloantibodies that are transferred to newborn calves via colostrum intake. In order to further elucidate BNP pathogenesis, the purpose of this study was to characterize and compare the protein composition of the associated vaccine to another vaccine directed against BVDV not related to BNP and the cell surface proteome of MDBK (Madin-Darby Bovine Kidney) cells, the cell line used for production of the associated vaccine.

Results

By SDS-PAGE and mass spectrometry, we were able to detect several coagulation-related and immune modulatory proteins, as well as cellular and serum derived molecules being shared between the associated vaccine and MDBK cells. Furthermore, the number of proteins identified in the BNP related vaccine was almost as high as the number of surface proteins detected on MDBK cells and exceeded the amount of proteins identified in the non-BNP related vaccine over 3.5 fold. The great amount of shared cellular and serum derived proteins confirm that the BNP associated vaccine contained many molecules originating from MDBK cells and vaccine production.

Conclusions

The respective vaccine was not purified enough to prevent the development of alloantibodies. To narrow down possible candidate proteins, those most likely to represent a trigger for BNP pathogenesis are presented in this study, giving a fundament for further analysis in future research.

The biochemical and immunological characterization of two serpins from Clonorchis sinensis

Serpins (serine proteinase inhibitors) are evidenced to regulate numerous biological processes such as immunoregulation in parasitic helminths. The functions of serpins from Clonorchis sinensis remain unclear to date. In this study, two serpin genes, respectively denominated as CsproSERPIN and CsSERPIN2, had been selected from metacercaria cDNA library of C. sinensis. The biochemical activities of both recombinant proteins (rCsproSERPIN and rCsSERPIN2) were analyzed by assays of inhibition on some serine or cysteine proteases, the results showed that rCsproSERPIN significantly inhibited trypsin, chymotrypsin and thrombin, while rCsSERPIN2 inhibited only chymotrypsin. Moreover, cytokine and antibody measurements indicated that rats subcutaneously immunized with rCsproSERPIN and rCsSERPIN2 respectively developed a strong IFN-γ production and IgG2a levers of sera were higher than IgG1. Besides, immunoblot assays revealed that the rCsproSERPIN and rCsSERPIN2 could be recognized by the sera of rats infected with C. sinensis and the sera of rabbits immunized by excretory/secretory products. Furthermore, immunofluorescence assays illuminated the two were similarly localized in the reproductive organs such as vitelline glands, testis and eggs in adult stage. In short, all the results collectively indicated that CsproSERPIN and CsSERPIN2 might play important role in the parasite development by preventing the parasite from digestion by exogenous serine proteases, as well as CsproSERPIN and CsSERPIN2 probably involved in immunoregulation of host by inducing Th1-biased type cytokines in rats.

Proteomic and systems biology analysis of monocytes exposed to securinine, a GABA(A) receptor antagonist and immune adjuvant

Securinine, a GABA(A) receptor antagonist, has been reported to enhance monocyte cell killing of Coxiella burnetii without obvious adverse effects in vivo. We employed multiplex 2D gel electrophoresis using Zdyes, a new generation of covalently linked fluorescent differential protein detection dyes to analyze changes in the monocyte proteome in response to Securinine. Securinine antagonism of GABA(A) receptors triggers the activation of p38. We used the differential protein expression results to guide a search of the literature and network analysis software to construct a systems biology model of the effect of Securinine on monocytes. The model suggests that various metabolic modulators (fatty acid binding protein 5, inosine 5'-monophosphate dehydrogenase, and thioredoxin) are at least partially reshaping the metabolic landscape within the monocytes. The actin bundling protein L-plastin, and the Ca(2+) binding protein S100A4 also appear to have important roles in the immune response stimulated by Securinine. Fatty acid binding protein 5 (FABP5) may be involved in effecting lipid raft composition, inflammation, and hormonal regulation of monocytes, and the model suggests that FABP5 may be a central regulator of metabolism in activated monocytes. The model also suggests that the heat shock proteins have a significant impact on the monocyte immune response. The model provides a framework to guide future investigations into the mechanisms of Securinine action and with elaboration may help guide development of new types of immune adjuvants.