Bacteria battle for zinc in the CF Lungs

Scientists have found that the human protein calprotectin is locked in a perpetual battle with the bacteria Pseudomonas aeruginosa to procure zinc, a metal that can be found outside the body in batteries and baked beans (and many places in between). It all sounds rather like the plot of a sci-fi film: a dystopian future where warring inhabitants of a broken-down planet scavenge the Earth for metal. But this tale does not belong to the realm of fiction, it’s a very real and human story.

Pseudomonas lives Within the lungs of many CF patients; a pesky bug that tends to set-up camp and then refuses to leave. Pseudomonas is a key pathogen of interest (POI), endemic not just to the lungs of CF patients, but also common in hospital-acquired infections, where it has been linked to the contamination of surgical tools, showers, and drinking water. Pseudomonas belongs to an infamous group of bacteria known as the ESKAPE pathogens (like the microbiologist’s version of the Sinister Six), with a well-known capacity for multi-drug resistance.

CF researchers have spent an abundance of time and money studying pseudomonas, and the findings presented here are just the latest in a series of attempts to understand how the bacteria colonizes the CF lungs. Recently, a team of researchers from the hospitals and research centers surrounding Dartmouth College in Hanover, NH, grew pseudomonas in the lab to assess its dependence on zinc.

Pseudomonas is known to make use of metals like zinc and iron, but the bacteria does not roam the lungs unchallenged. Cells of the immune system fight back in a number of ways. Some cells - called phagocytes - engulf the bacteria whole and try to destroy it directly. Others try to damage pseudomonas indirectly by stealing away its resources. Immune cells called neutrophils accomplish this by producing a protein called calprotectin that binds up zinc and sequesters it away.

To demonstrate how neutrophils fight back against pseudomonas with calprotectin, the Dartmouth team exposed the lab-grown pseudomonas to the protein and showed that it had several detrimental effects. For one, it hurt the ability of pseudomonas to fend off other CF lung bacteria. Exposure of pseudomonas to calprotectin reduced the activity of the pseudomonas protein LasA, which works to degrade the cell wall of fellow CF pathogen S. aureus. And calprotectin exposure had another beneficial effect - it reduced the activity of a pseudomonas protein LasB, which has a known capacity to damage lung tissue by digesting collagen.

If depriving pseudomonas of zinc makes it less damaging to the CF lungs and less successful at attacking other CF bacteria, then CF researchers may have a new anti-bacterial approach on their hands: boosting the immune system’s capacity to take away zinc, or finding other ways to steal zinc away.

Jumpstart your research! To learn more about pseudomonas, CF lung bacteria, and the battle for metal within the body, check out the aforementioned article and the associated knowledge map below:

Featured Article: Vermilyea DM, Crocker AW, Gifford AH, Hogan DA. Calprotectin-Mediated Zinc Chelation Inhibits Pseudomonas aeruginosa Protease Activity in Cystic Fibrosis Sputum. J Bacteriol. 2021 Jun 8;203(13):e0010021. doi: 10.1128/JB.00100-21. Epub 2021 Jun 8.

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Clinical Progress: Improved Care for CF Patients

It is estimated that 30 million Americans - roughly 1 in 10 - are diabetic. Unfortunately, this number swells every year. Yet our capacity to treat diabetes is advancing at a similar rate, and allows diabetics to live productive lives. Prior to the 1920s, when the young Canadian scientist Frederick Banting (still the youngest Nobel laureate, at 32 years of age, for the category of physiology & medicine) discovered insulin as a treatment to control blood sugar, diabetes was virtually untreatable and fatal without exception. Today, diabetics can make use of sophisticated continuous glucose monitors (CGM’s) that automatically sense low insulin levels and warn them to administer more. Many CGMs even come with automatic insulin dispensers.

Looking forward, physicians are focused on early monitoring. Type II diabetes, unlike its auto-immune disease counterpart (type I), is largely preventable (although there is evidence that some people are genetically disposed to develop type II diabetes). As the early onset phase of the disease is better understood, there will be demand for more genetic screening and earlier monitoring of blood glucose levels to detect blood sugar abnormalities, so patients may be treated before full-blown diabetes takes hold. Even those who do go on to develop diabetes could come to terms more quickly with what needs to be done to manage the disease and spend less time struggling with diabetes management.

Why do these developments in diabetes matter to CF patients? The reason is that people with CF are prone to a special type of diabetes called CFRD (CF-related diabetes), which occurs in up to 50% of CF adults (although this statistic may change positively due to the present, widespread treatment with CF modulators). CF as a disease is more than mucus buildup in the lungs: the same sort of problem arises in other parts of the body as well. The digestive enzyme-secreting ducts of the pancreas get clogged (that’s why most CF patients take digestive enzymes with food). And over time, in many patients, this blockage also affects the insulin-secreting beta cells of the pancreas. Insulin, as a hormone, helps keep blood sugar in check, and when it is not being produced (or the body doesn’t respond to it properly), the result is ultimately diabetes.

Clinical trials are underway to develop better guidelines for diagnosing and managing CFRD. The current diagnostic criteria are modeled after those for adult-onset type II diabetes - and while similar to type II diabetes, clinicians suspect that the trajectory of CFRD development is unique. Using continuous glucose monitors, a recently-completed study sponsored by the University of Colorado investigated how blood sugar levels in CF patients change over time. The researchers rigged up CGMs to CF patients (a mix of individuals: some with diabetes, and others with pre-diabetes – they have abnormal blood sugar levels, but not abnormal enough to be considered diabetic). The goal of the study was to identify how blood sugar abnormalities arise in individuals in the early stages of CFRD, what effects these changes have on BMI and lung function (both already of concern for CF patients), and how early intervention may slow disease progression.

Results from this study are not yet available - but this and related studies are of significant importance to both the CF and diabetic communities: successful early diagnosis and management of CF-related diabetes could serve as a model to help those patients that may also develop type II diabetes. Helping the 30 thousand US citizens with CF could help 30 million more.

Jumpstart your research! If you want to learn more about efforts underway to understand and treat CF-related diabetes, check out the aforementioned clinical trial and the associated knowledge map below:

Featured Clinical Trial: Glycemic Monitoring in Cystic Fibrosis (GEM), Sponsor: University of Colorado, Denver. ClinicalTrials.gov Identifier: NCT02211235.

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Drug Discovery: New Medicines on the Horizon

We live in an age of molecular medicine – scientists are no longer limited to discovering new drugs by sifting through the soil for chemicals that might, on the off chance, have a positive impact against disease . We know how to identify malfunctioning proteins that contribute to disease (such as the CFTR protein), and select suitable drug compounds on the basis of how well they bind to such proteins, or otherwise improve their function.

A good example of biology-based drug discovery are the recently approved CF modulator drugs (Elexacaftor, Tezacaftor, Ivacaftor). Candidate molecules were tested in cells engineered to possess a dysfunctional CFTR protein to simulate how well they could correct it. The CFTR protein works like a floodgate: when it is operating well, water streams out of cells. The CF modulators are very effective at opening the floodgate.

However, the floodgates do not open for all, as the CF modulator drugs are only approved for patients with at least one F508del mutation, which affects roughly 90% of all CF patients. This leaves many CF patients with rare mutations that do not respond to these treatments without highly effective treatment.

One such rare mutation is the ‘splice-site mutation’. If we use the analogy of sandwich making to understand protein building, each gene can be said to provide the “recipe” for the whole sandwich (by transcribing DNA to mRNA), with specific parts of the gene corresponding to instructions for specific parts of the protein (the protein parts, called exons, are like the sandwich ingredients). When these instructions are altered, the protein is not made properly. The wrong ingredients are added to the sandwich (or some of the right ingredients are omitted). To deliver the correct instructions, the “recipe” for the protein (the mRNA transcribed from DNA) must be corrected.

So what can be done? Researchers at the University of North Carolina, Oregon State, and Initos Pharmaceuticals seem to have an answer. They’ve been working on a treatment that makes use of compounds called splice-switching oligonucleotides (SSOs). Essentially, these molecules ensure the mRNA instructions are correct to form a functional protein. Other researchers have previously made unsuccessful attempts at creating SSO compounds, but this team seem to have perfected its delivery – combining the SSOs with PPMOs (molecules that ensure the SSOs spread widely throughout the lung and other tissues) and OECs (which fight off the cell’s tendency to degrade SSOs before they have any positive impact).

With this and other inventive therapies on the horizon, we soon may see a day where all CF patients benefit from highly-effective modulator therapy - and where all cell-sandwiches come out just right.

Jumpstart your research! If you want to learn more about SSOs in CF drug development, check out the aforementioned article and the associated knowledge map below:

Featured Article: Dang Y, van Heusden C, Nickerson V, Chung F, Wang Y, Quinney NL, Gentzsch M, Randell SH, Moulton HM, Kole R, Ni A, Juliano RL, Kreda SM. Enhanced delivery of peptide-morpholino oligonucleotides with a small molecule to correct splicing defects in the lung. Nucleic Acids Res. 2021 Jun 21;49(11):6100-6113. doi: 10.1093/nar/gkab488. PMID: 34107015; PMCID: PMC8216463.

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Featured Five CF Stories

It’s impossible to list all of the amazing research that is on-going for CF. Below is a quick list of a few fascinating articles that seem to show significant promise.

CFTR is Not Enough: Scientists tests drugs on mice and pigs to inhibit ENaC, a channel protein that pumps sodium out of the CF airways and helps produce thick, sticky mucus. (European Journal of Pharmacology)

Pseudomonas Beyond the Lungs: New review sheds light on the many other ways that pseudomonas aeruginosa can invade the body and wreak havoc - from post-surgical wounds to eye infections. (Virulence)

Genetic Counseling and Family-Building: Researchers find that genetic counseling can help people with CF assess assisted fertility treatment options, and that repeated and consistent counseling is ideal. (Reproductive Biomedicine & Society)

Finding a Better CF Diet: A clinical trial is underway to investigate if a low carbohydrate diet will help ward off CF-related diabetes and other GI complications (Boston Children’s Hospital)

Fungus Among Us: It’s not just pseudomonas and its fellow bacterial fiends that are pathogens of concern - fungal species are big players in the CF lungs too. This review discusses the current understanding of fungal infection risk, standards of diagnosis, and treatment options (Mycopathologia)

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Clinical Trial Watch: Moving CF Research Forward

The latest news on CF drug development and clinical trials.

Clinical Trial Recruiting: As we race to develop effective treatment strategies against emerging CF fungal pathogens, a new clinical trial is testing the drug Posaconazole against the fungus Aspergillus fumigatus. The trial aims to evaluate the effectiveness of the drug and to provide insights into the threat that Aspergillus poses to members of the CF community. (Bambino Gesù Hospital and Research Institute)

Clinical Trial Recruiting: What is the impact of pseudomonas infection on the immune system? If we know how the bacteria impairs immune function, we can start to fight back by developing clever therapies that boost the immune system and fend off bacterial assault. What’s more, this trial will also look at the effect of CF modulator drugs and pulmonary exacerbation (an acute decline in lung function, often accompanied by hospitalization) on immune function. (Assistance Publique - Hôpitaux de Paris)

Clinical Trial Recruiting: How effective is MRI imaging at recognizing changes in lung health after treatment with Trikafta? This study aims to find out - by comparing MRI to other diagnostic methods like spirometry that assess the patterns and strength of breathing - whether MRI can detect changes in lung function just as well. Why this study? Clinicians want to know if the diagnostic tests they run on patients are actually providing an accurate indication of patient health. (University Hospitals Cleveland Medical Center)

Clinical Trial Complete: VX-371, a sodium channel inhibitor developed by Vertex Pharmaceuticals, has failed to improve lung function when combined with inhaled hypertonic saline. The drug is well tolerated, though, when combined with existing CF modulators taken by CF patients. Vertex is going back to the drawing board on this drug, and turning to its arsenal of other CF compounds (Parion Sciences + Vertex Pharmaceuticals)

*Note: If you or a family member are interested in entering clinical trials that are currently recruiting, please click the link to ClinicalTrials.gov and See ‘Contacts and Locations’ for participating research institutions, and speak to your clinician for guidance.

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A Call to Action

Cystic fibrosis (CF) research is very much dependent on the strength of the CF community. It’s not simply an effort carried out by scientists in white lab coats - although there are many of them, and their work has enormous impact. Advances in research also depend on the technicians and engineers who operate the laboratory equipment that enables drug discovery, and the industrial machinery that allows drug development. Research depends on both business and marketing professionals, those who make biopharma companies viable and promote clinical trials. Successful research further depends on clinical trial coordinators, who carry out studies and work tirelessly to recruit and support patients throughout the complicated trial process. Particularly for rare diseases like cystic fibrosis, research depends on the work of foundations and patient advocates, which includes in the United States organizations such as the CF Foundation, Emily’s Entourage, CFRI, and the Boomer Esiason Foundation, as well as countless other across the globe, and hundreds of committed clinicians and researchers. Most importantly, research depends on people with CF and their devoted families and friends.

There can be no progress in CF research without patients willing to participate in clinical trials: not only to test new drugs, but also to provide, quite literally, their flesh and blood. It is with the help of patient samples that scientists can understand the damage that CF inflicts upon the human body, and also how drugs developed by the research community can remedy these damages.

This newsletter aims to pull all of these threads together; allowing the CF community to more fully appreciate how well the aims of its many members are aligned (and it extends an invitation to all readers not yet a part of the CF community, to embrace the cause and take up the task of pushing CF research forward). There’s something here for everyone - those interested in the clinical side of CF care, or in drug development, or the technical work performed in CF-centered laboratories. The newsletter also has as its objective to showcase new clinical trials; an opportunity for patients and clinicians to take part. Wherever and whoever you are in the world, you too may push CF research forward - either by direct participation, or simply by reading and sharing this newsletter with others.