Objective
To investigate the mechanism underlying neutrophil migration into the articular cavity in experimental arthritis and, by extension, human inflammatory synovitis.
Methods
Antigen‐induced ...arthritis (AIA) was generated in mice with methylated bovine serum albumin (mBSA). Migration assays and histologic analysis were used to evaluate neutrophil recruitment to knee joints. Levels of inflammatory mediators were measured by enzyme‐linked immunosorbent assay. Antibodies and pharmacologic inhibitors were used in vivo to determine the role of specific disease mediators. Samples of synovial tissue and synovial fluid from rheumatoid arthritis (RA) or osteoarthritis patients were evaluated for CXCL1 and CXCL5 expression.
Results
High levels of CXCL1, CXCL5, and leukotriene B4 (LTB4) were expressed in the joints of arthritic mice. Confirming their respective functional roles, repertaxin (a CXCR1/CXCR2 receptor antagonist), anti‐CXCL1 antibody, anti‐CXCL5 antibody, and MK886 (a leukotriene synthesis inhibitor) reduced mBSA‐induced neutrophil migration to knee joints. Repertaxin reduced LTB4 production in joint tissue, and neutrophil recruitment induced by CXCL1 or CXCL5 was inhibited by MK886, suggesting a sequential mechanism. Levels of both CXCL1 and CXCL5 were elevated in synovial fluid and were released in vitro by RA synovial tissues. Moreover, RA synovial fluid neutrophils stimulated with CXCL1 or CXCL5 released significant amounts of LTB4.
Conclusion
Our data implicate CXCL1, CXCL5, and LTB4, acting sequentially, in neutrophil migration in AIA. Elevated levels of CXCL1 and CXCL5 in the synovial compartment of RA patients provide robust comparative data indicating that this mechanism plays a role in inflammatory joint disease. Together, these results suggest that inhibition of CXCL1, CXCL5, or LTB4 may represent a potential therapeutic strategy in RA.
Abstract
Objective
To investigate the mechanism underlying neutrophil migration into the articular cavity in experimental arthritis and, by extension, human inflammatory synovitis.
Methods
...Antigen‐induced arthritis (AIA) was generated in mice with methylated bovine serum albumin (mBSA). Migration assays and histologic analysis were used to evaluate neutrophil recruitment to knee joints. Levels of inflammatory mediators were measured by enzyme‐linked immunosorbent assay. Antibodies and pharmacologic inhibitors were used in vivo to determine the role of specific disease mediators. Samples of synovial tissue and synovial fluid from rheumatoid arthritis (RA) or osteoarthritis patients were evaluated for CXCL1 and CXCL5 expression.
Results
High levels of CXCL1, CXCL5, and leukotriene B
4
(LTB
4
) were expressed in the joints of arthritic mice. Confirming their respective functional roles, repertaxin (a CXCR1/CXCR2 receptor antagonist), anti‐CXCL1 antibody, anti‐CXCL5 antibody, and MK886 (a leukotriene synthesis inhibitor) reduced mBSA‐induced neutrophil migration to knee joints. Repertaxin reduced LTB
4
production in joint tissue, and neutrophil recruitment induced by CXCL1 or CXCL5 was inhibited by MK886, suggesting a sequential mechanism. Levels of both CXCL1 and CXCL5 were elevated in synovial fluid and were released in vitro by RA synovial tissues. Moreover, RA synovial fluid neutrophils stimulated with CXCL1 or CXCL5 released significant amounts of LTB
4
.
Conclusion
Our data implicate CXCL1, CXCL5, and LTB
4
, acting sequentially, in neutrophil migration in AIA. Elevated levels of CXCL1 and CXCL5 in the synovial compartment of RA patients provide robust comparative data indicating that this mechanism plays a role in inflammatory joint disease. Together, these results suggest that inhibition of CXCL1, CXCL5, or LTB
4
may represent a potential therapeutic strategy in RA.
1 The Wistar Institute, 36th and Spruce Streets, Philadelphia, Pennsylvania 19104, U.S.A.
and 2 MRC Virology Unit, University of Glasgow, Church Street, Glasgow G11 5JR, U.K.
In peripheral sensory ...ganglia latently infected with herpes simplex virus type 1 (HSV-1) transcription is restricted. A set of viral latency-associated transcripts, the LATs, have been characterized by Northern blotting and in situ hybridization. These transcripts have previously been mapped to a 3 kb region of the viral genome within the repeat long region. However, transcription from adjacent regions of the genome can be detected by in situ hybridization, which cannot be detected by Northern blotting. These RNAs are termed minor LATs or m-LAT. In this study we show that in ganglia latently infected with the HSV-1 variant 1704, which is deleted in one complete copy of the LAT gene and in the promoter and 5' portion of the other copy, m-LATs are not detected by in situ hybridization. Furthermore, the levels of DNA in nervous system tissue latently infected with the parental and the 1704 variant virus are similar. Thus we propose that the sequence elements necessary for initiating transcription or stabilizing m-LATs are within the region deleted in variant 1704 that codes for the promoter and the 5' end of the LATs.
Received 29 September 1989;
accepted 7 December 1989.
Reprogramming of cellular metabolism is a key event during tumorigenesis. Despite being known for decades (Warburg effect), the molecular mechanisms regulating this switch remained unexplored. Here, ...we identify SIRT6 as a tumor suppressor that regulates aerobic glycolysis in cancer cells. Importantly, loss of SIRT6 leads to tumor formation without activation of known oncogenes, whereas transformed SIRT6-deficient cells display increased glycolysis and tumor growth, suggesting that SIRT6 plays a role in both establishment and maintenance of cancer. By using a conditional SIRT6 allele, we show that SIRT6 deletion in vivo increases the number, size, and aggressiveness of tumors. SIRT6 also functions as a regulator of ribosome metabolism by corepressing MYC transcriptional activity. Lastly, Sirt6 is selectively downregulated in several human cancers, and expression levels of SIRT6 predict prognosis and tumor-free survival rates, highlighting SIRT6 as a critical modulator of cancer metabolism. Our studies reveal SIRT6 to be a potent tumor suppressor acting to suppress cancer metabolism.
Display omitted
► SIRT6 is a tumor suppressor that regulates cancer metabolism ► SIRT6 can lead to tumor formation even in the absence of oncogene activation ► SIRT6 levels predict tumor-free survival time in human cancers ► Inhibition of glycolysis in SIRT6-deficient cells abrogates tumor formation
The loss of Sirt6 promotes the metabolic reprogramming of cancer cells by increasing aerobic glycolysis and ribosome biosynthesis.
An E. coli and K. pneumoniae phenotype resistant to piperacillin/tazobactam has recently emerged. Here, the authors show that hyperproduction of the β-lactamase driving this resistance occurs due to ...excision and reinsertion of a translocatable unit containing bla TEM-1B, creating a tandem array.
Abstract
A phenotype of
Escherichia coli
and
Klebsiella pneumoniae
, resistant to piperacillin/tazobactam (TZP) but susceptible to carbapenems and 3rd generation cephalosporins, has emerged. The ...resistance mechanism associated with this phenotype has been identified as hyperproduction of the β-lactamase TEM. However, the mechanism of hyperproduction due to gene amplification is not well understood. Here, we report a mechanism of gene amplification due to a translocatable unit (TU) excising from an IS
26
-flanked pseudo-compound transposon, PTn
6762
, which harbours
bla
TEM-1B
. The TU re-inserts into the chromosome adjacent to IS
26
and forms a tandem array of TUs, which increases the copy number of
bla
TEM-1B,
leading to TEM-1B hyperproduction and TZP resistance. Despite a significant increase in
bla
TEM-1B
copy number, the TZP-resistant isolate does not incur a fitness cost compared to the TZP-susceptible ancestor. This mechanism of amplification of
bla
TEM-1B
is an important consideration when using genomic data to predict susceptibility to TZP.
The Genome of the Kinetoplastid Parasite, Leishmania major Ivens, Alasdair C.; Peacock, Christopher S.; Worthey, Elizabeth A. ...
Science (American Association for the Advancement of Science),
07/2005, Letnik:
309, Številka:
5733
Journal Article
Recenzirano
Odprti dostop
Leishmania species cause a spectrum of human diseases in tropical and subtropical regions of the world. We have sequenced the 36 chromosomes of the 32.8-megabase haploid genome of Leishmania major ...(Friedlin strain) and predict 911 RNA genes, 39 pseudogenes, and 8272 protein-coding genes, of which 36% can be ascribed a putative function. These include genes involved in host-pathogen interactions, such as proteolytic enzymes, and extensive machinery for synthesis of complex surface glycoconjugates. The organization of protein-coding genes into long, strand-specific, polycistronic clusters and lack of general transcription factors in the L. major, Trypanosoma brucei, and Trypanosoma cruzi (Tritryp) genomes suggest that the mechanisms regulating RNA polymerase II-directed transcription are distinct from those operating in other eukaryotes, although the trypanosomatids appear capable of chromatin remodeling. Abundant RNA-binding proteins are encoded in the Tritryp genomes, consistent with active posttranscriptional regulation of gene expression.
IMPORTANCE: Within 2 decades of onset, 80% of untreated patients with relapsing-remitting multiple sclerosis (MS) convert to a phase of irreversible disability accrual termed secondary progressive ...MS. The association between disease-modifying treatments (DMTs), and this conversion has rarely been studied and never using a validated definition. OBJECTIVE: To determine the association between the use, the type of, and the timing of DMTs with the risk of conversion to secondary progressive MS diagnosed with a validated definition. DESIGN, SETTING, AND PARTICIPANTS: Cohort study with prospective data from 68 neurology centers in 21 countries examining patients with relapsing-remitting MS commencing DMTs (or clinical monitoring) between 1988-2012 with minimum 4 years’ follow-up. EXPOSURES: The use, type, and timing of the following DMTs: interferon beta, glatiramer acetate, fingolimod, natalizumab, or alemtuzumab. After propensity-score matching, 1555 patients were included (last follow-up, February 14, 2017). MAIN OUTCOME AND MEASURE: Conversion to objectively defined secondary progressive MS. RESULTS: Of the 1555 patients, 1123 were female (mean baseline age, 35 years SD, 10). Patients initially treated with glatiramer acetate or interferon beta had a lower hazard of conversion to secondary progressive MS than matched untreated patients (HR, 0.71; 95% CI, 0.61-0.81; P < .001; 5-year absolute risk, 12% 49 of 407 vs 27% 58 of 213; median follow-up, 7.6 years IQR, 5.8-9.6), as did fingolimod (HR, 0.37; 95% CI, 0.22-0.62; P < .001; 5-year absolute risk, 7% 6 of 85 vs 32% 56 of 174; median follow-up, 4.5 years IQR, 4.3-5.1); natalizumab (HR, 0.61; 95% CI, 0.43-0.86; P = .005; 5-year absolute risk, 19% 16 of 82 vs 38% 62 of 164; median follow-up, 4.9 years IQR, 4.4-5.8); and alemtuzumab (HR, 0.52; 95% CI, 0.32-0.85; P = .009; 5-year absolute risk, 10% 4 of 44 vs 25% 23 of 92; median follow-up, 7.4 years IQR, 6.0-8.6). Initial treatment with fingolimod, alemtuzumab, or natalizumab was associated with a lower risk of conversion than initial treatment with glatiramer acetate or interferon beta (HR, 0.66; 95% CI, 0.44-0.99; P = .046); 5-year absolute risk, 7% 16 of 235 vs 12% 46 of 380; median follow-up, 5.8 years IQR, 4.7-8.0). The probability of conversion was lower when glatiramer acetate or interferon beta was started within 5 years of disease onset vs later (HR, 0.77; 95% CI, 0.61-0.98; P = .03; 5-year absolute risk, 3% 4 of 120 vs 6% 2 of 38; median follow-up, 13.4 years IQR, 11-18.1). When glatiramer acetate or interferon beta were escalated to fingolimod, alemtuzumab, or natalizumab within 5 years vs later, the HR was 0.76 (95% CI, 0.66-0.88; P < .001; 5-year absolute risk, 8% 25 of 307 vs 14% 46 of 331, median follow-up, 5.3 years IQR, 4.6-6.1). CONCLUSIONS AND RELEVANCE: Among patients with relapsing-remitting MS, initial treatment with fingolimod, alemtuzumab, or natalizumab was associated with a lower risk of conversion to secondary progressive MS vs initial treatment with glatiramer acetate or interferon beta. These findings, considered along with these therapies’ risks, may help inform decisions about DMT selection.
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