Biosignatures distinguish between tuberculosis and sarcoidosis

May 7, 2012 in Diseases, Conditions, Syndromes

With a range of diseases, doctors need unique features which they can use to unequivocally identify a patient's illness for an appropriate diagnosis. Scientists therefore search for the biomarkers for an illness or a combination of biomarkers, known as biosignatures, which are as easy as possible to measure. Researchers at the Max Planck Institute for Infection Biology in Berlin have now created complete gene and microRNA expression profiles together with important inflammatory mediators in the blood of tuberculosis and sarcoidosis patients. Although they have identified a signature that distinguishes healthy individuals from patients, the biosignatures of both diseases are nevertheless very similar. It is almost impossible, therefore, to distinguish between tuberculosis and sarcoidosis with just a single signature. A set of different biosignatures is better suited for distinguishing in a first step between diseased and healthy individuals and, in a further step, between the specific diseases.

Biosignatures cover a profile of different features, which can be used to identify diseases and distinguish them from similar clinical pictures. These features include the presence of mediators and gene expression profiles in the blood. In recent years, for example, researchers have discovered signatures for tuberculosis, which doctors can use to distinguish between patients with tuberculosis and healthy individuals.

Equally important is the distinction between different diseases with similar clinical appearance, such as tuberculosis and . Therefore, using gene and microRNA expression in and in , the scientists at the Max Planck Institute for Infection Biology selected sets of markers characteristic for tuberculosis and sarcoidosis patients. Although both diseases primarily damage the lungs and produce similar symptoms, they have very different causes. While tuberculosis is caused by an infection with , sarcoidosis is not contagious.

Studies show that the two diseases are not only similar clinically; their biosignatures also have a number of elements in common. Compared to healthy individuals, most genes in sarcoidosis and tuberculosis patients are regulated in a similar way: "Of approximately 13,000 genes whose expression differs, depending on whether the individual is healthy or diseased, approximately 9,000 genes are expressed in the same way in both diseases. Only 700 genes differ in their expression between tuberculosis and sarcoidosis patients – but these can be used to unequivocally identify the two diseases," says Stefan Kaufmann from the Max Planck Institute for Infection Biology.

In addition, microRNAs, which modulate the formation of certain proteins by inhibiting gene expression, appear in a similar pattern in both diseases. In total, around 150 microRNAs shared by both diseases differed from healthy individuals. Only four microRNAs are suitable for distinguishing tuberculosis and sarcoidosis patients. The overlap is less pronounced in the profile of inflammatory substances in the blood: while only one of these cytokines is modified equally in tuberculosis and sarcoidosis compared to healthy individuals, twelve of these signal mediators are suitable for distinguishing between the two diseases.

The results obtained by the Berlin researchers show that modified can be traced back to processes that occur not only in one specific disease, e.g. immune responses. The immune response therefore draws on the same basic elements in different clinical pictures, and only a few of these elements are specific to a particular disease. These commonalities also reveal a lot to scientists about the general causes and mechanisms underlying many diseases.

A single biosignature is therefore not enough to distinguish between healthy and diseased individuals, and to distinguish between different diseases with a similar clinical phenotype. Although the combination of many genes increases specificity and sensitivity in distinguishing between healthy and diseased individuals, it automatically leads to a lower specificity compared to other clinical pictures. "Instead, we should first of all distinguish between healthy and diseased individuals and then separate the individual diseases from one another in the next steps. We can then unequivocally identify a using a handful of genes per step," explains Kaufmann.

This means that doctors could concentrate on diseases that actually occur locally. In African countries, where tuberculosis is widespread, it would then be possible to identify , AIDS and malaria quickly.

More information: Common patterns and disease-related signatures in tuberculosis and sarcoidosis. Jeroen Maertzdorf, January Weiner, Hans-Joachim Mollenkopf, TBornotTB Network, Torsten Bauer, Antje Prasse, Joachim Müller-Quernheim and Stefan H. E. Kaufmann, PNAS, May 2, 2012. www.pnas.org/cgi/d… s.1121072109

Journal reference: Proceedings of the National Academy of Sciences search and more info website

Provided by Max Planck Society search and more info website

not rated yet  

Rank not rated yet
Relevant PhysicsForums posts

More news stories

New research identifies practice changes to improve value and quality of GI procedures

There are significant cost and risk factors associated with two procedures commonly used to diagnose or treat gastrointestinal problems, according to research presented at Digestive Disease Week (DDW).

Diseases, Conditions, Syndromes created 4 hours ago | popularity not rated yet | comments 0

Consuming coffee linked to lower risk of detrimental liver disease, study finds

Regular consumption of coffee is associated with a reduced risk of primary sclerosing cholangitis (PSC), an autoimmune liver disease, Mayo Clinic research shows. The findings were being presented at the Digestive Disease ...

Diseases, Conditions, Syndromes created 4 hours ago | popularity not rated yet | comments 0 | with audio podcast

New case of SARS-like virus in Saudi: ministry

A new case of the deadly coronavirus has been detected in Saudi Arabia where 15 people have already died after contracting it, the health ministry announced on Saturday on its Internet website.

Diseases, Conditions, Syndromes created 17 hours ago | popularity not rated yet | comments 0

Little evidence for prediction rules for low back pain

(HealthDay)—Few randomized clinical trials have been done to assess clinical prediction rules for patients with lower back pain, and the trials that have been done are of low quality and do not provide ...

Diseases, Conditions, Syndromes created May 17, 2013 | popularity not rated yet | comments 0 | with audio podcast

New malaria test kit gives a boost to elimination efforts worldwide

A new, highly sensitive blood test that quickly detects even the lowest levels of malaria parasites in the body could make a dramatic difference in efforts to tackle the disease in the UK and across the world, according to ...

Diseases, Conditions, Syndromes created May 17, 2013 | popularity not rated yet | comments 0


Ketamine shows significant therapeutic benefit in people with treatment-resistant depression

Patients with treatment-resistant major depression saw dramatic improvement in their illness after treatment with ketamine, an anesthetic, according to the largest ketamine clinical trial to-date led by researchers from the ...

Research examines new methods for managing digestive health

Research presented at Digestive Disease Week (DDW) explores new methods for managing digestive health through diet and lifestyle.

New smartphone application improves colonoscopy preparation

The use of a smartphone application significantly improves patients' preparation for a colonoscopy, according to new research presented today at Digestive Disease Week (DDW). The preparation process, which begins days in ...

New research identifies risks, interventions for children's GI health

An increasing number of U.S. children are experiencing gastrointestinal issues that require interventions to resolve, according to research presented at Digestive Disease Week (DDW).

US psychiatry gets makeover in new manual

The latest makeover to a massive psychiatric tome honored by some, reviled by others and even called the "Bible" of mental disorders is being released Saturday with a host of new changes.

New colonoscope provides ground-breaking view of colon

A ground-breaking advance in colonoscopy technology signals the future of colorectal care, according to research presented today at Digestive Disease Week(DDW). Additional research focuses on optimizing the minimal withdrawal ...