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Posts Tagged ‘Chemokine receptor’


Are CXCR4 Antagonists Making a Comeback in Cancer Chemotherapy?

Reporter: Stephen J. Williams, Ph.D.

Biospace News reported that Massachusetts based X4 Pharmaceuticals is using $34B to launch two clinical trials on its CXCR4 inhibitor X4P-001 in refractory clear cell renal cell carcinoma and refractory epithelial ovarian cancer.

The full report is below:

X4 Pharma Uses $37.5 Million to Push Cancer Therapies into Human Trials

 

December 14, 2015
By Alex Keown, BioSpace.com Breaking News Staff

CAMBRIDGE, Mass. – Massachusetts based X4 Pharmaceuticals is beginning human trials for its oncology program using CXCR4 inhibitors, the Boston Business Journal reported this morning.

After spending years in stealth mode, the company, helmed by former Genzyme executives, is launching two clinical two clinical studies initiating in 2016 in refractory clear cell renal cell carcinoma and refractory epithelial ovarian cancer with its lead drug candidate, X4P-001.

The company’s pipeline is based on drug compounds that originate from a portfolio of oral CXCR4 inhibitors exclusively licensed from Sanofi (SNY), X4 said in a statement. Inhibition of CXCR4, a receptor over-expressed in many cancers, is designed to block non-cancerous immuno-suppressive and pro-angiogenic cells from populating the tumor, thereby disrupting the cancer microenvironment and restoring normal immune surveillance functions. The novel mechanism of CXCR4 inhibition increases the ability of T-Cells to track and destroy cancer. X4 is leveraging its CXCR4 research against past experience working with Genzyme’s plerixafor, which is also a CXCR4 blocker.

In an interview with the Journal, Paula Ragan, X4’s chief executive officer, said the CXCR4 protein “acts as a beacon to attract cells to surround a tumor, effectively hiding the tumor from the body’s T cells that would otherwise destroy them.” Developing a therapy to block the protein will prevent the tumors from hiding and allow it to be treated.

Ragan said the Phase Ia trial for X4P-001 will test safety and dosage in a small trial of about 20 people, the Journal reported. If all goes well the company would start a Phase 2a trial by the end of 2016 in around 50 or 60 patients, the Journal said.

In September, Ragan said a CXCR4 antagonist could potentially be paired with promising oncology drugs like Merck & Co. (MRK)’s Keytruda, or Bristol-Myers Squibb (BMY)’s Opdivo. Keytruda has been shown to be effective in treating patients with three types of cancer, melanoma, lung cancer and mesothelioma. Opdivo is a treatment of patients with metastatic squamous non-small cell lung cancer (NSCLC) with progression on or after platinum-based chemotherapy.

The cytokines and cytokine receptors have been investigated before for their utility as a chemotherapeutic target as they are highly expressed on tumors and promote metastasis. The general idea was that tumor cells secrete cytokines which promote their growth and metastases and attract immune cells which also secrete growth-promoting cytokines. Many tumor types have shown increased expression of these cytokines and cytokine receptors. However only some development efforts have shown promise, there have been no approved drugs in this class. As written in a previous post (Tumor Associated Macrophages: The Double-Edged Sword Resolved?), there could be many biological reasons for this, as well as difficulties in interpreting preclinical results in immunocompromised mice.

CXCR4: from the review by Ori Wald, Oz M. Shapira, Uzi Izha

 

Source: Wald O, Shapira OM, Izhar U. CXCR4/CXCL12 Axis in Non Small Cell Lung Cancer (NSCLC) Pathologic Roles and Therapeutic Potential. Theranostics 2013; 3(1):26-33. doi:10.7150/thno.4922. Available from http://www.thno.org/v03p0026.htm

 

Chemokines, a family of 48 chemotactic cytokines interact with their 7 transmembrane G-protein-coupled receptors to guide immune cell trafficking in the body under both physiologic and pathologic conditions (20, 21). Tumor cells, which express a relatively restricted repertoire of chemokine and chemokine receptors, utilize and manipulate the chemokine system in a manner that benefits both local tumor growth and distant dissemination (20, 22, 23). In the tumor microenvironment autocrine and paracrine chamokine/chemokine receptor loops interact to promote tumor cell survival and growth, and also to enhance tumor neo-angiogenesis (20, 22, 23). At distant sites, it is the tissue-produced chemokine which guide/attracts the metastasis of chemokine receptor expressing tumor cells (20).

Among the 19 chemokine receptors, CXCR4 is the receptor most widely expressed by malignant tumors and whose role in tumor biology is most thoroughly studied (20). The chemokine CXCL12 is the sole ligand of CXCR4 and the majority of research that focus on the role of CXCR4 in cancer relates to this chemokine/chemokine receptor pair (24, 25). Nevertheless, in 2006 another receptor for CXCL12 was identified and named CXCR7 (26). CXCR7 is expressed during embriogenesis, angiogenesis and in various malignant tissues including NSCLC. CXCR7 is thought to act in part as a scavenger of CXCL12 however additional functions for this receptor have also been reported (2628). In distinct form CXCR4, CXCR7 binds not only CXCL12 but also the chemokine CXCL11 (26, 27). Moreover, the signaling cascades that are generated upon binding of CXCL12 to CXCR4 or CXCR7 vary at least partly, depending on which of the receptors is engaged (26, 27). This review focuses mainly on data collected regarding the expression and function of CXCR4 in NSCLC, nevertheless it is important to keep in mind that whenever CXCL12 is mentioned the effects related to its expression may be attributed in part to CXCR7 expression and function.

Relative to normal cells in the tumor’s tissue of origin, malignant cells often over express CXCR4, this phenotype can be induced by multiple oncogenic alternations and appears to promote tumor cell survival, proliferation, invasion and metastasis (20, 2935).

 

 

 

cxcrimagetumorncls

Potential roles for CXCR4/CXCL12 in NSCLC. NSCLC tumor cells express CXCR4 and produce CXCL12. Tumor expressed CXCR4 guides metastatic spread to sights such as the brain, bone marrow and liver that express high levels of CXCL12. In addition, CXCR4/CXCL12 interactions act locally in autocrine and paracrine manners to enhance primary tumor growth and to alter its inflammatory milieu. Tumor and tumor microenvironment secreted CXCL12 enhance tumor cell survival and growth and may also guide trafficking of immune and bone marrow derived cells into the tumor microenvironment. Furthermore, alternations in the tumor microenvironment result from the stimulation of tumor cells with CXCL12 that in turn enhance the production of additional chemokines such as the pro-inflammatory and pro-proliferative chemokine CCL20) pro-angiogenic and pro-proliferative chemokine (CXCL1 – IL-8). Figure from Wald O, Shapira OM, Izhar U. CXCR4/CXCL12 Axis in Non Small Cell Lung Cancer (NSCLC) Pathologic Roles and Therapeutic Potential. Theranostics 2013; 3(1):26-33. doi:10.7150/thno.4922. Available from http://www.thno.org/v03p0026.htm

For further reference on CXCR4 and development of CXCR4 inhibitors please see the following references:

  1. Peled A, Wald O, Burger J. Development of novel CXCR4-based therapeutics. Expert Opin Investig Drugs. 2012Mar;21(3):341-53
  2. Balkwill FR. The chemokine system and cancer. J Pathol. 2012Jan;226(2):148-57
  3. Burger JA, Kipps TJ. CXCR4: a key receptor in the crosstalk between tumor cells and their microenvironment. Blood. 2006Mar1;107(5):1761-7
  4. Burger JA, Peled A. CXCR4 antagonists: targeting the microenvironment in leukemia and other cancers. Leukemia. 2009Jan;23(1):43-52
  5. Otsuka S, Bebb G. The CXCR4/SDF-1 chemokine receptor axis: a new target therapeutic for non-small cell lung cancer. J Thorac Oncol. 2008Dec;3(12):1379-83

 

Current CXCR4 inhibitors in development

somecxcr4inhibitors

Figure. Structures of Representative Small Molecule CXCR4 Antagonists and CXCL12 Inhibitors. From JJ Zariek et al. Fragment-Based Optimization of Small Molecule CXCL12 Inhibitors for Antagonizing the CXCL12/CXCR4 Interaction. Curr Top Med Chem. 2012; 12(24): 2727–2740.

 

A Phase 1 Trial of LY2510924, a CXCR4 Peptide Antagonist, in Patients with Advanced Cancer

This manuscript reports the results of a phase I study designed to evaluate the safety and tolerability of the C-X-C motif receptor 4 (CXCR4) inhibitor LY2510924 in patients with advanced cancer. LY2510924 is a peptide antagonist, which blocks stromal cell-derived factor-1 (SDF-1) from CXCR4 binding. CXCR4 is often overexpressed in many cancers and involved in the metastasis of solid tumors. LY2510924 was tolerated with mostly Grade 1/2 adverse events, revealed favorable pharmacokinetics, and demonstrated evidence of target engagement as indicated by dose dependent increases in CD34+ cells.

Anti-CXCR4 (BMS-936564) Alone and in Combination With Lenalidomide/Dexamethasone or Bortezomib/Dexamethasone in Relapsed/Refractory Multiple Myeloma

The purpose of this study is to determine 1) the safety and tolerability of multiple intravenous doses of anti-CXCR4 (BMS-936564) as monotherapy and as combination, and 2) the maximum tolerated dose (MTD) of BMS-936564 in combination with Lenalidomide/Dexamethasone or Bortezomib/Dexamethasone in subjects with relapsed or refractory multiple myeloma.

 

Novel CXCR4 Antagonist BL-8040 Enters Clinical Testing for CML – See more at: http://www.cancernetwork.com/chronic-myeloid-leukemia/novel-cxcr4-antagonist-enters-clinical-testing-cml#sthash.RoXCC5W6.dpuf

 

Other posts on this Open Access Journal on CXCR4 and Chemokines in Cancer Include

Assessing effects of antimetastatic treatment

Understanding the Stem Cell Niche: A Webinar by The Scientist

Protein regulator of HIV replication

Immunotherapy in Cancer: A Series of Twelve Articles in the Frontier of Oncology by Larry H Bernstein, MD, FCAP

Humanized Mice May Revolutionize Cancer Drug Discovery

Tumor Associated Macrophages: The Double-Edged Sword Resolved?

 

 

 

 

 

 

 

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Understanding the Stem Cell Niche: A Webinar by The Scientist

Reporter: Stephen J. Williams, Ph.D.

 

The Scientist

nature stem cell

Schematic diagram showing some of the factors implicated in each process. Haematopoietic stem cells (HSCs) bound to the bone-marrow niche are mobilized in response to granulocyte colony-stimulating factor (G-CSF) or cyclophosphamide, or after peripheral myeloablation following treatment with 5-fluorouracil (5-FU). After extravasation from the bone-marrow cords into the microvasculature, HSCs enter the circulation and are distributed to peripheral tissues such as the spleen or liver. HSCs locate close to endothelial cells in the splenic red pulp. They home to the bone-marrow cords through the circulation, a process that is controlled by a number of adhesion molecules such as very late antigen 4 (VLA4), VLA5, lymphocyte function-associated antigen 1 (LFA1) or selectins. After entering the bone marrow, HSCs specifically lodge in the niche, a process requiring membrane-bound stem-cell factor (SCF), CXC-chemokine ligand 12 (CXCL12), osteopontin (OPN), hyaluronic acid, and their corresponding receptors. CXCR4, CXC-chemokine receptor 4; E-selectin, endothelial-cell selectin; P-selectin, platelet selectin; PSGL1, P-selectin glycoprotein ligand 1.

 

Understanding the Stem Cell Niche

  This presentation will begin on Tuesday, December 01, 2015 at 02:30 PM Eastern Standard Time.
   

Free Webinar
Tuesday December 1, 2015
2:30 – 4:00 PM EST

Stem cells provide an attractive model to study human physiology and disease. However, technical challenges persist in the biological characterization and manipulation of stem cells in their native microenvironment. The Scientist brings together a panel of experts to discuss interactions between stem cells and external cues, and the role of the stem cell niche in development and disease. Topics to be covered include the molecular mechanisms of hematopoietic stem cell niche interactions and techniques for engineering 3-D stem-cell microenvironments. Following the presentations, attendees will have an opportunity to ask questions concerning their specific applications and receive answers in real-time.

Speakers:

Dr. Jon Hoggatt, Assistant Professor of Medicine, Cancer Center and Center for Transplantation Sciences, Harvard Medical School/Massachusetts General Hospital.

Dr. Todd McDevitt, Senior Investigator, Gladstone Institute of Cardiovascular Disease, Professor, Department of Bioengineering & Therapeutic Sciences, UCSF.

 

Understanding the Stem Cell Niche
Click Here To Watch The Video

To find out about our upcoming events follow us on Twitter @LabMgrEvents

 

Notes from Webinar:

Hematopoetic stem cells good model since now we have liquid biopsies (as a result field has skyrocketed).

Two processes involved with stem cells finding their niche

  1. Homing; CXCR4-SDK1 dependent process into the bone marrow.
  2. Mobilization: stem cells moving from bone into blood (found that GMCSF main factor responsible for this process)

Dr. Raymond Schofield was one of the first to propose the existence of this stem cell niche (each progenitor will produce a unique factor {possibly a therapeutic target} for example leptin+ receptor target perivascular cells so one target is good for only a small subset of stem cells)

Therefore it may be possible or advantageous to target the whole stem cell milieu. One such possible target they are investigating is CD26 (dipeptyl peptidase). The diabetes drug Januvia is an inhibitor of CD26.

It was also noticed if inhibit the GMCSF receptor complex can inhibit the whole stem cell niche.

Prostoglandins and stem cell niche

  • Indomethacin blocks the mobilization step
  • Prostaglandin E increases homing
  • GMCSF and malaxocam (COX2 inhibitor) flattens osteoblast cells and may be a mechanism how inhibition of prostaglandin synthesis blocks mobilization
  • Found that the PGE4 receptor is ultimately responsible for the NSAID effect

The niche after G-CSF

Dr. Hoggat found that macrophages are supplying the factors that support the niche. He will be presenting the findings at 2015 Hematology conference. (See information about his conference presentation here).

From the 57th Annual American Society of Hematology Meeting (2015) please see Dr. Hoggat’s moderated section Hematopoiesis and Stem Cells: Microenvironment, Cell Adhesion and Stromal Stem Cells: Hematopoietic Stem Cell Niche

 

Relevant articles from Dr. Hoggat

Anti-CD47 Therapy Is More Than a Dinner Bell October 19, 2015

Dr. Hoggatt looks at the therapeutic effects of blocking CD47 aside from alerting macrophages to devour tumor cells.

Hematopoietic Stem Cells Should Hold Their Breath August 12, 2015

Dr. Hoggatt and Hannah Rasmussen discuss new approaches to the use of hematopoietic stem cells considering observer effects that emerge due to our experimental systems for HSCs.

Prostaglandin E2 enhances hematopoietic stem cell homing, survival, and proliferation. Hoggatt J, Singh P, Sampath J, Pelus LM. Blood. 2009 May 28;113(22):5444-55. doi: 10.1182/blood-2009-01-201335. Epub 2009 Mar 26.

 

Prostaglandin E2 enhances long-term repopulation but does not permanently alter inherent stem cell competitiveness. Hoggatt J, Mohammad KS, Singh P, Pelus LM. Blood. 2013 Oct 24;122(17):2997-3000. doi: 10.1182/blood-2013-07-515288. Epub 2013 Sep 18.

 

Pharmacologic increase in HIF1α enhances hematopoietic stem and progenitor homing and engraftment. Speth JM, Hoggatt J, Singh P, Pelus LM. Blood. 2014 Jan 9;123(2):203-7. doi: 10.1182/blood-2013-07-516336. Epub 2013 Oct 28.

 

Blockade of prostaglandin E2 signaling through EP1 and EP3 receptors attenuates Flt3L-dependent dendritic cell development from hematopoietic progenitor cells. Singh P, Hoggatt J, Hu P, Speth JM, Fukuda S, Breyer RM, Pelus LM. Blood. 2012 Feb 16;119(7):1671-82. doi: 10.1182/blood-2011-03-342428. Epub 2011 Nov 22.

 

Recovery from hematopoietic injury by modulating prostaglandin E(2) signaling post-irradiation. Hoggatt J, Singh P, Stilger KN, Plett PA, Sampson CH, Chua HL, Orschell CM, Pelus LM. Blood Cells Mol Dis. 2013 Mar;50(3):147-53. doi: 10.1016/j.bcmd.2012.11.006. Epub 2012 Nov 30.

 

Pulse exposure of haematopoietic grafts to prostaglandin E2 in vitro facilitates engraftment and recovery. Pelus LM, Hoggatt J, Singh P. Cell Prolif. 2011 Apr;44 Suppl 1:22-9. doi: 10.1111/j.1365-2184.2010.00726.x.

 

Pleiotropic effects of prostaglandin E2 in hematopoiesis; prostaglandin E2 and other eicosanoids regulate hematopoietic stem and progenitor cell function. Pelus LM, Hoggatt J. Prostaglandins Other Lipid Mediat. 2011 Nov;96(1-4):3-9. doi: 10.1016/j.prostaglandins.2011.06.004. Epub 2011 Jun 21. Review.

 

Differential stem- and progenitor-cell trafficking by prostaglandin E2. Hoggatt J, Mohammad KS, Singh P, Hoggatt AF, Chitteti BR, Speth JM, Hu P, Poteat BA, Stilger KN, Ferraro F, Silberstein L, Wong FK, Farag SS, Czader M, Milne GL, Breyer RM, Serezani CH, Scadden DT, Guise TA, Srour EF, Pelus LM. Nature. 2013 Mar 21;495(7441):365-9. doi: 10.1038/nature11929. Epub 2013 Mar 13.

 

Eicosanoid regulation of hematopoiesis and hematopoietic stem and progenitor trafficking.Hoggatt J, Pelus LM. Leukemia. 2010 Dec;24(12):1993-2002. doi: 10.1038/leu.2010.216. Epub 2010 Sep 30. Review.

 

Hematopoietic stem cell mobilization with agents other than G-CSF. Hoggatt J, Pelus LM. Methods Mol Biol. 2012;904:49-67. doi: 10.1007/978-1-61779-943-3_4.

 

Mobilization of hematopoietic stem cells from the bone marrow niche to the blood compartment. Hoggatt J, Pelus LM. Stem Cell Res Ther. 2011 Mar 14;2(2):13. doi: 10.1186/scrt54. Review.

 

Engineering 3D Pluripotent Stem Cell Microenvironments by Todd McDevitt, Ph.D.

In recent years, it has finally been shown how to produce centrally derived (self assembling) organoids (microtissues).

 

How to specifically deliver specific morphogens in 3D organoids

 

  1. Microparticle (MP)-mediated delivery (can do in mouse and human): reduces the amount needed to be delivered

 

 

What are other effects of introduced MP in ES (embryonic stem cell) aggregates?

  1. a) physiocomechanical changes –mechanical effects of materials
  2. b) how changes in local presentation of factors affect bioavailbility and binding properties

 

 

 

 

 

 

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Introduction to Signaling

Curator: Larry H. Bernstein, MD, FCAP

 

We have laid down a basic structure and foundation for the remaining presentations.  It was essential to begin with the genome, which changed the course of teaching of biology and medicine in the 20th century, and introduced a central dogma of translation by transcription.  Nevertheless, there were significant inconsistencies and unanswered questions entering the twenty first century, accompanied by vast improvements in technical advances to clarify these issues. We have covered carbohydrate, protein, and lipid metabolism, which function in concert with the development of cellular structure, organ system development, and physiology.  To be sure, the progress in the study of the microscopic and particulate can’t be divorced from the observation of the whole.  We were left in the not so distant past with the impression of the Sufi story of the elephant and the three blind men, who one at a time held the tail, the trunk, and the ear, each proclaiming that it was the elephant.

I introduce here a story from the Brazilian biochemist, Jose

Eduardo des Salles Rosalino, on a formativr experience he had with the Nobelist, Luis Leloir.

Just at the beginning, when phosphorylation of proteins is presented, I assume you must mention that some proteins are activated by phosphorylation. This is fundamental in order to present self –organization reflex upon fast regulatory mechanisms. Even from an historical point of view. The first observation arrived from a sample due to be studied on the following day of glycogen synthetase. It was unintended left overnight out of the refrigerator. The result was it has changed from active form of the previous day to a non-active form. The story could have being finished here, if the researcher did not decide to spent this day increasing substrate levels (it could be a simple case of denaturation of proteins that changes its conformation despite the same order of amino acids). He kept on trying and found restoration of maximal activity. This assay was repeated with glycogen phosphorylase and the result was the opposite – it increases its activity. This led to the discovery

  • of cAMP activated protein kinase and
  • the assembly of a very complex system in the glycogen granule
  • that is not a simple carbohydrate polymer.

Instead, it has several proteins assembled and

  • preserves the capacity to receive from a single event (rise in cAMP)
  • two opposing signals with maximal efficiency,
  • stops glycogen synthesis,
  • as long as levels of glucose 6 phosphate are low
  • and increases glycogen phosphorylation as long as AMP levels are high).

I did everything I was able to do by the end of 1970 in order to repeat the assays with PK I, PKII and PKIII of M. Rouxii and using the Sutherland route to cAMP failed in this case. I then asked Leloir to suggest to my chief (SP) the idea of AA, AB, BB subunits as was observed in lactic dehydrogenase (tetramer) indicating this as his idea. The reason was my “chief”(SP) more than once, had said to me: “Leave these great ideas for the Houssay, Leloir etc…We must do our career with small things.” However, as she also had a faulty ability for recollection she also used to arrive some time later, with the very same idea but in that case, as her idea.
Leloir, said to me: I will not offer your interpretation to her as mine. I think it is not phosphorylation, however I think it is glycosylation that explains the changes in the isoenzymes with the same molecular weight preserved. This dialogue explains why during the reading and discussing “What is life” with him he asked me if as a biochemist in exile, talking to another biochemist, I expressed myself fully. I had considered that Schrödinger would not have confronted Darlington & Haldane because he was in U.K. in exile. This might explain why Leloir could have answered a bad telephone call from P. Boyer, Editor of The Enzymes, in a way that suggested that the pattern could be of covalent changes over a protein. Our FEBS and Eur J. Biochemistry papers on pyruvate kinase of M. Rouxii is wrongly quoted in this way on his review about pyruvate kinase of that year (1971).

 

Another aspect I think you must call attention to the following. Show in detail with different colors what carbons belongs to CoA, a huge molecule in comparison with the single two carbons of acetate that will produce the enormous jump in energy yield

  • in comparison with anaerobic glycolysis.

The idea is

  • how much must have been spent in DNA sequences to build that molecule in order to use only two atoms of carbon.

Very limited aspects of biology could be explained in this way. In case we follow an alternative way of thinking, it becomes clearer that proteins were made more stable by interaction with other molecules (great and small). Afterwards, it’s rather easy to understand how the stability of protein-RNA complexes where transmitted to RNA (vibrational +solvational reactivity stability pair of conformational energy).

Millions of years later, or as soon as, the information of interaction leading to activity and regulation could be found in RNA, proteins like reverse transcriptase move this information to a more stable form (DNA). In this way it is easier to understand the use of CoA to make two carbon molecules more reactive.

The discussions that follow are concerned with protein interactions and signaling.

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Approach to Controlling Pathogenic Inflammation in Arthritis

Curator: Larry H Bernstein, MD, FCAP

A network approach to controlling pathogenic inflammation: Sequence sharing pattern peptides downregulate experimental arthritis

a new approach to network regulation of inflammation based on

Chai Ezerzer, Raanan Margalit and Irun R. Cohen

Aberrant inflammation probably results from aberrant regulation of the molecules that mediate inflammation; the actual molecules mediating inflammation –

  • chemokines,
  • cytokines, and
  • growth factors and their receptors –
    • would appear to be normal in their chemical structure.

If faulty regulation is indeed the problem,

  • a reasonable approach to alleviating inflammatory diseases might be to influence the interactions
  • within the network of connectivity of the disease-associated proteins (DAPs).
Aberrant inflammation appears to be a pathogenic factor in autoimmune diseases and other noxious inflammatory
conditions in which the inflammatory process
  1. is misapplied,
  2. exaggerated,
  3. recurrent or chronic.
The protein molecules involved in pathogenic inflammation—
disease-associated proteins (DAP )
  1. chemokines,
  2. cytokines, and
  3. growth factors and their receptors,
  • appear normal; their networks of interaction are at fault.

These researchers asked the question – 

  • whether shared amino acid sequence motifs among DAPs
  • might identify novel peptide treatments for regulating inflammation.

We aligned the sequences of 37 DAPs previously discovered to be associated with arthritis

  • to uncover shared sequence motifs.

We focused on chemokine receptor molecules because

  • chemokines and chemokine receptors play important roles in directing the migration of inflammatory cells into sites of tissue inflammation.
  •  different chemokine receptors shared amino acid sequence motifs in their extra-cellular loop domains (ECL2);
  • the ECL2 loop is outside of the known ligand binding site.

These shared sequence motifs established what we term a sequence-sharing network (SSN). SSN motifs exhibited very low E-values,

  • indicating their preservation during evolution.
This study demonstrates a new
  • approach to network regulation of inflammation based on peptide sequence motifs
  • shared by the second extra-cellular loop (EC L2) of different chemokine receptors;
  • previously known chemokine receptor binding sites have not involved the EC L2 loop.
These motifs of 9 amino acids, which were detected by sequence alignment, manifest very low E-values
  • compared with slightly modified sequence variations,
  • indicating that they were not likely to have evolved by chance.
To test whether this shared sequence network (SSN) might serve a regulatory function,
  • theysynthesized 9-amino acid SSN peptides from the EC L2 loops of three different chemokine receptors.
Theye administered these peptides to rats during the
Two of the peptides significantly downregulated the arthritis; one of the peptides
  • synergized with non-specific anti-inflammatory treatment with dexamethasone.
These findings suggest that
  • the SSN peptide motif reported here is likely to have adaptive value in controlling inflammation.
  • detection of SSN motif peptides could provide a network-based approach to immune modulation.
administering a highly connected chemokine receptor peptide motif , as done here, induced
  • the downregulation of inflammation in a rat model of arthritis.
Thus, study of the SSN provides a new network approach toward modulating inflammation
English: Typical chemokine receptor structure ...

English: Typical chemokine receptor structure showing seven transmembrane domains and a chanracteristic “DRY” motif in the second intracelluar domain. (Photo credit: Wikipedia)

Structure of Chemokines

Structure of Chemokines (Photo credit: Wikipedia)

Chemokine receptor

Chemokine receptor (Photo credit: Wikipedia)

 

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