Blogger: Jane Atesoh Awuh, Postdoctoral Fellow, Department of Cancer Research and Molecular Medicine and Centre of Molecular Inflammation Research (SFF-CEMIR).

Most often we become passionate and involved in issues in this life for very personal reasons. I am particularly drawn to infectious diseases because I hail from a society that is plagued by one kind of infection or the other. If you are not killed by one infectious disease you will be by the other, and if not by disease, it will be by war or hunger. I know two relatives who died of tuberculosis, one of them only a couple of months ago. Tuberculosis (TB) is still a disease of poverty although there is increasing incidence even in developed countries. HIV and TB are a dangerous liaison wherein HIV infects and destroys the very cells that should protect us from TB. These diseases are still considered shameful and surrounded by stigma.

To survive TB, support from family, friends and communities is as important as medication. TB can be treated through a long course of several antibiotics, over a minimum of six months. The medications might make you more sick, but if taken regularly, you will be completely well again. Six months is a short time compared to an entire life time, although many still fail to take their medication regularly. Even more fail to get treatment at all, because they are used to being poor and ill, and do not seek help in time.

3D-reconstruction of mycobacteria (red rods) with a macrophage. Photo: Marianne S. Beckwith

Thanks to the amazing work of basic scientists around the world, there is always a little light at the end of the tunnel. The work of basic scientists is often the foundation of whatever treatment and prevention strategies that eventually end up at the bedside of patients. And the steps to arriving at the very first clinical trial is often accompanied by a succession of failures, hopelessness and sleepless nights. Yet they are not always given enough credits and funding. The causal agents of mycobacterial diseases are an intriguing group of microorganisms that continue to baffle these brilliant minds around the world even when we think we have got it all figured out. Of these, Mycobacterium tuberculosis which causes tuberculosis is one force to reckon with especially in individuals who are immunocompromised for one reason or the other. Another one of these bugs causes leprosy and indeed the Norwegian scientist G. H. Armauer Hansen in 1873 discovered the bug, making it the first bacterium to be identified to cause disease in humans and since then pioneered research in leprosy. It’s amazing that these infections have been with us for thousands of years yet we are still struggling to keep it in check. How can a single-celled organism like these be so complex that they cannot be untangled by even the most brilliant minds in the field?

Confocal image of mycobacteria (red rods) within a macrophage coated with LAMP1. Photo: Alexandre Gidon

Approaching the end of the year could not be a better time to summarize current research findings in the world of these creepy, invisible creatures. In a recent issue of the journal Cellular and Molecular Life Sciences, we summarize the current standing on how these bugs have managed to stay with mankind for so long and I have a feeling we are still only scratching the surface of this enigma. To add to the whole complexity is the fact that these bugs actually prefer and thrive in one of the deadliest immune cells known – the macrophage, as a natural habitat. How can that be?

Macrophages play an essential role in the immune system by ingesting and degrading invading pathogens, initiating an inflammatory response and instructing adaptive immune cells, and resolving inflammation to restore homeostasis. We summarize mechanisms by which intracellular pathogens, with an emphasis on mycobacteria, manipulate macrophage functions to circumvent killing and live inside these cells even under considerable immunological pressure. Remember the good news; these infections are treatable although rise in drug resistance continues to be a challenge as with all other infectious diseases. A clear understanding of host responses elicited by a specific pathogen and strategies employed by the microbe to evade or exploit these is of significant importance for the development of effective vaccines and targeted immunotherapy against persistent intracellular infections like tuberculosis. Read more here.

Mycobacterial evasion strategies within a macrophage.

CEMIR researcher Marie Hjelmseth Aune looks at macrophages ( blue ). The screen image shows a macrophage engulfing a bacterium (red). Photo: Geir Mogen, NTNU

Some bacteria and viruses take advantage of the way our immune system works to infect us.  Researchers at Centre of Molecular Inflammation Research (CEMIR) are uncovering the mechanisms by which this trickery takes place.

Read more on GEMINI.no: Uncovering the secrets of immune system invaders, written by Nancy Bazilchuk.

Blogger: Marte Singsås Dragset
Researcher at Centre of Molecular Inflammation Research (SFF-CEMIR), Department of Cancer Research and Molecular Medicine (IKM)

24 March is the World Tuberculosis Day. Here in Norway, most people know tuberculosis (TB) from media, school and vaccination programs. Some people have a parent, grandparent or great grandparent who suffered this infectious disease.Luckily, on the World TB Day of 2015, the occurrence of TB in Norway is relatively low (350-400 reported cases/year). We have antibiotics for treatment, and most of the Norwegian cases are actually non-active, non-contagious so-called latent TB.
However, and here is why we need a World TB Day, globally TB is still a gigantic public health problem! In fact, only beaten by HIV/AIDS, TB is the deadliest infectious disease in the world. World Health Organization reports that 1.5 million people died from TB in 2013. That is almost every third Norwegian. The increase of antibiotic-resistant bacteria is at the same time a major emerging threat to human health, and TB resistant to our current drugs is on a rise. We urgently need new drugs for TB treatment.

To develop a new antibacterial drug is a time consuming process. It often starts with a large screen searching for compounds that kill the pathogen in question. Hit compounds are then typically optimized further, and for rational drug design purposes it is important to identify how the compound actually kills the bacteria. In our study, recently published in Antimicrobial Agents and Chemotherapy, we found the apparent mechanism of a new compound (PZP) that kills the TB-causing bacterium Mycobacterium tuberculosis. And the mechanism caught us by surprise.

Estimated TB incidence rates, 2013. (Source: WHO, 2014)

A relatively new method used to identify the drug target and the mechanism of a new potential drug is to sequence the whole genome of bacteria that shows resistance to the compound in question. For instance, the mechanism of Bedaquiline, which is the first new TB drug on the marked in over 40 years (!), was discovered using this method. Genome sequences of M. tuberculosis resistant to Bedaquiline revealed mutations in the enzyme that provides the bacteria with energy; ATP synthase. This finding subsequently led to the discovery that Bedaquiline binds and inhibits the pathogen’s energy production unit.

Likewise, TB bacteria resistant to the new anti-TB compound we are interested in, PZP, were genome sequenced. The mutations discovered mapped to a gene that is important for the bacteria to take up iron from the surroundings. As for us humans, M. tuberculosis needs iron to live. Could it be that PZP binds and inhibits this iron uptake protein of M. tuberculosis so the bacterium cannot get a hold of the iron it needs? Just like Bedaquiline binds and inhibits ATP synthase and starves the bacterium for energy? We set out to confirm this hypothesis, however, step by step it became clear that our theory failed. PZP did not target iron uptake. Puzzled by this finding, the sharp chemists on our team did another discovery; PZP is in fact an iron chelator! That means, PZP can strongly bind to iron. So, instead of inhibiting bacterial uptake of iron, PZP seems to enter the bacterial cells and bind the iron the bacteria has already taken up, making it unavailable for the bacteria to use. PZP apparently starves the TB bacteria for iron from the inside!

Together with our collaborators at research institutions in Boston, Rome, Texas, Seattle and New York we learned an important lesson from this study, important also for other researchers in the drug development field. Things are not always as they seem. The gene that maps to resistance towards an antimicrobial compound is not necessarily the target of the compound. But, even if it is not the target, to identify such genes can give us crucial hints about the true mechanism of the new drug candidate. As for us; we were successfully pointed in the direction of iron metabolism.

Reference: A Novel Antimycobacterial Compound Acts as an Intracellular Iron Chelator, Antimicrobial Agents and Chemotherapy, April 2015 vol. 59 no. 4.

Blogger:Trude Helen Flo, co-director CEMIR

The Research Council of Norway has recently awarded grants under the funding scheme Independent Basic Research Projects – Medicine, Health Sciences and Biology (FRIMEDBIO). There is tough competition for this funding nationally, and only the best projects get through. The Faculty of Medicine, NTNU, has been awarded funding for three talented young researchers, three research projects and two post docs. You can read about all these projects on the blog over the coming weeks. Trude Helen Flo and her colleagues at CEMIR were awarded funding to their research project: New Principles of mycobacterial killing in host macrophages (MycoHosPath).

Mycobacterial infections are a global health problem. Tuberculosis (TB) is caused by a bacterium known as Mycobacterium tuberculosis (Mtb) and kills more than 1.4 million people worldwide each year. Environmental mycobacteria like Mycobacterium avium can cause disease in immunocompromised people like HIV/AIDS patients who are not on anti-retroviral treatment. Mycobacterial infections require long treatment with antibiotics and drug resistance is emerging. Thus we need new drugs and vaccines in order to reach the UN millennium goal of eradication of tuberculosis.

To discover new therapeutic targets we need to learn more about the mycobacterium and how it interacts with its human host.

Mycobacterium tuberculosis (Mtb) and kills more than 1.4 million people worldwide each year

To discover new therapeutic targets we need to learn more about the mycobacterium and how it interacts with its human host.

Some major scientific and technological advances during the last decade have contributed significantly to progress in the field: studying the genetic makeup of mycobacteria provides clues about how the bacteria may infect and survive in the host. On the other hand, studying genetic variations in humans also provides insights in to how humans may become susceptible to mycobacterial infections.

Major breakthroughs in how our first line of defense, the innate immune response, can discriminate between different pathogens and shape the following second line of defense, the adaptive immune response, was awarded the 2011 Nobel Prize in Medicine. The adaptive immune response is crucial for the development of immunological memory. Despite these major advances, we still lack a complete understanding of mycobacterial immunity.

TB incidence rates and multidrug-resistant TB cases (click to enlarge image)

The primary research goal of the MycoHosPath project is to identify new principles of mycobacterial killing during acute and chronic infection. We will approach this by studying the interplay between three cellular pathways that are central for killing and intracellular survival of mycobacteria: Phagocytosis, Inflammatory signaling and Autophagy.

Phagocytosis is the process by which bacteria are taken up by innate immune cells like macrophages and dendritic cells. Normally this leads to destruction, but pathogenic mycobacteria have found ways to avoid it.

Autophagy is a similar process used by cells to detect and degrade garbage in their interior, including intracellular pathogens. Understanding how mycobacteria avoid these killing mechanisms and survive within macrophages may aid in discovery of new drug targets.

Inflammatory signaling is the macrophage response to infection. Infected macrophages produce potent molecules to alarm and recruit other immune cells to help clear the infection. Some of these molecules also help the infected cell to directly kill the invading micobes. However, since pathogenic mycobacteria can live in our body for a lifetime, this does not work perfectly. If we can improve our understanding on how a perfect immune response to mycobacteria should look like we could contribute to new vaccine strategies.

The combined processes of phagocytosis, autophagy and inflammatory signaling in host macrophages, and strategies used by the mycobacterium to manipulate them to its own advantage, will influence activation of mycobacterium-specific immune cells that we need to clear the infection and create immunity to further infection.

Our research group studies several of these aspects in the bacterium, in cells isolated from healthy and HIV-infected individuals, and in mouse model systems. As part of SFF-CEMIR we have access to national and international expertise on inflammation research and advanced imaging, state-of-the-art methodologies and new labs in Kunnskapssenteret.

We have also engaged strong national and US collaborators on autophagy and mycobacterial research who will contribute in what we hope will be a successful project. We are looking forward to realizing MycoHosPath next year.

In CEMIR we will work with infection, or inflammation. Why? Because inflammation is important for health, including global health, and we believe that a better understanding of how inflammatory processes are initiated and regulated will contribute to the development of new drugs and vaccines.

Inflammation is the body’s response to danger. Cells from the immune system have receptors that recognize microbial structures, tissue damage or harmful changes in the body’s own molecules. Binding to the receptors activates immune cells and acute inflammation ensues. The cells secrete signalling molecules to recruit new immune cells and antimicrobial programmes are activated, all with the purpose of removing the intruders, repairing the damage and healing the wounds. The principles are the same, but the receptors that are activated are specific to different molecules and thus the immune response adapts to the type of attack to which the body is exposed

If the body is unable to handle or clear the insult, the inflammation can become chronic, as seen in rheumatoid arthritis, inflammatory bowel disease, some cancers and cardiovascular disease. And herein lays the key: If we know, at a molecular level, what host defense mechanisms are mobilized by immune cells in response to different attacks, we can identify new and specific therapeutic targets for a number of diseases where inflammation is central.

If we know, at a molecular level, what host defense mechanisms are mobilized by immune cells in response to different attacks, we can identify new and specific therapeutic targets for a number of diseases where inflammation is central.

What about inflammation from a global health perspective? Recent figures show that even though infectious diseases are still a major cause of death in low-income countries, populations are aging and people are dying from cardiovascular disease, lung disease, diabetes, dementia and cancer – all chronic diseases that have a significant inflammation component (Lozano et al, The Lancet 2012). Some of the most deadly infectious diseases are also chronic, such as HIV / AIDS, tuberculosis and malaria.

My research group is particularly interested in tuberculosis caused by the bacterium Mycobacterium tuberculosis. One-and-a-half million people still die from tuberculosis each year, and it is estimated that one-third of the world’s population is infected with the tubercle bacillus. Treatment is complicated and lengthy, there is an increasing incidence of resistance to the drugs we have today, and the only available vaccine, the BCG vaccine, is not effective against adult pulmonary tuberculosis. There is therefore a great need for both new vaccines and more effective drugs against tuberculosis.

We believe we can contribute to these needs by studying the interaction between mycobacteria and the host immune system, in particular how mycobacteria are able to survive inside a host cell that is specialized in destruction of microbes, the macrophage. A number of processes are initiated in the macrophage when the mycobacteria bind to receptors on the surface (see Figure 1): lectin receptors contribute in uptake of the bacterium into the cell. This happens in a process called phagocytosis whereby the cell membrane wraps around the bacterium creating a closed vesicle, a phagosome. At the same time, the inflammatory process is activated in the macrophage via Toll-like receptors, while signalling molecules are secreted and an antibacterial programme is initiated.

But here’s what happens that makes mycobacteria special: Normally the phagosome would become gradually more acidic, the bacterium destroyed and pieces of it presented to more professional immune cells, the T cells. Pathogenic mycobacteria can prevent this process and live for a long time inside the host without being killed. This is called immune evasion, and may explain why so many people are walking around with latent tuberculosis.

Figur 1

Our goal is to understand the molecular mechanisms that make this possible, both in the mycobacteria and in the macrophage. If we can strengthen the macrophage or weaken the mycobacteria such that T cells are activated in a timely manner, we can hopefully provoke an immune response that effectively kills the bacteria and provides immunity. It is only through a detailed understanding of what happens between mycobacteria and the host that we can find new therapeutic targets and develop new vaccines.

Mycobacteria require iron to grow. We have shown that the body has an antibacterial protein, lipocalin 2, which starves bacteria for iron (Flo et al., Nature 2004). Unfortunately, we have also found that lipocalin 2 is not as effective as a defence against mycobacteria because the pathogen hides inside macrophages, in phagosomes, where lipocalin 2 cannot get access (Halaas et al., Journal of Infectious Diseases 2010, see Figure 2).

If we can find other ways to starve mycobacteria for iron, they will weaken enough that the macrophages will be able to take care of them. Better knowledge of mycobacterial iron metabolism may help us find a new point of attack.

Figure 2. Mycobacteria live in the body’s macrophages and hide from defence proteins such as lipocalin 2. The pictures show a macrophage that is infected with a fluorescent mycobacteria (green) and then labelled with the defence protein lipocalin 2 (red) and lysosomes (blue). Lipocalin 2 is transported into the lysosomes where it is degraded (the overlapping red and blue becomes purple), while mycobacteria move to other parts of the macrophage, where they are neither broken down nor come into contact with lipocalin 2. This is called “immune evasion”, a survival strategy at which mycobacteria are expert. Source: Halaas et al., Journal of Infectious Diseases 2010. Photos: Øyvind Halaas

Recent research has shown that macrophages can take care of mycobacteria using an internal waste disposal system called autophagy. Autophagy is similar to phagocytosis, but occurs inside cells, when old and damaged organelles, aggregated proteins, bacteria and viruses are surrounded by an inner membrane (Figure 1). The vesicle that is formed is called an autophagosome, and the contents are destroyed by fusion with lysosomes in the same way as for normal phagocytosis.

Autophagy is regulated by inflammatory proteins and inflammation is affected by autophagy. We believe that a better understanding of these relationships can make it possible to influence these processes in a way that enhances the killing of mycobacteria, improves the activation of T-cells, and hopefully resolves the infection. Autophagy is also important in heart failure, cancer and nerve disorders: defects in autophagy can increase the aggregation of proteins, such as is seen in Alzheimer’s disease.

So is inflammation relevant to global health? Definitely. Inflammatory mechanisms are common to both infections and chronic inflammatory diseases caused by harmful changes in the body’s own molecules. But they are used differently, and at CEMIR we hope to identify the similarities and differences in the molecular mechanisms of inflammation that may eventually give us new drugs, new vaccines and new diagnostic tools.

The official opening of the Norwegian University of Science and Technology’s four new centres of excellence (CoE) will take place on Monday 10 June. CEMIR, the Centre of Molecular Inflammation Research, is one of these new centres. CEMIR researchers will study new mechanisms that set off inflammatory responses. We hope this will provide us with information that could help in the development of new treatment methods and the diagnosis of diseases in which inflammation plays a crucial role. You can read more about CEMIR at http://www.ntnu.edu/cemir

In June there will be more blogs from CEMIR researchers.