the case of the missing monocyte

This came across my inbox at work, and I thought it might interest some of you, as it did me:

The case of the missing monocyte

 

CHAPEL HILL, N.C. – An estimated 1.3 million people in the United States suffer from rheumatoid arthritis. The causes behind this chronic disease — which can exhibit itself as pain, swelling, stiffness, deformation, and loss of function in the joints — have eluded scientists for centuries. A new study by UNC researchers offers tantalizing glimmers about the roles of a gene called CCR2, an immune system cell called Th17 cell, and a missing monocyte. The study contributes to a better understanding of the disease mechanism and has implications to guide the clinical trial strategy, said lead researcher Peng Liu, MD, PhD, research assistant professor at the UNC Thurston Arthritis Research Center. Her team’s findings were reported online in PLoS One on Oct. 4. The mystery began several years ago when arthritis researchers zeroed in on a gene called CCR2. CCR2 is highly expressed in the joints of patients with rheumatoid arthritis, which led researchers to believe it might contribute to the disease. “Scientists thought that if you inhibited CCR2 you would have a beneficial effect,” said Liu. “But actually, the result was the opposite.” Studies revealed that suppressing CCR2 in fact cannot ameliorate joint inflammation, in some cases, it leads to disease exacerbation.Intrigued, Liu and her team used mice to investigate how CCR2 affects immune system cells. The immune system is critical because rheumatoid arthritis is an autoimmune disease, in which the immune system attacks the body’s own tissues, causing inflammation. They found the smoking gun when they looked at a type of immune cell known as Th17 cell. Arthritic mice without the CCR2 gene produced three times the amount of Th17 cells, increasing the inflammation in their joints. “We found that an enhanced Th17 cell response is responsible, at least in part, for the increased disease severity,” said Liu. Inhibiting the activities of Th17 cell, therefore, may be a promising new direction for drug treatments for rheumatoid arthritis. The team also found that a particular type of monocyte (a type of white blood cell) disappeared from certain tissues in the mice without CCR2. They hypothesize that the CCR2-expressing monocyte plays an important regulatory role, so without the monocyte, Th17 cells proliferate. “The potential link between CCR2 and the Th17 cells is the monocyte subset,” said Liu.“This subset of monocytes may have a suppressive function in autoimmune disease,” said Liu. The finding opens the door to new treatment possibilities, such as injecting this monocyte subset into patients with rheumatoid arthritis: “Finding this monocyte may be important for later development of cell-based therapy,” said Liu. Other collaborators from the UNC Thurston Arthritis Research Center include Teresa Tarrant, MD, Alan Fong, PhD, Rishi Rampersad, Christopher Vallanat, Tatiana Quintero-Matthews and Michael Weeks. Additional collaborators include Denise Esserman, PhD, from the UNC Department of Medicine and UNC Department of Biostatistics, Jennifer Clark of the UNC Department of Biostatistics and Franco Di Padova, MD and Dhavalkumar Patel, MD, PhD of the Novartis Institutes for Biomedical Research, Switzerland. For a report of the research, see: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025833. Support for the research comes from the North Carolina Translational and Clinical Science (NC TraCS) Institute, home of the UNC-Chapel Hill Clinical and Translational Science Award (CTSA); the Arthritis Foundation; and the National Heart Lung and Blood Institute.

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medical jargon: studies show anti-TNF drugs don’t raise cancer risk

There was an interesting Arthritis Today Magazine article sent to me by the Arthritis Foundation not too long ago: Several studies have found there is not statistically significant cancer risk for those who take anti-TNF medications, like Enbrel or Remicade.

This could be a big deal; even though I take a TNF-blocker (hello, Enbrel) and I’ve been on several others in the past (hi there, Humira and Remicade and Orencia) because they’re the only things I’ve found so far that make my psoriatic arthritis manageable, I was and remain aware of the potential for an increased risk of cancer. I imagine all of us on these types of drugs have that knowledge in the back of our minds, and I’m certainly aware of people who decided not to take these drugs because of that risk. It’s a choice only each of us can make.

But, perhaps, this will put some minds at ease and allow more people to get on these treatments—if that’s what they want. I know they’ve helped me, and I wouldn’t be able to do everything I do without Enbrel, as I found out last year when I went off it for just six months and quickly found myself in one of the worst flares I’ve ever experienced. So, despite the risks, I’ll take my weekly injection; even so, this will let my mind rest a bit easier.