There remains much to learn about endocrinology, and most of the conditions we treat do not have definitive cures. To help advance the field, the faculty in our Division direct endocrinology-focused research ranging from laboratory biomedical science to clinical studies. Here we report some of our noteworthy progress.
The Pediatric Endocrine Society (PES) is a professional organization of over 1,600 endocrinologists with the purpose of advancing treatment of youth with endocrine disorders. The PES held its annual meeting May 5-8 in San Diego. Several of our division faculty attended the meeting. Dr. Pesce presented at one of the symposium session on Endocrinology in the Neonatal Intensive Care Unit. Dr. Parra Villasmil presenter her research, conducted under the mentorship of Dr. Pinnaro, on Screening for Turner Syndrome-associated Hyperglycemia. Dr. Parra Villasmil’s work was selected as one of the top-ranking abstracts, receiving a PES Presidential Poster award. In addition, our future fellow, Dr. Kyle Baum, currently a pediatric resident at Sanford School of Medicine, also had an abstract selected for a PES Presidential Poster award.
Potent medications have recently been developed to treat cystic fibrosis. These new therapies dramatically improve lung disease for those with cystic fibrosis. Persons with cystic fibrosis often develop a unique form of diabetes termed cystic fibrosis related diabetes (CFRD). It is not yet clear how the new therapies will impact the propensity of persons with cystic fibrosis to develop CFRD. A group of researchers, clinical experts, and patients/families were assembled by the NIH and the Cystic Fibrosis Foundation to discuss research priorities to better understand treat and prevent CFRD. This group convened in June of 2021 at a workshop open to the public. This group has now written and published a summary describing their collective thoughts on research priorities priorities CFRD, Their writings appear this month in the two journals Diabetes and Diabetes Care. Contributing to the article were two physicians from our division: Dr. Norris and Dr. Larson Ode, with Dr. Norris serving as one of the lead authors of the work. The publication can be found at the following Pubmed link.
The triple combination therapy consisting of elexacaftor/tezacaftor/ivacaftor (ETI) has made a tremendous impact for the health of persons with one of the most serious and most common genetic forms of cystic fibrosis. This medication dramatically improves lung health and helps persons with CF live a longer and healthier life. These medications also help persons with CF regain weight, which is important for health because being underweight in those with CF is associated with a higher risk of worsening lung disease and mortality. However, what is not yet known is whether the weight gain with ETI therapy is healthy weight gain such as muscle mass or less health gain such as excess adipose tissue. To address this knowledge gap, Dr. Katie Larson Ode from our division teamed with a group of investigators at several other hospitals across the country to study this in persons on ETI therapy. They found, perhaps concerningly, that the weight gain occurred mainly as increased fat mass and that the changes were associated with reduced insulin sensitivity. These results indicate a need to closely monitor and further study the metabolic impact of ETI therapy. Their study has been published in the journal Pediatric Pulmonology and is titled “The Impact of elexacaftor/tezacaftor/ivacaftor on Body Composition in a Small Cohort of Youth with Cystic Fibrosis”. It can be found at this pubmed link.
Turner syndrome (TS) is a karyotype disorder in which the sex chromosomes consist of an intact X chromosome and partial-to-complete loss of the other sex chromosome. TS includes a number of phenotypic features, including many that have variable expression. The degree of second sex chromosome loss explains the risk of some but not all TS features. Modifier genes are one possible explanation for TS features whose risk is not explained by karyotype. In this case, the modifier genes would be polymorphisms on autosomal chromosomes. This postulate served as the basis for a recent research study by Dr. Cat Pinnaro. Specifically, she sought to determine whether autosomal genes might influence the risk of cardiovascular malformations in TS. She focused on genes involved in pathways already known to impact cardiac development. The identified that specific variants in the CRELD1 gene were associated with risk of having a bicuspid aortic valve in TS. This study serves as proof-of-concept that modifier genes impact TS phenotype, and paves the way for future studies searching for additional modifier genes that might impact other aspects of phenotype in TS and other karyotype disorders. The work is published in the journal Human Genetics (pubmed link here).
Although it has long been known that persons with Turner syndrome have increased risk of developing diabetes, the reasons are not well understood. Relatedly, there are no known preventative strategies and no directed therapies. Dr. Pinnaro and Dr. Alexandrou from our Division have teamed up to review published knowledge in this area and map out critical gaps in understanding. Their review, entitled “Hyperglycemia in Turner syndrome: Impact, mechanisms, and areas for future research” has just been published in the peer reviewed literature. Also contributing to the manuscript were student Cameron Mitsch and division member Dr. Norris. The paper appears in the journal Frontiers in Endocrinology and can be found here (doi: link or pubmed link ). Dr. Pinnaro is leading a team working to find the root causes of diabetes linked to Turner syndrome. It remains important for persons with Turner syndrome to receive expert endocrine care, such as can be obtained from Dr. Alexandrou; see this link for contact information for her Turner syndrome clinic .
Growth hormone is required for children to realize their full potential to grow taller. Those children who are unable to make normal amount of growth hormone do not grow well. Fortunately, daily growth hormone injections are an available therapy and robustly restore growth in these children. More rarely, some children can make growth hormone but can not respond to it properly due to various genetic reasons. One such reason is mutation of a gene termed PAPPA2. This gene produces a protein required for growth hormone to work. Specifically, the PAPPA2 protein liberates IGF-1 — the major growth hormone induced growth factor — to allow it to promote growth. Persons who lack a proper PAPPA2 gene thus do not grow well. An active question in the field regards whether giving IGF-1 supplements might overcome this issue and promote growth in children with this condition. Dr. Eirene Alexandrou from our Division was part of a team that studied this question and have now published their findings. Their results suggest that indeed IGF-1 can improve growth in children with genetic mutations in PAPPA2, but that the therapy may not completely normalize growth. Because IGF-1 therapy can have side effects, they suggest weighing pros and cons with each family when considering treatment. Their findings have been published in the journal Hormone Research in Paediatrics. The abstract has been indexed in Pubmed and can be found here.
Persons with cystic fibrosis typically have an imbalance in their fatty acid levels. A prominent aspect of this imbalance is a deficiency of linoleic acid, which is one of the so-called essential fatty acids. Despite decades of research, the mechanisms of the imbalance are not fully understood. To better understand this fatty acid imbalance, a group of researchers at the University of Iowa, Kansas State University, and the Karolinska Institutet in Stockholm Sweden worked together to study pigs and ferret with cystic fibrosis. The results showed that the imbalance exists at birth even before first feeding. This result argues strongly against one of the leading prior hypotheses which was that the imbalance might stem from the nutrient malabsorption that occurs in cystic fibrosis. Instead, the results suggest that several molecular mechanisms might be responsible for the imbalance, including excess metabolism of arachidonic acid, oxidative isomerization of unsaturated fatty acids, and/or biliary loss of phospholipids containing unsaturated fatty acids. The senior author of the resulting manuscript describing the findings was Dr. Norris from our Division. The work can be found published in the journal Clinical Science (link).
Cystic fibrosis is a genetic disease that causes dysfunction in multiple systems, but especially in the lungs which progressively deteriorate. The past few years have seen massive progress in the medical treatment of cystic fibrosis. Drugs have come to market that correct the basic molecular defects that cause cystic fibrosis. These drugs are classified as “highly effective modulator therapies”. These therapies must be tailored to each person, by matching to the different mutations that cause cystic fibrosis. In 2019, a blend of three modulators was approved for treatment of the most common form of cystic fibrosis involving the “F508del” mutation. This therapy combines elexacaftor, tezacaftor, and ivacaftor (“ETI”). This therapy dramatically improves lung dysfunction in persons with cystic fibrosis due to F508del mutation. Persons with cystic fibrosis are at very high risk to develop diabetes. For example, those who have only have F508del mutation have an over 80% chance of developing diabetes by middle age. It is currently not known if ETI-therapy for cystic fibrosis will impact diabetes risk. To address this knowledge gap, investigators from 5 institutions conducted a study of twenty persons with cystic fibrosis. Each person underwent an oral glucose tolerance test before and roughly 10 months after starting ETI-therapy. Interestingly, there was not a significant change in glucose levels after starting ETI. However, C-peptide levels increased with ETI therapy, consistent increased insulin secretion. Accordingly, an insulin resistance index significantly increased as did body mass index. Taken together, these results suggest that ETI therapy produces a degree of insulin resistance, likely related to an increase in body mass index. The longer term impact of ETI and related therapies on diabetes risk and body weight will need careful ongoing study. The faculty investigators involved in the study from our division were Dr. Larson Ode and Dr. Norris. The publication describing the study and results can be found at this Pubmed link.
Therapies for cystic fibrosis are becoming far more effective, improving health and extending life for those with this genetic disease. Decades ago, most persons with cystic fibrosis often died before reaching reproductive capacity. Thankfully, this is no longer the case. For this reason, counseling about reproduction is thus more important than ever in this population. However, little is known about how often health care teams provide reproductive counseling for these patients. This is even more important, because pregnancy can have a highly adverse impact on health in those with cystic fibrosis. To better understand the issue, Dr. Katie Larson Ode and colleagues have reviewed medical charts of persons with cystic fibrosis. They found that most patients did not receive documented reproductive counseling. This highlights a potential gap in care that could be readily addressed. The results from the study have now been published in the journal Pediatric Pulmonology, and indexed in PubMed at this link.
Over the past decade, evidence has emerged indicating that high blood sugars in type 1 diabetes cause adverse brain changes in children. The adverse changes include abnormal brain structural alterations and reduced functioning on some cognitive tests. Over the past few years, hybrid closed-loop insulin pumps have become commercially available. These devices combine a continuous glucose monitor (CGM) with an insulin pump that is controlled by an algorithm that uses the CGM data to inform insulin delivery. The hybrid closed-loop insulin pumps aim to keep blood sugar in the low 100s (mg/dL). These systems can often improve average blood sugars and reduce the severity and frequency of low and high blood sugars. It is thus natural to ask whether the improved blood sugar control offered by a hybrid closed-loop insulin pumps might reduce the adverse brain effects of type 1 diabetes in children. Dr. Mike Tansey and Dr. Eva Tsalikian from our Division were among a small group of diabetes physicians across the United States who designed such a study to answer this very question. The initial results from the study were just published in the prestigious journal Nature Communications (click for PubMed link). Their randomized clinical study involved 42 adolescents with type 1 diabetes who were randomized to a hybrid closed-loop insulin pump versus conventional therapy. They were studied 6 months later, undergoing a brain MRI and cognitive testing. Although this study was considered a pilot trial, the results showed significantly less adverse impacts in those randomized to the hybrid closed-loop insulin pumps. The hybrid closed-loop insulin pump group performed better on a cognitive test of perceptual reasoning and had fewer abnormal structural brain changes. These results add to the growing evidence showing that excessive hyperglycemia is damaging to the developing brain during childhood. Thus study shows the important positive impact that hybrid closed-loop insulin pumps can make in improving blood sugar levels and long term outcomes in children with diabetes.
