The N-terminus domain of the a2 isoform of vacuolar ATPase can regulate interleukin-1beta production from mononuclear cells in co-culture with JEG-3 choriocarcinoma cells

The (pro)renin receptor ((P)RR) and soluble (pro)renin receptor (s(P)RR) in pregnancy

The (pro)renin receptor ((P)RR) is a multi-functional protein that can be proteolytically cleaved and released in a soluble form (s(P)RR). Recently, the (P)RR and s(P)RR have become of interest in pregnancy and its associated pathologies. This is because the (P)RR not only activates tissue renin angiotensin systems, but it is also an integral component of vacuolar-ATPase, activates the wingless/integrated (Wnt)/β-catenin and extracellular signal regulated kinases 1 and 2/mitogen-activated protein kinase signalling pathways, and stabilises the β subunit of pyruvate dehydrogenase. Additionally, s(P)RR is detected in plasma and urine, and maternal plasma levels are elevated in pregnancy complications including fetal growth restriction, preeclampsia and gestational diabetes mellitus. Therefore, s(P)RR has potential as a biomarker for these pregnancy pathologies. Preliminary functional findings suggest that s(P)RR may be important for regulating fluid balance, inflammation and blood pressure, all of which contribute to a successful pregnancy. The (P)RR and s(P)RR regulate pathways that are known to be important in maintaining pregnancy, however their role in the physiological context of pregnancy is poorly characterised. This review summarises the known and potential functions of the (P)RR and s(P)RR in pregnancy, and how their dysregulation may contribute to pregnancy complications. It also highlights the need for further research into the source and function of s(P)RR in pregnancy. Soluble (P)RR levels could be indicative of placental, kidney or liver dysfunction and therefore be a novel clinical biomarker, or therapeutic target, to improve the detection and treatment of pregnancy pathologies.

Cancer-associated V-ATPase induces delayed apoptosis of protumorigenic neutrophils

Tumors and neutrophils undergo an unexpected interaction, in which products released by tumor cells interact to support neutrophils that in turn support cancer growth, angiogenesis, and metastasis. A key protein that is highly expressed by cancer cells in tumors is the a2 isoform V‐ATPase (a2V). A peptide from a2V (a2NTD) is secreted specifically by cancer cells, but not normal cells, into the tumor microenvironment. This peptide reprograms neutrophils to promote angiogenesis, cancer cell invasiveness, and neutrophil recruitment. Here, we provide evidence that cancer‐associated a2V regulates the life span of protumorigenic neutrophils by influencing the intrinsic pathway of apoptosis. Immunohistochemical analysis of human cancer tissue sections collected from four different organs shows that levels of a2NTD and neutrophil counts are increased in cancer compared with normal tissues. Significant increases in neutrophil counts were present in both poorly and moderately differentiated tumors. In addition, there is a positive correlation between the number of neutrophils and a2NTD expression. Human neutrophils treated with recombinant a2NTD show significantly delayed apoptosis, and such prolonged survival was dependent on NF‐κB activation and ROS generation. Induction of antiapoptotic protein expression (Bcl‐xL and Bcl‐2A1) and decreased expression of proapoptotic proteins (Bax, Apaf‐1, caspase‐3, caspase‐6, and caspase‐7) were a hallmark of these treated neutrophils. Autocrine secretion of prosurvival cytokines of TNF‐α and IL‐8 by treated neutrophils prolongs their survival. Our findings highlight the important role of cancer‐associated a2V in regulating protumorigenic innate immunity, identifying a2V as a potential important target for cancer therapy.

Cancer derived peptide of vacuolar ATPase 'a2' isoform promotes neutrophil migration by autocrine secretion of IL-8

Neutrophils play significant regulatory roles within the tumor microenvironment by directly promoting tumor progression that leads to poor clinical outcomes. Identifying the tumor associated molecules that regulate neutrophil infiltration into tumors may provide new and specific therapeutic targets for cancer treatment. The a2-isoform of vacuolar ATPase (a2V) is uniquely and highly expressed on cancer cell plasma membrane. Cancer cells secrete a peptide from a2V (a2NTD) that promotes the pro-tumorigenic properties of neutrophils. This provides a2V the propensity to control neutrophil migration. Here, we report that the treatment of human neutrophils with recombinant a2NTD leads to neutrophil adherence and polarization. Moreover, a2NTD treatment activates surface adhesion receptors, as well as FAK and Src kinases that are essential regulators of the migration process in neutrophils. Functional analysis reveals that a2NTD can act as a chemo-attractant and promotes neutrophil migration. In addition, a2Neuɸ secrete high levels of IL-8 via NF-κB pathway activation. Confirmatory assays demonstrate that the promoted migration of a2Neuɸ was dependent on the autocrine secretion of IL-8 from a2Neuɸ. These findings demonstrate for the first time the direct regulatory role of cancer associated a2-isoform V-ATPase on neutrophil migration, suggesting a2V as a potential target for cancer therapy.

Breast cancer associated a2 isoform vacuolar ATPase immunomodulates neutrophils: potential role in tumor progression

In invasive breast cancer, tumor associated neutrophils (TAN) represent a significant portion of the tumor mass and are associated with increased angiogenesis and metastasis. Identifying the regulatory factors that control TAN behavior will help in developing ideal immunotherapies. Vacuolar ATPases (V-ATPases), multi-subunit proton pumps, are highly expressed in metastatic breast cancer cells. A cleaved peptide from a2 isoform V-ATPase (a2NTD) has immunomodulatory role in tumor microenvironment. Here, we report for the first time the role of V-ATPase in neutrophils modulation. In invasive breast cancer cells, a2NTD was detected and a2V was highly expressed on the surface. Immunohistochemical analysis of invasive breast cancer tissues revealed that increased neutrophil recruitment and blood vessel density correlated with increased a2NTD levels. In order to determine the direct regulatory role of a2NTD on neutrophils, recombinant a2NTD was used for the treatment of neutrophils isolated from the peripheral blood of healthy volunteers. Neutrophils treated with a2NTD (a2Neuɸ) showed increased secretion of IL-1RA, IL-10, CCL-2 and IL-6 that are important mediators in cancer related inflammation. Moreover, a2Neuɸ exhibited an increased production of protumorigenic factors including IL-8, matrix metaloprotinase-9 and vascular endothelial growth factor. Further, functional characterization of a2Neuɸ revealed that a2Neuɸ derived products induce in vitro angiogenesis as well as increase the invasiveness of breast cancer cells. This study establishes the modulatory effect of breast cancer associated a2V on neutrophils, by the action of a2NTD, which has a positive impact on tumor progression, supporting that a2V can be a potential selective target for breast cancer therapy.

Selective inhibition of tumor cell associated Vacuolar-ATPase 'a2' isoform overcomes cisplatin resistance in ovarian cancer cells

Development of resistance to platinum compounds significantly hinders successful ovarian cancer (OVCA) treatment. In tumor cells, dysregulated pH gradient across cell membranes is a key physiological mechanism of metastasis/chemo-resistance. These pH alterations are mediated by aberrant activation of key multi-subunit proton pumps, Vacuolar-ATPases (V-ATPases). In tumor cells, its 'a2' isoform (V-ATPase-V0a2) is a component of functional plasma-membrane complex and promotes tumor invasion through tumor-acidification and immuno-modulation. Its involvement in chemo-resistance has not been studied. Here, we show that V-ATPase-V0a2 is over-expressed in acquired-cisplatin resistant OVCA cells (cis-A2780/cis-TOV112D). Of all the 'a' subunit isoforms, V-ATPase-V0a2 exhibited an elevated expression on plasma membrane of cisplatin-resistant cells compared to sensitive counterparts. Immuno-histochemistry revealed V-ATPase-V0a2 expression in both low grade (highly drug-resistant) and high grade (highly recurrent) human OVCA tissues indicating its role in a centralized mechanism of tumor resistance. In cisplatin resistant cells, shRNA mediated inhibition of V-ATPase-V0a2 enhanced sensitivity towards both cisplatin and carboplatin. This improved cytotoxicity was mediated by enhanced cisplatin-DNA-adduct formation and suppressed DNA-repair pathway, leading to enhanced apoptosis. Suppression of V0a2 activity strongly reduced cytosolic pH in resistant tumor cells, which is known to enhance platinum-associated DNA-damage. As an indicator of reduced metastasis and chemo-resistance, in contrast to plasma membrane localization, a diffused cytoplasmic localization of acidic vacuoles was observed in V0a2-knockdown resistant cells. Interestingly, pre-treatment with monoclonal V0a2-inhibitory antibody enhanced cisplatin cytotoxicity in resistant cells. Taken together, our findings suggest that the isoform specific inhibition of V-ATPase-V0a2 could serve as a therapeutic strategy for chemo-resistant ovarian carcinoma and improve efficacy of platinum drugs.

Vacuolar ATPase 'a2' isoform exhibits distinct cell surface accumulation and modulates matrix metalloproteinase activity in ovarian cancer

Tumor associated vacuolar H+-ATPases (V-ATPases) are multi-subunit proton pumps that acidify tumor microenvironment, thereby promoting tumor invasion. Subunit ‘a’ of its V0 domain is the major pH sensing unit that additionally controls sub-cellular targeting of V-ATPase and exists in four different isoforms. Our study reports an elevated expression of the V-ATPase-V0a2 isoform in ovarian cancer(OVCA) tissues and cell lines(A2780, SKOV-3 and TOV-112D). Among all V0’a’ isoforms, V0a2 exhibited abundant expression on OVCA cell surface while normal ovarian epithelia did not. Sub-cellular distribution of V-ATPase-V0a2 confirmed its localization on plasma-membrane, where it was also co-associated with cortactin, an F-actin stabilizing protein at leading edges of cancer cells. Additionally, V0a2 was also localized in early and late endosomal compartments that are sites for modulations of several signaling pathways in cancer. Targeted inhibition of V-ATPase-V0a2 suppressed matrix metalloproteinase activity(MMP-9 & MMP-2) in OVCA cells. In conclusion, V-ATPase-V0a2 isoform is abundantly expressed on ovarian tumor cell surface in association with invasion assembly related proteins and plays critical role in tumor invasion by modulating the activity of matrix-degrading proteases. This study highlights for the first time, the importance of V-ATPase-V0a2 isoform as a distinct biomarker and possible therapeutic target for treatment of ovarian carcinoma.

Role of Notch signaling during lipopolysaccharide-induced preterm labor

Notch signaling pathways exert effects throughout pregnancy and are activated in response to TLR ligands. To investigate the role of Notch signaling in preterm labor, Notch receptors (Notch1-4), its ligand Delta-like protein-1, transcriptional repressor hairy and enhancer of split-1, and Notch deregulator Numb were assessed. Preterm labor was initiated on gestation d 14.5 by 1 of 2 methods: 1) inflammation-induced preterm labor: intrauterine injection of LPS (a TLR4 agonist) and 2) hormonally induced preterm labor: subcutaneous injection of mifepristone. Delta-like protein-1, Notch1, and hairy and enhancer of split-1 were elevated significantly, and Numb was decreased in the uterus and placenta of inflammation-induced preterm labor mice but remained unchanged in hormonally induced preterm labor compared with their respective controls. F4/80(+) macrophage polarization was skewed in the uterus of inflammation-induced preterm labor toward M1-positive (CD11c(+)) and double-positive [CD11c(+) (M1) and CD206(+) (M2)] cells. This process is dependent on activation of Notch signaling, as shown by suppression of M1 and M2 macrophage-associated cytokines in decidual macrophages in response to γ-secretase inhibitor (an inhibitor of Notch receptor processing) treatment ex vivo. γ-Secretase inhibitor treatment also diminished the LPS-induced secretion of proinflammatory cytokines and chemokines in decidual and placental cells cultured ex vivo. Furthermore, treatment with recombinant Delta-like protein-1 ligand enhanced the LPS-induced proinflammatory response. Notch ligands (Jagged 1 and 2 and Delta-like protein-4) and vascular endothelial growth factor and its receptor involved in angiogenesis were reduced significantly in the uterus and placenta during inflammation-induced preterm labor. These results suggest that up-regulation of Notch-related inflammation and down-regulation of angiogenesis factors may be associated with inflammation-induced preterm labor but not with hormonally induced preterm labor.

Inhibition of vacuolar ATPase subunit in tumor cells delays tumor growth by decreasing the essential macrophage population in the tumor microenvironment

In cancer cells, vacuolar ATPase (V-ATPase), a multi-subunit enzyme, is expressed on the plasma as well as vesicular membranes and critically influences metastatic behavior. The soluble, cleaved N-terminal domain of V-ATPase a2 isoform is associated with in vitro induction of tumorigenic characteristics in macrophages. This activity led us to further investigate its in vivo role in cancer progression by inhibition of a2 isoform (a2V) in tumor cells and the concomitant effect on tumor microenvironment in the mouse 4T-1 breast cancer model. Results showed that macrophages cocultivated with a2V knockdown (sh-a2) 4T-1 cells produce lower amounts of tumorigenic factors in vitro and have reduced ability to suppress T-cell activation and proliferation compared with control 4T-1 cells. Data analysis showed a delayed mammary tumor growth in Balb/c mice inoculated with sh-a2 4T-1 cells compared with control. The purified CD11b(+) macrophages from sh-a2 tumors showed a reduced expression of mannose receptor-1 (CD206), interleukin-10, transforming growth factor-β, arginase-1, matrix metalloproteinase and vascular endothelial growth factor. Flow cytometric analysis of tumor-infiltrated macrophages showed a significantly low number of F4/80(+)CD11c(+)CD206(+) macrophages in sh-a2 tumors compared with control. In sh-a2 tumors, most of the macrophages were F4/80(+)CD11c(+) (antitumor M1 macrophages) suggesting it to be the reason behind delayed tumor growth. Additionally, tumor-infiltrating macrophages from sh-a2 tumors showed a reduced expression of CD206 compared with control whereas CD11c expression was unaffected. These findings demonstrate that in the absence of a2V in tumor cells, the resident macrophage population in the tumor microenvironment is altered which affects in vivo tumor growth. We suggest that by involving the host immune system, tumor growth can be controlled through targeting of a2V on tumor cells.

Altered autophagic flux enhances inflammatory responses during inflammation-induced preterm labor

Cellular organelles and proteins are degraded and recycled through autophagy, a process during which vesicles known as autophagosomes fuse with lysosomes. Altered autophagy occurs in various diseases, but its role in preterm labor (PTL) is unknown. We investigated the role of autophagic flux in two mouse models of PTL compared to controls: 1) inflammation-induced PTL (IPTL), induced by toll-like receptor agonists; and 2) non-inflammation (hormonally)-induced PTL (NIPTL). We demonstrate that the autophagy related genes Atg4c and Atg7 (involved in the lipidation of microtubule-associated protein 1 light chain 3 (LC3) B-I to the autophagosome-associated form, LC3B-II) decrease significantly in uterus and placenta during IPTL but not NIPTL. Autophagic flux is altered in IPTL, as shown by the accumulation of LC3B paralogues and diminishment of lysosome associated membrane protein (LAMP)-1, LAMP-2 and the a2 isoform of V-ATPase (a2V, an enzyme involved in lysosome acidification). These alterations in autophagy are associated with increased activation of NF-κB and proinflammatory cytokines/chemokines in both uterus and placenta. Similar changes are seen in macrophages exposed to TLR ligands and are enhanced with blockade of a2V. These novel findings represent the first evidence of an association between altered autophagic flux and hyper-inflammation and labor in IPTL.

An independent endocytic pathway stimulates different monocyte subsets by the a2 N-terminus domain of vacuolar-ATPase

The vacuolar ATPase (V-ATPase) plays an important role in tumor progression and metastases. A novel peptide from the a2 isoform of V-ATPase called a2NTD has been shown to exert an immunoregulatory role in the tumor microenvironment by controlling the maturation of monocytes toward a tumor-associated macrophage phenotype. Our data indicate that a2NTD binds to the surface of monocytes. a2NTD was preferentially endocytosed by pro-inflammatory monocytes bearing a CD14⁺⁺CD16⁺ phenotype, which is associated with the monocyte-to-macrophage maturation process. Both a2NTD binding and internalization led to production of the pro-inflammatory cytokines interleukin (IL)-1α and IL-1β by CD14⁺⁺CD16^- (classical) and CD14⁺⁺CD16⁺ (intermediate) monocytes. a2NTD was internalized via a macropinocytosis mechanism utilizing scavenger receptors. However, the inhibition of a2NTD endocytosis did not reduce cytokine production by monocytes. This points to the existence of two receptors that respond to a2NTD: scavengers receptors that mediate cellular uptake and an hitherto unidentified receptor stimulating the production of inflammatory cytokines. Both of these monocyte receptors may be important in generating the localized inflammation that is often required to promote tumor growth and hence may constitute novel targets for the development of anticancer drugs.

Regulation of apoptosis and innate immune stimuli in inflammation-induced preterm labor

An innate immune response is required for successful implantation and placentation. This is regulated, in part, by the a2 isoform of V-ATPase (a2V) and the concurrent infiltration of M1 (inflammatory) and M2 (anti-inflammatory) macrophages to the uterus and placenta. The objective of the present study was to identify the role of a2V during inflammation-induced preterm labor in mice and its relationship to the regulation of apoptosis and innate immune responses. Using a mouse model of infection-induced preterm delivery, gestational tissues were collected 8 h after intrauterine inoculation on day 14.5 of pregnancy with either saline or peptidoglycan (PGN; a TLR 2 agonist) and polyinosinic-polycytidylic acid [poly(I:C); a TLR3 agonist], modeling Gram-positive bacterial and viral infections, respectively. Expression of a2V decreased significantly in the placenta, uterus, and fetal membranes during PGN+poly(I:C)-induced preterm labor. Expression of inducible NO synthase was significantly upregulated in PGN+poly(I:C)-treated placenta and uterus. PGN+poly(I:C) treatment disturbed adherens junction proteins and increased apoptotic cell death via an extrinsic pathway of apoptosis among uterine decidual cells and spongiotrophoblasts. F4/80(+) macrophages were increased and polarization was skewed in PGN+poly(I:C)-treated uterus toward double-positive CD11c(+) (M1) and CD206(+) (M2) cells, which are critical for the clearance of dying cells and rapid resolution of inflammation. Expression of Nlrp3 and activation of caspase-1 were increased in PGN+poly(I:C)-treated uterus, which could induce pyroptosis. These results suggest that the double hit of PGN+poly(I:C) induces preterm labor via reduction of a2V expression and simultaneous activation of apoptosis and inflammatory processes.

Expression of a2 vacuolar ATPase in spermatozoa is associated with semen quality and chemokine-cytokine profiles in infertile men

Background

A number of laboratory tests have been developed to determine properties of spermatozoa quality but few have been adopted into routine clinical use in place of the WHO semen analysis. We investigated whether Atp6v0a2 (a2 isoform of vacuolar ATPase) is associated with abnormal semen quality and changes in chemokine-cytokine profiles in infertile men.

Patients and Methods

Semen samples were collected from 35 healthy donors and 35 infertile men at the Andrology laboratory from August 2011 to June 2012. The levels of Atp6v0a2 mRNA and protein, and its localization in spermatozoa were determined. a2NTD (the N-terminal portion of Atp6v0a2) and secreted chemokine-cytokine profiles in seminal fluid were measured.

Results

Atp6v0a2 protein (P<0.05) and mRNA (P<0.05) in spermatozoa from infertile men were significantly lower than those from fertile men. Fluorescent microscopy revealed that Atp6v0a2 is mainly expressed in the acrosomal region. Infertile men’s seminal fluid had significantly lower G-CSF (P<0.01), GM-CSF (P<0.01), MCP-1 (P<0.05), MIP-1α (P<0.01) and TGF-β1 (P<0.01) levels when compared to the seminal fluid from fertile men. Seminal fluid a2NTD levels were significantly correlated with G-CSF (P<0.01), GM-CSF (P<0.01), MCP-1 (P<0.05), MIP-1α (P<0.01) and TGF-β1 (P<0.01) which are key molecules during the onset of pregnancy.

Conclusion

These results suggested that a critical level of Atp6v0a2 is required for the fertile spermatozoa and its decreased level in spermatozoa could be used to predict male infertility. This study provides a possibility that Atp6v0a2 could be potentially used as a diagnostic marker for the evaluation of male infertility.

Placental Vacuolar ATPase Function Is a Key Link between Multiple Causes of Preeclampsia

Preeclampsia, a relatively common pregnancy disorder, is one of the major causes of maternal and fetal morbidity and mortality. Despite numerous research, the etiology of this syndrome remains not well understood as the pathogenesis of preeclampsia is complex, involving interaction between genetic, immunologic, and environmental factors. Preeclampsia, originating in placenta abnormalities, is induced by the circulating factors derived from the abnormal placenta. Recent work has identified various molecular mechanisms related to placenta development, including renin-angiotensin system, 1, 25-dihydroxyvitamin D, and lipoxin A4. Interestingly, advances suggest that vacuolar ATPase, a key molecule in placentation, is closely associated with them. Therefore, this intriguing molecule may represent an important link between various causes of preeclampsia. Here, we review that vacuolar ATPase works as a key link between multiple causes of preeclampsia and discuss the potential molecular mechanisms. The novel findings outlined in this review may provide promising explanations for the causation of preeclampsia and a rationale for future therapeutic interventions for this condition.

Further characterization of ATP6V0A2-related autosomal recessive cutis laxa

Autosomal recessive cutis laxa (ARCL) syndromes are phenotypically overlapping, but genetically heterogeneous disorders. Mutations in the ATP6V0A2 gene were found to underlie both, autosomal recessive cutis laxa type 2 (ARCL2), Debré type, and wrinkly skin syndrome (WSS). The ATP6V0A2 gene encodes the a2 subunit of the V-type H(+)-ATPase, playing a role in proton translocation, and possibly also in membrane fusion. Here, we describe a highly variable phenotype in 13 patients with ARCL2, including the oldest affected individual described so far, who showed strikingly progressive dysmorphic features and heterotopic calcifications. In these individuals we identified 17 ATP6V0A2 mutations, 14 of which are novel. Furthermore, we demonstrate a localization of ATP6V0A2 at the Golgi-apparatus and a loss of the mutated ATP6V0A2 protein in patients' dermal fibroblasts. Investigation of brefeldin A-induced Golgi collapse in dermal fibroblasts as well as in HeLa cells deficient for ATP6V0A2 revealed a delay, which was absent in cells deficient for the ARCL-associated proteins GORAB or PYCR1. Furthermore, fibroblasts from patients with ATP6V0A2 mutations displayed elevated TGF-β signalling and increased TGF-β1 levels in the supernatant. Our current findings expand the genetic and phenotypic spectrum and suggest that, besides the known glycosylation defect, alterations in trafficking and signalling processes are potential key events in the pathogenesis of ATP6V0A2-related ARCL.

V-ATPase upregulation during early pregnancy: a possible link to establishment of an inflammatory response during preimplantation period of pregnancy

Various mechanisms exist to prevent a potentially deleterious maternal immune response that results in compromising survival of semiallogeneic fetus. In pregnancy, there is a necessary early preimplantation inflammatory stage followed by a postimplantation anti-inflammatory stage. Thus, there is a biphasic 'immune response' observed during the course of pregnancy. We provide the evidence that capacitation of sperm induced the expression of a2 isoform of V-ATPase (ATP6V0A2 referred to as a2V), leukemia inhibitory factor (Lif), Il1b, and Tnf in the sperm. Capacitated sperm also released cleaved N-terminal domain of a2V-ATPase (a2NTD), which upregulates the gene expression of Lif, Il1b, Tnf, and monocyte chemotactic protein-1 (Ccl2 (Mcp1)) in the uterus. Unfertilized eggs had low a2V expression, but after fertilization, the expression of a2V increased in zygotes. This increased level of a2V expression was maintained in preimplantation embryos. Seminal plasma was necessary for upregulation of a2V expression in preimplantation embryos, as mating with seminal vesicle-deficient males failed to elicit an increase in a2V expression in preimplantation embryos. The infiltration of macrophages into the uterus was significantly increased after insemination of both sperm and seminal plasma during the preimplantation period of pregnancy. This dynamic infiltration into the uterus corresponded with the uterine a2V expression through the induction of Ccl2 expression. Furthermore, the polarization ratio of M1:M2 (pro-inflammatory/anti-inflammatory) macrophages in the uterus fluctuated from a ratio of 1.60 (day 1) to 1.45 (day 4) when female mice were inseminated with both sperm and seminal plasma. These data provide evidence that exposure to semen may initiate an inflammatory milieu by inducing a2V and cytokine/chemokine expression, which triggers the influx of macrophages into the preimplantation uterus during the onset of pregnancy and ultimately leads to successful pregnancy outcome.

Abortion-prone mating influences alteration of systemic a2 vacuolar ATPase expression in spleen and blood immune cells

PROBLEM

a2 isoform of vacuolar ATPase (Atp6v0a2) is important for maintaining the delicate immunological balance required for successful pregnancy. The objective of this investigation is to study the dynamic changes in spleen and blood that appear during spontaneous abortion in mice.

METHOD OF STUDY

Atp6v0a2 was measured in multiple immune cell populations from spleen and blood recovered from non-abortion-prone and abortion-prone mating combinations.

RESULTS

Atp6v0a2 expression was significantly lower (P ≤ 0.01) in the spleen recovered from abortion-prone ♀CBA × ♂DBA mating on days 12 and 16 of pregnancy when compared to non-abortion-prone ♀BALB/c × ♂BALB/c and ♀CBA × ♂BALB/c matings. Flow cytometric studies showed that significantly decreased expression of Atp6v0a2 in splenic CD4(+), CD8(+), CD19(+), and CD14(+) cells directly correlated with the high percentages of fetal resorption observed in abortion-prone mating on days 12 and 16 of pregnancy. In blood, CD4(+), CD8(+), and CD19(+) cells had a significantly reduced expression of Atp6v0a2 in abortion-prone mating compared to the non-abortion-prone mating combinations only on day 12.

CONCLUSION

This deceased expression of Atp6v0a2 in the various immune cell populations of the spleen and blood suggests that the maternal environment is not supportive to fetus and leads to poor pregnancy outcome in the abortion-prone mating model.

Tumor-associated a2 vacuolar ATPase acts as a key mediator of cancer-related inflammation by inducing pro-tumorigenic properties in monocytes

Cancer-related inflammation profoundly affects tumor progression. Tumor-associated macrophages (TAMs) are known regulators of that inflammation, but the factors that initiate cancer-related inflammation are poorly understood. Tumor invasiveness and poor clinical outcome are linked to increased expression of cell surface-associated vacuolar adenosine triphosphatases. The a2 isoform vacuolar adenosine triphosphatase is found on the surface on many solid tumors, and we have identified a peptide cleaved from a2 isoform vacuolar adenosine triphosphatase called a2NTD. a2NTD has properties necessary to induce monocytes into a pro-oncogenic TAM phenotype. The peptide upregulated both pro- and anti-inflammatory mediators. These included IL-1β and IL-10, which are important in promoting inflammation and immune escape by tumor cells. The secretion of inflammatory cytokine IL-1β was dependent on ATP, K(+) efflux, and reactive oxygen species, all mediators that activate the inflammasome. These findings describe a mechanism by which tumor cells affect the maturation of TAMs via a nontraditional cytokine-like signal, the a2NTD peptide.

The a2 isoform of vacuolar ATPase is a modulator of implantation and feto-maternal immune tolerance in early pregnancy

In mammalian reproduction, two immunologically disparate entities, the mother and her fetus, co-exist in close proximity and mutually tolerate each other. The maternal immune system plays a major contributing role in the reproductive outcome. A coordinated set of immunological events takes place between the maternal and fetal cells to ensure fetal survival. Among these, cytokines secreted by proximal maternal immune cells as well as fetal trophoblast cells play a major role in feto-maternal tolerance. In this review, we describe the role of the vacuolar ATPase (and more specifically the a2 isoform, a2V-ATPase) in controlling the expression of these vital cytokines. a2V-ATPase is a key enzyme that controls the acidification of intracellular vesicles and the extracellular environment, processes that play a major role in cellular function. The localization of a2V-ATPase in tissues and immune cells of the reproductive tract which are essential for pregnancy will be described. Information will be provided on the role of a2V-ATPase on aspects of cell development in pregnancy, from fertilization to implantation and fetal growth. Particular emphasis will be placed on the role of a2V-ATPase in (a) regulating parts of the cytokine network at the implantation site and (b) attenuating the potentially harmful maternal immune response against trophoblast cells.

Novel role for the N-terminus domain of the a2 isoform of vacuolar ATPase in interleukin-1beta production

Interleukin-1beta (IL-1beta) is a mediator cytokine that is released by macrophages and epithelial cells in pregnancy and tumorigenesis before antigen recognition. a2V-ATPase is a protein expressed during pregnancy and tumorigenesis and has a novel role in immune regulation. It is expressed as a 70 kDa molecule in intracellular vesicles. Upon cell stimulation it migrates to the surface followed by the cleavage of a 20 kDa portion (a2 N-terminus domain, a2NTD). This study aimed to determine whether a2NTD could induce IL-1beta production in immune cells. Peripheral blood mononuclear cells (PMBC) were stimulated with a2NTD and analyzed for cytokine gene expression by gene arrays. Supernatants were analyzed for IL-1beta by enzyme-linked immunosorbent assay, and cells were analyzed for intracellular expression of IL-1alpha, IL-1beta, and TNF-alpha by flow cytometry. When PBMC were cultured with a2NTD, there was a 2.5-fold increase in IL1A and IL1B gene expression and no induction of TNF gene expression. There was a 72-fold increase in IL-1beta in supernatants of PBMC cultured with a2NTD. Finally, there was a 204-fold increase in intracellular expression of IL-1beta in monocytes incubated with a2NTD. These results indicate a regulatory role for a2NTD in IL-1 cytokine production and suggest a unique role for this molecule in inflammation.