IL-5-producing CD4+ T cells and eosinophils cooperate to enhance response to immune checkpoint blockade in breast cancer

Immune checkpoint blockade (ICB) has heralded a new era in cancer therapy. Research into the mechanisms underlying response to ICB has predominantly focused on T cells; however, effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. Here, we combine unbiased analysis of blood and tumors from metastatic breast cancer patients treated with ICB with mechanistic studies in mouse models of breast cancer. We observe an increase in systemic and intratumoral eosinophils in patients and mice responding to ICB treatment. Mechanistically, ICB increased IL-5 production by CD4⁺ T cells, stimulating elevated eosinophil production from the bone marrow, leading to systemic eosinophil expansion. Additional induction of IL-33 by ICB-cisplatin combination or recombinant IL-33 promotes intratumoral eosinophil infiltration and eosinophil-dependent CD8⁺ T cell activation to enhance ICB response. This work demonstrates the critical role of eosinophils in ICB response and provides proof-of-principle for eosinophil engagement to enhance ICB efficacy.

Neoadjuvant immune checkpoint blockade triggers persistent and systemic Treg activation which blunts therapeutic efficacy against metastatic spread of breast tumors

The clinical successes of immune checkpoint blockade (ICB) in advanced cancer patients have recently spurred the clinical implementation of ICB in the neoadjuvant and perioperative setting. However, how neoadjuvant ICB therapy affects the systemic immune landscape and metastatic spread remains to be established. Tumors promote both local and systemic expansion of regulatory T cells (T_regs), which are key orchestrators of tumor-induced immunosuppression, contributing to immune evasion, tumor progression and metastasis. T_regs express inhibitory immune checkpoint molecules and thus may be unintended targets for ICB therapy counteracting its efficacy. Using ICB-refractory models of spontaneous primary and metastatic breast cancer that recapitulate the poor ICB response of breast cancer patients, we observed that combined anti-PD-1 and anti-CTLA-4 therapy inadvertently promotes proliferation and activation of T_regs in the tumor, tumor-draining lymph node and circulation. Also in breast cancer patients, T_reg levels were elevated upon ICB. Depletion of T_regs during neoadjuvant ICB in tumor-bearing mice not only reshaped the intratumoral immune landscape into a state favorable for ICB response but also induced profound and persistent alterations in systemic immunity, characterized by elevated CD8+ T cells and NK cells and durable T cell activation that was maintained after treatment cessation. While depletion of T_regs in combination with neoadjuvant ICB did not inhibit primary tumor growth, it prolonged metastasis-related survival driven predominantly by CD8+ T cells. This study demonstrates that neoadjuvant ICB therapy of breast cancer can be empowered by simultaneous targeting of T_regs, extending metastasis-related survival, independent of a primary tumor response.

Pro-mutagenic effects of the gut microbiota in a Lynch syndrome mouse model

The gut microbiota strongly impacts the development of sporadic colorectal cancer (CRC), but it is largely unknown how the microbiota affects the pathogenesis of mismatch-repair-deficient CRC in the context of Lynch syndrome. In a mouse model for Lynch syndrome, we found a nearly complete loss of intestinal tumor development when animals were transferred from a conventional "open" animal facility to specific-pathogen-free (SPF) conditions. Using 16S sequencing we detected large changes in microbiota composition between the two facilities. Transcriptomic analyses of tumor-free intestinal tissues showed signs of strong intestinal inflammation in conventional mice. Whole exome sequencing of tumors developing in Msh2-Lynch mice revealed a much lower mutational load in the single SPF tumor than in tumors developing in conventional mice, suggesting reduced epithelial proliferation in SPF mice. Fecal microbiota transplantations with conventional feces altered the immune landscape and gut homeostasis, illustrated by increased gut length and elevated epithelial proliferation and migration. This was associated with drastic changes in microbiota composition, in particular increased relative abundances of different mucus-degrading taxa such as Desulfovibrio and Akkermansia, and increased bacterial-epithelial contact. Strikingly, transplantation of conventional microbiota increased microsatellite instability in untransformed intestinal epithelium of Msh2-Lynch mice, indicating that the composition of the microbiota influences the rate of mutagenesis in MSH2-deficient crypts.

Tumor-educated Tregs drive organ-specific metastasis in breast cancer by impairing NK cells in the lymph node niche

Breast cancer is accompanied by systemic immunosuppression, which facilitates metastasis formation, but how this shapes organotropism of metastasis is poorly understood. Here, we investigate the impact of mammary tumorigenesis on regulatory T cells (Tregs) in distant organs and how this affects multi-organ metastatic disease. Using a preclinical mouse mammary tumor model that recapitulates human metastatic breast cancer, we observe systemic accumulation of activated, highly immunosuppressive Tregs during primary tumor growth. Tumor-educated Tregs show tissue-specific transcriptional rewiring in response to mammary tumorigenesis. This has functional consequences for organotropism of metastasis, as Treg depletion reduces metastasis to tumor-draining lymph nodes, but not to lungs. Mechanistically, we find that Tregs control natural killer (NK) cell activation in lymph nodes, thereby facilitating lymph node metastasis. In line, an increased Treg/NK cell ratio is observed in sentinel lymph nodes of breast cancer patients compared with healthy controls. This study highlights that immune regulation of metastatic disease is highly organ dependent.

The Multifaceted Role of Regulatory T Cells in Breast Cancer

The microenvironment of breast cancer hosts a dynamic cross talk between diverse players of the immune system. While cytotoxic immune cells are equipped to control tumor growth and metastasis, tumor-corrupted immunosuppressive immune cells strive to impair effective immunity and promote tumor progression. Of these, regulatory T cells (T_regs), the gatekeepers of immune homeostasis, emerge as multifaceted players involved in breast cancer. Intriguingly, clinical observations suggest that blood and intratumoral T_regs can have strong prognostic value, dictated by breast cancer subtype. Accordingly, emerging preclinical evidence shows that T_regs occupy a central role in breast cancer initiation and progression and provide critical support to metastasis formation. Here, T_regs are not only important for immune escape but also promote tumor progression independent of their immune regulatory capacity. Combining insights into T_reg biology with advances made across the rapidly growing field of immuno-oncology is expected to set the stage for the design of more effective immunotherapy strategies.

Neutrophils create a fertile soil for metastasis

Neutrophils can facilitate the metastatic spread of cancer; however, how neutrophils are activated at metastatic sites remains poorly understood. In this issue, Xiao et al. demonstrate that the protease cathepsin C, secreted by breast cancer cells, triggers neutrophils to form neutrophil extracellular traps in the metastatic niche, thereby promoting lung metastasis.

Therapeutic targeting of macrophages enhances chemotherapy efficacy by unleashing type I interferon response

Recent studies have revealed a role for macrophages and neutrophils in limiting chemotherapy efficacy; however, the mechanisms underlying the therapeutic benefit of myeloid-targeting agents in combination with chemotherapy are incompletely understood. Here, we show that targeting tumour-associated macrophages by colony-stimulating factor-1 receptor (CSF-1R) blockade in the K14cre;Cdh1^F/F;Trp53^F/F transgenic mouse model for breast cancer stimulates intratumoural type I interferon (IFN) signalling, which enhances the anticancer efficacy of platinum-based chemotherapeutics. Notably, anti-CSF-1R treatment also increased intratumoural expression of type I IFN-stimulated genes in patients with cancer, confirming that CSF-1R blockade is a powerful strategy to trigger an intratumoural type I IFN response. By inducing an inflamed, type I IFN-enriched tumour microenvironment and by further targeting immunosuppressive neutrophils during cisplatin therapy, antitumour immunity was activated in this poorly immunogenic breast cancer mouse model. These data illustrate the importance of breaching multiple layers of immunosuppression during cytotoxic therapy to successfully engage antitumour immunity in breast cancer.

NK cell heparanase controls tumor invasion and immune surveillance

NK cells are highly efficient at preventing cancer metastasis but are infrequently found in the core of primary tumors. Here, have we demonstrated that freshly isolated mouse and human NK cells express low levels of the endo-β-D-glucuronidase heparanase that increase upon NK cell activation. Heparanase deficiency did not affect development, differentiation, or tissue localization of NK cells under steady-state conditions. However, mice lacking heparanase specifically in NK cells (Hpsefl/fl NKp46-iCre mice) were highly tumor prone when challenged with the carcinogen methylcholanthrene (MCA). Hpsefl/fl NKp46-iCre mice were also more susceptible to tumor growth than were their littermate controls when challenged with the established mouse lymphoma cell line RMA-S-RAE-1β, which overexpresses the NK cell group 2D (NKG2D) ligand RAE-1β, or when inoculated with metastatic melanoma, prostate carcinoma, or mammary carcinoma cell lines. NK cell invasion of primary tumors and recruitment to the site of metastasis were strictly dependent on the presence of heparanase. Cytokine and immune checkpoint blockade immunotherapy for metastases was compromised when NK cells lacked heparanase. Our data suggest that heparanase plays a critical role in NK cell invasion into tumors and thereby tumor progression and metastases. This should be considered when systemically treating cancer patients with heparanase inhibitors, since the potential adverse effect on NK cell infiltration might limit the antitumor activity of the inhibitors.

Targeting cytokine signaling checkpoint CIS activates NK cells to protect from tumor initiation and metastasis

The cytokine-induced SH2-containing protein CIS belongs to the suppressor of cytokine signaling (SOCS) protein family. Here, we show the critical role of CIS in suppressing natural killer (NK) cell control of tumor initiation and metastasis. Cish-deficient mice were highly resistant to methylcholanthrene-induced sarcoma formation and protected from lung metastasis of B16F10 melanoma and RM-1 prostate carcinoma cells. In contrast, the growth of primary subcutaneous tumors, including those expressing the foreign antigen OVA, was unchanged in Cish-deficient mice. The combination of Cish deficiency and relevant targeted and immuno-therapies such as combined BRAF and MEK inhibitors, immune checkpoint blockade antibodies, IL-2 and type I interferon revealed further improved control of metastasis. The data clearly indicate that targeting CIS promotes NK cell antitumor functions and CIS holds great promise as a novel target in NK cell immunotherapy.

Effects of Exendin-4 on human adipose tissue inflammation and ECM remodelling

BACKGROUND/OBJECTIVES:

Subjects with type-2 diabetes are typically obese with dysfunctional adipose tissue (AT). Glucagon-like peptide-1 (GLP-1) analogues are routinely used to improve glycaemia. Although, they also aid weight loss that improves AT function, their direct effect on AT function is unclear. To explore GLP-1 analogues' influence on human AT's cytokine and extracellular matrix (ECM) regulation, we therefore obtained and treated omental (OMAT) and subcutaneous (SCAT) AT samples with Exendin-4, an agonist of the GLP-1 receptor (GLP-1R).

SUBJECTS/METHODS:

OMAT and abdominal SCAT samples obtained from women during elective surgery at the Royal Devon & Exeter Hospital (UK) were treated with increasing doses of Exendin-4. Changes in RNA expression of adipokines, inflammatory cytokines, ECM components and their regulators were assessed and protein secretion analysed by ELISA. GLP-1R protein accumulation was compared in paired AT depot samples.

RESULTS:

Exendin-4 induced an increase in OMAT adiponectin (P=0.02) and decrease in elastin expression (P=0.03) in parallel with reduced elastin secretion (P=0.04). In contrast to OMAT, we did not observe an effect on SCAT. There was no change in the expression of inflammatory markers (CD14, TNFA, MCP-1), collagens, TGFB1 or CTGF. GLP-1R accumulation was higher in SCAT.

CONCLUSIONS:

Independently of weight loss, which may bias findings of in vivo studies, GLP-1 analogues modify human OMAT physiology favourably by increasing the insulin-sensitising cytokine adiponectin. However, the reduction of elastin and no apparent effect on AT's inflammatory cytokines suggest that GLP-1 analogues may be less beneficial to AT function, especially if there is no associated weight loss.

Wnt4 antagonises Wnt3a mediated increases in growth and glucose stimulated insulin secretion in the pancreatic beta-cell line, INS-1

The Wnt signalling pathway in beta-cells has been linked to the development of type 2 diabetes. Investigating the impact of a non-canonical Wnt ligand, Wnt4, on beta-cell function we found that in INS-1 cells, Wnt4 was able to completely block Wnt3a stimulated cell growth and insulin secretion. However, despite high levels of Wnt4 protein being detected in INS-1 cells, reducing the expression of Wnt4 had no impact on cell growth or Wnt3a signalling. As such, the role of the endogenously expressed Wnt4 in beta-cells is unclear, but the data showing that Wnt4 can act as a negative regulator of canonical Wnt signalling in beta-cells suggests that this pathway could be a potential target for modulating beta-cell function.

Candida albicans in oral biofilms could prevent caries

Streptococcus mutans is a Gram-positive bacterium involved in development to caries, the most common infectious disease of our time. Streptococcus mutans interacts with other microbes, like the fungus Candida albicans and both are commonly isolated from patients with caries. Since the role of C. albicans in caries remains unknown, our aim was to unravel this using an in vitro dual-species cariogenic oral biofilm model. Biofilms were grown for 24-72 h on glass cover slips or hydroxyapatite (HA) disks to mimic the surface of teeth. Medium pH, lactic acid production capacity and calcium release from HA disks were determined. All 24-h biofilms had external pH values below the critical pH of 5.5 where enamel dissolves. In contrast, 72-h dual-species biofilms had significantly higher pH (above the critical pH) and consequently decreased calcium release compared to single-species S. mutans biofilms. Counter intuitively, lactic acid production and growth of S. mutans were increased in 72-h dual-species biofilms. Candida albicans modulates the pH in dual-species biofilms to values above the critical pH where enamel dissolves. Our results suggest that C. albicans is not by definition a cariogenic microorganism; it could prevent caries by actively increasing pH preventing mineral loss.

In humans the adiponectin receptor R2 is expressed predominantly in adipose tissue and linked to the adipose tissue expression of MMIF-1

In this study, the regional adipose tissue-adiponectin (AT-ADN) and adiponectin receptor (R1 and R2) expression and their relation with metabolic parameters, circulating and AT-derived cytokine expressions were compared. Paired subcutaneous adipose tissue (SCAT) and visceral adipose tissue (VAT) were taken from 18 lean and 39 obese humans, AT-mRNA expression of adipokines analysed by RT-PCR and corresponding serum levels by enzyme-linked immunosorbent assay (ELISA). R1 and R2 adipocyte expression was compared with 17 other human tissues. ADN-gene expression was lower in VAT than SCAT [mean (SD) 1.54 (1.1) vs. 2.84 (0.87); p < 0.001], and lower in obese subjects (VAT : p = 0.01;SCAT : p < 0.001). SCAT-ADN correlated positively with serum ADN (r = 0.33;p = 0.036) but not VAT-ADN. AT expressions of ADN and macrophage migration inhibiting factor (MMIF), IL18 and cluster of differentiation factor 14 (CD14) in both depots showed inverse correlations. R1 and R2 were expressed ubiquitously and R2 highest in SCAT, and this is much higher (x100) than R1 (x100). R expression was similar in lean and obese subjects and unrelated to the metabolic syndrome, however, receptors correlated with VAT-MMIF (R 1: r = 0.4;p = 0.008;R 2: r = 0.35,p = 0.02) and SCAT-MMIF expression (R 2: r = 0.43;p = 0.004). Unlike ADN, its receptors are expressed in many human tissues. Human R2 expression is not highest in the liver but in AT where it is associated with MMIF expression. The adiponectin-dependent insulin-sensitizing action of thiazolidinediones is thus probably to differ amongst species with weaker effects on the human liver.

The adipokine zinc-alpha2-glycoprotein (ZAG) is downregulated with fat mass expansion in obesity

INTRODUCTION

Zinc-alpha2-glycoprotein (ZAG) is a novel adipokine, which may act locally to influence adipocyte metabolism. This study assessed the effect of increased adiposity on ZAG expression in adipose tissue in human subjects. The study also examined the association between ZAG and adiponectin expression in human adipose tissue, and whether ZAG modulates adiponectin secretion by human adipocytes.

METHODS

Adipose tissue (visceral and subcutaneous) was collected from human subjects with a wide range of BMIs. Human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were used for in vitro studies. ZAG mRNA levels were quantified by real-time PCR and protein by Western blotting.

RESULTS

In human subjects, ZAG mRNA level was negatively correlated with BMI (r = -0.61, P < 0.001, n = 23, visceral; r = -0.6, P < 0.05, n = 14, subcutaneous) and fat mass (r = -0.62, P < 0.01, visceral; r = -0.6, P < 0.05, subcutaneous). Negative associations were also found between ZAG mRNA and insulin resistance parameters including plasma insulin (r = -0.65, P < 0.001, visceral; r = -0.55, P < 0.05, subcutaneous) and homeostasis model of insulin resistance (HOMA-IR) (r = -0.65, P < 0.001, visceral; r = -0.52, P = 0.055, subcutaneous), and C reactive protein (CRP) (r = -0.46, P < 0.05, visceral; r = -0.53, P < 0.05, subcutaneous). However, ZAG mRNA was positively correlated with adiponectin (r = 0.5, P < 0.05, visceral; r = 0.82, P < 0.001, subcutaneous) but negatively associated with leptin mRNA (r = -0.42, P < 0.05, visceral; r = -0.54, P < 0.05, subcutaneous). ZAG secretion by differentiated human adipocytes was abundant. Addition of recombinant ZAG stimulated adiponectin release from human adipocytes.

CONCLUSION

ZAG gene expression in adipose tissue is downregulated with increased adiposity and circulating insulin. ZAG mRNA is positively correlated with adiponectin mRNA, and ZAG enhances adiponectin production by human adipocytes. We suggest that ZAG is linked to obesity and obesity-related insulin resistance.

DPP-IV inhibition enhances the antilipolytic action of NPY in human adipose tissue

CONTEXT

Dipeptidyl peptidase IV (DPP-IV) inactivates the incretin hormone glucagon-like peptide. It can also affect the orexigenic hormone neuropeptide Y (NPY(1-36)) which is truncated by DPP-IV to NPY(3-36), as a consequence NPY's affinity changes from receptor Y1, which mediates the antilipolytic function of NPY, to other NPY receptors. Little is known whether DPP-IV inhibitors for the treatment of type 2 diabetic (T2DM) patients could influence these pathways.

AIMS

To investigate the in vitro effects of NPY with DPP-IV inhibition in isolated abdominal subcutaneous (AbdSc) adipocytes on fat metabolism, and assessment of NPY receptor and DPP-IV expression in adipose tissue (AT).

METHODS

Ex vivo human AT was taken from women undergoing elective surgery (body mass index: 27.5 (mean +/- s.d.) +/- 5 kg/m2, age: 43.7 +/- 10 years, n = 36). Isolated AbdSc adipocytes were treated with human recombinant (rh)NPY (1-100 nM) with and without DPP-IV inhibitor (1 M); glycerol release and tissue distribution of DPP-IV, Y1 and Y5 messenger RNA (mRNA) were measured and compared between lean and obese subjects.

RESULTS AND CONCLUSION

rhNPY reduced glycerol release, an effect that was further enhanced by co-incubation with a DPP-IV inhibitor [control: 224 (mean +/- s.e.) +/- 37 micromol/l; NPY, 100 nM: 161 +/- 27 micromol/l**; NPY 100 nM/DPP-IV inhibitor, 1 M: 127 +/- 14 micromol/l**; **p < 0.01, n = 14]. DPP-IV was expressed in AbdSc AT and omental AT with relative DPP-IV mRNA expression lower in AbdSc AT taken from obese [77 +/- 6 signal units (SU)] vs. lean subjects (186 +/- 29 SU*, n = 10). Y1 was predominantly expressed in fat and present in all fat depots but higher in obese subjects, particularly the AbdSc AT-depot (obese: 1944 +/- 111 SU vs. lean: 711 +/- 112 SU**, n = 10). NPY appears to be regulated by AT-derived DPP-IV. DPP-IV inhibitors augment the antilipolytic effect of NPY in AT. Further studies are required to show whether this explains the lack of weight loss in T2DM patients treated with DPP-IV inhibitors.

Ghrelin and the differential regulation of des-acyl (DSG) and oct-anoyl ghrelin (OTG) in human adipose tissue (AT)

OBJECTIVES

Ghrelin, an important central acting orexigenic hormone, is predominantly secreted in the gastrointestinal tract. However little is known about the action of ghrelin in human adipose tissue (AT).

AIM

To study the expression of ghrelin in AT, the effects of octanoyl-(OTG) and des-acyl (DSG) ghrelin on lipolysis and lipogenesis, leptin release and potential peripheral signalling through the Y1 receptor.

METHODS

Ex vivo human AT was obtained from women undergoing elective surgery (46 (mean +/- SD) 6.8 years, body mass index (BMI): 25.6 +/- 5.0 kg/m(2), n = 20). Abdominal-subcutaneous (AbdSc) adipocytes were isolated and treated with recombinant human (rh) OTG and DSG to assess lipid metabolism leptin release and the influence of Y1-receptor blocker.

RESULTS

Ghrelin was expressed in AbdScAT and negatively correlated with BMI (lean: 3.6 +/- 0.74 optical-density-units (OD), obese: 1.64 +/- 0.45 OD, *P < 0.05). Only DSG significantly suppressed glycerol release (Control (C): 286 +/- 58 microl/l; DSG 1 nm: 224 +/- 38 microl/l downward arrow*; DSG 100 nm: 172 +/- 13 microl/l downward arrow*,* downward arrow P < 0.05, n = 7) and reduced hormone sensitive lipase expression (C: 1.0 +/- 0.3 OD; DSG 1 nm: 0.8 +/- 0.3 OD downward arrow*; DSG 100 nm: 0.6 +/- 0.1 OD downward arrow*, n = 4). However, both isoforms increased lipoprotein lipase expression (C: 1.0 +/- 0.3OD; DSG 100 nm: 0.2 +/- 0.4 OD upward arrow*; OTG 100 nm: 2.5 +/- 0.3 OD upward arrow*, n = 4), whilst blockade of Y1 eliminated this effect in both. Leptin was down-regulated by DSG only (DSG 1 nm: 5.3 +/- 0.7 ng/ml; DSG 100 nm: 4.1 +/- 0.7 ng/ml*) and was significant after BMI adjustment (P = 0.029).

CONCLUSION

Ghrelin was expressed in human AbdSc AT. In vitro, both OGT and DSG appear to mediate fat deposition with the lipogenic effects in part mediated by the Y1 receptor, whilst the influence of DSG affected lipolysis, lipogenesis and leptin secretion. Taken together, these studies support a local action for ghrelin isoforms on lipid and adipokine metabolism that further supports a cross talk between organs.

Comparison of maternal ghrelin and leptin in healthy mothers and mothers with Type 1 diabetes

AIMS

Maternal leptin affects placental growth hormone (GH), whereas ghrelin, a natural ligand of the growth-hormone-secretagogue receptor, modulates GH action. Both hormones may affect fetal growth, and dysregulation in diabetes may lead to fetal growth disturbances. The aim was to investigate changes in maternal ghrelin during pregnancy with diabetes and to establish reference leptin levels.

METHODS

Twelve healthy non-diabetic (ND) and 12 pregnant women with Type 1 diabetes (T1DM) were recruited. Age and body mass index (BMI) [ND: age 29.9 +/- 4.7 years (mean +/- sd), BMI 25.2 +/- 3.7 kg/m2; T1DM: age 31 +/- 5.5 years, BMI 27 +/- 3.1 kg/m2] were similar in the groups. HbA1c in T1DM was 6.2 +/- 1.1% at 20 weeks, 6.3 +/- 1.1% at 30 weeks' gestation and 7.8 +/- 2.1% postpartum. Fasting plasma ghrelin, total leptin, free leptin (FL) and soluble leptin receptor (sOB-R) levels were measured at 20 and 30 weeks' gestation and postpartum and determined by radioimmunoassay.

RESULTS

All pregnancies resulted in full-term singleton births with no differences in birth weight between groups [T1DM: 3.4 +/- 0.56 kg (mean +/- SE); ND: 3.6 +/- 0.3 kg, P = NS]. Ghrelin levels were lower in T1DM when corrected for age and mothers' weight (T1DM: 458 +/- 36 pg/ml and 432.9 +/- 26.6 pg/ml; ND: 562 +/- 52 pg/ml and 515.8 +/- 63 pg/ml at 20 and 30 weeks, respectively, P < 0.05). T1DM mothers had higher levels of sOB-R and FL levels declined at 30 weeks' gestation in T1DM (P = 0.04) but not in ND.

CONCLUSION

In a population of pregnant women with expected changes in leptin levels as previously reported, ghrelin levels were lower in T1DM pregnancies at 20 and 30 weeks. This may have implications for fetal development and requires further study in diabetes, particularly in pregnancies that result in macrosomia.

Adiponectin complexes in human cerebrospinal fluid: distinct complex distribution from serum

AIMS/HYPOTHESIS

Adiponectin is an adipocyte-derived secretory factor that is specifically produced in adipocytes. It exerts effects on energy homeostasis via peripheral and central mechanisms. However, it is not clear whether adiponectin crosses the blood-brain barrier in humans. In serum, adiponectin circulates in several different complexes, each of which has distinct functions. Here, we wanted to test whether adiponectin can be found in human cerebrospinal fluid (CSF) and whether specific adiponectin complexes are enriched in CSF compared with peripheral serum samples. We also wanted to establish whether there is a sex-related difference with regard to the distribution of adiponectin oligomers in CSF.

MATERIALS AND METHODS

We studied 22 subjects (11 men, 11 women) in this study. Their average BMI was 28.0+/-4.7 kg/m2; average age was 70+/-7 years.

RESULTS

Analysis of total adiponectin revealed that adiponectin protein is present in human CSF at approximately 0.1% of serum concentration. The distribution of adiponectin oligomers differs considerably in CSF from that of serum within matched samples from the same patients. Only the adiponectin trimeric and low-molecular-mass hexameric complexes are found in CSF, with a bias towards the trimeric form in most patients. Male subjects have a higher CSF:serum ratio of total adiponectin (p<0.05; n=20) and have slightly higher trimer levels in serum and CSF than female subjects.

CONCLUSIONS/INTERPRETATION

We conclude that the adiponectin trimer is the predominant oligomer in human CSF.

Activin type II receptors in embryonic dorsal root ganglion neurons of the chicken

Activin induces neuropeptide expression in chicken ciliary ganglion neurons. To determine if activin might also influence neuropeptide expression in developing sensory neurons, we examined whether type II activin receptors are expressed during embryonic development of the chicken dorsal root ganglia (DRG), and also examined the effects of activin on neuropeptide expression in cultured DRG neurons. Using reverse transcription polymerase chain reaction (rtPCR), we detected mRNAs for both the activin receptors type IIA (ActRIIA) and type IIB (ActRIIB) in DRG from embryonic day 7 through posthatch day 1. With in situ hybridization, we found that morphologically identifiable neurons express mRNAs for both ActRIIA and ActRIIB. With developmental age, a subset of neurons that hybridizes more intensely with riboprobes to these receptor mRNAs becomes evident. A similar pattern of expression is observed with immunocytochemical staining using antisera against activin type II receptors. To examine whether embryonic DRG cells respond to activin we treated dissociated cultures of DRG with activin A and assessed the expression of vasoactive intestinal peptide (VIP) and calcitonin gene related peptide (CGRP) mRNAs using semiquantitative rtPCR. Activin treatment results in an increase in VIP mRNA, but does not affect CGRP mRNA levels. These observations indicate that neurons in the embryonic chicken DRG can respond to activin and suggest that activin has the potential to play a role in the development and function of DRG sensory neurons.

Synergy of activin and ciliary neurotrophic factor signaling pathways in the induction of vasoactive intestinal peptide gene expression

Activin, a member of the transforming growth factor-beta superfamily, can regulate neuropeptide gene expression in the nervous system and in neuroblastoma cells. Among the neuropeptide genes whose expression can be regulated by activin is the gene encoding the neuropeptide vasoactive intestinal peptide (VIP). To investigate the molecular mechanisms by which activin regulates neuronal gene expression, we have examined activin's regulation of VIP gene expression in NBFL neuroblastoma cells. We report here that NBFL cells respond to activin by increasing expression of VIP mRNA. Activin regulates VIP gene transcription in NBFL cells through a 180-bp element in the VIP promoter that was previously characterized to be necessary and sufficient to mediate the induction of VIP by the neuropoietic cytokines and termed the cytokine response element (CyRE). We find that the VIP CyRE is necessary and sufficient to mediate the transcriptional response to activin. In addition, ciliary neurotrophic factor (CNTF), a neuropoietic cytokine, synergizes with activin to increase VIP mRNA expression and transcription through the VIP CyRE. Mutations in either the Stat (signal transducer and activator of transcription) or AP-1 sites within the CyRE that reduce the response to CNTF, also reduce the response to activin. However, mutating both the Stat and AP-1 sites within the wild-type CyRE, while reducing the separate responses to either activin or CNTF, eliminates the synergy between them. These data suggest that activin and CNTF, two factors that appear to signal though distinct pathways, activate VIP gene transcription through a common transcriptional element, the VIP CyRE.

High-intensity nanosecond photorefractive spatial solitons

We report the observation of high-intensity solitons in a bulk strontium barium niobate crystal. The solitons are observed by use of 8-ns optical pulses with optical intensities greater than 100 MW/cm(2). Each soliton forms and attains its minimum width after roughly ten pulses and reaches e(-1) of the steady-state width after the first pulse. We find good agreement between experimental observations and theoretical predictions for the soliton existence curve.

Cloning of a novel human ELF-1-related ETS transcription factor, ELFR, its characterization and chromosomal assignment relative to ELF-1

The ETS gene family encodes a group of proteins that function as transcription factors under physiological conditions and, if aberrantly expressed, can lead to cellular transformation. ETS transcription factors are characterized by a unique conserved DNA binding domain. A subset of these proteins is rearranged with EWS in Ewing tumors (ET). We recently described a spectrum of ETS genes coexpressed with EWS-FLI1 in an ETcell line to define proteins that potentially compete in target site selection. We now report on the cloning and characterization of a novel ETS family member, ELFR, displaying 92% homology to ELF-1 in its DNA binding domain while diverging in the rest of the protein. ELFR expression was found in a very tissue restricted pattern with the highest abundancy in placenta. We also report the chromosomal assignment of ELFR and ELF-1 to Xq26 and 13q13, respectively, by means of fluorescence in-situ hybridization (FISH).

Target tissue influence on somatostatin expression in the avian ciliary ganglion

Activin as a neurodifferentiation factor. Our studies of neurotransmitter expression have focused on the expression of neuropeptide transmitters in the avian ciliary ganglion (CG) and have examined the influence of choroidal vascular smooth muscle cells in regulating the differential expression of somatostatin in the CG. In these activities we have identified activin A as a potential target-derived neurodifferentiation factor that can stimulate somatostatin expression in cultured CG neurons. In cultured CG neurons, activin can stimulate the expression of somatostatin in choroid neurons, the pattern of neurotransmitter expression found in vivo, and in the ciliary neurons that would normally not express somatostatin. In vivo, mRNA transcripts of the cActR-IIA appear to be expressed by both choroid and ciliary CG neurons. This suggests that activin might serve as an instructive factor in controlling neuropeptide phenotype. For activin to serve as an instructive factor requires that activin be produced by choroid smooth-muscle target cells. Indeed, activin mRNA and activin-like immunoreactivity are found in choroid cells, in vitro. However, the lack of somatostatin expression by ciliary neurons suggests that activin is not produced by their targets, the iris and ciliary body. This simple view is countered by the observation that activin A mRNA is also present in the iris and activin-like immunoreactivity is detectable in the iris and ciliary body. Instead, the production of the specific activin inhibitor follistatin in the iris and ciliary body is likely to limit the availability of activin to only those neurites innervating the choroid layer, thus accounting for the differential expression of somatostatin in only the choroid CG neurons. This somewhat more complicated arrangement is similar to the mechanism thought to be employed for primary induction during frog embryogenesis. The observations reviewed here are all consistent with the hypothesized role for activin as a molecule whose availability to neurites in the target regulates neurotransmitter expression. Additional in vivo perturbation experiments are needed to further examine this hypothesis; nevertheless, activin appears as a strong candidate for a target-derived neurotransmitter differentiation factor. Activin's potential roles in differentiation: A wide variety of biological effects have been ascribed to activin. Initially identified and purified as a gonadal hormone stimulating the production and release of FSH from the pituitary, activin is also implicated in the stimulation of erythroid differentiation, as a modulator of follicular granulosa cell differentiation, as a mesodermalizing factor in both amphibian and avian early development, and as a component in establishing left-right axial patterning in the chicken embryo. Activin has also been found to be a survival factor for several neuronal cell lines and for rat embryonic neural retina cells in culture. However, activin is not a survival factor for chicken CG neurons in culture. Our observation that activin may play a function in target-derived control of neuropeptide expression adds yet another aspect to the list of its potential biological functions. In addition, activin shares regions of amino acid sequence identity with members of the TGF-beta superfamily, which includes the TGF-betas, Mullerian inhibitory substance, Drosophila decapentaplegic gene product, dorsalin, bone morphogenetic proteins, inhibin, and glial-derived neurotrophic factor. Interestingly, these are all factors that have effects upon cellular differentiation. Effects of activin on other neurons. Activin A--as well as two other TGF-beta superfamily members, BMP-2 and BMP-6--has been shown to induce expression of mRNAs for several neuropeptides in cultured rat sympathetic neurons. In addition, activin A induces ChAT mRNA in cultured sympathetic neurons. (ABSTRACT TRUNCATED)

Activin receptor mRNA expression by neurons of the avian ciliary ganglion

Previous studies have suggested that activin may serve as a neurodifferentiation factor regulating somatostatin expression in neurons of the avian ciliary ganglion (CG). As one aspect of examining the role of activin in CG development, we inquired whether any of the known activin receptors are expressed by developing CG neurons in vivo. In addition, we examined whether activin A mRNA is expressed in the choroid layer and iris of the chicken eye. Oligonucleotide primers were designed for the chicken activin receptor type IIA (cActR-IIA), type IIB (cActR-IIB), and activin A. In reverse-transcription-polymerase chain reaction (rtPCR), an appropriately sized product was amplified from CG cDNA using primers to the cActR-IIA but not the cActR-IIB. Sequencing confirmed the identity of the PCR product as a fragment of the cActR-IIA. It thus appears that mRNA for the type IIA but not the type IIB activin receptor is expressed in the chicken CG. An antisense strand digoxigenin-labeled riboprobe complimentary to a 358-bp portion of the cActR-IIA kinase region hybridized to cells within cryostat sections of embryonic CG. From E6.5-E18, hybridization of this probe appears to be specific for cells with a neuronal morphology. Using rtPCR with activin A-specific primers we detected activin mRNA in the choroid layer of E14 and E19 eyes, and from the iris at E14. Our results are consistent with a role for activin as a neurodifferentiation factor in vivo, and imply that within the CG, the cActR-IIA is specifically expressed by neurons, and that activin A is expressed in the targets of these neurons.

Variability of nm23-H1/NDPK-A expression in human lymphomas and its relation to tumour aggressiveness

The nm23-H1 gene is a putative metastasis-suppressor gene encoding a 17 kDa protein with nucleoside diphosphate kinase activity. Expression of nm23-H1/NDPK-A correlates inversely with the metastasising potential of some human tumours and experimental animal cells. No nm23 expression studies exist for human malignant lymphomas so far. In this study, we examined nm23-H1 expression by Northern and immunohistochemical analysis in 106 primary lymphoma samples from patients with Hodgkin's disease (HD) (n = 15), high-grade non-Hodgkin's lymphoma (NHL) from different lineages (n = 71) and low-grade NHL (n = 20). Both inter- and intra-subtype variations in nm23-H1/NDPK-A expression levels were demonstrated by all disease subtypes. Besides this heterogeneity, a general trend towards highly malignant samples expressing higher nm23-H1/NDPK-A, levels than the low-grade lymphomas was observed. Both adult and childhood HD and high-grade NHL samples exhibited significantly higher NDPK-A expression than the low-grade NHL found only in adults. High nm23-H1/NDPK-A levels in lymphoma samples did not always reflect proliferative activity of tumour cells as monitored by Ki-67 antigen staining. Fifty samples were further investigated for possible mutations in the nm23-H1 coding sequence by means of reverse transcriptase-polymerase chain reaction (RT-PCR) and single-strand conformation polymorphism (SSCP) analysis. No mutation was found by this screening. Our results suggest a role for nm23-H1 expression in the disease aggressiveness of lymphomas.

High nm23-H1/NDPK-A expression in Ewing tumors: paradoxical immunohistochemical reactivity and lack of prognostic significance

Expression of nm23-H1/NDPK-A has been reported to correlate inversely with metastasizing potential of rodent experimental cells and some human tumors. In the search for reliable molecular prognostic indicators for Ewing tumors (ET), a group of aggressive presumably neuroectodermal malignancies in children and adolescents, we studied nm23-H1/NDPK-A expression. Northern-blot and RT-PCR analyses were employed to semi-quantificatively measure nm23-H1 mRNA levels in ET cell lines and tissue extracts. A panel of monoclonal antibodies (MAbs) were used to evaluate protein abundance by Western blotting and immunohistochemistry. The nm23-H1/NDPK-A gene was also investigated on the DNA level to define possible genomic alterations. Our results revealed neither nm23-H1 allelic loss nor gene amplification and failed to show any significant variation in nm23-H1 mRNA or NDPK-A protein levels of primary or metastatic ET. NDPK-A protein levels were high and comparable to those of MCF-7 breast-cancer cells and to aggressive stage-IV neuroblastoma cell lines. nm23-H2/NDPK-B expression in ET was slightly more variable but generally lower than in MCF-7 cells. In the immunohistochemical analysis, however, discrepancies in the reactivity patterns with different antibodies were observed. Differential sensitivity to various fixation methods and heat treatment pointed to a structurally polymorphic NDPK-A protein. nm23-H1 expression studies using immunohistochemistry for prognostic counselling should thus be interpreted with caution.

Role of 1,25-dihydroxyvitamin D3 in the generation of the acute-phase response in rats with talc-induced granulomatosis

Subcutaneous injection of nonspecific irritants such as magnesium silicate (talc) provokes granulomatous inflammation in the rat. Part of the acute phase response (APR) in these animals is the loss of trabecular bone at sites distant from the site of inflammation. To assess the possible involvement of vitamin D in the bone loss, we studied the development of the acute phase response in vitamin D-deprived rats. The serum APR provoked by subcutaneous inflammation in rachitic rats consisted of hypozincemia, hypercupremia, increased alkaline phosphatase activity and adrenocorticotropic hormone (ACTH) concentration, and was similar to that in control animals except for the absence of hypoferremia. Control rats with talc-induced subcutaneous inflammation also had splenomegaly and decreased total and mononuclear peripheral blood cell counts, while subcutaneous inflammation did not induce spleen changes in rachitic rats. Subcutaneous inflammation induced the loss of trabecular bone and decreased the osteoblastic cell count in tibial metaphyses in control animals. Rachitic rats had abundant osteoid on trabecular surfaces, and the number of osteoblasts and osteoclasts was comparable to that of the controls. Subcutaneous inflammation did not affect any of the bone parameters in rachitic rats. These results indicate that vitamin D plays an important role in the generation of the acute phase response during inflammation, particularly in the induction of spleen and bone cell changes. The discrepancy of the blood on one hand and bone and spleen indices of the APR on the other, indicate that they may be divergent pathways in the generation of the inflammatory response, some of which may be dependent on vitamin D.

Acute zinc deficiency and trabecular bone loss in rats with talc granulomatosis

Subcutaneous inflammation induced by magnesium silicate (talc) leads to the suppression of bone elongation, osteoblast insufficiency, and subsequent bone loss in rats. Since bone and immunological changes in talc granulomatosis are similar to those observed in zinc deficiency, we investigated the kinetics of zinc tissue distribution and the effects of zinc supplementation on the development of bone loss in rats with talc-induced inflammation. Decrease in serum zinc concentration was observed between 5 and 15 h in rats with talc granulomatosis. It was paralleled by the accumulation of zinc in the liver and rapid disappearance of osteoblasts from the trabecular bone surfaces. However, talc-injected rats supplemented parenterally and orally with zinc sulfate exhibited a decrease in osteoblast trabecular surface comparable to that of unsupplemented rats bearing granulomas despite normalized serum zinc concentrations. Zinc supplementation slightly increased osteoblast trabecular surface in all supplemented groups, but this effect was not significant. We conclude that zinc is the earliest indicator of the acute-phase response in rats with talc granulomatosis. Although zinc appears to be important for the normal function of bone cells, there is no causative relationship between acute zinc deficiency and decreased osteoblast number and activity in rats with talc granulomatosis.

Talc granulomatosis in the rat. Involvement of bone in the acute-phase response

We investigated the dynamics of the acute-phase response (APR) and osteoblast trabecular surface in rats with subcutaneous inflammation provoked by magnesium silicate (talc). The first visible indicator of the APR was a rapid and profound hypozincemia, paralleled by a decrease in metaphyseal trabecular surfaces covered with osteoblasts in long bones. Both the intensity of serum APR and the decrease in osteoblast trabecular surface were directly proportional to the number of granulomas. Alterations in bone metabolism were specific for the inflammation, whereas mild hypozincemia and decrease in mononuclear and increase in polymorphonuclear peripheral white blood cell fractions developed in animals pair-fed with rats bearing two or four granulomas. Rats with talc granulomatosis had high serum ACTH and corticosterone levels, but neither adrenalectomy nor high doses of hydrocortisone could revert bone alterations in talc-injected animals. Glucocorticoids were necessary for the development of hypozincemia and hypercupremia seen in talc granulomatosis, as well as for normal bone metabolism. Inhibition of prostaglandin synthesis had no effect on bone alterations and serum APR in rats bearing talc-induced granulomas. We conclude that the decrease in bone formation constitutes an important aspect of the host acute-phase response in a rat model of talc granulomatosis.

Peripheral nerve lesions in haemophilia

Among 234 haemophiliacs (A and B) treated between 1948 and 1975 at the First Medical Clinic of the University of Vienna, 25 (10.8%) with 36 peripheral nerve lesions have been observed. This amounts to 15.3% or 2.4 lesions within 100 observation years. The average age of the patients at the time of development of lesion was 26.4 years. Correlations between severity of haemophilia and frequency of occurrence of lesions were found. Patients with mild haemophilia did not show peripheral nerve disturbances. The numbers of times individual nerves were affected are as follows: maxillary (1), radial (2), medial (6), ulnar (4), obturator (1), lateral cutaneous nerve of thigh (1), femoral (12), including lesions of the 2nd and 3rd lumbar roots, sciatic (6), including lesions of te 5th lumbar and the 1st sacral roots, peroneal (3), and tibial (1). In 1978, 11 patients who previously had sustained 16 peripheral lesions were reexamined. Of these, 10 had fully recovered, 4 showed some persisting sensory disturbances, and 2 were unchanged. Motor nerve conduction velocity, distal latency and compound nerve action potentials were systematically examined in 11 cases on both sides of the body. In contrast to our expectations, no signs of subclinical peripheral nerve lesions were found. The comparability of the presence and previous results is discussed.