Ask Joanna Melia, MD, what her biggest practice challenge is, and she’d say the need for more precision medicine in inflammatory bowel disease.
Gastroenterologists have more treatments at their disposal today than ever before, particularly in the last decade. “We have had tremendous advances in many areas of understanding contributors to disease,” said Dr. Melia, an assistant professor of medicine at Johns Hopkins Medicine in Baltimore who specializes in inflammatory bowel disease (IBD). But the hurdle is in translating the science to clinical care that is individualized to each patient based on condition and stage of the condition.
Dr. Joanna Melia
“That still remains a bit of a dream,” she said. Much of her career has been devoted to chasing down a particular genetic variant that contributes to IBD, with the goal of reaching more precise treatments for patients.
In an interview, she shared how she entered this line of work, and what her research has revealed about Crohn’s disease, manganese, and a common genetic variant known as ZIP8.
Q: Your expertise is in inflammatory bowel disease and manganese deficiency. Why did you choose these two areas as your focus in GI?
Dr. Melia: In talking to many patients with IBD, I was always struck by the questions around nutritional factors related to disease. As a fellow, I was embedded in a lab that focused on genetics of IBD. A micronutrient transporter, ZIP8, has a mutation in it that increases the risk of Crohn’s disease.
I’ve dedicated the last 8 years to understanding how this mutation can increase risk. It initially started out as a project focused on zinc, because that’s what the transporter was thought to regulate. However, it’s evolved as we’ve learned more about it, underscoring the importance of manganese, another micronutrient that we derive from food.
We have established that having this mutation changes how the body handles manganese and affects downstream processes that involve manganese. What I’m doing now is trying to connect those dots on why those processes are important in Crohn’s disease and whether we can target them for treatment.
Q: How does manganese deficiency lead to chronic IBD?
Dr. Melia: In individuals with this mutation, their blood manganese levels are lower than people who don’t have this mutation. When we talk about manganese deficiency or insufficiency, what we’re really talking about is lower blood levels. But it’s more complicated than that at the tissue level.
What we and other groups are working on right now is trying to understand if the manganese levels change in the gut and what happens in inflammation. The gut is a particularly interesting area for manganese, in that much of the manganese that we eat is excreted. We only absorb a small amount of it. And so, manganese levels within the gut lumen may actually be quite high – and may be even higher in inflammation. But there are things we don’t understand about that and how it relates to mucosal levels of manganese and Crohn’s disease. The ileum, the site of the Crohn’s disease that’s specifically associated with this mutation, might be particularly sensitive to changes in the manganese levels or the downstream processes that changing manganese availability affects.
One of those processes is glycosylation. Manganese is important to properly glycosylate your proteins. Many enzymes help cells put sugars on proteins, and many of those enzymes need manganese to do it. Glycosylation of proteins is important so cells know where those proteins should go, and the sugars help them stay where they need to be. When you change protein glycosylation, you can stress the cells. We know individuals who carry this mutation have changes in the glycosylation of their proteins. What we’re working on right now is understanding which key proteins might change when that happens, and why that’s a potential problem, especially in the ileum.
Q: How might your research inform clinical practice?
Dr. Melia: We’ve seen significant progress in new medications and new pathways that have emerged. We still have this fundamental problem that our immune-targeting medicines are only helping about 50% of the patients.
It’s critical that we begin to identify new pathways. And my hope is that in studying genes like the ZIP8 (SLC39A8), which is associated with the dysregulated processing of manganese, we can understand different pathways and mechanisms to target.
As an example, if we could help correct the glycosylation problem, that would help to boost the barrier function of the gut and perhaps decrease the activation of those immune cells, because you’re just reinforcing the barrier integrity of the gut.
We want to target that glycosylation problem as we would treat patients with congenital disorders of glycosylation by giving supplemental sugars. We think this problem of glycosylation extends beyond patients with the ZIP8 mutation, but it is also really important for patients with the mutation. So, the goal would be to use ZIP8 genetics to help prioritize patients for therapy targeting this problem.
Q: You’re involved in the American Gastroenterological Association Future Leaders Program. What is your role in this program? Why is it important?
Dr. Melia: I was very grateful for the opportunity to participate in the AGA’s Future Leaders Program. I think it was exceedingly valuable for two main reasons. One, it really offered an insight into the role of the AGA and the important role that the AGA plays in the careers of gastroenterologists. Two, it was such a unique opportunity to work with colleagues nationwide and to build a network of individuals who are all at a similar stage in their careers. It was a very inspiring group to meet and to have the opportunity to work with as part of that program, and I thank the AGA for supporting such an initiative.
Q: What teacher or mentor had the greatest impact on you?
Dr. Melia: I have been blessed by many clinical and research mentors through my career. I was inspired to do science at the lab of Ramnik Xavier, MD, at Massachusetts General Hospital. At Johns Hopkins, I credit Cindy Sears, MD, and Anne Marie O’Broin Lennon, MBBCh, PhD, as two physician scientists who have really shaped how I have tried to integrate my clinical and research career.
LIGHTNING ROUND
Do you prefer texting or talking?
Texting
If you weren’t a gastroenterologist, what would you be?
Teacher
What was the last movie you watched?
Great Bear Rainforest
What is your most favorite city in the U.S.?
Surry, Maine
What song do you absolutely have to sing along with when you hear it?
Any song by Whitney Houston.
Are you an introvert or extrovert?
Introvert
How many cups of coffee do you drink per day?
One
Summary content
7 Key Takeaways
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Developed a paper-based colorimetric sensor array for chemical threat detection.
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Can detect 12 chemical agents, including industrial toxins.
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Production cost is under 20 cents per chip.
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Utilizes dye-loaded silica particles on self-adhesive paper.
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Provides rapid, simultaneous identification through image analysis.
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Inspired by the mammalian olfactory system for pattern recognition.
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Future developments include a machine learning-enabled reader device.
The guidelines emphasize four-hour gastric emptying studies over two-hour testing. How do you see this affecting diagnostic workflows in practice?
Dr. Staller: Moving to a four-hour solid-meal scintigraphy will actually simplify decision-making. The two-hour reads miss a meaningful proportion of delayed emptying; standardizing on four hours reduces false negatives and the “maybe gastroparesis” purgatory that leads to repeat testing. Practically, it means closer coordination with nuclear medicine (longer slots, consistent standardized meal), updating order sets to default to a four-hour protocol, and educating front-line teams so patients arrive appropriately prepped. The payoff is fewer equivocal studies and more confident treatment plans.
Metoclopramide and erythromycin are the only agents conditionally recommended for initial therapy. How does this align with what is being currently prescribed?
Dr. Staller: This largely mirrors real-world practice. Metoclopramide remains the only FDA-approved prokinetic for gastroparesis, and short “pulsed” erythromycin courses are familiar to many of us—recognizing tachyphylaxis limits durability. Our recommendation is “conditional” because the underlying evidence is modest and patient responses are heterogeneous, but it formalizes what many clinicians already do: start with metoclopramide (lowest effective dose, limited duration, counsel on neurologic adverse effects) and reserve erythromycin for targeted use (exacerbations, bridging).
Several agents, including domperidone and prucalopride, received recommendations against first-line use. How will that influence discussions with patients who ask about these therapies?
Dr. Staller: Two points I share with patients: evidence and access/safety. For domperidone, the data quality is mixed, and US access is through an FDA IND mechanism; you’re committing patients to EKG monitoring and a non-trivial administrative lift. For prucalopride, the gastroparesis-specific evidence isn’t strong enough yet to justify first-line use. So, our stance is not “never,” it’s just “not first.” If someone fails or cannot tolerate initial therapy, we can revisit these options through shared decision-making, setting expectations about benefit, monitoring, and off-label use. The guideline language helps clinicians have a transparent, evidence-based conversation at the first visit.
The guidelines suggest reserving procedures like G-POEM and gastric electrical stimulation for refractory cases. In your practice, how do you decide when a patient is “refractory” to medical therapy?
Dr. Staller: I define “refractory” with three anchors.
1. Adequate trials of foundational care: dietary optimization and glycemic control; an antiemetic; and at least one prokinetic at appropriate dose/duration (with intolerance documented if stopped early).
2. Persistent, function-limiting symptoms: ongoing nausea/vomiting, weight loss, dehydration, ER visits/hospitalizations, or malnutrition despite the above—ideally tracked with a validated instrument (e.g., GCSI) plus nutritional metrics.
3. Objective correlation: delayed emptying on a standardized 4-hour solid-meal study that aligns with the clinical picture (and medications that slow emptying addressed).
At that point, referral to a center with procedural expertise for G-POEM or consideration of gastric electrical stimulation becomes appropriate, with multidisciplinary evaluation (GI, nutrition, psychology, and, when needed, surgery).
What role do you see dietary modification and glycemic control playing alongside pharmacologic therapy in light of these recommendations?
Dr. Staller: They’re the bedrock. A small-particle, lower-fat, calorie-dense diet—often leaning on nutrient-rich liquids—can meaningfully reduce symptom burden. Partnering with dietitians early pays dividends. For diabetes, tighter glycemic control can improve gastric emptying and symptoms; I explicitly review medications that can slow emptying (e.g., opioids; consider timing/necessity of GLP-1 receptor agonists) and encourage continuous glucose monitor-informed adjustments. Pharmacotherapy sits on top of those pillars; without them, medications will likely underperform.
The guideline notes “considerable unmet need” in gastroparesis treatment. Where do you think future therapies or research are most urgently needed?
Dr. Staller: I see three major areas.
1. Truly durable prokinetics: agents that improve emptying and symptoms over months, with better safety than legacy options (e.g., next-gen motilin/ghrelin agonists, better-studied 5-HT4 strategies).
2. Endotyping and biomarkers: we need to stop treating all gastroparesis as one disease. Clinical, physiologic, and microbiome/omic signatures that predict who benefits from which therapy (drug vs G-POEM vs GES) would transform care.
3. Patient-centered trials: larger, longer RCTs that prioritize validated symptom and quality-of-life outcomes, include nutritional endpoints, and reflect real-world medication confounders.
Our guideline intentionally highlights these gaps to hopefully catalyze better trials and smarter referral pathways.
Dr. Staller is with the Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston.