Identification of a Novel Human Granzyme B Inhibitor Secreted by Cultured Sertoli Cells

Granzyme serine proteases in inflammation and rheumatic diseases

Granzymes (granule-secreted enzymes) are a family of serine proteases that have been viewed as redundant cytotoxic enzymes since their discovery more than 30 years ago. Predominantly produced by cytotoxic lymphocytes and natural killer cells, granzymes are delivered into the cytoplasm of target cells through immunological synapses in cooperation with the pore-forming protein perforin. After internalization, granzymes can initiate cell death through the cleavage of intracellular substrates. However, evidence now also demonstrates the existence of non-cytotoxic, pro-inflammatory, intracellular and extracellular functions that are granzyme specific. Under pathological conditions, granzymes can be produced and secreted extracellularly by immune cells as well as by non-immune cells. Depending on the granzyme, accumulation in the extracellular milieu might contribute to inflammation, tissue injury, impaired wound healing, barrier dysfunction, osteoclastogenesis and/or autoantigen generation.

Mating-Induced Common and Sex-Specific Behavioral, Transcriptional Changes in the Moth Fall Armyworm (Spodoptera frugiperda, Noctuidae, Lepidoptera) in Laboratory

The intermediate process between mating and postmating behavioral changes in insects is still poorly known. Here, we studied mating-induced common and sex-specific behavioral and transcriptional changes in both sexes of Spodoptera frugiperda and tested whether the transcriptional changes are linked to postmating behavioral changes in each sex. A behavioral study showed that mating caused a temporary suppression of female calling and male courting behavior, and females did not lay eggs until the next day after the first mating. The significant differences on daily fecundity under the presence of males or not, and the same or novel males, suggest that females may intentionally retain eggs to be fertilized by novel males or to be fertilized competitively by different males. RNA sequencing in females revealed that there are more reproduction related GO (gene ontology) terms and KEGG (Kyoto encyclopedia of genes and genomes) pathways (mainly related to egg and zygote development) enriched to upregulated DEGs (differentially expressed genes) than to downregulated DEGs at 0 and 24 h postmating. In males, however, mating induced DEGs did not enrich any reproduction related terms/pathways, which may be because male reproductive bioinformatics is relatively limited in moths. Mating also induced upregulation on soma maintenance (such as immune activity and stress reaction) related processes in females at 0, 6 and 24 h postmating. In males, mating also induced upregulation on soma maintenance related processes at 0 h postmating, but induced downregulation on these processes at 6 and 24 h postmating. In conclusion, this study demonstrated that mating induced sex-specific postmating behavioral and transcriptional changes in both sexes of S. frugiperda and suggested that the transcriptional changes are correlated with postmating physiological and behavioral changes in each sex.

Complementing Testicular Immune Regulation: The Relationship between Sertoli Cells, Complement, and the Immune Response

Sertoli cells within the testis are instrumental in providing an environment for spermatogenesis and protecting the developing germ cells from detrimental immune responses which could affect fertility. Though these immune responses consist of many immune processes, this review focuses on the understudied complement system. Complement consists of 50+ proteins including regulatory proteins, immune receptors, and a cascade of proteolytic cleavages resulting in target cell destruction. In the testis, Sertoli cells protect the germ cells from autoimmune destruction by creating an immunoregulatory environment. Most studies on Sertoli cells and complement have been conducted in transplantation models, which are effective in studying immune regulation during robust rejection responses. In grafts, Sertoli cells survive activated complement, have decreased deposition of complement fragments, and express many complement inhibitors. Moreover, the grafts have delayed infiltration of immune cells and contain increased infiltration of immunosuppressive regulatory T cells as compared to rejecting grafts. Additionally, anti-sperm antibodies and lymphocyte infiltration have been detected in up to 50% and 30% of infertile testes, respectively. This review seeks to provide an updated overview of the complement system, describe its relationship with immune cells, and explain how Sertoli cells may regulate complement in immunoprotection. Identifying the mechanism Sertoli cells use to protect themselves and germ cells against complement and immune destruction is relevant for male reproduction, autoimmunity, and transplantation.

Beyond target cell death - Granzyme serine proteases in health and disease

Granzymes are a family of small (∼32 kDa) serine proteases with a range of substrate specificities that are stored in, and released from, the cytoplasmic secretory vesicles ('granules') of cytotoxic T lymphocytes and natural killer cells. Granzymes are not digestive proteases but finely tuned processing enzymes that target their substrates in specific ways to activate various signalling pathways, or to inactivate viral proteins and other targets. Great emphasis has been placed on studying the pro-apoptotic functions of granzymes, which largely depend on their synergy with the pore-forming protein perforin, on which they rely for penetration into the target cell cytosol to access their substrates. While a critical role for granzyme B in target cell apoptosis is undisputed, both it and the remaining granzymes also influence a variety of other biological processes (including important immunoregulatory functions), which are discussed in this review. This includes the targeting of many extracellular as well as intracellular substrates, and can also lead to deleterious outcomes for the host if granzyme expression or function are dysregulated or abrogated. A final important consideration is that granzyme repertoire, biochemistry and function vary considerably across species, probably resulting from the pressures applied by viruses and other pathogens across evolutionary time. This has implications for the interpretation of granzyme function in preclinical models of disease.

Granzyme B as a therapeutic target: an update in 2022

INTRODUCTION

Granzyme B is a serine protease extensively studied for its implication in cytotoxic lymphocyte-mediated apoptosis. In recent years, the paradigm that the role of granzyme B is restricted to immune cell-mediated killing has been challenged as extracellular roles for the protease have emerged. While mostly absent from healthy tissues, granzyme B levels are elevated in several autoimmune and/or chronic inflammatory conditions. In the skin, its accumulation significantly impairs proper wound healing.

AREAS COVERED

After an overview of the current knowledge on granzyme B, a description of newly identified functions will be presented, focussing on granzyme B ability to promote cell-cell and dermal-epidermal junction disruption, extracellular matrix degradation, vascular permeabilization, and epithelial barrier dysfunction. Progress in granzyme B inhibition, as well as the use of granzyme B inhibitors for the treatment of tissue damage, will be discussed.

EXPERT OPINION

The absence of endogenous extracellular inhibitors renders extracellular granzyme B accumulation deleterious for the proper healing of chronic wounds due to sustained proteolytic activity. Consequently, specific granzyme B inhibitors have been developed as new therapeutic approaches. Beyond applications in wound healing, other autoimmune and/or chronic inflammatory conditions related to exacerbated granzyme B activity may also benefit from the development of these inhibitors.

Noncytotoxic Roles of Granzymes in Health and Disease

Granzymes are serine proteases previously believed to play exclusive and somewhat redundant roles in lymphocyte-mediated target cell death. However, recent studies have challenged this paradigm. Distinct substrate profiles and functions have since emerged for each granzyme while their dysregulated proteolytic activities have been linked to diverse pathologies.

Reprogramming alveolar macrophage responses to TGF-β reveals CCR2+ monocyte activity that promotes bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major impediment to lung transplant survival and is generally resistant to medical therapy. Extracorporeal photophoresis (ECP) is an immunomodulatory therapy that shows promise in stabilizing BOS patients, but its mechanisms of action are unclear. In a mouse lung transplant model, we show that ECP blunts alloimmune responses and inhibits BOS through lowering airway TGF-β bioavailability without altering its expression. Surprisingly, ECP-treated leukocytes were primarily engulfed by alveolar macrophages (AMs), which were reprogrammed to become less responsive to TGF-β and reduce TGF-β bioavailability through secretion of the TGF-β antagonist decorin. In untreated recipients, high airway TGF-β activity stimulated AMs to express CCL2, leading to CCR2+ monocyte-driven BOS development. Moreover, we found TGF-β receptor 2-dependent differentiation of CCR2+ monocytes was required for the generation of monocyte-derived AMs, which in turn promoted BOS by expanding tissue-resident memory CD8+ T cells that inflicted airway injury through Blimp-1-mediated granzyme B expression. Thus, through studying the effects of ECP, we have identified an AM functional plasticity that controls a TGF-β-dependent network that couples CCR2+ monocyte recruitment and differentiation to alloimmunity and BOS.

Potential role of extracellular granzyme B in wet age-related macular degeneration and fuchs endothelial corneal dystrophy

Age-related ocular diseases are the leading cause of blindness in developed countries and constitute a sizable socioeconomic burden worldwide. Age-related macular degeneration (AMD) and Fuchs endothelial corneal dystrophy (FECD) are some of the most common age-related diseases of the retina and cornea, respectively. AMD is characterized by a breakdown of the retinal pigment epithelial monolayer, which maintains retinal homeostasis, leading to retinal degeneration, while FECD is characterized by degeneration of the corneal endothelial monolayer, which maintains corneal hydration status, leading to corneal edema. Both AMD and FECD pathogenesis are characterized by disorganized local extracellular matrix (ECM) and toxic protein deposits, with both processes linked to aberrant protease activity. Granzyme B (GrB) is a serine protease traditionally known for immune-mediated initiation of apoptosis; however, it is now recognized that GrB is expressed by a variety of immune and non-immune cells and aberrant extracellular localization of GrB substantially contributes to various age-related pathologies through dysregulated cleavage of ECM, tight junction, and adherens junction proteins. Despite growing recognition of GrB involvement in multiple age-related pathologies, its role in AMD and FECD remains poorly understood. This review summarizes the pathophysiology of, and similarities between AMD and FECD, outlines the current knowledge of the role of GrB in AMD and FECD, as well as hypothesizes putative contributions of GrB to AMD and FECD pathogenesis and highlights the therapeutic potential of pharmacologically inhibiting GrB as an adjunctive treatment for AMD and FECD.

Downregulation of Sepina3n Aggravated Blood-Brain Barrier Disruption after Traumatic Brain Injury by Activating Neutrophil Elastase in Mice

Traumatic brain injury (TBI) is the leading cause of death in young adults and the main cause of mortality and disability across all ages worldwide. We previously analyzed the expression profile data of TBI models obtained from the Gene Expression Omnibus (GEO) database and found that the seripina3n mRNA was markedly upregulated in the acute phase of TBI in four mRNA expression profile data sets, indicating that serpina3n may be involved in the pathophysiological process of TBI. Therefore, we further investigated the biological role and molecular mechanism of serpina3n in traumatic brain injury in this study. As a result, the endogenous level of sepina3n was markedly elevated in the cortex around the contusion sit in mice at day 1 and day 3 after TBI. Inhibiting the expression of serpina3n caused aggravation of neutrophil elastase (NE) expression, BBB disruption, and neurological deficit. With the inactivation of NE, even if serpina3n was silenced, the disruption of the BBB was not further aggravated. In vitro experiments further proved that recombinant serpina3n dose-dependently inhibited the activity of recombinant NE. Based on the above, this study demonstrated that the endogenous level of sepina3n was significantly elevated in the cortex around the contusion sit after TBI in mice, which reduced the secondary blood-brain barrier disruption by inhibiting the activity of neutrophil elastase.

Sertoli Cell Immune Regulation: A Double-Edged Sword

The testis must create and maintain an immune privileged environment to protect maturing germ cells from autoimmune destruction. The establishment of this protective environment is due, at least in part, to Sertoli cells. Sertoli cells line the seminiferous tubules and form the blood-testis barrier (BTB), a barrier between advanced germ cells and the immune system. The BTB compartmentalizes the germ cells and facilitates the appropriate microenvironment necessary for spermatogenesis. Further, Sertoli cells modulate innate and adaptive immune processes through production of immunoregulatory compounds. Sertoli cells, when transplanted ectopically (outside the testis), can also protect transplanted tissue from the recipient’s immune system and reduce immune complications in autoimmune diseases primarily by immune regulation. These properties make Sertoli cells an attractive candidate for inflammatory disease treatments and cell-based therapies. Conversely, the same properties that protect the germ cells also allow the testis to act as a reservoir site for infections. Interestingly, Sertoli cells also have the ability to mount an antimicrobial response, if necessary, as in the case of infections. This review aims to explore how Sertoli cells act as a double-edged sword to both protect germ cells from an autoimmune response and activate innate and adaptive immune responses to fight off infections.

Therapeutical Significance of Serpina3n Subsequent Cerebral Ischemia via Cytotoxic Granzyme B Inactivation

Ischemic stroke is a devastating CNS insult with few clinical cures. Poor understanding of underlying mechanistic network is the primary limitation to develop novel curative therapies. Extracellular accumulation of granzyme B subsequent ischemia promotes neurodegeneration. Inhibition of granzyme B can be one of the potent strategies to mitigate neuronal damage. In present study, we investigated the effect of murine Serpina3n and human (homolog) SERPINA3 against cerebral ischemia through granzyme B inactivation. Recombinant Serpina3n/SERPINA3 were expressed by transfected 293 T cells, and eluted proteins were examined for postischemic influence both in vitro and in vivo. During in vitro test, Serpina3n was found effective enough to inhibit granzyme B, while SERPINA3 was ineffectual to counter cytotoxic protease. Treatment of hypoxic culture with recombinant Serpina3n/SERPINA3 significantly increased cell viability in dosage-dependent manner, recorded maximum at the highest concentration (4 mM). Infarct volume analysis confirmed that 50 mg/kg dosage of exogenous Serpina3n was adequate to reduce disease severity, while SERPINA3 lacked behind in analeptic effect. Immunohistochemical test, western blot analysis, and protease activity assay’s results illustrated successful diffusion of applied protein to the ischemic lesion and reactivity with the target protease. Taken together, our findings demonstrate therapeutic potential of Serpina3n by interfering granzyme B-mediated neuronal death subsequent cerebral ischemia.

Granzyme B in Epithelial Barrier Dysfunction and Related Skin Diseases

The predominant function of the skin is to serve as a barrier - to protect against external insults and to prevent water loss. Junctional and structural proteins in the stratum corneum, the outermost layer of the epidermis, are critical to the integrity of the epidermal barrier as it balances ongoing outward migration, differentiation, and desquamation of keratinocytes in the epidermis. As such, epidermal barrier function is highly susceptible to upsurges of proteolytic activity in the stratum corneum and epidermis. Granzyme B is a serine protease scarce in healthy tissues but present at high levels in tissues encumbered by chronic inflammation. Discovered in the 1980s, Granzyme B is currently recognized for its intracellular roles in immune cell-mediated targeted apoptosis as well as extracellular roles in inflammation, chronic injuries, tissue remodeling, and processing of cytokines, matrix proteins, and autoantigens. Increasing evidence has emerged in recent years supporting a role for Granzyme B in promoting barrier dysfunction in the epidermis by direct cleavage of barrier proteins and eliciting immunoreactivity. Likewise, Granzyme B contributes to impaired epithelial function of the airways, retina, gut and vessels. In the present review, the role of Granzyme B in cutaneous epithelial dysfunction is discussed in the context of specific conditions with an overview of underlying mechanisms as well as utility of current experimental and therapeutic inhibitors.

Contact-Dependent Granzyme B-Mediated Cytotoxicity of Th17-Polarized Cells Toward Human Oligodendrocytes

Multiple sclerosis (MS) is characterized by the loss of myelin and of myelin-producing oligodendrocytes (OLs) in the central nervous system (CNS). Pro-inflammatory CD4+ Th17 cells are considered pathogenic in MS and are harmful to OLs. We investigated the mechanisms driving human CD4+ T cell-mediated OL cell death. Using fluorescent and brightfield in vitro live imaging, we found that compared to Th2-polarized cells, Th17-polarized cells show greater interactions with primary human OLs and human oligodendrocytic cell line MO3.13, displaying longer duration of contact, lower mean speed, and higher rate of vesicle-like structure formation at the sites of contact. Using single-cell RNA sequencing, we assessed the transcriptomic profile of primary human OLs and Th17-polarized cells in direct contact or separated by an insert. We showed that upon close interaction, OLs upregulate the expression of mRNA coding for chemokines and antioxidant/anti-apoptotic molecules, while Th17-polarized cells upregulate the expression of mRNA coding for chemokines and pro-inflammatory cytokines such as IL-17A, IFN-γ, and granzyme B. We found that secretion of CCL3, CXCL10, IFN-γ, TNFα, and granzyme B is induced upon direct contact in cocultures of human Th17-polarized cells with human OLs. In addition, we validated by flow cytometry and immunofluorescence that granzyme B levels are upregulated in Th17-polarized compared to Th2-polarized cells and are even higher in Th17-polarized cells upon direct contact with OLs or MO3.13 cells compared to Th17-polarized cells separated from OLs by an insert. Moreover, granzyme B is detected in OLs and MO3.13 cells following direct contact with Th17-polarized cells, suggesting the release of granzyme B from Th17-polarized cells into OLs/MO3.13 cells. To confirm granzyme B–mediated cytotoxicity toward OLs, we showed that recombinant human granzyme B can induce OLs and MO3.13 cell death. Furthermore, pretreatment of Th17-polarized cells with a reversible granzyme B blocker (Ac-IEPD-CHO) or a natural granzyme B blocker (serpina3N) improved survival of MO3.13 cells upon coculture with Th17 cells. In conclusion, we showed that human Th17-polarized cells form biologically significant contacts with human OLs and exert direct toxicity by releasing granzyme B.

Integrated Multiomics Analysis Identifies a Novel Biomarker Associated with Prognosis in Intracerebral Hemorrhage

Existing treatments for intracerebral hemorrhage (ICH) are unable to satisfactorily prevent development of secondary brain injury after ICH and multiple pathological mechanisms are involved in the development of the injury. In this study, we aimed to identify novel genes and proteins and integrated their molecular alternations to reveal key network modules involved in ICH pathology. A total of 30 C57BL/6 male mice were used for this study. The collagenase model of ICH was employed, 3 days after ICH animals were tested neurological. After it, animals were euthanized and perihematomal brain tissues were collected for transcriptome and TMT labeling-based quantitative proteome analyses. Protein-protein interaction (PPI) network, Gene Set Enrichment Analysis (GSEA), and regularized Canonical Correlation Analysis (rCCA) were performed to integrated multiomics data. For validation of hub genes and proteins, qRT-PCR and Western blot were carried out. The candidate biomarkers were further measured by ELISA in the plasma of ICH patients and the controls. A total of 2218 differentially expressed genes (DEGs) and 353 differentially expressed proteins (DEPs) between the ICH model group and control group were identified. GSEA revealed that immune-related gene sets were prominently upregulated and significantly enriched in pathways of inflammasome complex, negative regulation of interleukin-12 production, and pyroptosis during the ICH process. The rCCA network presented two highly connective clusters which were involved in the sphingolipid catabolic process and inflammatory response. Among ten hub genes screened out by integrative analysis, significantly upregulated Itgb2, Serpina3n, and Ctss were validated in the ICH group by qRT-PCR and Western blot. Plasma levels of human SERPINA3 (homologue of murine Serpina3n) were elevated in ICH patients compared with the healthy controls (SERPINA3: 13.3 ng/mL vs. 11.2 ng/mL, p = 0.015). Within the ICH group, higher plasma SERPINA3 levels with a predictive threshold of 14.31 ng/mL (sensitivity = 64.3%; specificity = 80.8%; AUC = 0.742, 95% CI: 0.567-0.916) were highly associated with poor outcome (mRS scores 4-6). Taken together, the results of our study exhibited molecular changes related to ICH-induced brain injury by multidimensional analysis and effectively identified three biomarker candidates in a mouse ICH model, as well as pointed out that Serpina3n/SERPINA3 was a potential biomarker associated with poor functional outcome in ICH patients.

Somatic-Immune Cells Crosstalk In-The-Making of Testicular Immune Privilege

Immunological infertility contributes significantly to the etiology of idiopathic male infertility. Shielding the spermatogenic cells from systemic immune responses is fundamental to secure normal production of spermatozoa. The body's immune system is tuned with the host self-components since the early postnatal period, while sperm first develops during puberty, thus rendering spermatogenic proteins as 'non-self' or 'antigenic.' Development of antibodies to these antigens elicits autoimmune responses affecting sperm motility, functions, and fertility. Therefore, the testes need to establish a specialized immune-privileged microenvironment to protect the allogenic germ cells by orchestration of various testicular cells and resident immune cells. This is achieved through sequestration of antigenic germ cells by blood-testis barrier and actions of various endocrine, paracrine, immune-suppressive, and immunomodulatory mechanisms. The various mechanisms are very complex and need conceptual integration to disclose the exact physiological scenario, and to facilitate detection and management of immunogenic infertility caused by disruption of testicular immune regulation. The present review aims to (a) discuss the components of testicular immune privilege; (b) explain testicular somatic and immune cell interactions in establishing and maintaining the testicular immune micro-environment; and (c) illustrate the integration of multiple mechanisms involved in the control of immune privilege of the testis.

Neonatal Pig Sertoli Cells Survive Xenotransplantation by Creating an Immune Modulatory Environment Involving CD4 and CD8 Regulatory T Cells

The acute cell-mediated immune response presents a significant barrier to xenotransplantation. Immune-privileged Sertoli cells (SC) can prolong the survival of co-transplanted cells including xenogeneic islets, hepatocytes, and neurons by protecting them from immune rejection. Additionally, SC survive as allo- and xenografts without the use of any immunosuppressive drugs suggesting elucidating the survival mechanism(s) of SC could be used to improve survival of xenografts. In this study, the survival and immune response generated toward neonatal pig SC (NPSC) or neonatal pig islets (NPI), nonimmune-privileged controls, was compared after xenotransplantation into naïve Lewis rats without immune suppression. The NPSC survived throughout the study, while NPI were rejected within 9 days. Analysis of the grafts revealed that macrophages and T cells were the main immune cells infiltrating the NPSC and NPI grafts. Further characterization of the T cells within the grafts indicated that the NPSC grafts contained significantly more cluster of differentiation 4 (CD4) and cluster of differentiation 8 (CD8) regulatory T cells (Tregs) at early time points than the NPI grafts. Additionally, the presence of increased amounts of interleukin 10 (IL-10) and transforming growth factor (TGF) β and decreased levels of tumor necrosis factor (TNF) α and apoptosis in the NPSC grafts compared to NPI grafts suggests the presence of regulatory immune cells in the NPSC grafts. The NPSC expressed several immunoregulatory factors such as TGFβ, thrombospondin-1 (THBS1), indoleamine-pyrrole 2,3-dioxygenase, and galectin-1, which could promote the recruitment of these regulatory immune cells to the NPSC grafts. In contrast, NPI grafts had fewer Tregs and increased apoptosis and inflammation (increased TNFα, decreased IL-10 and TGFβ) suggestive of cytotoxic immune cells that contribute to their early rejection. Collectively, our data suggest that a regulatory graft environment with regulatory immune cells including CD4 and CD8 Tregs in NPSC grafts could be attributed to the prolonged survival of the NPSC xenografts.

T Lymphocytes and Testicular Immunity: A New Insight into Immune Regulation in Testes

The immune privilege of the testes is necessary to prevent immune attacks to gamete-specific antigens and paternal major histocompatibility complex (MHC) antigens, allowing for normal spermatogenesis. However, infection and inflammation of the male genital tract can break the immune tolerance and represent a significant cause of male infertility. Different T cell subsets have been identified in mammalian testes, which may be involved in the maintenance of immune tolerance and pathogenic immune responses in testicular infection and inflammation. We reviewed the evidence in the published literature on different T subtypes (regulatory T cells, helper T cells, cytotoxic T cells, γδ T cells, and natural killer T cells) in human and animal testes that support their regulatory roles in infertility and the orchitis pathology. While many in vitro studies have indicated the regulation potential of functional T cell subsets and their possible interaction with Sertoli cells, Leydig cells, and spermatogenesis, both under physiological and pathological processes, there have been no in situ studies to date. Nevertheless, the normal distribution and function of T cell subsets are essential for the immune privilege of the testes and intact spermatogenesis, and T cell-mediated immune response drives testicular inflammation. The distinct function of different T cell subsets in testicular homeostasis and the orchitis pathology suggests a considerable potential of targeting specific T cell subsets for therapies targeting chronic orchitis and immune infertility.

SerpinA3N deficiency deteriorates impairments of learning and memory in mice following hippocampal stab injury

Traumatic brain injury is a global leading cause of disability and death, which puts patients at high risk for developing dementia. Early intervention is believed as the key to minimize the development of brain damages that could aggravate the symptoms. Here, we report that the serine protease inhibitor SerpinA3N is upregulated in hippocampal neurons in the early stage of hippocampal stab injury (HSI), while its deficiency causes a greater degree of neuronal apoptosis and severer impairments of spatial learning and memory in mice after HSI. We further show that MMP2 is a key substrate of SerpinA3N, and MMP2 specific inhibitor (ARP100) can protect against neuronal apoptosis and cognitive dysfunction in mice after HSI. These findings demonstrate a critical role for SerpinA3N in neuroprotection, suggesting that SerpinA3N and MMP2 inhibitors might be a novel therapeutic agents for neurotrauma.

Characterization of rodent Sertoli cell primary cultures

Sertoli cells play a vital role in spermatogenesis by offering physical and nutritional support to the differentiating male germ cells. They form the blood-testis barrier and secrete growth factors essential for germ cell differentiation. Sertoli cell primary cultures are critical for understanding the regulation of spermatogenesis; however, obtaining pure cultures has been a challenge. Rodent Sertoli cell isolation protocols do not rule out contamination by the interstitial or connective tissue cells. Sertoli cell-specific markers could be helpful, but there is no consensus. Vimentin, the most commonly used marker, is not specific for Sertoli cells since its expression has been reported in peritubular myoid cells, mesenchymal stem cells, fibroblasts, macrophages, and endothelial cells, which contaminate Sertoli cell preparations. Markers based on transcription and growth factors also have limitations. Thus, the impediment to obtaining pure Sertoli cell cultures pertains to both the method of isolation and marker usage. The aim of this review is to discuss improvements to current methods of rodent Sertoli cell primary cultures, assess the properties of prepubertal versus mature Sertoli cell cultures, and propose steps to improve cellular characterization. Potential benefits of using contemporary approaches, including lineage tracing, specific cell ablation, and RNA-seq for obtaining Sertoli-specific transcript markers are discussed. Evaluating the specificity and applicability of these markers at the protein level to characterize Sertoli cells in culture would be critical. This review is expected to positively impact future work using primary cultures of rodent Sertoli cells.

Mouse Sertoli cells isolation by lineage tracing and sorting

Sertoli cells play a key role in spermatogenesis by supporting the germ cells throughout differentiation. The isolation of Sertoli cells is essential to study their functions. However, the close contact of Sertoli cells with other testicular cell types and the high proliferation of contaminating cells are obstacles to obtain pure primary cultures. Current rodent Sertoli cell isolation protocols result in enriched, rather than pure Sertoli cells. Therefore, novel approaches are necessary to improve the purity of Sertoli cell primary cultures. The goal of this study is to obtain pure mouse Sertoli cells using lineage tracing and fluorescence-activated cell sorting (FACS). We bred the Amh-Cre mouse line with tdTomato line to generate mice constitutively expressing red fluorescence specifically in Sertoli cells. Primary cultures of Sertoli cells isolated from prepubertal mice showed that 79% of cells expressed tdTomato, as evaluated by fluorescence microscopy and flow cytometry; however, nearly all adherent cells were positive for vimentin. Most of the tomato-negative cells expressed α-smooth muscle actin (α-SMA), a peritubular myoid cell marker, but double-negative populations were also present. These findings suggest that vimentin lacks Sertoli cell-specificity and that α-SMA is not adequate to identify all of the contaminating cells. Upon FACS sorting; however, virtually 100% of the cells were tdTomato positive, expressed vimentin, but not α-SMA. Prepubertal mice yielded a higher number of Sertoli cells compared to adults, but both could be adequately sorted. In conclusion, our study shows that lineage tracing and sorting is an efficient strategy for acquiring pure populations of murine Sertoli cells.

Granzyme B as a therapeutic target for wound healing

Introduction: Granzyme B is a serine protease traditionally understood as having a role in immune-mediated cytotoxicity. Over the past decade, this dogma has been challenged, with a new appreciation that granzyme B can exert alternative extracellular roles detrimental to wound closure and remodeling. Granzyme B is elevated in response to tissue injury, chronic inflammation and/or autoimmune skin diseases, resulting in impaired wound healing. Areas covered: This review provides a historical background of granzyme B and a description of how it is regulated. Details are provided on the role of granzyme B in apoptosis as well as newly identified extracellular roles, focusing on those affecting wound healing, including on inflammation, dermal-epidermal junction separation, re-epithelialization, scarring and fibrosis, and autoimmunity. Finally, the use of pharmacological granzyme B inhibitors as potential therapeutic options for wound treatment is discussed. Expert opinion: Endogenous extracellular granzyme B inhibitors have not been identified in human bio-fluids, thus in chronic wound environments granzyme B appears to remain uncontrolled and unregulated. In response, targeted granzyme B inhibitors have been developed for therapeutic applications in wounds. Animal studies trialing inhibitors of granzyme B show improved healing outcomes, and may therefore provide a novel therapeutic approach for wound treatment.

Do porcine Sertoli cells represent an opportunity for Duchenne muscular dystrophy?

Sertoli cells (SeC) are responsible for the immunoprivileged status of the testis thanks to which allogeneic or xenogeneic engraftments can survive without pharmacological immune suppression if co‐injected with SeC. This peculiar ability of SeC is dependent on secretion of a plethora of factors including maturation factors, hormones, growth factors, cytokines and immunomodulatory factors. The anti‐inflammatory and trophic properties of SeC have been largely exploited in several experimental models of diseases, diabetes being the most studied. Duchenne muscular dystrophy (DMD) is a lethal X‐linked recessive pathology in which lack of functional dystrophin leads to progressive muscle degeneration culminating in loss of locomotion and premature death. Despite a huge effort to find a cure, DMD patients are currently treated with anti‐inflammatory steroids. Recently, encapsulated porcine SeC (MC‐SeC) have been injected ip in the absence of immunosuppression in an animal model of DMD resulting in reduction of muscle inflammation and amelioration of muscle morphology and functionality, thus opening an additional avenue in the treatment of DMD. The novel protocol is endowed with the advantage of being potentially applicable to all the cohort of DMD patients regardless of the mutation. This mini‐review addresses several issues linked to the possible use of MC‐SeC injected ip in dystrophic people.

Transforming Growth Factor Beta Signaling in Dendritic Cells Is Required for Immunotolerance to Sperm in the Epididymis

The epididymis exhibits a less restrictive physical blood–tissue barrier than the testis and, while numerous immunosuppressive factors have been identified in the latter, no mechanisms for epididymal immunotolerance have been identified to date. Therefore, data are currently insufficient to explain how the immune system tolerates the extremely large load of novel antigens expressed on sperm, which become present in the male body after puberty, i.e., long after central tolerance was established. This study tested the hypothesis that transforming growth factor beta (TGFβ) signaling in dendritic cells (DCs) is required for immunotolerance to sperm located in the epididymis, and that male mice lacking TGFβ signaling in DCs would develop severe epididymal inflammation. To test this, we employed adult Tgfbr2^ΔDC males, which exhibit a significant reduction of Tgfbr2 expression and TGFβ signaling in DCs, as reported previously. Results show that Tgfbr2^ΔDC males exhibit sperm-specific immune response and severe epididymal leukocytosis. This phenotype is consistent with epididymal loss of immunotolerance to sperm and suggests that TGFβ signaling in DCs is a factor required for a non-inflammatory steady state in the epididymis, and therefore for male tract homeostasis and function.

Preliminary investigation of the function of hsa_circ_0006215 in pancreatic cancer

The incidence of pancreatic cancer is increasing annually in Asia as a whole. Pancreatic cancer ranks sixth in terms of incidence of all malignant tumors. Circular RNA (circRNA) is a type of non-coding RNA which forms a covalently closed continuous loop. CircRNA is extensively expressed in the cytoplasm, and is markedly conservative and stable. MicroRNA (miR)-378a-3p and human (hsa)_circ_0006215 were detected using the reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in tissue and cells. Western blot analysis detected the SERPINA4 and hsa_circ_0006215 expression in tissue. A Cell Counting Kit-8 assay was used to determine cell stability. Flow cytometry was used to determine the cell apoptotic rate. Transwell assays were used to determine cell migration. hsa_circ_0006215 was identified as a significantly upregulated circRNA. RT-qPCR results verified that, in 30 samples of pancreatic cancer tissue and paracancerous tissue, hsa_circ_0006215 expression was increased in pancreatic cancer tissue, miR-378a-3p expression was decreased in pancreatic cancer tissue, and SERPINA4 expression was increased in pancreatic cancer tissue (P<0.05). Using bioinformatics database and bioinformatics analysis, the interaction network of hsa_circ_0006215 indicated that this circRNA was most likely to regulate the expression of miR-378a-3p. Further interaction analysis revealed that the SERPINA4 gene was a regulatory target gene most likely to have an influence. The present study identified the effects of hsa_circ_0006215, miR-378a-3p and SERPINA4 signaling pathways in pancreatic cancer cells.

Granzyme B-inhibitor serpina3n induces neuroprotection in vitro and in vivo

Background

Multiple sclerosis (MS) is an autoimmune inflammatory and neurodegenerative disease of the central nervous system (CNS). It is widely accepted that inflammatory cells play major roles in the pathogenesis of MS, possibly through the use of serine protease granzyme B (GrB) secreted from the granules of cytotoxic T cells. We have previously identified GrB as a mediator of axonal injury and neuronal death. In this study, our goal was to evaluate the effect of GrB inhibition in the human system in vitro, and in vivo in EAE using the newly isolated GrB-inhibitor serpina3n.

Methods

We used a well-established in vitro model of neuroinflammation characterized by a co-culture system between human fetal neurons and lymphocytes. In vivo, we induced EAE in 10- to 12-week-old female C57/BL6 mice and treated them intravenously with serpina3n.

Results

In the in vitro co-culture system, pre-treatment of lymphocytes with serpina3n prevented neuronal killing and cleavage of the cytoskeletal protein alpha-tubulin, a known substrate for GrB. Moreover, in EAE, 50 μg serpina3n substantially reduced the severity of the disease. This dose was administered intravenously twice at days 7 and 20 post EAE induction. serpina3n treatment reduced axonal and neuronal injury compared to the vehicle-treated control group and maintained the integrity of myelin. Interestingly, serpina3n treatment did not seem to reduce the infiltration of immune cells (CD4⁺ and CD8⁺ T cells) into the CNS.

Conclusion

Our data suggest further studies on serpina3n as a potentially novel therapeutic strategy for the treatment of inflammatory-mediated neurodegenerative diseases such as MS.

Electronic supplementary material

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Identification of CTLA2A, DEFB29, WFDC15B, SERPINA1F and MUP19 as Novel Tissue-Specific Secretory Factors in Mouse

Secretory factors in animals play an important role in communication between different cells, tissues and organs. Especially, the secretory factors with specific expression in one tissue may reflect important functions and unique status of that tissue in an organism. In this study, we identified potential tissue-specific secretory factors in the fat, muscle, heart, lung, kidney and liver in the mouse by analyzing microarray data from NCBI’s Gene Expression Omnibus (GEO) public repository and searching and predicting their subcellular location in GeneCards and WoLF PSORT, and then confirmed tissue-specific expression of the genes using semi-quantitative PCR reactions. With this approach, we confirmed 11 lung, 7 liver, 2 heart, 1 heart and muscle, 7 kidney and 2 adipose and liver-specific secretory factors. Among these genes, 1 lung-specific gene - CTLA2A (cytotoxic T lymphocyte-associated protein 2 alpha), 3 kidney-specific genes - SERPINA1F (serpin peptidase inhibitor, Clade A, member 1F), WFDC15B (WAP four-disulfide core domain 15B) and DEFB29 (defensin beta 29) and 1 liver-specific gene - MUP19 (major urinary protein 19) have not been reported as secretory factors. These genes were tagged with hemagglutinin at the 3’end and then transiently transfected to HEK293 cells. Through protein detection in cell lysate and media using Western blotting, we verified secretion of the 5 genes and predicted the potential pathways in which they may participate in the specific tissue through data analysis of GEO profiles. In addition, alternative splicing was detected in transcripts of CTLA2A and SERPINA1F and the corresponding proteins were found not to be secreted in cell culture media. Identification of novel secretory factors through the current study provides a new platform to explore novel secretory factors and a general direction for further study of these genes in the future.

The serine protease inhibitor SerpinA3N attenuates neuropathic pain by inhibiting T cell-derived leukocyte elastase

Neuropathic pain is a major, intractable clinical problem and its pathophysiology is not well understood. Although recent gene expression profiling studies have enabled the identification of novel targets for pain therapy, classical study designs provide unclear results owing to the differential expression of hundreds of genes across sham and nerve-injured groups, which can be difficult to validate, particularly with respect to the specificity of pain modulation. To circumvent this, we used two outbred lines of rats, which are genetically similar except for being genetically segregated as a result of selective breeding for differences in neuropathic pain hypersensitivity. SerpinA3N, a serine protease inhibitor, was upregulated in the dorsal root ganglia (DRG) after nerve injury, which was further validated for its mouse homolog. Mice lacking SerpinA3N developed more neuropathic mechanical allodynia than wild-type (WT) mice, and exogenous delivery of SerpinA3N attenuated mechanical allodynia in WT mice. T lymphocytes infiltrate the DRG after nerve injury and release leukocyte elastase (LE), which was inhibited by SerpinA3N derived from DRG neurons. Genetic loss of LE or exogenous application of a LE inhibitor (Sivelastat) in WT mice attenuated neuropathic mechanical allodynia. Overall, we reveal a novel and clinically relevant role for a member of the serpin superfamily and a leukocyte elastase and crosstalk between neurons and T cells in the modulation of neuropathic pain.

Unc93b1 -Dependent Endosomal Toll-Like Receptor Signaling Regulates Inflammation and Mortality during Coxsackievirus B3 Infection

Coxsackievirus strain B serotype 3 (CVB3)-induced myocarditis is an important human disease that causes permanent tissue damage and can lead to death from acute infection or long-term morbidity caused by chronic inflammation. The timing and magnitude of immune activation following CVB3 infection can mediate a positive host outcome or increase tissue pathology. To better elucidate the role of endosomal Toll-like receptor (TLR) signaling in acute CVB3 infection, we studied mice with a loss-of-function mutation, known as Letr for 'loss of endosomal TLR response', in Unc93b1, which is a chaperone protein for TLR3, TLR7 and TLR9. Using Unc93b1(Letr/)(Letr) mice, we determined that Unc93b1-dependent TLR activation was essential for the survival of acute CVB3-induced myocarditis. We also determined that a lack of endosomal TLR signaling was associated with a higher viral load in target organs and that it increased inflammation, necrosis and fibrosis in cardiac tissue. Loss of Unc93b1 function was also associated with increased cardiac expression of Ifn-b and markers of tissue injury and fibrosis including Lcn2 and Serpina3n early after CVB3 infection. These observations establish a significant role for Unc93b1 in the regulation of the host inflammatory response to CVB3 infection and also reveal potential mediators of host tissue damage that merit further investigation in acute viral myocarditis.

Serpina3n accelerates tissue repair in a diabetic mouse model of delayed wound healing

Chronic, non-healing wounds are a major complication of diabetes and are characterized by chronic inflammation and excessive protease activity. Although once thought to function primarily as a pro-apoptotic serine protease, granzyme B (GzmB) can also accumulate in the extracellular matrix (ECM) during chronic inflammation and cleave ECM proteins that are essential for proper wound healing, including fibronectin. We hypothesized that GzmB contributes to the pathogenesis of impaired diabetic wound healing through excessive ECM degradation. In the present study, the murine serine protease inhibitor, serpina3n (SA3N), was administered to excisional wounds created on the dorsum of genetically induced type-II diabetic mice. Wound closure was monitored and skin wound samples were collected for analyses. Wound closure, including both re-epithelialization and contraction, were significantly increased in SA3N-treated wounds. Histological and immunohistochemical analyses of SA3N-treated wounds revealed a more mature, proliferative granulation tissue phenotype as indicated by increased cell proliferation, vascularization, fibroblast maturation and differentiation, and collagen deposition. Skin homogenates from SA3N-treated wounds also exhibited greater levels of full-length intact fibronectin compared with that of vehicle wounds. In addition, GzmB-induced detachment of mouse embryonic fibroblasts correlated with a rounded and clustered phenotype that was prevented by SA3N. In summary, topical administration of SA3N accelerated wound healing. Our findings suggest that GzmB contributes to the pathogenesis of diabetic wound healing through the proteolytic cleavage of fibronectin that is essential for normal wound closure, and that SA3N promotes granulation tissue maturation and collagen deposition.

TAp73 is essential for germ cell adhesion and maturation in testis

The p53 family member TAp73 is required for sperm maturation through promotion of adhesion between developing germ cells and Sertoli nurse cells.

A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germ line is unknown. Here, we reveal that TAp73 unexpectedly functions as an adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73 knockout (TAp73KO) and p73KO mice, but not ΔNp73KO mice, display a “near-empty seminiferous tubule” phenotype due to massive premature loss of immature germ cells. The cellular basis of this phenotype is defective cell–cell adhesions of developing germ cells to Sertoli nurse cells, with likely secondary degeneration of Sertoli cells, including the blood–testis barrier, which leads to disruption of the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, which is produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors, and integrins required for germ–Sertoli cell adhesion and dynamic junctional restructuring. Thus, we propose the testis as a unique organ with strict division of labor among all family members: p63 and p53 safeguard germ line fidelity, whereas TAp73 ensures fertility by enabling sperm maturation.

Mouse Sertoli cells sustain de novo generation of regulatory T cells by triggering the notch pathway through soluble JAGGED1

FOXP3(+) regulatory T cells (Tregs) are central to the maintenance of immunological homeostasis and tolerance. It has long been known that Sertoli cells are endowed with immune suppressive properties; however, the underlying mechanisms as well as the effective nature and role of soluble factors secreted by Sertoli cells have not been fully elucidated as yet. We hypothesized that conditioned medium from primary mouse Sertoli cells (SCCM) may be able and sufficient to induce Tregs. By culturing CD4(+)CD25(-)EGFP(-) T splenocytes purified from FOXP3-EGFP knock-in mice in SCCM, here we show, by flow cytometry and suppression assay, the conversion of peripheral CD4(+)FOXP3(-) T cells into functional CD4(+)FOXP3(+) Tregs. We also demonstrate that the Notch/Jagged1 axis is involved in regulating the de novo generation of Tregs although this process is transforming growth factor-beta1 (TGF-B) dependent. In particular, we identified by Western blot analysis a soluble form of JAGGED1 (JAG1) in SCCM that significantly influences the induction of Tregs, as demonstrated by performing the conversion assay in presence of a JAG1-specific neutralizing antibody. In addition, we show that SCCM modulates the Notch pathway in converted Tregs by triggering the recruitment of the Notch-specific transcription factor CSL/RBP-Jk to the Foxp3 promoter and by inducing the Notch target gene Hey1, as shown by chromatin immunoprecipitation assay and by real time-RT-PCR experiments, respectively. Overall, these results contribute to a better understanding of the molecular mechanisms involved in Sertoli cell-mediated immune tolerance and provide a novel approach to generate ex vivo functional Tregs for therapeutic purpose.

Sertoli cells--immunological sentinels of spermatogenesis

Testicular germ cells, which appear after the establishment of central tolerance, express novel cell surface and intracellular proteins that can be recognized as 'foreign antigens' by the host's immune system. However, normally these germ cells do not evoke an auto-reactive immune response. The focus of this manuscript is to review the evidence that the blood-testis-barrier (BTB)/Sertoli cell (SC) barrier along with the SCs ability to modulate the immune response is vital for protecting auto-antigenic germ cells. In normal testis, the BTB/SC barrier protects the majority of the auto-antigenic germ cells by limiting access by the immune system and sequestering these 'new antigens'. SCs also modulate testis immune cells (induce regulatory immune cells) by expressing several immunoregulatory factors, thereby creating a local tolerogenic environment optimal for survival of nonsequesetred auto-antigenic germ cells. Collectively, the fortress created by the BTB/SC barrier along with modulation of the immune response is pivotal for completion of spermatogenesis and species survival.

Transcriptome characterization by RNA-Seq reveals the involvement of the complement components in noise-traumatized rat cochleae

Acoustic trauma, a leading cause of sensorineural hearing loss in adults, induces a complex degenerative process in the cochlea. Although previous investigations have identified multiple stress pathways, a comprehensive analysis of cochlear responses to acoustic injury is still lacking. In the current study, we used the next-generation RNA-sequencing (RNA-Seq) technique to sequence the whole transcriptome of the normal and noise-traumatized cochlear sensory epithelia (CSE). CSE tissues were collected from rat inner ears 1d after the rats were exposed to a 120-dB (sound pressure level) noise for 2 h. The RNA-Seq generated over 176 million sequence reads for the normal CSE and over 164 million reads for the noise-traumatized CSE. Alignment of these sequences with the rat Rn4 genome revealed the expression of over 17,000 gene transcripts in the CSE, over 2000 of which were exclusively expressed in either the normal or noise-traumatized CSE. Seventy-eight gene transcripts were differentially expressed (70 upregulated and 8 downregulated) after acoustic trauma. Many of the differentially expressed genes are related to the innate immune system. Further expression analyses using quantitative real time PCR confirmed the constitutive expression of multiple complement genes in the normal organ of Corti and the changes in the expression levels of the complement factor I (Cfi) and complement component 1, s subcomponent (C1s) after acoustic trauma. Moreover, protein expression analysis revealed strong expression of Cfi and C1s proteins in the organ of Corti. Importantly, these proteins exhibited expression changes following acoustic trauma. Collectively, the results of the current investigation suggest the involvement of the complement components in cochlear responses to acoustic trauma.

Orchestrated leukocyte recruitment to immune-privileged sites: absolute barriers versus educational gates

Complex barriers separate immune-privileged tissues from the circulation. Here, we propose that cell entry to immune-privileged sites through barriers composed of tight junction-interconnected endothelium is associated with destructive inflammation, whereas border structures comprised of fenestrated vasculature enveloped by tightly regulated epithelium serve as active and selective immune-skewing gates in the steady state. Based on emerging knowledge of the central nervous system and information from other immune-privileged sites, we propose that these sites are endowed either with absolute endothelial-based barriers and epithelial gates that enable selective and educative transfer of trafficking leukocytes or with selective epithelial gates only.

Pertussis toxin exacerbates and prolongs airway inflammatory responses during Bordetella pertussis infection

Throughout infection, pathogenic bacteria induce dramatic changes in host transcriptional repertoires. An understanding of how bacterial factors influence host reprogramming will provide insight into disease pathogenesis. In the human respiratory pathogen Bordetella pertussis, the causative agent of whooping cough, pertussis toxin (PT) is a key virulence factor that promotes colonization, suppresses innate immune responses during early infection, and causes systemic disease symptoms. To determine the full extent of PT-associated gene regulation in the airways through the peak of infection, we measured global transcriptional profiles in the lungs of BALB/c mice infected with wild-type (WT) or PT-deficient (ΔPT) B. pertussis. ΔPT bacteria were inoculated at a dose equivalent to the WT dose and at a high dose (ΔPT(high)) to distinguish effects caused by higher bacterial loads achieved in WT infection from effects associated with PT. The results demonstrated that PT was associated with a significant upregulation of immune and inflammatory response genes as well as several other genes implicated in airway pathology. In contrast to the early, transient responses observed for ΔPT(high) infection, WT infection induced a prolonged expression of inflammatory genes and increased the extent and duration of lung histopathology. In addition, the administration of purified PT to ΔPT(high)-infected mice 1 day after bacterial inoculation exacerbated and prolonged inflammatory responses and airway pathology. These data indicate that PT not only is associated with exacerbated host airway responses during peak B. pertussis infection but also may inhibit host mechanisms of attenuating and resolving inflammation in the airways, suggesting possible links between PT and pertussis disease symptoms.

Thrombospondin-1 type 1 repeats in a model of inflammatory bowel disease: transcript profile and therapeutic effects

Thrombospondin-1 (TSP-1) is a matricellular protein with regulatory functions in inflammation and cancer. The type 1 repeats (TSR) domains of TSP-1 have been shown to interact with a wide range of proteins that result in the anti-angiogenic and anti-tumor properties of TSP-1. To ascertain possible functions and evaluate potential therapeutic effects of TSRs in inflammatory bowel disease, we conducted clinical, histological and microarray analyses on a mouse model of induced colitis. We used dextran sulfate sodium (DSS) to induce colitis in wild-type (WT) mice for 7 days. Simultaneously, mice were injected with either saline or one form of TSP-1 derived recombinant proteins, containing either (1) the three type 1 repeats of the TSP-1 (3TSR), (2) the second type 1 repeat (TSR2), or (3) TSR2 with the RFK sequence (TSR2+RFK). Total RNA isolated from the mice colons were processed and hybridized to mouse arrays. Array data were validated by real-time qPCR and immunohistochemistry. Histological and disease indices reveal that the mice treated with the TSRs show different patterns of leukocytic infiltration and that 3TSR treatment was the most effective in decreasing inflammation in DSS-induced colitis. Transcriptional profiling revealed differentially expressed (DE) genes, with the 3TSR-treated mice showing the least deviation from the WT-water controls. In conclusion, this study shows that 3TSR treatment is effective in attenuating the inflammatory response to DSS injury. In addition, the transcriptomics work unveils novel genetic data that suggest beneficial application of the TSR domains in inflammatory bowel disease.

Protection of porcine islet xenografts in mice using sertoli cells and monoclonal antibodies

BACKGROUND

To remedy the shortage of human donor islets, xenotransplantation of neonatal porcine islets (NPI) provides an attractive alternative source of donor tissue so long as graft rejection can be circumvented. Thus, in this study, we sought to determine whether cotransplantation of NPI with Sertoli cells (SC) combined with a short-course treatment of monoclonal antibody (mAb) could provide long-term islet xenograft survival.

METHODS

NPI alone or NPI cotransplanted with neonatal porcine SC were transplanted into diabetic C57BL/6 mice. These mice were left untreated or were treated with a short course of antileukocyte function associated antigen-1 (LFA-1), anti-CD154, or anti-CD45RB mAb. Blood glucose levels were monitored twice a week to assess graft function. At more than 100 days posttransplantation or on the day of rejection, graft-bearing kidneys were collected for characterization using immunohistochemistry.

RESULTS

None of the untreated control mice transplanted with NPI alone (0/5) or NPI cotransplanted with SC (0/8) achieved normoglycemia. However, of the mice receiving NPI alone, 3 of 7 treated with anti-LFA-1 mAb, 2 of 7 treated with anti-CD154 mAb, and 1 of 7 treated with anti-CD45RB mAb achieved long-term graft survival (>100 days). These proportions improved considerably when NPI were cotransplanted with SC, as 15 of 15 mice treated with anti-LFA-1 mAb, 7 of 8 mice treated with anti-CD154 mAb, and 4 of 9 mice treated with anti-CD45RB mAb achieved long-term graft survival.

CONCLUSIONS

These results show that transient administration of anti-LFA-1 mAb or anti-CD154 mAb is efficacious in prolonging NPI xenograft survival when islets are cotransplanted with SC. Interleukin-4 and Serpina3n may be important mediators of protection observed in this model.

Identification of new altered genes in rat cochleae with noise-induced hearing loss

Because genes that are highly expressed in the cochlea after noise stress may have crucial regulatory roles in hearing, the identification of these genes may be useful for restoring normal auditory function. This study assessed altered gene expression at 1h following the cessation of noise exposure by using microarrays and real-time polymerase chain reaction (qPCR) in rats. In addition, the auditory threshold shifts and morphological changes of hair cells were observed. This study indicated that applied noise induced outer hair cell loss and a 40-50 dB hearing loss. Totally 239 altered genes were involved in the immune system process, response to stress, or response to stimulus. The expression of five up-regulated genes (Reg3b, Lcn2, Serpina3n, Nob1 and Hamp) was confirmed by qPCR. Future experiments will focus on several of these new candidate genes and may provide insight into the underlying auditory pathophysiology.

Testosterone and interleukin-1β increase cardiac remodeling during coxsackievirus B3 myocarditis via serpin A 3n

Myocarditis and dilated cardiomyopathy (DCM) are often caused by viral infections and occur more frequently in men than in women, but the reasons for the sex difference remain unclear. The aim of this study was to assess whether gene changes in the heart during coxsackievirus B3 (CVB3) myocarditis in male and female BALB/c mice predicted worse DCM in males. Although myocarditis (P = 4.2 × 10(-5)) and cardiac dilation (P = 0.008) were worse in males, there was no difference in viral replication in the heart. Fibrotic remodeling genes, such as tissue inhibitor of metalloproteinase (TIMP)-1 and serpin A 3n, were upregulated in males during myocarditis rather than during DCM. Using gonadectomy and testosterone replacement, we showed that testosterone increased cardiac TIMP-1 (P = 0.04), serpin A 3n (P = 0.007), and matrix metalloproteinase (MMP)-8 (P = 0.04) during myocarditis. Testosterone increased IL-1β levels in the heart (P = 0.02), a cytokine known to regulate cardiovascular remodeling, and IL-1β in turn increased cardiac serpin A 3n mRNA (P = 0.005). We found that 39 of 118 (33%) genes identified in acute DCM patients were significantly altered in the heart during CVB3 myocarditis in mice, including serpin A 3n (3.3-fold change, P = 0.0001). Recombinant serpin A 3n treatment induced cardiac fibrosis during CVB3 myocarditis (P = 0.0008) while decreasing MMP-3 (P = 0.04) and MMP-9 (P = 0.03) levels in the heart. Thus, serpin A 3n was identified as a gene associated with fibrotic cardiac remodeling and progression to DCM in male myocarditis patients and mice.

Granzyme B inhibits vaccinia virus production through proteolytic cleavage of eukaryotic initiation factor 4 gamma 3

Cytotoxic T lymphocytes (CTLs) are the major killer of virus-infected cells. Granzyme B (GrB) from CTLs induces apoptosis in target cells by cleavage and activation of substrates like caspase-3 and Bid. However, while undergoing apoptosis, cells are still capable of producing infectious viruses unless a mechanism exists to specifically inhibit viral production. Using proteomic approaches, we identified a novel GrB target that plays a major role in protein synthesis: eukaryotic initiation factor 4 gamma 3 (eIF4G3). We hypothesized a novel role for GrB in translation of viral proteins by targeting eIF4G3, and showed that GrB cleaves eIF4G3 specifically at the IESD¹⁴⁰⁸S sequence. Both GrB and human CTL treatment resulted in degradation of eIF4G3 and reduced rates of translation. When Jurkat cells infected with vaccinia virus were treated with GrB, there was a halt in viral protein synthesis and a decrease in production of infectious new virions. The GrB-induced inhibition of viral translation was independent of the activation of caspases, as inhibition of protein synthesis still occurred with addition of the pan-caspase inhibitor zVAD-fmk. This demonstrated for the first time that GrB prevents the production of infectious vaccinia virus by targeting the host translational machinery.

Lymphocytes, a type of white blood cell, are the major killer of virus-infected cells. Lymphocytes secrete proteins like granzyme B that are responsible for the destruction of the virus-infected host cell. However, killing an infected cell through this pathway may take several hours, thus allowing viral replication to occur while the cell is in the process of dying. In this study, we identified a new role of granzyme B in preventing viral replication during the killing process. We found that granzyme B disables the ability of the host cell to make new proteins, including viral proteins of infected cells. Thus, granzyme B is able to halt the production of new viruses by inhibiting protein production.

Serpina3n attenuates granzyme B-mediated decorin cleavage and rupture in a murine model of aortic aneurysm

Granzyme B (GZMB) is a proapoptotic serine protease that is released by cytotoxic lymphocytes. However, GZMB can also be produced by other cell types and is capable of cleaving extracellular matrix (ECM) proteins. GZMB contributes to abdominal aortic aneurysm (AAA) through an extracellular, perforin-independent mechanism involving ECM cleavage. The murine serine protease inhibitor, Serpina3n (SA3N), is an extracellular inhibitor of GZMB. In the present study, administration of SA3N was assessed using a mouse Angiotensin II-induced AAA model. Mice were injected with SA3N (0–120 μg/kg) before pump implantation. A significant dose-dependent reduction in the frequency of aortic rupture and death was observed in mice that received SA3N treatment compared with controls. Reduced degradation of the proteoglycan decorin was observed while collagen density was increased in the aortas of mice receiving SA3N treatment compared with controls. In vitro studies confirmed that decorin, which regulates collagen spacing and fibrillogenesis, is cleaved by GZMB and that its cleavage can be prevented by SA3N. In conclusion, SA3N inhibits GZMB-mediated decorin degradation leading to enhanced collagen remodelling and reinforcement of the adventitia, thereby reducing the overall rate of rupture and death in a mouse model of AAA.