Perforin: structure, function, and role in human immunopathology

Effects of Candida albicans infection on defense effector secretion by human oral mucosal epithelial cells

OBJECTIVE

The aim of this study was to investigate the effects of Candida albicans on the production of defense effector molecules by human oral mucosal epithelial cells in vitro.

DESIGN

Immortalized human oral mucosal epithelial (Leuk-1) cells and C. albicans strain 5314 were cocultured at different cell-to-C. albicans ratios. The viability of Leuk-1 cells was determined by MTT and RTCA measurements. The secretory levels of multiple defense effector molecules were determined by Enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our results indicated that C. albicans significantly decreased the secretion of IgG, cystatin C, lactoferrin, and TGF-β1 in a dose-dependent manner and remarkably reduced the production of IgA independent of the cell-to-C. albicans ratio. However, C. albicans clearly enhanced the secretion of IgM, galectin-3, P-selectin, granzyme B and perforin.

CONCLUSION

These results suggest that C. albicans may exert a regulatory role in the defense response of oral mucosal epithelial cells by altering secretory levels of defense effector molecules.

Store-Operated Ca2+ Entry in Tumor Progression: From Molecular Mechanisms to Clinical Implications

The remodeling of Ca²⁺ homeostasis has been implicated as a critical event in driving malignant phenotypes, such as tumor cell proliferation, motility, and metastasis. Store-operated Ca²⁺ entry (SOCE) that is elicited by the depletion of the endoplasmic reticulum (ER) Ca²⁺ stores constitutes the major Ca²⁺ influx pathways in most nonexcitable cells. Functional coupling between the plasma membrane Orai channels and ER Ca²⁺-sensing STIM proteins regulates SOCE activation. Previous studies in the human breast, cervical, and other cancer types have shown the functional significance of STIM/Orai-dependent Ca²⁺ signals in cancer development and progression. This article reviews the information on the regulatory mechanisms of STIM- and Orai-dependent SOCE pathways in the malignant characteristics of cancer, such as proliferation, resistance, migration, invasion, and metastasis. The recent investigations focusing on the emerging importance of SOCE in the cells of the tumor microenvironment, such as tumor angiogenesis and antitumor immunity, are also reviewed. The clinical implications as cancer therapeutics are discussed.

The immunoregulatory effects of CD8 T-cell-derived perforin on diet-induced nonalcoholic steatohepatitis

The liver is a central immunologic organ with a high density of myeloid and lymphoid immune cells that play important roles in the development and progression of nonalcoholic steatohepatitis (NASH). However, the immune-cell-mediated regulation of NASH and its underlying mechanisms remain obscure. In this study, Prf1^null mice showed significantly higher plasma alanine transaminase levels, with increased liver fat accumulation, lobular inflammation, and focal necrosis compared with wild-type (WT) mice after 4 wk of feeding on a methionine- and choline-deficient diet (MCD) or 16 wk of feeding on a high-fat diet. Perforin deficiency promoted the M1 polarization of infiltrated monocytes. Moreover, MCD-fed Prf1^null mice exhibited increased accumulation, survival, activation, and proinflammatory cytokine production of CD8 T cells but not NK cells or CD4 T cells. Adoptive transfer of CD8 T cells or NK cells from WT or Prf1^null mice, together with non-CD8 cells or non-NK cells from WT mice, indicated that CD8 T-cell-derived perforin participates in the mechanism regulating liver inflammation and thus plays a protective role in the development of NASH. Perforin-deficient CD8 T cells exhibited decreased cytotoxicity toward bone marrow-derived M1 monocytes and macrophages. According to the RNA sequencing data, the perforin deficiency inhibited cell apoptosis and enhanced the activation, migration, and proinflammatory cytokine production of CD8 T cells in mice with NASH. Furthermore, we found higher plasma soluble perforin levels and hepatic perforin expression in NASH patients, suggesting clinical relevance of the findings. We have elucidated an important role for the cytotoxic immune effector molecule perforin from CD8 T cells in restricting hepatic inflammation in mice with NASH and suggest that therapies designed to maximize the function of endogenous perforin in CD8 T cells might have potential benefits as NASH treatments.-Wang, T., Sun, G., Wang, Y., Li, S., Zhao, X., Zhang, C., Jin, H., Tian, D., Liu, K., Shi, W., Tian, Y., Zhang, D. The immunoregulatory effects of CD8 T-cell-derived perforin on diet-induced nonalcoholic steatohepatitis.

Epstein-Barr Virus-Associated T and NK-Cell Lymphoproliferative Diseases

EBV-associated T and NK-cell lymphoproliferative diseases (EBV-T/NK LPDs) are characterized by the transformation and proliferation of EBV-infected T or NK cells. The 2016 revised World Health Organization classification recognizes the following EBV-positive lymphoproliferative disorders (LPD): chronic active EBV infection (CAEBV) of T- and NK-cell type (cutaneous and systemic forms), systemic EBV-positive T-cell lymphoma of childhood, aggressive NK-cell leukemia, extranodal NK/T-cell lymphoma, nasal type, and the new provisional entity primary EBV-positive nodal T/NK-cell lymphoma. EBV-associated hemophagocytic lymphohistiocytosis (HLH), although not included in the WHO classification because it is a reactive, inflammatory disease, is included in this review because it can be life-threatening and may have overlapping features with other EBV+ T/NK LPDs. EBV+ T/NK LPDs are rare diseases difficult to diagnose and manage properly, because some LPDs have unusual presentations, and discrepancies between clinical and histological findings might be encountered. Furthermore, EBV+ T/NK disorders share some clinico-pathological features, and may evolve into other categories during the clinical course, including malignant transformation of CAEBV. Here, we review the EBV+ T/NK LPDs in terms of their definitions, clinical features, histology, immunophenotype, molecular findings, and pathogenesis. This review aims to increase our understanding and awareness of the differential diagnosis among the different EBV+ T/NK LPDs. New insights into the genetic characteristics of these disorders will also be discussed.

Epstein-Barr Virus and Hemophagocytic Lymphohistiocytosis

Epstein–Barr virus (EBV) is a ubiquitous virus that infects nearly all people worldwide without serious sequela. However, for patients who have genetic diseases which predispose them to the development of hemophagocytic lymphohistiocytosis (HLH), EBV infection is a life-threatening problem. As a part of a themed collection of articles on EBV infection and human primary immune deficiencies, we will review key concepts related to the understanding and treatment of HLH.

Perforin gene variation influences survival in childhood acute lymphoblastic leukemia

Although a growing body of data links mutations in the perforin gene with increased susceptibility to hematologic malignancies, no studies discuss their influence on the clinical course of such diseases. The present study examines the impact of perforin gene variation on the clinical outcome in acute lymphoblastic leukemia (ALL) patients. The study enrolled 312 children aged 1-18 years, treated for ALL. PRF1 gene variants were analyzed through direct DNA sequencing. Variation in rs885822 was found to be associated with overall survival: patients carrying the GG genotype demonstrated a significantly increased risk of death compared to those carrying the A allele, independently of ALL risk groups (HR 3.13, 95%CI 1.16-7.8, p = 0.014). The effect was even more pronounced in high-risk ALL patients (p = 0.006). On the other hand, the presence of the rs35947132 minor A allele was slightly protective with regard to overall prognosis (p = 0.047). No differences in relapse-free survival were observed with regard to genotypes. The results of the study may imply that perforin gene variation has a role in modifying mortality in childhood ALL.

Innate Lymphoid Cells (ILCs) as Mediators of Inflammation, Release of Cytokines and Lytic Molecules

Innate lymphoid cells (ILCs) are an emerging group of immune cells that provide the first line of defense against various pathogens as well as contributing to tissue repair and inflammation. ILCs have been classically divided into three subgroups based on their cytokine secretion and transcription factor profiles. ILC nomenclature is analogous to that of T helper cells. Group 1 ILCs composed of natural killer (NK) cells as well as IFN-γ secreting ILC1s. ILC2s have the capability to produce T_H2 cytokines while ILC3s and lymphoid tissue inducer (LTis) are subsets of cells that are able to secrete IL-17 and/or IL-22. A recent subset of ILC known as ILC4 was discovered, and the cells of this subset were designated as NK17/NK1 due to their release of IL-17 and IFN-γ. In this review, we sought to explain the subclasses of ILCs and their roles as mediators of lytic enzymes and inflammation.

Sickle cells produce functional immune modulators and cytotoxics

Sickle erythrocytes' (SSRBCs) unique physical adaptation to hypoxic conditions renders them able to home to hypoxic tumor niches in vivo, shut down tumor blood flow and induce tumoricidal responses. SSRBCs are also useful vehicles for transport of encapsulated drugs and oncolytic virus into hypoxic tumors with enhanced anti-tumor effects. In search of additional modes for arming sickle cells with cytotoxics, we turned to a lentiviral β-globin vector with optimized Locus Control Region/β-globin coding region/promoter/enhancers. We partially replaced the β-globin coding region of this vector with genes encoding T cell cytolytics, perforin and granzyme or immune modulating superantigens SEG and SEI. These modified vectors efficiently transduced Sca⁺ ckit^- Lin^- hematopoietic stem cells (HSCs) from humanized sickle cell knockin mice. Irradiated mice reconstituted with these HSCs displayed robust expression of transgenic RNAs and proteins in host sickle cells that was sustained for more than 10 months. SSRBCs from reconstituted mice harboring SEG/SEI transgenes induced robust proliferation and a prototypical superantigen-induced cytokine reaction when exposed to human CD4+/CD8+ cells. The β-globin lentiviral vector therefore produces a high level of functional, erythroid-specific immune modulators and cytotoxics that circulate without toxicity. Coupled with their unique ability to target and occlude hypoxic tumor vessels these armed SSRBCs constitute a potentially useful tool for treatment of solid tumors.

Blinatumomab, a Bispecific T-cell Engager (BiTE(®)) for CD-19 Targeted Cancer Immunotherapy: Clinical Pharmacology and Its Implications

BACKGROUND AND OBJECTIVES

Blinatumomab is a bispecific T-cell engager (BiTE(®)) antibody construct that transiently links CD19-positive B cells to CD3-positive T cells, resulting in induction of T-cell-mediated serial lysis of B cells and concomitant T-cell proliferation. Blinatumomab showed anti-leukemia activity in clinical trials and was approved by the US Food and Drug Administration for the treatment of Philadelphia chromosome-negative relapsed/refractory B-cell precursor acute lymphoblastic leukemia (r/r ALL). The objectives of this work were to characterize blinatumomab pharmacokinetics and pharmacodynamics and to evaluate dosing regimens.

METHODS

Data from six phase I and II trials in patients with r/r ALL, minimal residual disease-positive ALL, and non-Hodgkin's lymphoma (NHL) were analyzed. Blinatumomab pharmacokinetics was characterized by non-compartmental and population pharmacokinetic analyses and pharmacodynamics was described graphically.

RESULTS

Blinatumomab exhibited linear pharmacokinetics under continuous intravenous infusion for 4-8 weeks per cycle over a dose range of 5-90 µg/m(2)/day, without target-mediated disposition. Estimated mean (standard deviation) volume of distribution, clearance, and elimination half-life were 4.52 (2.89) L, 2.72 (2.71) L/h, and 2.11 (1.42) h, respectively. Pharmacokinetics was similar in patients with ALL and NHL and was not affected by patient demographics, supporting fixed dosing in adults. Although creatinine clearance was a significant covariate of drug clearance, no dose adjustment was required in patients with mild or moderate renal impairment. Incidence of neutralizing antidrug antibodies was <1 %. Blinatumomab pharmacodynamics featured T-cell redistribution and activation, B-cell depletion, and transient dose-dependent cytokine elevation. Blinatumomab did not affect cytochrome P450 enzymes directly; cytokines may trigger transient cytochrome P450 suppression with low potential for inducing drug interactions.

CONCLUSIONS

Blinatumomab has unique pharmacokinetic and immunological features that require indication-dependent dosing regimens. Stepped dosing is required to achieve adequate efficacy and minimize cytokine release in diseases with high tumor burden.

Substituted arylsulphonamides as inhibitors of perforin-mediated lysis

The structure-activity relationships for a series of arylsulphonamide-based inhibitors of the pore-forming protein perforin have been explored. Perforin is a key component of the human immune response, however inappropriate activity has also been implicated in certain auto-immune and therapy-induced conditions such as allograft rejection and graft versus host disease. Since perforin is expressed exclusively by cells of the immune system, inhibition of this protein would be a highly selective strategy for the immunosuppressive treatment of these disorders. Compounds from this series were demonstrated to be potent inhibitors of the lytic action of both isolated recombinant perforin and perforin secreted by natural killer cells in vitro. Several potent and soluble examples were assessed for in vivo pharmacokinetic properties and found to be suitable for progression to an in vivo model of transplant rejection.

Modularly Constructed Synthetic Granzyme B Molecule Enables Interrogation of Intracellular Proteases for Targeted Cytotoxicity

Targeted therapies promise to increase the safety and efficacy of treatments against diseases ranging from cancer to viral infections. However, the vast majority of targeted therapeutics relies on the recognition of extracellular biomarkers, which are rarely restricted to diseased cells and are thus prone to severe and sometimes-fatal off-target toxicities. In contrast, intracellular antigens present a diverse yet underutilized repertoire of disease markers. Here, we report a protein-based therapeutic platform-termed Cytoplasmic Oncoprotein VErifier and Response Trigger (COVERT)-which enables the interrogation of intracellular proteases to trigger targeted cytotoxicity. COVERT molecules consist of the cytotoxic protein granzyme B (GrB) fused to an inhibitory N-terminal peptide, which can be removed by researcher-specified proteases to activate GrB function. We demonstrate that fusion of a small ubiquitin-like modifier 1 (SUMO1) protein to GrB yields a SUMO-GrB molecule that is specifically activated by the cancer-associated sentrin-specific protease 1 (SENP1). SUMO-GrB selectively triggers apoptotic phenotypes in HEK293T cells that overexpress SENP1, and it is highly sensitive to different SENP1 levels across cell lines. We further demonstrate the rational design of additional COVERT molecules responsive to enterokinase (EK) and tobacco etch virus protease (TEVp), highlighting the COVERT platform's modularity and adaptability to diverse protease targets. As an initial step toward engineering COVERT-T cells for adoptive T-cell therapy, we verified that primary human T cells can express, package, traffic, and deliver engineered GrB molecules in response to antigen stimulation. Our findings set the foundation for future intracellular-antigen-responsive therapeutics that can complement surface-targeted therapies.

Finding a Balance between Protection and Pathology: The Dual Role of Perforin in Human Disease

Perforin is critical for controlling viral infection and tumor surveillance. Clinically, mutations in perforin are viewed as unfavorable, as lack of this pore-forming protein results in lethal, childhood disease, familial hemophagocytic lymphohistiocytosis type 2 (FHL 2). However, many mutations in the coding region of PRF1 are not yet associated with disease. Animal models of viral-associated blood–brain barrier (BBB) disruption and experimental cerebral malaria (ECM) have identified perforin as critical for inducing pathologic central nervous system CNS vascular permeability. This review focuses on the role of perforin in both protecting and promoting human disease. It concludes with a novel hypothesis that diversity observed in the PRF1 gene may be an example of selective advantage that protects an individual from perforin-mediated pathology, such as BBB disruption.

Modern strategies and capabilities for activation of the immune response against tumor cells

Dendritic cells are professional antigen-presenting cells and the most potent stimulators of various immune responses, such as antitumor responses. Modern studies have not shown an effective antitumor immune response development in patients with malignant tumors. The major cause is the decrease in functional activity of dendritic cells in cancer patients through irregularities in the maturation process to a functionally active form and in the antigen presentation process to naive T lymphocytes. This review describes the main stages of cellular antitumor immune response induction in vitro, aimed at resolving the problems that are blocking the full functioning of dendritic cells, and additional stimulation of antitumor immune response.

Neurodevelopmental MACPFs: The vertebrate astrotactins and BRINPs

Astrotactins (ASTNs) and Bone morphogenetic protein/retinoic acid inducible neural-specific proteins (BRINPs) are two groups of Membrane Attack Complex/Perforin (MACPF) superfamily proteins that show overlapping expression in the developing and mature vertebrate nervous system. ASTN(1-2) and BRINP(1-3) genes are found at conserved loci in humans that have been implicated in neurodevelopmental disorders (NDDs). Here we review the tissue distribution and cellular localization of these proteins, and discuss recent studies that provide insight into their structure and interactions. We highlight the genetic relationships and co-expression of Brinps and Astns; and review recent knock-out mouse phenotypes that indicate a possible overlap in protein function between ASTNs and BRINPs.

Identification of a target protein of Hydra actinoporin-like toxin-1 (HALT-1) using GST affinity purification and SILAC-based quantitative proteomics

Hydra actinoporin-like toxin-1 (HALT-1) is a 20.8 kDa pore-forming toxin isolated from Hydra magnipapillata. HALT-1 shares structural similarity with actinoporins, a family that is well known for its haemolytic and cytolytic activity. However, the precise pore-forming mechanism of HALT-1 remains an open question since little is known about the specific target binding for HALT-1. For this reason, a comprehensive proteomic analysis was performed using affinity purification and SILAC-based mass spectrometry to identify potential protein-protein interactions between mammalian HeLa cell surface proteins and HALT-1. A total of 4 mammalian proteins was identified, of which only folate receptor alpha was further verified by ELISA. Our preliminary results highlight an alternative-binding mode of HALT-1 to the human plasma membrane. This is the first evidence showing that HALT-1, an actinoporin-like protein, binds to a membrane protein, the folate receptor alpha. This study would advance our understanding of the molecular basis of toxicity of pore-forming toxins and provide new insights in the production of more potent inhibitors for the toxin-membrane receptor interactions.

Dendritic cells, macrophages, NK and CD8+ T lymphocytes play pivotal roles in controlling HSV-1 in the trigeminal ganglia by producing IL1-beta, iNOS and granzyme B

Background

Herpes simplex virus type 1 (HSV-1) cause not only mild symptoms but also blindness and encephalitis. It was previously shown that the immune response against HSV-1 occurs mainly in the trigeminal ganglia (TG) and that Toll-like receptors 2 and 9 (TLR2/9) are important in mediating this response. It was also demonstrated that iNOS (nitric oxide synthase) and interleukin 1 beta (IL-1β) play an essential role in the defense against HSV-1 infection. Importantly, the present work aimed to identify the primary cells responsible for iNOS and IL-1β production and search for other important molecules and cells that might or might not depend on TLR2/9 receptors to mediate the immune response against HSV-1.

Methods

C57BL/6 (wild type, WT) and TLR2/9^−/− mice were infected by the intranasal route with HSV-1 (1 × 10⁶ p.f.u.). Cells were obtained from the TG and spleen tissues and the profile of immune cells was determined by flow cytometry in infected and mock infected WT and knockout mice. The percentage of cells producing iNOS, IL-1β, granzyme B and perforin was also determined by flow cytometry. Chemokine monocyte chemoattractant protein-1 (MCP1) was measured by Cytometric Bead Array (CBA) in the TG, spleen and lung. Expression of type I interferons (IFNs), interleukins (IL) 5 and 10, IL-1β and granzyme B were quantified by real time PCR.

Results

The results indicate that dendritic cells (DCs) and monocytes/macrophages (Mo/Mϕ) were the main sources of IL-1β and iNOS, respectively, which, together with type I IFNs, were essential for the immune response against HSV-1. Additionally, we showed that granzyme B produced by CD8⁺ T and NK lymphocytes and MCP-1 were also important for this immune response. Moreover, our data indicate that the robust production of MCP-1 and granzyme B is either TLR-independent or down regulated by TLRs and occurs in the TG of TLR2/9^−/− infected mice.

Conclusion

Taken together, our data provide strong evidence that the responses mediated by DCs, Mo/Mϕ, NK and CD8⁺ T lymphocytes through IL-1β, iNOS and granzyme B production, respectively, together with the production of type I IFN early in the infection, are crucial to host defense against HSV-1.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0692-x) contains supplementary material, which is available to authorized users.

Benzenesulphonamide inhibitors of the cytolytic protein perforin

The pore-forming protein perforin is a key component of mammalian cell-mediated immunity and essential to the pathway that allows elimination of virus-infected and transformed cells. Perforin activity has also been implicated in certain auto-immune conditions and therapy-induced conditions such as allograft rejection and graft versus host disease. An inhibitor of perforin activity could be used as a highly specific immunosuppressive treatment for these conditions, with reduced side-effects compared to currently accepted therapies. Previously identified first-in-class inhibitors based on a 2-thioxoimidazolidin-4-one core show suboptimal physicochemical properties and toxicity toward the natural killer (NK) cells that secrete perforin in vivo. The current benzenesulphonamide-based series delivers a non-toxic bioisosteric replacement possessing improved solubility.

Selective targeting of IL-2 to NKG2D bearing cells for improved immunotherapy

Despite over 20 years of clinical use, IL-2 has not fulfilled expectations as a safe and effective form of tumour immunotherapy. Expression of the high affinity IL-2Rα chain on regulatory T cells mitigates the anti-tumour immune response and its expression on vascular endothelium is responsible for life threatening complications such as diffuse capillary leak and pulmonary oedema. Here we describe the development of a recombinant fusion protein comprised of a cowpox virus encoded NKG2D binding protein (OMCP) and a mutated form of IL-2 with poor affinity for IL-2Rα. This fusion protein (OMCP-mutIL-2) potently and selectively activates IL-2 signalling only on NKG2D-bearing cells, such as natural killer (NK) cells, without broadly activating IL-2Rα-bearing cells. OMCP-mutIL-2 provides superior tumour control in several mouse models of malignancy and is not limited by mouse strain-specific variability of NK function. In addition, OMCP-mutIL-2 lacks the toxicity and vascular complications associated with parental wild-type IL-2.

Modulatory effects of perforin gene dosage on pathogen-associated blood-brain barrier (BBB) disruption

Background

CD8 T cell-mediated blood-brain barrier (BBB) disruption is dependent on the effector molecule perforin. Human perforin has extensive single nucleotide variants (SNVs), the significance of which is not fully understood. These SNVs can result in reduced, but not ablated, perforin activity or expression. However, complete loss of perforin expression or activity results in the lethal disease familial hemophagocytic lymphohistiocytosis type 2 (FHL 2). In this study, we address the hypothesis that a single perforin allele can alter the severity of BBB disruption in vivo using a well-established model of CNS vascular permeability in C57Bl/6 mice. The results of this study provide insight into the significance of perforin SNVs in the human population.

Methods

We isolated the effect a single perforin allele has on CNS vascular permeability through the use of perforin-heterozygous (perforin+/−) C57BL/6 mice in the peptide-induced fatal syndrome (PIFS) model of immune-mediated BBB disruption. Seven days following Theiler’s murine encephalomyelitis virus (TMEV) CNS infection, neuroinflammation and TMEV viral control were assessed through flow cytometric analysis and quantitative real-time PCR of the viral genome, respectively. Following immune-mediated BBB disruption, gadolinium-enhanced T1-weighted MRI, with 3D volumetric analysis, and confocal microscopy were used to define CNS vascular permeability. Finally, the open field behavior test was used to assess locomotor activity of mice following immune-mediated BBB disruption.

Results

Perforin-null mice had negligible CNS vascular permeability. Perforin-WT mice have extensive CNS vascular permeability. Interestingly, perforin-heterozygous mice had an intermediate level of CNS vascular permeability as measured by both gadolinium-enhanced T1-weighted MRI and fibrinogen leakage in the brain parenchyma. Differences in BBB disruption were not a result of increased CNS immune infiltrate. Additionally, TMEV was controlled in a perforin dose-dependent manner. Furthermore, a single perforin allele is sufficient to induce locomotor deficit during immune-mediated BBB disruption.

Conclusions

Perforin modulates BBB disruption in a dose-dependent manner. This study demonstrates a potentially advantageous role for decreased perforin expression in reducing BBB disruption. This study also provides insight into the effect SNVs in a single perforin allele could have on functional deficit in neurological disease.

Haemophagocytic lymphohistiocytosis presenting as neonatal liver failure: A case series

BACKGROUND AND STUDY AIM

Haemophagocytic lymphohistiocytosis (HLH) is a life-threatening clinical syndrome with liver involvement varying from mild dysfunction to severe fulminant failure. The aim of this study was to present a case series of four HLH patients presenting with acute liver failure (ALF) in the neonatal period.

PATIENTS AND METHODS

All four patients were neonates at the onset of symptoms. They presented to Cairo University Pediatric Hospital with ALF; they underwent prompt investigations including determination of ferritin, fibrinogen, and triglyceride levels as part of our ALF workup. Further investigations were tailored according to the associated clinical features and the results of preliminary investigations.

RESULTS

HLH was diagnosed according to HLH-2004 criteria. Three patients fulfilled at least five out of eight criteria. Fever, splenomegaly, elevated ferritin levels, and low fibrinogen levels were present in all patients. The fourth patient had a serum ferritin level >10,000ng/ml, favouring the diagnosis of HLH, despite fulfilling only four out of eight criteria. For three patients, positive consanguinity and previous sibling death were reported, suggesting a genetic aetiology of HLH.

CONCLUSION

ALF can be the presenting feature of HLH; thus, a high index of suspicion is necessary. Fever is a hallmark, especially in neonates. Diagnosis is important for this potentially treatable condition.

Necrosome core machinery: MLKL

In the study of regulated cell death, the rapidly expanding field of regulated necrosis, in particular necroptosis, has been drawing much attention. The signaling of necroptosis represents a sophisticated form of a death pathway. Anti-caspase mechanisms (e.g., using inhibitors of caspases, or genetic ablation of caspase-8) switch cell fate from apoptosis to necroptosis. The initial extracellular death signals regulate RIP1 and RIP3 kinase activation. The RIP3-associated death complex assembly is necessary and sufficient to initiate necroptosis. MLKL was initially identified as an essential mediator of RIP1/RIP3 kinase-initiated necroptosis. Recent studies on the signal transduction using chemical tools and biomarkers support the idea that MLKL is able to make more functional sense for the core machinery of the necroptosis death complex, called the necrosome, to connect to the necroptosis execution. The experimental data available now have pointed that the activated MLKL forms membrane-disrupting pores causing membrane leakage, which extends the prototypical concept of morphological and biochemical events following necroptosis happening in vivo. The key role of MLKL in necroptosis signaling thus sheds light on the logic underlying this unique "membrane-explosive" cell death pathway. In this review, we provide the general concepts and strategies that underlie signal transduction of this form of cell death, and then focus specifically on the role of MLKL in necroptosis.

Oropharyngeal squamous cell carcinomas differentially express granzyme inhibitors

Objectives

Patients with human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinomas (OPSCCs) have an improved prognosis compared to HPV-negative OPSCCs. Several theories have been proposed to explain this relatively good prognosis. One hypothesis is a difference in immune response. In this study, we compared tumor-infiltrating CD3+, CD4+, CD8+ T-cells, and granzyme inhibitors (SERPINB1, SERPINB4, and SERPINB9) between HPV-positive and HPV-negative tumors and the relation with survival.

Methods

Protein expression of tumor-infiltrating lymphocytes (TILs) (CD3, CD4, and CD8) and granzyme inhibitors was analyzed in 262 OPSCCs by immunohistochemistry (IHC). Most patients (67 %) received primary radiotherapy with or without chemotherapy. Cox regression analysis was carried out to compare overall survival (OS) of patients with low and high TIL infiltration and expression of granzyme inhibitors.

Results

HPV-positive OPSCCs were significantly more heavily infiltrated by TILs (p < 0.001) compared to HPV-negative OPSCCs. A high level of CD3+ TILs was correlated with a favorable outcome in the total cohort and in HPV-positive OPSCCs, while it reached no significance in HPV-negative OPSCCs. There was expression of all three granzyme inhibitors in OPSCCs. No differences in expression were found between HPV-positive and HPV-negative OPSCCs. Within the group of HPV-positive tumors, a high expression of SERPINB1 was associated with a significantly worse overall survival.

Conclusion

HPV-positive OPSCCs with a low count of CD3+ TILs or high expression of SERPINB1 have a worse OS, comparable with HPV-negative OPSCCs. This suggests that the immune system plays an important role in the carcinogenesis of the virally induced oropharynx tumors.

The role of natural killer cells in pathogenesis of autoimmune diseases

There is growing evidence that NK cell-mediated immunoregulation plays an important role in the control of autoimmunity. NK cells are a subset of lymphocytes that generally contribute to innate immunity but have also a great impact on the function of T and B lymphocytes. The major role of NK cells is cytotoxic reaction against neoplastic, infected and autoreactive cells, but they regulatory function seems to play more important role in the pathogenesis of autoimmune diseases. Numerous studies suggested the involvement of NK cells in pathogenesis of such a common autoimmune diseases as juvenile rheumatoid arthritis, type I diabetes and autoimmune thyroid diseases. The defects of NK cells regulatory function as well as cytotoxic abilities are common in patients with autoimmune diseases with serious consequences including HLH hemophagocytic lymphocytosis (HLH) and macrophage activation syndrome (MAS). The early diagnosis of NK cells defect responsible for the loss of the protective abilities is crucial for the prevention of life-threatening complications and implementation of necessary treatment.

Natural killer cell biology illuminated by primary immunodeficiency syndromes in humans

Natural killer (NK) cells are innate immune cytotoxic effector cells well known for their role in antiviral immunity and tumor immunosurveillance. In parts, this knowledge stems from rare inherited immunodeficiency disorders in humans that abrogate NK cell function leading to immune impairments, most notably associated with a high susceptibility to viral infections. Phenotypically, these disorders range from deficiencies selectively affecting NK cells to complex general immune defects that affect NK cells but also other immune cell subsets. Moreover, deficiencies may be associated with reduced NK cell numbers or rather impair specific NK cell effector functions. In recent years, genetic defects underlying the various NK cell deficiencies have been uncovered and have triggered investigative efforts to decipher the molecular mechanisms underlying these disorders. Here we review the associations between inherited human diseases and NK cell development as well as function, with a particular focus on defects in NK cell exocytosis and cytotoxicity. Furthermore we outline how reports of diverse genetic defects have shaped our understanding of NK cell biology.

Phenotype of NK Cells Determined on the Basis of Selected Immunological Parameters in Children Treated due to Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most frequent pediatric malignancy. The chemotherapy for ALL is associated with a profound secondary immune deficiency.We evaluated the number and phenotype of natural killer (NK) cells at diagnosis, after the intensive chemotherapy and following the completion of the entire treatment for patients with ALL. The fraction, absolute number, and percentage of NK cells expressing interferon-γ were determined in full blood samples. The fraction of NK cells expressing CD158a, CD158b, perforin, A, B, and K granzymes was examined in isolated NK cells.We have shown that patients assessed at ALL diagnosis showed significantly lower values of the fraction of NK cells and percentage of NK cells with the granzyme A expression. Additionally, the absolute number of NK cells, the expression of CD158a, CD158b, perforin, and granzyme A were significantly lower in patients who completed intensive chemotherapy. Also, there was a significantly higher fraction of NK cells expressing granzyme K in patients who completed the therapy.Abnormalities of NK cells were found at all stages of the treatment; however, the most pronounced changes were found at the end of intensive chemotherapy.

Levetiracetam Prevents Perforin Mediated Neuronal Injury Induced by Acute Cerebral Ischemia Reperfusion

The purpose of this study is to explore the neuroprotection mechanism of levetiracetam (LEV) with acute focal cerebral ischemia-reperfusion (I/P) mouse. The cerebral artery I/P animal model was prepared with a middle artery cerebral occlusion method. For drug intervention, mice were intraperitoneally injected with LEV with a dose of either 15 or 150 mg/kg. Neuronal injury was evaluated by measuring the infarct area, apoptosis ratio, and observation of blood-brain barrier ultrastructure with transmission electron microscope. CD8(+) antibody and perforin antibody were used to make cross-reference screen through flow cytometry to determine a perforin-positive rate in CD8(+) T lymphocytes (PFN + %). Injection of LEV can reduce infarct area, apoptosis ratio, and blood-brain barrier damage 24 h later after acute I/P in WT mice. In vitro, perforin can lower hippocampal neuron viability. In vivo, removing perforin can relieve neuronal injury. High dose injection of LEV (150 mg/kg) can inhibit perforin secreting from CD8(+)T lymphocytes. In addition, LEV can still protect neurons with perforin knockout mice. Therefore, our results suggested that LEV may contribute to neuron protection after cerebral ischemia reperfusion. The possible mechanism may be related with perforin release. However, we cannot roll out other mechanisms.

Mechanisms of Control of Mycobacterium tuberculosis by NK Cells: Role of Glutathione

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tb), continues to be one of the most prevalent infectious diseases in the world. There is an upward trend in occurrence due to emerging multidrug resistant strains and an increasingly larger proportion of immunocompromised patient populations as a result of the acquired immunodeficiency syndrome pandemic. The complex and often deadly combination of multidrug resistant M. tb (MDR-M. tb) along with human immunodeficiency virus (HIV) puts a significant number of people at high risk for pulmonary and extra-pulmonary TB without sufficient therapeutic options available. Natural killer (NK) cells and macrophages are major components of the body's innate immune system, contributing significantly to the body's ability to synergistically inhibit the growth of M. tb in immune compromised individuals lacking a sufficient T cell response. Direct mechanisms of control are largely through the secretory products perforin, granulysin, and granzymes, as well as multiple membrane-bound death receptors that facilitate target directed lysis. NK cells also have a role in indirectly stimulating an immune response through activation of macrophages and monocytes with multiple signaling pathways, including both reactive oxygen species and reactive nitrogen species. Glutathione (GSH) has been shown to play a part in inhibiting the growth of intracellular M. tb through bacteriostatic mechanisms. Enhancing cellular GSH through several cytokines and N-acetyl cysteine has been shown to increase these effects, at least in part, through their action on NK cells. Taken together, there is substantial evidence for a mechanistic correlation between NK cell activity and functionality in combating M. tb in HIV infection mediated through adequate GSH production and use.

Dendritic Cells Transfected with a DNA Construct Encoding Tumour-associated Antigen Epitopes Induce a Cytotoxic Immune Response Against Autologous Tumour Cells in a Culture of Mononuclear Cells from Colorectal Cancer Patients

Significant effort has been devoted to developing effective cancer vaccines based on dendritic cells (DCs) loaded with various tumour antigens, including DNA constructs that carry sequences of tumour-associated antigens (TAAs). Such vaccines efficiently and selectively activate the T cell immune response. In this study, we describe a method to induce an antitumour immune response in mononuclear cell (MNC) cultures from colorectal cancer patients using DNA-transfected DCs encoding TAA epitopes of carcinoembryonic antigen, epithelial cell adhesion molecule and mucin 4. DCs were obtained from peripheral blood monocytes of colorectal cancer patients. Magnetic-assisted transfection was used to deliver the genetic constructs to DCs. To assess the potency of the immune response, the antitumour cytotoxic response was assessed by lymphocyte intracellular perforin and the MNC cytotoxic activity against autologous tumour cells. We showed that polyepitope DNA-transfected DCs enhanced MNC antitumour activity, increasing tumour cell death and the percentage of perforin-positive lymphocytes. In addition, DNA-transfected DCs elicited a cytotoxic response that was as efficient as that of tumour lysate-loaded DCs. Taken together, the data suggest that it is feasible to induce an antitumour immune response in colorectal MNCs using transfected DCs. Thus, the DNA construct reported in this study may potentially be used in therapeutic and prophylactic DC-based vaccines.

Ancient Venom Systems: A Review on Cnidaria Toxins

Cnidarians are the oldest extant lineage of venomous animals. Despite their simple anatomy, they are capable of subduing or repelling prey and predator species that are far more complex and recently evolved. Utilizing specialized penetrating nematocysts, cnidarians inject the nematocyst content or "venom" that initiates toxic and immunological reactions in the envenomated organism. These venoms contain enzymes, potent pore forming toxins, and neurotoxins. Enzymes include lipolytic and proteolytic proteins that catabolize prey tissues. Cnidarian pore forming toxins self-assemble to form robust membrane pores that can cause cell death via osmotic lysis. Neurotoxins exhibit rapid ion channel specific activities. In addition, certain cnidarian venoms contain or induce the release of host vasodilatory biogenic amines such as serotonin, histamine, bunodosine and caissarone accelerating the pathogenic effects of other venom enzymes and porins. The cnidarian attacking/defending mechanism is fast and efficient, and massive envenomation of humans may result in death, in some cases within a few minutes to an hour after sting. The complexity of venom components represents a unique therapeutic challenge and probably reflects the ancient evolutionary history of the cnidarian venom system. Thus, they are invaluable as a therapeutic target for sting treatment or as lead compounds for drug design.

The In Vivo Granulopoietic Response to Dexamethasone Injection Is Abolished in Perforin-Deficient Mutant Mice and Corrected by Lymphocyte Transfer from Nonsensitized Wild-Type Donors

Exogenously administered glucocorticoids enhance eosinophil and neutrophil granulocyte production from murine bone-marrow. A hematological response dependent on endogenous glucocorticoids underlies bone-marrow eosinophilia induced by trauma or allergic sensitization/challenge. We detected a defect in granulopoiesis in nonsensitized, perforin-deficient mice. In steady-state conditions, perforin- (Pfp-) deficient mice showed significantly decreased bone-marrow and blood eosinophil and neutrophil counts, and colony formation in response to GM-CSF, relative to wild-type controls of comparable age and/or weight. By contrast, peripheral blood or spleen total cell and lymphocyte numbers were not affected by perforin deficiency. Dexamethasone enhanced colony formation by GM-CSF-stimulated progenitors from wild-type controls, but not Pfp mice. Dexamethasone injection increased bone-marrow eosinophil and neutrophil counts in wild-type controls, but not Pfp mice. Because perforin is expressed in effector lymphocytes, we examined whether this defect would be corrected by transferring wild-type lymphocytes into perforin-deficient recipients. Short-term reconstitution of the response to dexamethasone was separately achieved for eosinophils and neutrophils by transfer of distinct populations of splenic lymphocytes from nonsensitized wild-type donors. Transfer of the same amount of splenic lymphocytes from perforin-deficient donors was ineffective. This demonstrates that the perforin-dependent, granulopoietic response to dexamethasone can be restored by transfer of innate lymphocyte subpopulations.

Decreased expression of NKG2D, NKp46, DNAM-1 receptors, and intracellular perforin and STAT-1 effector molecules in NK cells and their dim and bright subsets in metastatic melanoma patients

Although natural killer (NK) cells play an important antitumor role, melanoma cells may affect their effector functions. In this study, we analyzed the expression of various receptors and effector molecules in NK cells and their subsets in metastatic melanoma (MM) patients compared with healthy controls (HCs). In HC and MM patients, we analyzed NK cell activity using a chromium release assay and the expression of CD107a degranulation marker, activating NKG2D, NKp46, DNAM-1, and inhibitory CD158a and CD158b receptors, IL-12R beta 1, IL-12R beta 2, intracellular interferon (IFN)-γ, perforin, and STAT-1 in CD3-CD56+ NK cells, and cytotoxic CD3-CD56 and immunoregulatory CD3-CD56 subsets by flow cytometry. MM patients compared with HC not only had significantly decreased NK cell activity, lower expression of CD107a, and impaired IFN-γ production but also had decreased expression of activating NKG2D, NKp46, and DNAM-1 receptors, which was followed by lower expression of perforin, STAT-1, and both IL-12R subunits in NK cells. In MM patients only, there was a positive correlation between NKG2D expression and degranulation capacity, as well as IFN-γ production in NK cells. Analysis of the expression of various parameters of NK cell effector functions between MM patients with different localization of distant metastases showed that patients in the unfavorable M1c subclass had decreased expression of NKG2D and NKp46 on NK cells compared with patients in the M1a+b group. Downregulated NKG2D, NKp46, and DNAM-1 receptors associated with impaired NK cell effector function are important biomarkers of advanced disease with a poor prognosis in melanoma patients.

The role of heat shock protein 70 (Hsp70) in radiation-induced immunomodulation

Despite enormous progress in radiation technologies (high precision image-guided irradiation, proton irradiation, heavy ion irradiation) and radiotherapeutic concepts (hypofractionated irradiation schemes), the clinical outcome of radiotherapy in locally advanced and metastasized tumors and in hypoxic tumors which are radiation-resistant remains unsatisfactory. Given their key influence on a number of biological and immunological parameters, this article considers the influence of irradiation-induced stress proteins on radiation-induced immunomodulation. Depending on its location, the major stress-inducible Heat shock protein 70 (Hsp70) has been found to fulfill multiple roles. On the one hand, increased intracellular Hsp70 levels have been found to play a key role in the recovery from stress such as radio(chemo)therapy, and on the other hand extracellular Hsp70 proteins are potent stimulators of the innate immune system and mediators of anti-tumor immunity. Furthermore, if loaded with tumor-derived peptides, members of the Heat Shock Protein 70 (HSP70) and 90 (HSP90) families can stimulate the adaptive immune system via antigen cross-presentation. An irradiation-induced enhancement of the selective expression of a membrane form of Hsp70 on the surface of tumor cells which can act as a recognition structure for activated NK cells might have significant clinical relevance, in that the outcome of irradiation therapy for advanced tumors could be improved by combining it with cell-based and other immunotherapies that target this membrane form of Hsp70.

A mutation in caspase-9 decreases the expression of BAFFR and ICOS in patients with immunodeficiency and lymphoproliferation

Lymphocyte apoptosis is mainly induced by either death receptor-dependent activation of caspase-8 or mitochondria-dependent activation of caspase-9. Mutations in caspase-8 lead to autoimmunity/lymphoproliferation and immunodeficiency. This work describes a heterozygous H237P mutation in caspase-9 that can lead to similar disorders. H237P mutation was detected in two patients: Pt1 with autoimmunity/lymphoproliferation, severe hypogammaglobulinemia and Pt2 with mild hypogammaglobulinemia and Burkitt lymphoma. Their lymphocytes displayed defective caspase-9 activity and decreased apoptotic and activation responses. Transfection experiments showed that mutant caspase-9 display defective enzyme and proapoptotic activities and a dominant-negative effect on wild-type caspase-9. Ex vivo analysis of the patients' lymphocytes and in vitro transfection experiments showed that the expression of mutant caspase-9 correlated with a downregulation of BAFFR (B-cell-activating factor belonging to the TNF family (BAFF) receptor) in B cells and ICOS (inducible T-cell costimulator) in T cells. Both patients carried a second inherited heterozygous mutation missing in the relatives carrying H237P: Pt1 in the transmembrane activator and CAML interactor (TACI) gene (S144X) and Pt2 in the perforin (PRF1) gene (N252S). Both mutations have been previously associated with immunodeficiencies in homozygosis or compound heterozygosis. Taken together, these data suggest that caspase-9 mutations may predispose to immunodeficiency by cooperating with other genetic factors, possibly by downregulating the expression of BAFFR and ICOS.

Cord blood PRF1 methylation patterns and risk of lower respiratory tract infections in infants: findings from the Ulm Birth Cohort

Lower respiratory tract infections (LRTIs) are a major cause of morbidity in children. DNA methylation provides a mechanism for transmitting environmental effects on the genome, but its potential role in LRTIs is not well studied. We investigated the methylation pattern of an enhancer region of the immune effector gene perforin-1 (PRF1), which encodes a cytolytic molecule of cytotoxic T lymphocytes (CTLs) and natural killer cells (NK), in cord blood DNA of children recruited in a German birth cohort in association with LRTIs in the first year of life.Pyrosequencing was used to determine the methylation levels of target cytosine-phosphate-guanines (CpGs) in a 2-stage case-control design. Cases were identified as children who developed ≥2 episodes of physician-recorded LRTIs during the first year of life and controls as children who had none. Discovery (n = 87) and replication (n = 90) sets were arranged in trios of 1 case and 2 controls matched for sex and season of birth.Logistic regression analysis revealed higher levels of methylation at a CpG that corresponds to a signal transducer and activator of transcription 5 (STAT5) responsive enhancer in the discovery (odds ratio [OR] per 1% methylation difference 1.24, 95% confidence interval [CI] 1.03-1.50) and replication (OR per 1% methylation difference 1.25, 95% CI 1.04-1.50) sets. Adjustment for having siblings <5 years old in the discovery and replication sets produced ORs of 1.19 (95% CI 0.98-1.45) and 1.25 (95% CI 1.04-1.50), respectively. Adjustment for gestational age in the replication set had no influence on the results. Methylation levels at adjacent CpGs varied with maternal age, smoking, education, and having siblings <5 years old.Our data support an association between cord blood PRF1 enhancer methylation patterns and subsequent risk of LRTIs in infants. Methylation levels at specific CpGs of the PRF1 enhancer varied according to maternal and family environmental factors suggesting a role for DNA methylation in mediating environmental influences on gene function.

Spectrum of perforin gene mutations in familial hemophagocytic lymphohistiocytosis (FHL) patients in India

BACKGROUND

Inherited perforin deficiency is a rare autosomal recessive disorder that causes severe form of hemophagocytic lymphohistiocytosis (FHL2). The main aim of this study was to analyze the nature of gene mutations in a cohort of Indian patients with FHL2 and to utilize this knowledge for genetic counseling and prenatal diagnosis.

METHODS

13 HLH patients with abnormal perforin expression on NK cells by flow cytometry were included in the study. The entire coding region and intronic splice sites of the PRF1 gene were sequenced from the genomic DNA of these patients.

RESULTS

10 patients from the present series had an early presentation with severe clinical manifestations, while 3 had a delayed onset with unusual presenting features viz Hodgkin's lymphoma, tuberculosis and acute lymphoblastic leukemia. Sequence analysis revealed 11 different mutations (8 novel and 3 previously reported) spread over the entire coding region of PRF1 gene. Missense mutation Trp129Ser in heterozygous state was present in all the 3 patients with a delayed onset of the disease.

CONCLUSION

A wide heterogeneity was observed in the nature of mutations in Indian FHL2 patients. Molecular characterization of PRF1 gene was not only used in the confirmation of diagnosis but also in genetic counseling and pre-natal diagnosis in affected families.

Impact of allogenic and autologous transfusion on immune function in patients with tumors

OBJECTIVE

To observe the effects of allogeneic and autologous transfusion on cellular immunity, humoral immunity and secretion of serum inflammatory factors and perforin during the perioperative period in patients with malignant tumors.

METHODS

A total of 80 patients (age: 38-69 years; body weight: 40-78 kg; ASA I - II) receiving radical operation for gastro-intestinal cancer under general anesthesia were selected. All the patients were divided into four groups based on the methods of infusion and blood transfusion: blank control group (Group C), allogeneic transfusion group (group A), hemodiluted autotransfusion Group (Group H) and hemodiluted autotransfusion + allogenic transfusion Group (A+H group). Venous blood was collected when entering into the surgery room (T0), immediately after surgery (T1) and 24h (T2), 3d (T3) and 7d (T4) after surgery, respectively. Moreover, flow cytometry was applied to assess changes of peripheral blood T cell subpopulations and NK cells. Enzyme linked immunosorbent assays were performed to determine levels of IL-2, IL-10, TNF-α and perforin. Immune turbidimetry was employed to determine the changes in serum immunoglobulin.

RESULTS

Both CD3+ and NK cells showed a decrease at T1 and T2 in each group, among which, in group A, CD3+ decreased significantly at T2 (P<0.05) compared with other groups, and CD3+ and NK cell reduced obviously only in group A at T3 and T4 (P<0.05). CD4+ cells and the ratio of D4+/CD8+ were decreased in groups A, C and A+H at T1 and T2 (P<0.05). No significant intra- and inter-group differences were observed in CD8+ of the four groups (P<0.05). IL-2 declined in group C at T1 and T2 (P<0.05) and showed a decrease in group A at each time point (P<0.05). Moreover, IL-2 decreased in group A + H only at T1. No significant difference was found in each group at T1 (P<0.05). More significant decrease in group C at T2, T3 and T4 compared with group A (P<0.05), and there were no significant differences among other groups (P>0.05). IL-10 increased at T1 and T2 in each group (P<0.05), in which it had an obvious increase in group A, and increase of IL-10 occurred only in group A at T3 and T4 (P<0.05). TNF-α level rose at T1 (P<0.05), no inter- and intra-group difference was found in perforin in all groups (P<0.05). Compared with the preoperation, both IgG and IgA level decreased at T1 in each group (P<0.05), and they declined only in Group A at T2 and T3 (P<0.05), and these parameters were back to the preoperative levels in other groups. No significant differences were observed between preoperative and postoperative IgG and IgA levels in each group at T4 (P>0.05). No obvious inter- and intra-group changes were found in IgM in the four groups (P>0.05).

CONCLUSIONS

Allogeneic transfusion during the perioperative period could obviously decrease the number of T cell subpopulations and NK cells and the secretion of stimulating cytokines and increase the secretion of inhibiting cytokines in patients with malignant tumors, thus causing a Th1/Th2 imbalance and transient decreasing in the content of plasma immune globulin. Autologous transfusion has little impact and may even bring about some improvement of postoperative immune function in patients with tumors. Therefore, cancer patients should receive active autologous transfusion during the perioperative period in place of allogeneic transfusion.

Effects of Treg cells and IDO on human epithelial ovarian cancer cells under hypoxic conditions

The aim of the present study was to explore the effect of hypoxia on ovarian cancer. A total of 6 samples were analyzed: SKOV3‑IP cells (ovarian cancer cell line); SKOV3‑IP and regulatory T (Treg) cells; SKOV3‑IP and cytotoxic T lymphocytes (CTLs); SKOV3‑IP and natural killer (NK) cells; SKOV3‑IP co-cultured with CTLs and Treg cells; and SKOV3‑IP co-cultured with Treg cells and NK cells. The expression of indoleamine 2,3‑dioxygenase (IDO) was detected by reverse transcription-polymerase chain reaction (RT‑PCR) and western blot analysis. An enzyme‑linked immunosorbent assay (ELISA) was used to detect the concentration of transforming growth factor‑β (TGF‑β), interferon‑γ (IFN‑γ), interleukin‑2 (IL‑2), interleukin‑10 (IL‑10), and perforin. Moreover, ovarian cancer cell apoptosis and invasive ability were examined using flow cytometry and a Transwell chamber assay. IDO expression was significantly reduced in hypoxia and enhanced by Treg cells. Treg cells inhibited the IL‑2, IFN‑γ and perforin secretion, and significantly (P<0.05) increased the IL‑10 and TGF‑β levels. The effects of Treg cells were enhanced with prolongation of the cell exposure to hypoxic conditions. In addition, Treg cells attenuated the promotive effect of CTLs and NK cells on cancer cell apoptosis. In addition, Treg cells significantly increased the SKOV3‑IP invasive ability (P=0.00109) under hypoxic conditions. Our results suggest that IDO and Treg cells may serve as important therapeutic targets for patients with ovarian cancer.

Variations of the perforin gene in patients with chronic inflammatory demyelinating polyradiculoneuropathy

Perforin (PRF) has a key role in the function of cytotoxic T and natural killer cells. Rare variations of PRF1 predispose to autoimmunity. Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune disease of the peripheral nervous system, involving defective lymphocyte apoptosis. The aim of this study was to investigate the role of PRF1 in CIDP. The entire coding region of PRF1 was sequenced in 94 patients and 158 controls. We found three missense variations leading to amino acid substitutions and one nonsense variation resulting in a premature stop codon. All variations would decrease PRF activity. Their overall frequency was significantly higher in patients than in controls (odds ratio (OR)=4.47). The most frequent variation was p.Ala91Val (OR=3.92) previously associated with other autoimmune diseases. Clinical analysis showed that PRF1 variations were more frequent in relapsing patients and in patients displaying axonal damage. These data suggest that PRF1 variations may influence CIDP development and course.

Human perforin mutations and susceptibility to multiple primary cancers

Loss-of-function mutations in the gene coding for perforin (PRF1) markedly reduce the ability of cytotoxic T lymphocytes and natural killer cells to kill target cells, causing immunosuppression and impairing immune regulation. In humans, nearly half of the cases of type 2 familial hemophagocytic lymphohistiocytosis are due to bi-allelic PRF1 mutations. The partial inactivation of PRF1 due to mutations that promote protein misfolding or the common hypomorphic allele coding for the A91V substitution have been associated with lymphoid malignancies in childhood and adolescence. To investigate whether PRF1 mutations also predispose adults to cancer, we genotyped 566 individuals diagnosed with melanoma (101), lymphoma (65), colorectal carcinoma (30) or ovarian cancer (370). The frequency of PRF1 genotypes was similar in all disease groups and 424 matched controls, indicating that the PRF1 status is not associated with an increased susceptibility to these malignancies. However, four out of 15 additional individuals diagnosed with melanoma and B-cell lymphoma during their lifetime expressed either PRF1^A91V or the rare pathogenic PRF1^R28C variant (p = 0.04), and developed melanoma relatively early in life. Both PRF1^A91V- and PRF1^R28C-expressing lymphocytes exhibited severely impaired but measurable cytotoxic function. Our results suggest that defects in human PRF1 predispose individuals to develop both melanoma and lymphoma. However, these findings require validation in larger patient cohorts.

Macrophage-expressed perforins mpeg1 and mpeg1.2 have an anti-bacterial function in zebrafish

Macrophage-expressed gene 1 (MPEG1) encodes an evolutionarily conserved protein with a predicted membrane attack complex/perforin domain associated with host defence against invading pathogens. In vertebrates, MPEG1/perforin-2 is an integral membrane protein of macrophages, suspected to be involved in the killing of intracellular bacteria by pore-forming activity. Zebrafish have 3 copies of MPEG1; 2 are expressed in macrophages, whereas the third could be a pseudogene. The mpeg1 and mpeg1.2 genes show differential regulation during infection of zebrafish embryos with the bacterial pathogens Mycobacterium marinum and Salmonella typhimurium. While mpeg1 is downregulated during infection with both pathogens, mpeg1.2 is infection inducible. Upregulation of mpeg1.2 is partially dependent on the presence of functional Mpeg1 and requires the Toll-like receptor adaptor molecule MyD88 and the transcription factor NFκB. Knockdown of mpeg1 alters the immune response to M. marinum infection and results in an increased bacterial burden. In Salmonella typhimurium infection, both mpeg1 and mpeg1.2 knockdown increase the bacterial burdens, but mpeg1 morphants show increased survival times. The combined results of these two in vivo infection models support the anti-bacterial function of the MPEG1/perforin-2 family and indicate that the intricate cross-regulation of the two mpeg1 copies aids the zebrafish host in combatting infection of various pathogens.

Perforin expression in plaque psoriasis: an immunohistochemical study

Psoriasis (PsO) is T-cell-mediated disease resulting from aberrant activation of both innate and adaptive immunity. Perforin is a multi-domain, pore-forming protein. It is located within the cytoplasm of CD 8 cytotoxic T cells (CTLs) and natural killer cells (NK). The aim of this study was to evaluate the immunohistochemical (IHC) expression of perforin in lesional and perilesional skin of chronic plaque psoriatic patient and correlate its expression with the standard clinico-pathological variables. This prospective case-control study was conducted on 50 PsO patients and 30 age- and gender-matched healthy subjects as a control group. There were high-significant differences between lesional and perilesional skin of plaque PsO patients as regards to IHC perforin status and localization (p < 0.001 for both). There was a high-significant difference between positive and negative perforin cases as regards to psoriasis area severity index (PASI) (p < 0.000). There were significant differences between mild and moderate-to-severe intensity of IHC perforin expression as regards to triggering factors and PASI (p = 0.02 and 0.03, respectively). Localization of IHC perforin positive lymphocytes in both epidermis and dermis was significantly associated with higher degree of acanthosis and higher degree of inflammatory infiltrates in comparison with positive cells located in dermis (p = 0.001 for both). Perforin might have a putative signaling in early and late plaque PsO. Plaque psoriatic patients with positive perforin expression could be a candidate for a future target therapy to stop the proposed scenario and achieve a therapeutic response.

Presence of perforin in endomyocardial biopsies of patients with inflammatory cardiomyopathy predicts poor outcome

AIMS

Intramyocardial inflammation is considered an adverse prognostic factor in inflammatory cardiomyopathy (CMi). However, the precise nature of immune system factors relevant for the prediction of long-term course remains elusive. The aim of this study was to analyse the prognostic relevance of perforin in a large cohort of patients with CMi.

METHODS AND RESULTS

We investigated 495 consecutive patients with suspected CMi, undergoing endomyocardial biopsies (EMBs), and examined haemodynamic measurements after a long follow-up period (interquartile range 10.2-37.1 months). In EMBs, myocardial inflammation was assessed by histology and immunohistology. At follow-up, 388 patients (Group I) showed stable mild dysfunction or significant improvement, with LVEF rising from 46.2 ± 14.8% to 64.3 ± 12.3% (P < 0.0001). Lack of improvement of LV function or significant deterioration of LVEF from 42.1 ± 14.2% to 32.3 ± 11.6% (P < 0.0001) was observed in 107 patients (Group II). Multivariable statistical analysis of LVEF and immunohistochemical parameters in all patients revealed that the single most important predictor of LVEF development was detection of perforin in EMBs, with an odds ratio (OR) of 7.922 [95% confidence interval (CI) 4.380-14.326; P < 0.001] for deteriorating LVEF. Importantly, baseline LVEF (OR 0.962), LV end-diastolic diameter (OR 1.847), and other immmunohistochemical parameters (CD3, Mac-1, CD45R0, LFA-1, HLA-1, and ICAM-1) made minor or insignificant contributions to LVEF course in these 495 patients.

CONCLUSIONS

In this EMB-based analysis of the long-term course of CMi we identified, for the first time, that detection of perforin in the myocardium is a key predictor of LVEF course.

The preclinical pharmacokinetic disposition of a series of perforin-inhibitors as potential immunosuppressive agents

The cytolytic protein perforin is a key component of the immune response and is implicated in a number of human pathologies and therapy-induced conditions. A novel series of small molecule inhibitors of perforin function have been developed as potential immunosuppressive agents. The pharmacokinetics and metabolic stability of a series of 16 inhibitors of perforin was evaluated in male CD1 mice following intravenous administration. The compounds were well tolerated 6 h after dosing. After intravenous administration at 5 mg/kg, maximum plasma concentrations ranged from 532 ± 200 to 10,061 ± 12 ng/mL across the series. Plasma concentrations were greater than the concentrations required for in vitro inhibitory activity for 11 of the compounds. Following an initial rapid distribution phase, the elimination half-life values for the series ranged from 0.82 ± 0.25 to 4.38 ± 4.48 h. All compounds in the series were susceptible to oxidative biotransformation. Following incubations with microsomal preparations, a tenfold range in in vitro half-life was observed across the series. The data suggests that oxidative biotransformation was not singularly responsible for clearance of the compounds and no direct relationship between microsomal clearance and plasma clearance was observed. Structural modifications however, do provide some information as to the relative microsomal stability of the compounds, which may be useful for further drug development.