POS0032 FUNCTIONAL ROLE OF SURVIVIN IN ORGANIZATION OF BIVALENT CHROMATIN REGIONS AND CONSEQUENCE FOR ARTHRITIS-RELEVANT GENE EXPRESSION

Background

Bivalent chromatin (BvCR) is characterized by the presence of simultaneous active and repressive modifications on histone H3 proteins. Influencing expression of the genes, BvCR determine cell fate and direct differentiation and lineage commitment in primary T cells and contribute to autoimmunity. Survivin is highly expressed during cell division and in effector Th1 cells contributing to aggravation of autoimmune inflammation. Survivin can physically bind to DNA, specifically to Threonine-3 of histone H3 (1). Thus, functional, and mechanistic data point to a potential chromatin regulatory role for survivin, potentially acting in combination with histone epigenetic modifications (EMs).

Objectives

The goal of our study is to establish the colocalization of survivin with BvCRs and to deduce functional effects of this collaboration on chromatin organization and gene expression.

Methods

Chromatin from CD4+ T cells of 14 female subjects was immunoprecipitated with survivin antibodies and histone H3K27ac, H3K27me3, H3K4me3 antibodies, and coupled with DNA sequencing (ChIPseq, Hiseq2000, Illumina). BvCR were identified as exact overlaps of the three histone EM peaks and the overlapping regions were searched for co-localization with survivin using the ‘ChIPPeakAnno’ Bioconductor package. Tag counts K27me3>K27ac were defined as inactive/poised BvCR, while tag count K27me3<K27ac were identified asactive BvCR. Motif search was done through the MEME tool, and high/moderate complexity motifs with E-value >10e-5 were selected and scanned through the HOCOMOCO database to identify consensus transcription factor (TF) motifs. TFs co-localized with the BvCD were identified through ReMap database. To identify survivin sensitive genes, CD4+ T cells were treated with survivin inhibitor YM155 and a list of reproducible DEG (log2FC>[0.4], >1 experiment) was mapped and analysed for clustering with BvCR.

Results

Co-localization of survivin ChIP peaks with individual H3-peaks was significantly less frequent compared to overlap with all three (a3)-H3 BvCR (7.1 vs 29.8%, p=8.9e-13). Overlap of a3-H3 peaks not containing survivin was less frequent (34%) compared to those which contained survivin (66%). Notably, survivin peak size was 5.5-fold higher when colocalized with a3-H3 peaks, compared to no, or any single H3 (p<2.2e-16). In contrast, no size difference for any of the H3 EM peaks was found.

Further analysis of two non-redundant groups of BvCR that contain (survivin-a3H3, n=4085), and not containing survivin (a3H3noSurv, n = 2131) demonstrated that survivin was mostly associated with inactive BvCR (OR1.29, p=6.6e-6), while no such specificity was found for BvCR with no survivin. Additionally, survivin containing BvCR contained abundant binding sites matching known consensus TF motifs. No sequence-specific motifs were identified in BvCR with no survivin. Comparison of results obtained through HOCOMOCO and ReMap databases resulted in a list of 68 unique TFs. Many of those are key regulators of adaptive immune responses, cellular metabolism, and pluripotency. Differentially expressed genes mapped to BvCR demonstrated enrichment for cellular hormone metabolic processes, regeneration and DNA biosynthesis.

Conclusion

This study provides experimental evidence that survivin defines binding specificity in bivalent chromatin regions being associated with regulation of cellular metabolism and renewal of CD4+ T cells that are functionally important to resist autoimmunity.

References

[1]Kelly AE, Ghenoiu C, Xue JZ, Zierhut C, Kimura H, Funabiki H. Survivin reads phosphorylated histone H3 threonine 3 to activate the mitotic kinase Aurora B Science. 2010 Oct 8; 330(6001): 235–239.

Disclosure of Interests

None declared

POS0702 ANTI-RHEUMATIC TREATMENT ALTERS PFKFB3 EXPRESSION, KEY OF GLYCOLYSIS, IN CD14+ MONOCYTES OF RA PATIENTS, WHICH CONTRIBUTES TO DISSIMILARITIES OF THE IFNg-SIGNATURE

Background

Interferon-gamma (IFNαnterferon-gamma (IFNRheumatology clinic, Gothenburg, Swedenh, Göteborg, Swedenmonocytes of RA patients, which contributes to dissimilarities of the IFNg-signature Peter C. Taylor Consultant of: AbbVie, Biogen, Eli Lilly and Company, Fresenius, Galapagos, mulation is energy consuming and often demands metabolic adaptation of a cell by switching glucose metabolism from the tricarboxylic acid cycle (TCA) to the pentose phosphate pathway (PPP) alternative of glycolysis that dramatically increases glucose intake. Fructose-2,6-biphosphatase 3 (coded by PFKFB3) has been identified as the rate-limiting regulator of glucose metabolism suppressed in leukocytes of RA patients (2).

Objectives

To study effect of anti-rheumatic treatment on the cellular energy metabolism of CD14+ mononuclear cells and its connection to the phenotype and IFNαmononuclear.

Methods

CD14+ cells were sorted from the peripheral blood of the randomly recruited 60 RA patients (mean age 59.6y, DD 13.8y). The cells were LPS activated for 2h and submitted to RNA sequencing (RNAseq, IluminaNextseq). The patients were divided by actual DMARD treatment into those who had no DMARDs (n=8), methotrexate (MTX) only (n=15), biologics (MTX+aTNF n=12, MTX+RTX n=4) and JAK-inhibitors (JAKi, n=24). Differentially expressed gene (DEG) analysis between the groups was performed in R-studio, Bioconductor package, DESeq2. Reported IFN signatures (1) were combined in a set of 51 IFN signature genes (ISG) and analyzed in relation to the transcriptomic profile behind the cellular energy metabolism and DMARD treatment.

Results

MTX and JAKi but not biologics make a significant and opposing contribution of the transcriptomic of energy metabolism in CD14+ cells. MTX-treated patients had significantly higher levels of the rate-limiting enzyme of glycolysis PFKFB3 and PGAM1 compared to those with no DMARDS, which normalized aerobic glycolysis by increasing expression of the pyruvate dehydrogenase complex proteins PDHA1, PHDX and PDK3 linking glycolysis with TCA and decreasing PPP enzymes PGLS, RPIA and TKT. In contrast, PFKFB3 was suppressed in patients treated with JAK-inhibitors compared to those treated with MTX (cor.p=1.32e-8), which significantly activated glycolysis downstream of PFKFB3 and shunting metabolism to PPP inducing expression of G6PD (cor.p=5.0e-92) and PGLS (cor.p=3.1e-46) and increased the major glucose transporter SLC2A1 (cor.p=1.11e-24).

These differences in glucose metabolism were linked to divergent phenotype of CD14+ cells being short-lived CD14intCD11chi cells and IL6 producing in MTX-treated patients and long-lived mature CD14hiCD11bhiCX3CR1hi cells and IFNαcells and IFN producing in MTX-treated pa+ cells of JAKi-treated patients expressed low levels of STAT1 and ISGs compared to MTX-treated patients.

Conclusion

DMARD treatment har divergent effect on glycolysis of CD14+ cells, acting through PFKFB3. This has significant impact on the phenotype of CD14+ cells and inflammatory ability.

References

[1]Lamot L. Et.al. Clin Exp Rheumatol 2019, 37, 1077.

[2]Yang Z. et al, Science Translational Medicine 2016, 8, 331, 331ra38.

Disclosure of Interests

None declared

AB0024 PLURIPOTENCY MARKER PBX1 PREDICTS TREATMENT EFFECT IN RHEUMATOID ARTHRITIS

Background

Accelerated immunosenescence with contraction of T cell repertoire, demise of thymic function and expansion of CD28null T cells with poor T cell reconstitution is the hallmark of rheumatoid arthritis (RA)1.

Objectives

In this study we assessed if PBX1 transcription factor that maintains the pluripotency of hematopoietic stem cells could be used to predict treatment response in RA patients.

Methods

CD4+ T cells of 87 RA female patients (age, median 61y (23-76); disease duration, median 9y (0-45)) were isolated from the perpheral blood, activated with aCD3 and subjected to transcriptional analysis by RNAseq (Illumina). External RNAseq of CD4+ T cells of 80 RA patients (f 56, m 24) was used for validation. The genes differentially expressed (DEG, nominal p<0.05) between PBX1hi and PBX1lo groups were identified by R-studio using Benjamini-Hochberg correction (Bioconductor, DESeq2 package). DEGs were clustered by covariance to identify PBX1 associated genes and biological processes. Clinical variates and treatment regimens in PBX1hi and PBX1lo groups were compared.

Results

The patients of PBX1hi and PBX1lo groups were of similar age and disease duration but differed in anti-rheumatic treatment. PBX1hi group was often treated with conventional DMARDs and monotherapy, while PBX1lo group was mostly treated with biologics and/or JAK-inhibitors in combination with cDMARDs (χ2, p=0.0099). This treatment led to sufficient disease control in both PBX1 groups (median DAS28; 2.6 and 2.7, respectively). In the external RA cohort of the patients resistant to conventional DMARDs, PBX1hi patients had significantly fewer frequency of non-responders to anti-TNF treatment compared to PBX1lo (χ2, p=0.026).

Pathway analysis of the DEGs identified strong enrichment for regulation of transcription (cor.p=10-23), RNA metabolic processes (cor.p=10-18) and differentiation (cor.p=10-7) in PBX1hi CD4+ cells, which corresponds to the known biological properties of PBX12. PBX1hiCD4+ cells in both datasets had imprinted features of pluripotency3 and expressed higher levels of KIT and CAT, low proliferation markers Ki67 and BIRC5, and had virtually no cytokine production. In the main cohort, PBX1hiCD4+ cells were recognized by naïve T cell marks CD62L (SELL) and CD45 (PTPRC), and also PECAM1, CR2, and CD28, indicating recent thymic egress. In the validation cohort, PBX1hiCD4+ cells were enriched with stem cell markers CD34, MEG3, and DNMT3B. Lineage specific TFs (TBET, GATA3, FOXP3, RORC) and cytokines (IFNG, TNF, IL10, IL17F, etc.) were accumulated in PBX1loCD4+ cells indicating terminally differentiated effector CD4+ T cells.

Conclusion

This study shows that enrichment with PBX1hi CD4+ cells is associated with naïve pluripotent phenotype of CD4 lymphocytes. Patients with high PBX1 expression are less heavily treated and respond better to treatment. This suggests boosting of PBX1-expression to be a way of treating RA.

References

[1]Keotz K et al, PNAS 2000:97(16) 9203-9208. T cell homeostasis in patients with rheumatoid arthritis.

[2]Veiga RN et al, J Mol Med (Berl) 2021:99(12) 1667-1680. PBX1: a key character of the hallmarks of cancer.

[3]Bock C et al, Cell 2011:144(3) 439-452. Reference Maps of human ES and iPS cell variation enable high-throughput characterization of pluripotent cell lines

Disclosure of Interests

None declared

Antibacterial activity of apramycin at acidic pH warrants wide therapeutic window in the treatment of complicated urinary tract infections and acute pyelonephritis

Background

The clinical-stage drug candidate EBL-1003 (apramycin) represents a distinct new subclass of aminoglycoside antibiotics for the treatment of drug-resistant infections. It has demonstrated best-in-class coverage of resistant isolates, and preclinical efficacy in lung infection models. However, preclinical evidence for its utility in other disease indications has yet to be provided. Here we studied the therapeutic potential of EBL-1003 in the treatment of complicated urinary tract infection and acute pyelonephritis (cUTI/AP).

Methods

A combination of data-base mining, antimicrobial susceptibility testing, time-kill experiments, and four murine infection models was used in a comprehensive assessment of the microbiological coverage and efficacy of EBL-1003 against Gram-negative uropathogens. The pharmacokinetics and renal toxicology of EBL-1003 in rats was studied to assess the therapeutic window of EBL-1003 in the treatment of cUTI/AP.

Findings

EBL-1003 demonstrated broad-spectrum activity and rapid multi-log CFU reduction against a phenotypic variety of bacterial uropathogens including aminoglycoside-resistant clinical isolates. The basicity of amines in the apramycin molecule suggested a higher increase in positive charge at urinary pH when compared to gentamicin or amikacin, resulting in sustained drug uptake and bactericidal activity, and consequently in potent efficacy in mouse infection models. Renal pharmacokinetics, biomarkers for toxicity, and kidney histopathology in adult rats all indicated a significantly lower nephrotoxicity of EBL-1003 than of gentamicin.

Interpretation

This study provides preclinical proof-of-concept for the efficacy of EBL-1003 in cUTI/AP. Similar efficacy but lower nephrotoxicity of EBL-1003 in comparison to gentamicin may thus translate into a higher safety margin and a wider therapeutic window in the treatment of cUTI/API.

Funding

A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

Insights into Elution of Anion Exchange Cartridges: Opening the Path toward Aliphatic 18F-Radiolabeling of Base-Sensitive Tracers

Aliphatic nucleophilic substitution (S_N2) with [¹⁸F]fluoride is the most widely applied method to prepare ¹⁸F-labeled positron emission tomography (PET) tracers. Strong basic conditions commonly used during ¹⁸F-labeling procedures inherently limit or prohibit labeling of base-sensitive scaffolds. The high basicity stems from the tradition to trap [¹⁸F]fluoride on anion exchange cartridges and elute it afterward with basic anions. This sequence is used to facilitate the transfer of [¹⁸F]fluoride from an aqueous to an aprotic organic, polar reaction medium, which is beneficial for S_N2 reactions. Furthermore, this sequence also removes cationic radioactive contaminations from cyclotron-irradiated [¹⁸O]water from which [¹⁸F]fluoride is produced. In this study, we developed an efficient elution procedure resulting in low basicity that permits S_N2 ¹⁸F-labeling of base-sensitive scaffolds. Extensive screening of trapping and elution conditions (>1000 experiments) and studying their influence on the radiochemical yield (RCY) allowed us to identify a suitable procedure for this. Using this procedure, four PET tracers and three synthons could be radiolabeled in substantially higher RCYs (up to 2.5-fold) compared to those of previously published procedures, even from lower precursor amounts. Encouraged by these results, we applied our low-basicity method to the radiolabeling of highly base-sensitive tetrazines, which cannot be labeled using state-of-art direct aliphatic ¹⁸F-labeling procedures. Labeling succeeded in RCYs of up to 20%. We believe that our findings facilitate PET tracer development by opening the path toward simple and direct S_N2 ¹⁸F fluorination of base-sensitive substrates.

Fully Automated GMP-Compliant Synthesis of [18F]FE-PE2I

In the struggle to understand and accurately diagnose Parkinson's disease, radiopharmaceuticals and medical imaging techniques have played a major role. By being able to image and quantify the dopamine transporter density, noninvasive diagnostic imaging has become the gold standard. In the shift from the first generation of SPECT tracers, the fluorine-18-labeled tracer [18F]FE-PE2I has emerged as the agent of choice for many physicians. However, implementing suitable synthesis for the production of [18F]FE-PE2I has proved more challenging than expected. Through a thorough analysis of the relevant factors affecting the final radiochemical yield, we were able to implement high-yielding fully automated GMP-compliant synthesis of [18F]FE-PE2I on a Synthera®+ platform. By reaching RCYs up to 62%, it allowed us to isolate 25 GBq of the formulated product, and an optimized formulation resulted in the shelf life of 6 h, satisfying the increased demand for this radiopharmaceutical.

OP0315 EFFECTOR CD4 T CELLS REQUIRE SURVIVIN FOR REGULATION OF GLUCOSE METABOLISM AND IFNg PRODUCTION

Background:

Interferon-gamma (IFNg) producing effector T cells play the leading role in triggering and perpetuation of inflammation in rheumatoid arthritis. Inflammation leads to metabolic reprogramming of T cells and high energy consumption supporting proliferation and IFNg production. Being a part of chromosomal passenger complex, oncoprotein survivin is essential for cell proliferation. It has also been identified as a marker of severe therapy-resistant rheumatoid arthritis. Thus, we aimed to explore the association between survivin and IFNg producing phenotype of CD4 T cells.

Objectives:

We study if survivin mediates the glucose dependent mechanism of IFNg production in CD4 T cells.

Methods:

CD4 cells were sorted from the peripheral blood of RA patients and healthy controls, activated with aCD3, cultured in presence of survivin inhibitor YM155 and subjected to RNA sequencing (Illumina, Life Science). IFNg levels in supernatants were measured by ELISA. To study glucose uptake in presence of YM155, CD4 cells were treated with IFNg+aCD3 overnight followed by 2NBD-glucose challenge for 30 min. Uptake of fluorescent 2NBD-glucose probe was measured by flow cytometry. Statistical analysis of RNAseq was performed in R-studio using the Bioconductor package DESeq2.

Results:

Comparison of the whole-genome transcription profile of CD4 cells different by levels of BIRC5, coding for survivin, demonstrated that the BIRC5hi group expressed significantly higher levels of IFNg (mRNA, p=10-26 and protein, p=10-4). Also, BIRC5hi CD4 cells had higher expression of glucose transporter GLUT1 (SLC2A1, p=0.0064) and of glycolytic enzymes glucose-6-phosphate dehydrogenase (G6PD, p=10-6), pyruvate kinase (PFKP, p=10-6), and lactate dehydrogenase (LDHA, p=10-14). On the contrary, expression of the key regulator of glycolysis 6-phosphofructo-2-kinase (PFKFB3) was significantly lower in the BIRC5hi group (p=4.4x10-5). Notably, expression of glycolytic enzymes G6PD and PFKFB3 correlated strongly to IFNg (r=0.880 and -0.698, respectively), TBX21 (r=0.811 and -0.698) and perforin (r=0.781 and -0.698). To demonstrate functional relevance of the connection between BIRC5 and glucose metabolism, survivin was inhibited in CD4 cell cultures. Survivin inhibition resulted in significant increase of PFKFB3 (p=7x10-6) and LDHA (p=0.0089), leading to inhibition of phosphoglycerate mutase PGAM1 and ATF citrate lyase ACLY (p=0.021 and p=0.0074, respectively), which dignify the restoration of aerobic glycolysis. Importantly, inhibition of survivin decreased 2NBD-glucose uptake by CD4 cells (p=0.031) and reduced expression of GLUT1 (p=0.034). These changes in glucose metabolism were followed by decreased IFNg production in supernatants (p=0.037).

Conclusion:

The study demonstrates a strong connection between IFNg production and glucose metabolism in CD4 cells. Survivin emerges as an important regulator of glycolysis acting through expression of glycolytic enzymes and glucose transport.

Disclosure of Interests:

None declared.

POS0360 COMPLEX LANDSCAPE OF BIRC5/SURVIVIN GENOME BINDING IN HUMAN CD4+ T CELLS

Background:

Survivin, coded by BIRC5 gene, is a multitasking protein essential for cell renewal and homeostasis. In autoimmune conditions as rheumatoid and psoriasis arthritis, survivin was associated with inflammation severity and joint damage. Importantly, inhibition of survivin alleviated experimental arthritis in mice. We have recently shown survivin to be essential for T cell differentiation and micro-RNA processing. The known anti-apoptotic and proliferation facilitating functions of survivin does not explain the nuclear localization of survivin in interphase.

Objectives:

We aimed to uncover nuclear functions of BIRC5/survivin in CD4 cell of RA patients and healthy.

Methods:

CD4 T cells were isolated from the peripheral blood using positive selection on magnetic beads (EasySep) and activated for 48h with ConA+LPS. Chromatin immunoprecipitation (ChIP) with polyclonal anti-survivin antibodies was done in four independent samples of healthy donors (n=5), healthy smokers (n=3), rheumatoid arthritis (n=3) and breast cancer (n=2). Pooled libraries were constructed for each group and ChIPseq was carried out (Illumina). For comparative RNAseq analysis, activated CD4 T cells were incubated with or without survivin inhibitor (YM155) for 24h. State-of-the-art bioinformatics pipelines were applied for NGS data and the survivin-binding peaks were used for comparison with genes, chromatin state annotation and functional gene- and regulatory regions-based functional analysis. Co-localization of peaks in the whole genome and in vicinity of the differentially expressed genes (DEG) was done using ReMap integrated ChIPseq datasets for all human cells and tissues.

Results:

We identified 13 thousands non-overlapping survivin ChIP-peaks (>3000 peaks were present in at least 3 samples). Survivin-bound regions were enriched near the genes and promoters (p=e-30 and p=e-8), which implied that survivin role in transcription could be mediated by known transcription factors. Thus, we analyzed survivin peaks vs binding regions of 1135 transcription regulators (TR) available in ReMap.

Potential partner proteins of survivin were selected based on the enrichment of the overlapping peaks in the whole genome and in CD4-active regulatory areas. Both, strict overlaps and location within 10 and 100kb survivin peak vicinity were analyzed. This approach allowed us to select >150 TRs enriched in all tests. The enriched TRs were involved in immunity and RA-relevant pathways including cytokine response and production, JAK-STAT signaling, etc. Among the TRs co-localized with survivin were CHD8, MAX, EP300, BRD2, CTCF and RAD21, all responsible for chromatin architecture. Several TRs were massively enriched in the vicinity of DEGs after survivin depletion including MAX, AR, CTCF, MYC and IRF1. Search for TR binding motifs in survivin peaks supported over-representation of binding sites for IRFs (p=e-5) and several proteins of the bZIP-family (p=e-5).

Conclusion:

Analysis of the survivin bound DNA in CD4 cells demonstrated the nonrandom distribution with specific enrichment within the regulatory elements of the genes and co-localizeation with protein partners to regulate their transcription.

Disclosure of Interests:

None declared

OP0026 IGF1R DEPENDENT CELL INTERACTION AND REGULATION OF AUTOANTIBODY PRODUCTION IN RHEUMATOID ARTHRITIS

Background:

The insulin-like growth factor 1 receptor (IGF1R) signalling mediates numerous developmental processes acting through downstream adaptor molecules IRS1/2, which activate Akt and inhibit the family of forkhead box class O (FoxO). Inhibition of IGF1R signalling alleviates rheumatoid arthritis (RA) (Erlandsson et al., 2017), however, the role of IGF1R signalling in the regulation of immune function is poorly understood.

Objectives:

To investigate the link between IGF1R signalling and antigen presentation in experimental arthritis.

Methods:

Arthritis was induced by immunising Balb/c mice with methylated bovine serum albumin (mBSA, n=18) and DBA/1 mice with type II collagen (CII, n=18). The mice were treated with a synthetic IGF1R inhibitor NT157 or with short hairpin RNA targeting IGF1R (shIGF1R) from the day prior to immunisation. Controls were treated with cyclodextrine vehicle/ non-targeting (nt)RNA, respectively. Flow cytometry was used for spleen cell phenotype. Antibody levels were measured by ELISA. Immunohistochemistry (IHC) of spleen was performed for assessment of marginal zone (MZ) and location of pS612IRS1+ and pS256FoxO1+ cells. IHC images were acquired by fluorescent confocal microscopy, and analysed using ZEN2009 and Cell Profiler soft ware.

Results:

The inhibition of IGF1R resulted in an 80% increase in MZ area in NT157-treated mice compared to controls (p=0.0001). This was supported by a significant increase of CD21+ (p=0.034) and CD23+ cell populations (p=0.00059), both among the CD19+ B cells and antigen-presenting MHCII+CD19- cells, implying that IGF1R expression regulates the populations of MZ and follicular cells. Additionally, there was a strong positive correlation between the decrease of IGF1R+ and ICOSL+ population on CD21+ cells (r=0.70, p=0.0071), which retained them in the MZ and prolonged communication with macrophages. Insufficient feedback from ICOSL- B cells limited expression of CXCR5 on CD4 cells. The IHC analysis displayed that, IGF1R inhibition led to abundance of inactivate pS612IRS1+ and pS256FoxO1+ cells within the MZ, compared with controls (p=0.0002). Alongside the increase of IgM+ B cell population (p=0.0022), we observed significant increase in number of antigen-presenting F4/80+ cells (p=0.043) and MARCO expression (p=0.043) after IGF1R intervention. Finally, the NT157- treated mice displayed a significant pleiotropic increase in IgM autoantibody production, with anti-CCP IgM (p=0.027), RF-IgM (p=0.0085), anti-DNA IgM (p=0.066) and in total IgM (p=0.027) levels, which correlated positively with pS256FoxO1+ cells (r=0.51, p=0.03). Levels of IgG were not changed.

Conclusion:

We show that IGF1R signalling is important for immune cell communication after antigen challenge. IGF1R controls ICOSL dependent trafficking of B cells through the MZ and facilitates interaction with T cells. Retention of B cells in the MZ tips the balance from T cell to macrophage-dependent processes, which permits the formation of autoantibody producing B cells.

References:

[1]Erlandsson, M., et.al., 2017. IGF-1R signalling contributes to IL-6 production and T cell dependent inflammation in rheumatoid arthritis. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 1863(9), pp.2158-2170.

Disclosure of Interests:

None declared

OP0127 TRANSCRIPTIONAL ACTIVITY OF SURVIVIN CONTRIBUTES TO MATURATION AND FUNCTION OF THE INTERFERON-GAMMA PRODUCING T CELLS IN RHEUMATOID ARTHRITIS

Background:

Interferon gamma (IFNg) signalling and downstream effects make important contribution in pathogenesis of rheumatoid arthritis (RA). Here, we propose a mechanism by which oncoprotein survivin participates in development of IFN-dependent repertoire of T cells in RA patients.

Objectives:

We study the role of survivin in the phenotype of CD4 T cells of RA patients.

Methods:

CD4 cells of RA patients and healthy controls were purified from blood, activated and subjected to RNAseq, ChIPseq with antibodies to survivin (BIRC5) was performed on CD4+ cells. Histone H3 ChIPseq was performed using antibodies to H3K27ac, H3K27me3 and H3K4me3. Statistical analysis was performed In R-studio using the Bioconductor package DESeq2, clustering using Spearman and Ward.D2.

Results:

Unsupervised clustering of CD4 samples by expression of 48 core Th cell markers identified subsets of CD28hiCD27hiIFNnegcentral memory cells (Tcm), CD28loCD27loIFNloeffector memory cells (Tem) and CD28nullCD27nullIFNhiterminal effector cells (Tte). Tte cells showed classical features of Th1 cells including high levels of TBX21, TNFa and IL32 and signs of activation in IFN signalling machinery. Interestingly, they combined the features of peripheral Tregs CD25hiFoxp3hiIKZF2negand IL10 producing cells together with type 1 regulatory cells, which rely on transcription factors BATF and IRF1 for the differentiation and produced high amounts of perforin and granzyme B. Importantly, Tte CD4 cells had also high transcription of BIRC5 (p=1.15e-18).

To study if BIRC5 is a part of IFN signalling, CD4 cells were cultured with survivin inhibitor YM155 and activated with IFNg. RNAseq analysis revealed 2033 (FC<2.0, n=336) differentially expressed genes in the IFN stimulated cultures. Interestingly, a substantial number of these IFN-dependent genes was significantly reduced in the survivin-deficient cultures and included among others CD28, FoxP3, IKZF2, ICOS, BATF, PRDM1, CXCR3, IRF4 and IRF8. Analysis of the peak sequences identified enrichment for composite motifs for IRFs (ETS:IRF, p1.0e-124; bZIP:IRF, p=1.0e-640), indicating that survivin is important for IFNg signalling. Numerically, the peaks containing ETS:IRF motifs were most prevalent and identified in total within 49.7% of all survivin-ChIP peaks. Frequent was co-localisation of the IRF:bZIP and IRF:ETS motifs within the survivin peaks. Among the IRF motifs dominated those suitable for IRF1 (p=1,0e-127) and IRF8 (p=1,0e-84). However, the DNA binding motifs of these two are alike.

Encouraged by the survivin ChIPseq results, we wanted to know its relation to histone marks. We observed that 50% of survivin peaks containing both IRF:bZIP and IRF:ETS motifs are co-localized with the H3K27ac marks. In total, 16 of 48 core Th cell markers used for patients clustering were identified by survivin ChIPseq, co-localized with IRF composite motifs and histone marks. They were also dependent of survivin for expression.

Conclusion:

his study showed that survivin binds to DNA and regulates the core gene expression contributing to maturation and function of the IFNg producing Th1 cells.

References:

-

Disclosure of Interests:

Malin Erlandsson: None declared, Karin ME Andersson: None declared, Nisha Nair: None declared, Anastasius Damdimopoulos: None declared, Sofia Töyrä Silfverswärd: None declared, Rille Pullerits: None declared, Anne Barton Consultant of: AbbVie, Maria I Bokarewa: None declared

THU0037 SURVIVIN INHIBITS TRANSCRIPTION OF PBX1 AND SUPPORTS THE EFFECTOR PHENOTYPE OF THE MEMORY CD4 T CELLS IN RHEUMATOID ARTHRITIS

Background:

The oncogenic protein survivin is a marker of severe rheumatoid arthritis (RA). High serum levels of Survivin predict progressive joint damage1and poor treatment response2.

Objectives:

To study the role of survivin in the transcriptional regulation of phenotype in CD4+T cells.

Methods:

CD4+T cells of RA female patients were isolated from the perpheral blood. Activated CD4+cells were treated with survivin inhibitor YM155. Transcriptional analysis was done by RNAseq (Illumina) and conventional qPCR. Chromatin of CD4 cells was immunoprecipitated using polyclonal antibodies to survivin and subjected to deep sequencing (survivin ChIPseq, Hiseq2000, Illumina) and aligned to GRCh38. Statistical analysis of differentially expressed genes (DEG) was done in R-studio using Benjamini-Hochberg adjustment for multiple testing (Bioconductor, DESeq2 package).

Results:

Survivin ChIPseq of the activated CD4+T cells was enriched with the genes engaged in regulatory transcription factor specific DNA binding (GO:0000987, adj p=0.0005) and RNA polymerase II regulatory transcription (GO:0000978, adj p = 0.0004). Among survivin targets were the genes of HOX-B cluster and TALE family proteins MEIS, PKNOX and PBX1 controlling early leukopoesis and T cell maturation. Inhibition of survivin in PBMC resulted in significant upregulation of PBX1 (p=0.023), MEIS3 (p=0.0036), similar tendency was observed for HOXB6 and HOXC4 genes. RNAseq analysis CD4 cells of RA patients with different transcription of PBX1, identified 1636 genes (adj p<10-5). BIRC5, coding for survivin, was 8.3 folds higher in CD4+cells with low PBX1 (p=0.0005). Among the core transcription factors of T helper cell differentiation, we identifed NF-kB1 and NF-kB2, TBX21, IRF4, IRF8 and STAT3, BATF and BATF3. This followed by significantly higher TNF, IFNg and IL17A and IL17F in PBX1lo CD4 T cells. The pathway enrichment analysis of DEG identified strong over-representation of cytokine-specific genes (GO:005125, GO:0005126, GO:0048018, GO:0030545, FDR q-values 10-12-10-9). The genes of IL4, IL5, IL13, IL9, IL3 and CSF2 located within the chromosome 5 were common for all GO-lists, and were higher in PBX1lo, but none of those genes was identified by survivin-ChIPseq or PBX1-ChIPseq. Analysis of ChIPseq data identified the genes of STAT3, IRF4, IRF8 and BATF as common targets for PBX1 and survivin.

Conclusion:

This genome-wide analysis indicates that survivin regulates transcription of the TALE family protein PBX1 in CD4+ T cells, which has essential effect for differentiation and phenotype of Th subsets. Low PBX1 in RA patients is associated with terminally differentiated effector CD4+ T cells.

References:

[1]Svensson, B.et.al.Smoking in combination with antibodies to cyclic citrullinated peptides is associated with persistently high levels of survivin in early rheumatoid arthritis: a prospective cohort study.Arthritis Res Ther16, R12 (2014).

[2]Levitsky, A.et.al.Serum survivin predicts responses to treatment in active rheumatoid arthritis: a post hoc analysis from the SWEFOT trial.BMC Med13, 247 (2015).

Disclosure of Interests:

None declared

In Vivo Veritas: 18F-Radiolabeled Glycomimetics Allow Insights into the Pharmacological Fate of Galectin-3 Inhibitors

Glycomimetic drugs have attracted increasing interest as unique targeting vectors or surrogates for endogenous biomolecules. However, it is generally difficult to determine the in vivo pharmacokinetic profile of these compounds. In this work, two galectin-3 inhibitors were radiolabeled with fluorine-18 and used as surrogate PET tracers of TD139 and GB1107. Both compounds are promising drugs for clinical applications. In vivo evaluation revealed that both surrogates strongly differed with respect to their biodistribution profile. The disaccharide (TD139 surrogate) was rapidly eliminated from blood while the monosaccharide (GB1107 surrogate) showed no sign of excretion. The data obtained allowed us to infer the different in vivo fate of TD139 and GB1107 and rationalize how different administration routes could boost efficacy. Whereas the fast excretion profile of the TD139 surrogate indicated that systemic application of disaccharides is unfavorable, the extended biological half-life of the GB1107 surrogate indicated that systemic administration is possible for monosaccharides.

Radiosynthesis and preclinical evaluation of [11 C]Cimbi-701 - Towards the imaging of cerebral 5-HT7 receptors

The serotonin 7 (5-HT₇ ) receptor is suggested to be involved in a broad variety of CNS disorders, but very few in vivo tools exist to study this important target. Molecular imaging with positron emission tomography (PET) would enable an in vivo characterization of the 5-HT₇ receptor. However, no clinical PET radiotracer exists for this receptor, and thus we aimed to develop such a tracer. In this study, we present the preclinical evaluation of [¹¹ C]Cimbi-701. Cimbi-701 was synthesized in a one-step procedure starting from SB-269970. Its selectivity profile was determined using an academic screening platform (NIMH Psychoactive Drug Screening Program). Successful radiolabeling of [¹¹ C]Cimbi-701 and subsequent in vivo evaluation was conducted in rats, pigs and baboon. In vivo specificity was investigated by 5-HT₇ and σ receptor blocking studies. P-gp efflux transporter dependency was investigated using elacridar. [¹¹ C]Cimbi-701 could successfully be synthesized. Selectivity profiling revealed high affinity for the 5-HT₇ (K_i = 18 nM), σ-1 (K_i = 9.2 nM) and σ-2 (K_i = 1.6 nM) receptors. In rats, [¹¹ C]Cimbi-701 acted as a strong P-gp substrate. After P-gp inhibition, rat brain uptake could specifically be blocked by 5-HT₇ and σ receptor ligands. In pig, high brain uptake and specific 5-HT₇ and σ-receptor binding was found for [¹¹ C]Cimbi-701 without P-gp inhibition. Finally, low brain uptake was found in baboons. Both the specific σ-receptor binding and the low brain uptake of [¹¹ C]Cimbi-701 displayed in baboon discouraged further translation to humans. Instead, we suggest exploration of this structural class as results indicate that selective 5-HT₇ receptor imaging might be possible when more selective non-P-gp substrates are identified.

Towards selective CNS PET imaging of the 5-HT7 receptor system: Past, present and future

Since its discovery in 1993, the serotonin receptor subtype 7 (5-HT₇) has attracted significant attention as a potential drug target; due to its elucidated roles in conditions such as insomnia, schizophrenia, and more. Therefore, it is unsurprising that there has been relatively early efforts undertaken to develop a positron emission tomography (PET) imaging agent for said receptor system. PET can be clinically used to probe receptor systems in vivo, permitting information such as a drug's occupancy against this system to be investigated. This review focuses on the efforts towards the development of a 5-HT₇R selective PET CNS tracer over the last 20 years, critically reflecting on applied strategies and commonly employed chemical frameworks and suggests future considerations that are needed to successfully develop a PET tracer for this clinically relevant target. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Development and Evaluation of Two Potential 5-HT7 Receptor PET Tracers: [18F]ENL09 and [18F]ENL10

The latest addition to the serotonin (5-HT) receptor family is the 5-HT₇ receptor (5-HT₇R). This receptor has gained interest as a drug target due to its involvement in various disorders such as depression or schizophrenia. There is currently no clinically validated positron emission tomography (PET) tracer for the 5-HT₇R available. But, the (arylpiperazinyl-butyl)oxindole scaffold provides a promising lead structure for this purpose. Here, we synthesized 12 (arylpiperazinyl-butyl)oxindole derivatives and in vitro affinity screening identified two structures with suitable affinity and selectivity to be radiolabeled and tested as 5-HT₇R selective PET tracers. Next, the radiolabeled products [¹⁸F]ENL09 and [¹⁸F]ENL10 were evaluated as PET tracers in rats. Both tracers were found to be P-gp substrates, but after P-gp inhibition the brain uptake showed a regional distribution in line with the known 5-HT₇R distribution.  The [¹⁸F]ENL10 brain binding was displaceable with a 5-HT₇R selective ligand, whereas [¹⁸F]ENL09 was not. We find that [¹⁸F]ENL10 is a promising 5-HT₇R selective PET tracer candidate that should be investigated in higher species.

Synthesis and Pharmacological Evaluation of [11C]4-Methoxy-N-[2-(thiophen-2-yl)imidazo[1,2-a]pyridin-3-yl]benzamide as a Brain Penetrant PET Ligand Selective for the δ-Subunit-Containing γ-Aminobutyric Acid Type A Receptors

The α_4/6βδ-containing GABA_A receptors are involved in a number of brain diseases. Despite the potential of a δ-selective imaging agent, no PET radioligand is currently available for in vivo imaging. Here, we report the characterization of DS2OMe (1) as a candidate radiotracer, ¹¹C-labeling, and subsequent evaluation of [¹¹C]DS2OMe in a domestic pig as a PET radioligand for visualization of the δ-containing GABA_A receptors.

Improved radiosynthesis and preliminary in vivo evaluation of the 11C-labeled tetrazine [11C]AE-1 for pretargeted PET imaging

Pretargeted nuclear imaging based on the ligation between tetrazines and nano-sized targeting agents functionalized with trans-cyclooctene (TCO) has recently been shown to improve both imaging contrast and dosimetry in nuclear imaging of nanomedicines. Herein, we describe the improved radiosynthesis of a ¹¹C-labeled tetrazine ([¹¹C]AE-1) and its preliminary evaluation in both mice and pigs. Pretargeted imaging in mice was carried out using both a new TCO-functionalized polyglutamic acid and a previously reported TCO-functionalized bisphosphonate system as targeting agents. Unfortunately, pretargeted imaging was not successful using these targeting agents in pair with [¹¹C]AE-1. However, brain imaging in pig indicated that the tracer crossed the blood-brain-barrier. Hence, we suggest that this tetrazine scaffold could be used as a starting point for the development of pretargeted brain imaging, which has so far been a challenging task.

Classics in Neuroimaging: The Serotonergic 2A Receptor System-from Discovery to Modern Molecular Imaging

Already in 1953, Woolley and Shaw speculated that serotonin could be involved in a range of central nervous system (CNS) disorders. Lysergic acid diethylamide (LSD) displayed an important role in this respect. It was used not only to antagonize biological effects of serotonin and to study the system itself, but also to identify serotonergic subtype receptors. The 5-HT_2A receptor was discovered in the 1970s and identified as the responsible receptor mediating psychedelic effects of LSD. The development of positron emission tomography (PET) allowed to study this receptor system in vivo. Parameters such as abundance of 5-HT_2A neuroreceptors or receptor occupancy can be determined using PET. As such, the development of 5-HT_2A receptor tracers started immediately after the introduction of PET in the mid-1970s. In this Viewpoint, we provide a historical overview from the discovery of serotonin to the identification of the 5-HT_2A receptor subtype and the subsequent development of 5-HT_2A receptor subtype specific PET tracers over the last four decades. We emphasize the interplay between pharmacology, medicinal chemistry, radiochemistry, and nuclear medicine that is important while developing a PET tracer. Moreover, we highlight selected examples applying 5-HT_2A receptor PET tracers within neurological diseases and drug occupancy studies.

Modeling Strategies for Quantification of In Vivo 18F-AV-1451 Binding in Patients with Tau Pathology

Aggregation of hyperphosphorylated tau is a major hallmark of many neurodegenerative diseases, including Alzheimer disease (AD). In vivo imaging with PET may offer important insights into pathophysiologic mechanisms, diagnosis, and disease progression. We describe different strategies for quantification of ¹⁸F-AV-1451 (T807) tau binding, including models with blood sampling and noninvasive alternatives. Methods: Fifteen subjects (4 controls, 6 AD, 3 progressive supranuclear palsy, 2 cortico basal syndrome) underwent 180-min PET with ¹⁸F-AV-1451 and arterial blood sampling. Modeling with arterial input functions included 1-, 2-, and 3-tissue-compartment models and the Logan plot. Using the cerebellum as reference region, we applied the simplified reference tissue model 2 and Logan reference plot. Finally, simplified outcome measures were calculated as ratio, with reference to cerebellar concentrations (SUV ratio [SUVR]) and SUVs. Results: Tissue compartment models were not able to describe the kinetics of ¹⁸F-AV-1451, with poor fits in 33%-53% of cortical regions and 80% in subcortical areas. In contrast, the Logan plot showed excellent fits and parameter variance (total volume of distribution SE < 5%). Compared with the 180-min arterial-based Logan model, strong agreement was obtained for the Logan reference plot also for a reduced scan time of 100 min (R² = 0.91) and SUVR 100-120 min (R² = 0.94), with 80-100 min already representing a reasonable compromise between duration and accuracy (R² = 0.93). Time-activity curves and kinetic parameters were equal for cortical regions and the cerebellum in control subjects but different in the putamen. Cerebellar total volumes of distribution were higher in controls than patients. For these methods, increased cortical binding was observed for AD patients and to some extent for cortico basal syndrome, but not progressive supranuclear palsy. Conclusion: The Logan plot provided the best estimate of tau binding using arterial input functions. Assuming that the cerebellum is a valid reference region, simplified methods seem to provide robust alternatives for quantification, such as the Logan reference plot with 100-min scan time. Furthermore, SUVRs between target and cerebellar activities obtained from an 80- to 100-min static scan offer promising potential for clinical routine application.

Necrotizing Encephalitis of Unknown Cause in Fennoscandian Arctic Foxes (Alopex Lagopus)

A neurologic disease affected a colony of endangered Fennoscandian arctic foxes ( Alopex lagopus) kept in captivity for breeding purposes. Several outbreaks of disease occurred between 1994 and 2004. The clinical signs included ataxia, indications of anosmia, blindness, and abnormal behavior. The disease was characterized by severe necrotizing encephalitis affecting mostly the cranial cerebrum, basal ganglia, and olfactory bulbs. Investigations to identify the etiology of the disease included testing for several infectious agents known to cause encephalitis in carnivores. Tests for Toxoplasma gondii, Encephalitozoon cuniculi, Neospora caninum, canine distemper virus, rabies, adenovirus type 1, Borna disease virus, and Listeria monocytogenes were negative. The colony was closed, and the cause of the disease remains undetermined.

Quantitative PET Imaging of Tissue Factor Expression Using 18F-Labeled Active Site-Inhibited Factor VII

Tissue factor (TF) is upregulated in many solid tumors, and its expression is linked to tumor angiogenesis, invasion, metastasis, and prognosis. A noninvasive assessment of tumor TF expression status is therefore of obvious clinical relevance. Factor VII is the natural ligand to TF. Here we report the development of a new PET tracer for specific imaging of TF using an (18)F-labeled derivative of factor VII.

METHODS

Active site-inhibited factor VIIa (FVIIai) was obtained by inactivation with phenylalanine-phenylalanine-arginine-chloromethyl ketone. FVIIai was radiolabeled with N-succinimidyl 4-(18)F-fluorobenzoate and purified. The corresponding product, (18)F-FVIIai, was injected into nude mice with subcutaneous human pancreatic xenograft tumors (BxPC-3) and investigated using small-animal PET/CT imaging 1, 2, and 4 h after injection. Ex vivo biodistribution was performed after the last imaging session, and tumor tissue was preserved for molecular analysis. A blocking experiment was performed in a second set of mice. The expression pattern of TF in the tumors was visualized by immunohistochemistry and the amount of TF in tumor homogenates was measured by enzyme-linked immunosorbent assay and correlated with the uptake of (18)F-FVIIai in the tumors measured in vivo by PET imaging.

RESULTS

The PET images showed high uptake of (18)F-FVIIai in the tumor regions, with a mean uptake of 2.5 ± 0.3 percentage injected dose per gram (%ID/g) (mean ± SEM) 4 h after injection of 7.3-9.3 MBq of (18)F-FVIIai and with an average maximum uptake in the tumors of 7.1 ± 0.7 %ID/g at 4 h. In comparison, the muscle uptake was 0.2 ± 0.01 %ID/g at 4 h. At 4 h, the tumors had the highest uptake of any organ. Blocking with FVIIai significantly reduced the uptake of (18)F-FVIIai from 2.9 ± 0.1 to 1.4 ± 0.1 %ID/g (P < 0.001). The uptake of (18)F-FVIIai measured in vivo by PET imaging correlated (r = 0.72, P < 0.02) with TF protein level measured ex vivo.

CONCLUSION

(18)F-FVIIai is a promising PET tracer for specific and noninvasive imaging of tumor TF expression. The tracer merits further development and clinical translation, with potential to become a companion diagnostics for emerging TF-targeted therapies.

Abstract 4930: Quantitative PET imaging of tissue factor expression using 18F-labeled active site inhibited factor VIIa

Objectives: Tissue factor (TF) is up regulated in many solid tumors and its expression is linked to tumor angiogenesis, invasion, metastasis and prognosis. Hence it would be of clinical relevance if one could assess tumor TF expression status non-invasively. Here we report the development of a new PET tracer for specific imaging of TF using a derivative of factor VII, the natural ligand to TF, labeled with 18F.

Methods: Active site inhibited factor VIIa (ASIS) was radiolabeled with N-succinimidyl 4-18F-fluorobenzoate ([18F]SFB) and purified. Nude mice (n=5) with subcutaneous human pancreatic xenograft tumors (BxPC-3) underwent small animal PET/CT imaging 1, 2 and 4 hours after injection of 7.3-9.3 MBq [18F]ASIS (∼37 µg) in 160 µL saline. Mice were euthanized following the last imaging session, and their tumors and major organs were resected for ex vivo gamma well counting. Tumor tissue was preserved for molecular analysis. A blocking experiment was performed in a second set of mice. The blocking group (n=3) received 500 µg non-labeled ASIS before injection of [18F]ASIS and was imaged after 4 hours. The expression pattern of TF in the tumors was visualized by immunohistochemistry and the amount of TF in tumor homogenates was measured by ELISA.

Results: The PET images showed high uptake of [18F]ASIS in the tumor regions with a mean uptake of 2.40 ±0.18, 2.56 ±0.20 and 2.54 ±0.27 %ID/g (Mean ±SEM) at 1, 2 and 4 hours after injection of [18F]ASIS and with an average maximum uptake in the tumors of 7.08 ±0.72 %ID/g at 4 hours. In comparison, the muscle uptake was 0.19 ±0.01 %ID/g at 4 hours. At 4 hours the tumors had the highest uptake of any organ. Blocking with cold ASIS significantly reduced the uptake of [18F]ASIS from 2.51 ±0.06 to 1.29 ±0.07 %ID/g (p&lt;0.001). Importantly, the uptake of [18F]ASIS measured in vivo by PET imaging correlated (r=0.72, p&lt;0.02) with TF expression at the protein level measured ex vivo in tumor homogenates by ELISA.

Conclusion: PET/CT imaging with [18F]ASIS can be used for specific, non-invasive imaging of TF expression.

Research Support: This work was supported by at grant from the Danish National Advanced Technology Foundation.

Citation Format: Carsten H. Nielsen, Maria Erlandsson, Mette M. Jensen, Jacob Madsen, Lars C. Petersen, Andreas Kjaer. Quantitative PET imaging of tissue factor expression using 18F-labeled active site inhibited factor VIIa. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4930. doi:10.1158/1538-7445.AM2014-4930

Cerebrospinal Flt3 ligand correlates to tau protein levels in primary Sjögren's syndrome

OBJECTIVES

Primary Sjögren's syndrome (pSS) is an autoimmune disease affecting the exocrine glands and internal organs including the central nervous system (CNS). The fms-related tyrosine kinase 3 ligand (Flt3L) is a maturation factor essential for brain homeostasis. Blood levels of Flt3L are increased in inflammatory diseases including the inflamed salivary glands in pSS. The present study evaluated the role of Flt3L in the CNS of patients with pSS and in two non-autoimmune conditions, fibromyalgia (FM) and Alzheimer's disease (AD).

METHOD

Levels of Flt3L were measured in cerebrospinal fluid (CSF) and serum of patients with pSS (n = 15), FM (n = 29), and AD (n = 39) and related to CNS symptoms and to markers of inflammation and degeneration.

RESULTS

Levels of CSF Flt3L in pSS and AD were significantly lower than in FM (p = 0.005 and p = 0.0003, respectively). Flt3L in pSS correlated to tau proteins [total tau (T-tau), r = 0.679; phosphorylated tau (P-tau), r = 0.646] and to a marker for microglia activation, monocyte chemoattractant protein 1 (MCP-1). Similar correlations were present in FM and AD patients. One-third of pSS patients had low levels of CSF Flt3L. This group had decreased levels of amyloid precursor protein metabolites (Aβ40 and Aβ42) in CSF, which was not seen in FM patients.

CONCLUSIONS

This study shows a strong correlation between CSF Flt3L and tau proteins in pSS patients suggesting ongoing degradation/remodelling in the CNS. In pSS patients, low levels of Flt3L were linked to changes in amyloid turnover and may represent processes similar to those in AD.

Effects of oestradiol and raloxifene on the induction and effector phases of experimental postmenopausal arthritis and secondary osteoporosis

Oestradiol and the selective oestrogen receptor modulator (SERM) raloxifene have been shown to ameliorate collagen-induced arthritis (CIA) in rats and in mice. One aim was to investigate if raloxifene exerts its anti-arthritic and anti-osteoporotic effects during the induction or effector phase of arthritis. A second aim was to analyse if raloxifene activates the oestrogen response element (ERE) to produce its immune-modulator effects. CIA or collagen-antibody-induced arthritis (CAIA) was induced in ovariectomized DBA/1-mice. CIA was used for evaluation of treatment during the induction, and CAIA for the effector phase of arthritis and osteoporosis development. Raloxifene, oestradiol or vehicle was administered 5 days/week. The clinical disease was evaluated continuously. Bone marrow density (BMD) was analysed with peripheral quantitative computer tomography, paws were collected for histological examination, and sera were analysed for markers of bone and cartilage turnover and proinflammatory cytokines. Transgenic luciferase (Luc)-ERE mice were immunized with collagen (CII), and after 10 days injected once with raloxifene, oestradiol or vehicle before termination. Spleens were analysed for luciferase activity to measure ERE activation. Treatment with oestradiol or raloxifene during the induction phase of CIA failed to affect arthritis. Raloxifene did not hamper disease activity in CAIA, whereas oestradiol delayed the onset and ameliorated the severity. Both raloxifene and oestradiol preserved BMD in CAIA. CII-immunization increased the oestradiol-induced ERE activation in spleen, and raloxifene activated the ERE at about 25% the intensity of oestradiol. Further experiments are needed to elucidate the exact mechanisms behind this finding.

Low antibiotic resistance rates in Staphylococcus aureus, Escherichia coli and Klebsiella spp but not in Enterobacter spp and Pseudomonas aeruginosa: a prospective observational study in 14 Swedish ICUs over a 5-year period

BACKGROUND

Intensive care units (ICUs) are hot zones for emergence and spread of antibiotic resistance because of frequent invasive procedures, antibiotic usage and transmission of bacteria. We report prospective data on antibiotic use and bacterial resistance from 14 academic and non-academic ICUs, participating in the ICU-STRAMA programme 1999-2003.

METHODS

The quantity of antibiotics delivered to each ICU was calculated as defined daily doses per 1,000 occupied bed days (DDD(1,000)). Specimens for culture were taken on clinical indications and only initial isolates were considered. Species-related breakpoints according to the Swedish Reference Group for Antibiotics were used. Antibiotic resistance was defined as the sum of intermediate and resistant strains.

RESULTS

Mean antibiotic use increased from 1,245 DDD(1,000) in 1999 to 1,510 DDD(1,000) in 2003 (P = 0.11 for trend). Of Staphylococcus aureus, 0-1.8% were methicillin resistant (MRSA). A presumptive extended spectrum beta-lactamase (ESBL) phenotype was found in <2.4% of Escherichia coli, based on cefotaxime susceptibility, except a peak in 2002 (4.6%). Cefotaxime resistance was found in 2.6-4.9% of Klebsiella spp. Rates of resistance among Enterobacter spp. to cefotaxime (20-33%) and among Pseudomonas aeruginosa to imipenem (22-33%) and ciprofloxacin (5-21%) showed no time trend.

CONCLUSION

MRSA and cefotaxime-resistant E. coli and Klebsiella spp strains were few despite high total antibiotic consumption. This may be the result of a slow introduction of resistant strains into the ICUs, and good infection control. The cause of imipenem and ciprofloxacin resistance in P. aeruginosa could reflect the increased consumption of these agents plus spread of resistant clones.

Modelling the effect of climate change on recovery of acidified freshwaters: relative sensitivity of individual processes in the MAGIC model

The MAGIC model was used to evaluate the relative sensitivity of several possible climate-induced effects on the recovery of soil and surface water from acidification. A common protocol was used at 14 intensively studied sites in Europe and eastern North America. The results show that several of the factors are of only minor importance (increase in pCO(2) in soil air and runoff, for example), several are important at only a few sites (seasalts at near-coastal sites, for example) and several are important at nearly all sites (increased concentrations of organic acids in soil solution and runoff, for example). In addition changes in forest growth and decomposition of soil organic matter are important at forested sites and sites at risk of nitrogen saturation. The trials suggest that in future modelling of recovery from acidification should take into account possible concurrent climate changes and focus specially on the climate-induced changes in organic acids and nitrogen retention.

Antibiotic prescription practices, consumption and bacterial resistance in a cross section of Swedish intensive care units

BACKGROUND

The purpose of this work was to study usage of antibiotics, its possible determinants, and patterns of bacterial resistance in Swedish intensive care units (ICUs).

METHODS

Prospectively collected data on species and antibiotic resistance of clinical isolates and antibiotic consumption specific to each ICU in 1999 were analyzed together with answers to a questionnaire. Antibiotic usage was measured as defined daily doses per 1000 occupied bed days (DDD1000).

RESULTS

Data were obtained for 38 ICUs providing services to a population of approximately 6 million. The median antibiotic consumption was 1257 DDD1000 (range 584-2415) and correlated with the length of stay but not with the illness severity score or the ICU category. Antibiotic consumption was higher in the ICUs lacking bedside devices for hand disinfection (2193 vs. 1214 DDD1000, p=0.05). In the ICUs with a specialist in infectious diseases responsible for antibiotic treatment the consumption pattern was different only for use of glycopeptides (58% lower usage than in other ICUs: 26 vs. 11 DDD1000,P=0.02). Only 21% of the ICUs had a written guideline on the use of antibiotics, 57% received information on antibiotic usage at least every 3 months and 22% received aggregated resistance data annually. Clinically significant antimicrobial resistance was found among Enterbacter spp. to cephalosporins and among Enterococcus spp. to ampicillin.

CONCLUSIONS

Availability of hand disinfection equipment at each bed and a specialist in infectious diseases responsible for antibiotic treatment were factors that correlated with lower antibiotic consumption in Swedish ICUs, whereas patient-related factors were not associated with antibiotic usage.

Estrogen receptor specificity for the effects of estrogen in ovariectomized mice

Estrogen exerts a variety of important physiological effects, which have been suggested to be mediated via the two known estrogen receptors (ERs), alpha and beta. Three-month-old ovariectomized mice, lacking one or both of the two estrogen receptors, were given estrogen subcutaneously (2.3 micro g/mouse per day) and the effects on different estrogen-responsive parameters, including skeletal effects, were studied. We found that estrogen increased the cortical bone dimensions in both wild-type (WT) and double ER knockout (DERKO) mice. DNA microarray analysis was performed to characterize this effect on cortical bone and it identified four genes that were regulated by estrogen in both WT and DERKO mice. The effect of estrogen on cortical bone in DERKO mice might either be due to remaining ERalpha activity or represent an ERalpha/ERbeta-independent effect. Other effects of estrogen, such as increased trabecular bone mineral density, thymic atrophy, fat reduction and increased uterine weight, were mainly ERalpha mediated.

Estrogen receptor alpha, but not estrogen receptor beta, is involved in the regulation of the OPG/RANKL (osteoprotegerin/receptor activator of NF-kappa B ligand) ratio and serum interleukin-6 in male mice

Estrogens are important for the male skeleton. Osteoprotegerin (OPG), receptor activator of NF-kappa B ligand (RANKL), interleukin-6 (IL-6), IL-1 and tumor necrosis factor alpha (TNFalpha) have been suggested to be involved in the skeletal effects of estrogen. We treated orchidectomized mice with estradiol for 2 weeks and observed a 143% increase in the trabecular bone mineral density of the distal metaphysis of femur that was associated with a decreased OPG/RANKL mRNA ratio in vertebral bone. A similar decreased OPG/RANKL ratio was also seen after estrogen treatment of ovariectomized female mice. The effect of estrogen receptor (ER) inactivation on the OPG/RANKL ratio was dissected by using intact male mice lacking ER alpha (ERKO), ER beta (BERKO) or both receptors (DERKO). The expression of OPG was increased in ERKO and DERKO but not in BERKO male mice, resulting in an increased OPG/RANKL ratio. Furthermore, serum levels of IL-6 and tartrate-resistant acid phosphatase 5b (TRAP 5b) were decreased in ERKO and DERKO, but not in BERKO male mice. These results demonstrate that ER alpha, but not ER beta, is involved in the regulation of the vertebral OPG/RANKL ratio, serum levels of IL-6 and TRAP 5b in male mice.