Maternal diesel particle exposure promotes offspring asthma through NK cell-derived granzyme B

Death receptors 4/5 mediate tumour sensitivity to natural killer cell-mediated cytotoxicity in mismatch repair deficient colorectal cancer

BACKGROUND

Identifying the target of natural killer (NK) cells in colorectal cancer (CRC) is critical for optimising the clinical use of NK cell-mediated immunotherapy. Mismatch repair deficiency (dMMR) is associated with high immune cell infiltration and MHC Class I defects. Whether dMMR CRC responses to NK cell therapy remains unclear.

METHODS

MLH1, DR4, and DR5 knockout cell lines were established using CRISPR-Cas9 system. NK92-MI or NK cell isolated from BABL/C mice were used as effector cells against tumour cells. Inflammatory cytokines secretion by CRC cells was assessed via cytokine analysis. NK-cell-deficient/proficient animal models were used to validate the NK cell sensitivity.

RESULTS

We observed that dMMR CRC cells were more sensitive to NK cell-mediated cytotoxicity than were mismatch-repair-proficient (pMMR) CRC cells. In dMMR CRC, Death receptor (DR)4/5 was upregulated and mediated sensitivity to NK cell-mediated cytotoxicity. DR4/5-mediated secretion of interleukin -12 sustained NK cell viability in dMMR CRC. NK cell depletion induced dMMR CRC tumour growth, and NK cell transfer inhibited lung metastasis of dMMR CRC with DR4/5 expression in vivo. TP53 upregulated DR4/DR5 expression in dMMR CRC.

CONCLUSIONS

dMMR associated with increased sensitivity to NK cell-mediated cytotoxicity in CRC. DR4/DR5 sensitise dMMR CRC to NK cell-mediated cytotoxicity.

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.

Maternal CXCR4 deletion results in placental defects and pregnancy loss mediated by immune dysregulation

CXCR4 is a key regulator of the development of NK cells and DCs, both of which play an important role in early placental development and immune tolerance at the maternal-fetal interface. However, the role of CXCR4 in pregnancy is not well understood. Our study demonstrates that adult-induced global genetic CXCR4 deletion, but not uterine-specific CXCR4 deletion, was associated with increased pregnancy resorptions and decreased litter size. CXCR4-deficient mice had decreased NK cells and increased granulocytes in the decidua, along with increased leukocyte numbers in peripheral blood. We found that CXCR4-deficient mice had abnormal decidual NK cell aggregates and NK cell infiltration into trophoblast areas beyond the giant cell layer. This was associated with low NK cell expression of granzyme B, a NK cell granule effector, indicative of NK cell dysfunction. Pregnancy failure in these mice was associated with abnormalities in placental vascular development and increased placental expression of inflammatory genes. Importantly, adoptive BM transfer of WT CXCR4+ BM cells into CXCR4-deficient mice rescued the reproductive deficits by normalizing NK cell function and mediating normal placental vascular development. Collectively, our study found an important role for maternal CXCR4 expression in immune cell function, placental development, and pregnancy maintenance.

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.

Granzyme B: A novel therapeutic target for treatment of atopic dermatitis

Granzyme B is a serine protease that can play multiple roles in intracellular and extracellular perforin-dependent or non-perforin-dependent mechanisms. Granzyme B has been found to be an important factor involved in the pathogenesis of atopic dermatitis and is increased in both skin lesions and peripheral blood of atopic dermatitis patients. In this article, we review the correlation between granzyme B and atopic dermatitis to provide a novel therapeutic targeting option for clinical treatment of the latter.

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.

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.

Gestational exposure to titanium dioxide, diesel exhaust, and concentrated urban air particles affects levels of specialized pro-resolving mediators in response to allergen in asthma-susceptible neonate lungs

Maternal gestational exposures to traffic and urban air pollutant particulates have been linked to increased risk and/or worsening asthma in children; however, mechanisms underlying this vertical transmission are not entirely understood. It was postulated that gestational particle exposure might affect the ability to elicit specialized proresolving mediator (SPM) responses upon allergen encounter in neonates. Lipidomic profiling of 50 SPMs was performed in lungs of neonates born to mice exposed to concentrated urban air particles (CAP), diesel exhaust particles (DEP), or less immunotoxic titanium dioxide particles (TiO2). While asthma-like phenotypes were induced with identical eosinophilia intensity across neonates of all particle-exposed mothers, levels of LXA4, HEPE and HETE isoforms, and HDoHe were only decreased by CAP and DEP only but not by TiO2. However, RvE2 and RvD1 were inhibited by all particles. In contrast, isomers of Maresin1 and Protectin D1 were variably elevated by CAP and DEP, whereas Protectin DX, PGE2, and TxB2 were increased in all groups. Only Protectin D1/DX, MaR1(n-3,DPA), 5(S),15(S)-DiHETE, PGE2, and RvE3 correlated with eosinophilia but the majority of other analytes, elevated or inhibited, showed no marked correlation with inflammation intensity. Evidence indicates that gestational particle exposure leads to both particle-specific and nonspecific effects on the SPM network.

Eosinophils Restrict Diesel Exhaust Particles Induced Cell Proliferation of Lung Epithelial A549 Cells, Vial Interleukin-13 Mediated Mechanisms: Implications for Tissue Remodelling And Fibrosis

BACKGROUND

Diesel exhaust particulates (DEPs) affect lung physiology and cause serious damage to the lungs. A number of studies demonstrated that, eosinophils play a very important role in the development of tissue remodelling and fibrosis of lungs. However, the exact mechanism of pathogenesis of tissue remodelling and fibrosis is not known.

METHODS

Both in vitro and in vivo models were used in the study. HL-60 and A549 cells were used in the study. Balb/C mice of 8 to 12 weeks old were used for in vivo study. Cell viability by MTT assay, RNA isolation by tri reagent was accomplished. mRNA expression of inflammatory genes were accomplished by real time PCR or qPCR. Immunohistochemistry was done to asses the localization and expressions of proteins. One way ANOVA followed by post hoc test were done for the statistical analysis. Graph-Pad Prism software was used for statistical analysis.

RESULTS

We for the first time demonstrate that, Interleukin-13 plays a very important role in the development of tissue remodelling and fibrosis. We report that, diesel exhaust particles significantly induce eosinophils cell proliferation and interleukin-13 release in in vitro culture conditions. Supernatant collected from DEP-induced eosinophils cells significantly restrict cell proliferation of epithelial cells in response to exposure of diesel exhast particles. Furthermore, purified interleukin-13 decreases the proliferation of A549 cells, highliting the involvement of IL-13 in tissue remodeling. Notably, Etoricoxib (selective COX-2 inhibitor) did not inhibit DEP-triggered release of interleukin-13, suggesting another cell signalling pathway. The in vivo exposer of DEP to the lungs of mice, resulted in high level of eosinophils degranulation as depicted by the EPX-1 immunostaining and altered level of mRNA expressions of inflammatory genes. We also found that, a-SMA, fibroblast specific protein (FSP-1) has been changed in response to DEP in the mice lungs along with the mediators of inflammation.

CONCLUSION

Altogether, we elucidated, the mechanistic role of eosinophils and IL-13 in the DEP-triggered proliferation of lungs cells thus providing an inside in the pathophysiology of tissue remodelling and fibrosis of lungs.

Pathological functions of granzyme B in inflammatory skin diseases

Dysregulated skin immunity is a hallmark of many skin diseases such as atopic dermatitis, autoimmune blistering diseases, and interface dermatitis. Current treatment options for the inflammatory skin diseases are limited and sometimes ineffective, therefore further understanding of pathomechanisms in the inflammatory skin conditions is necessary to develop new therapeutic alternatives. Recent studies suggest that the serine protease, granzyme B, is a key mediator in multiple inflammatory skin diseases, implying that strategies targeting granzyme B may be an attractive treatment option for such diseases. Specifically, granzyme B exhibits not only an intracellular apoptotic function but also extracellular proteolytic roles in inflammatory skin diseases including infectious diseases, pemphigoid diseases, atopic dermatitis, alopecia areata, and interface dermatitis. In this review, we summarize the current understanding with respect to the functions of granzyme B in the pathomechanism of various inflammatory skin diseases and evaluate the possibility of therapeutics targeting granzyme B.

An Exploratory Study of the Relationships Between Diesel Engine Exhaust Particle Inhalation, Pulmonary Inflammation and Anxious Behavior

Recent technical developments brought negative side effects such as air pollution and large-scale fires, increasingly exposing people to diesel engine exhaust particles (DEP). Testing how DEP inhalation triggers pathophysiology in animal models could be useful in determining how it affects humans. To this end, the aim of this study was to investigate the effects of pulmonary exposure to DEP for seven consecutive days in experimental male C5BL6/N mice. Twenty-four C5BL6/N mice were treated with one of the three test materials: distilled water for control, a low DEP exposure (5 mg/kg), or a high DEP exposure (15 mg/kg). Exposure to DEP induced decreased body weight; however, it gradually increased pulmonary weight in a DEP-dose-dependent manner. DEP exposure significantly elevated soot accumulation in the lungs, with the alteration of pulmonary homeostasis. It also elevated infiltrated immune cells, thus significantly increasing inflammatory cytokine mRNA and protein production in the lungs and broncho-alveolar lavage fluid, respectively. Pulmonary DEP exposure also altered behavioral responses in the open field test (OFT). Low exposure elevated moving distance and speed, while significantly decreasing the number of trials to enter the central zone. Different concentrations of DEP resulted in different behavioral changes; however, while anxiety levels increased, their degree was independent of DEP concentrations. Results suggest that DEP exposure may possess pro-inflammatory responses in the lungs and trigger anxiety.

Granzyme B Induces IRF-3 Phosphorylation through a Perforin-Independent Proteolysis-Dependent Signaling Cascade without Inducing Cell Death

Granzyme B (GrB) is an immune protease implicated in the pathogenesis of several human diseases. In the current model of GrB activity, perforin determines whether the downstream actions of GrB occur intracellularly or extracellularly, producing apoptotic cytotoxicity or nonapoptotic effects, respectively. In the current study, we demonstrate the existence of a broad range of GrB-dependent signaling activities that 1) do not require perforin, 2) occur intracellularly, and 3) for which cell death is not the dominant outcome. In the absence of perforin, we show that GrB enzymatic activity still induces substoichiometric activation of caspases, which through nonlethal DNA damage response signals then leads to activity-associated phosphorylation of IFN regulatory factor-3. These findings illustrate an unexpected potential interface between GrB and innate immunity separate from the traditional role of GrB in perforin-dependent GrB-mediated apoptosis that could have mechanistic implications for human disease.