A mammal’s first source of nutrients comes from milk. Filled with proteins, sugars, lipids, antibodies, cells, hormones, and prebiotics, milk provides the necessary nourishment to help babies develop into healthy adults (1). But scientists have discovered that milk components are not just important for child development; they can have therapeutic effects too.

Low weight babies fed breast milk have a reduced risk of death and of acquiring a dangerous gastrointestinal disease called necrotizing enterocolitis (2). Breastfeeding associates with a decreased risk of diarrheal disease and infections in infants as well as improved brain connectivity in preterm infants (3-4). While the beneficial effects of breast milk for infants is clear, many scientists wondered if some components of human milk might also benefit adults.

“If we think about infancy as the most vulnerable time period in human existence, we can come up with a thesis that the selective pressure would be highest for compounds to have beneficial, protective, or potentially even interventional effects,” said Alex Martinez, the leader and cofounder of Intrinsic Medicine, a company that develops therapeutics for a variety of diseases based on sugars found in human milk.

Betting on the link between the beneficial effects of breastfeeding on neurological development, researchers now investigate milk-derived compounds for treating neurological conditions as far afield as anxiety and depression in adults to brain injuries in preterm infants.

Peptides for stress and depression

For the team of researchers at Lactocore, a Boston-based company focused on designing milk-derived therapies, peptides are the future of mental health treatment. Research in rats revealed that the milk protein lactoferrin relieved maternal separation stress in pups and fear-induced stress in adult rats (5,6). The fact that milk proteins had an effect in adult rats as well as in young ones intrigued Anton Malyshev, the leader and cofounder of Lactocore. He wondered if other milk-derived proteins could help relieve stress and other mental health conditions in adults.

“We tested different types of those casein-derived and general milk-derived peptides, and we discovered that they actually play a big role in this mother-to-child interaction [in rodents],” Malyshev said. “We found out that they can modulate other behavioral patterns like anxiety or mood in newborns, but also in grown up rats.”

Malyshev and his team decided to target voltage-gated calcium channels and GABA_A receptors because they are important targets for current antianxiety and antidepressant medications. Working with a team of molecular biologists and computational scientists, the researchers at Lactocore used docking technology to identify a binding site on the voltage-gated calcium channels and the GABA_A receptor. They then used proprietary algorithms to screen milk-derived peptides with the highest binding affinities for the receptor proteins and identified one they called LCGA-17 (7).

When the researchers administered LCGA-17 to zebrafish or mice in stressful situations, the peptide reduced the animals’ anxiety behaviors. For example, zebrafish prefer dark spaces, so when the researchers administered LCGA-17, the fish spent more time in the anxiety-inducing light tank than they did without LCGA-17. Rats with chronic stress have fewer social interactions with other rats, but when the researchers gave them LCGA-17, the stressed rats engaged in more social behavior than untreated ones.

In a follow-up study, the team demonstrated that when they delivered LCGA-17 intranasally to rats with post-traumatic stress disorder or depression, the compound had antianxiety and antidepressive effects (8). Malyshev was encouraged by the beneficial effects of intranasal administration of LCGA-17.

Malyshev hopes that these milk-derived peptides will be easy for people with stress related disorders to take “because sometimes it's even hard to take a pill or several pills during the day,” he said. 

He and his team are optimizing the formulation of LCGA-17 for intranasal delivery and performing pharmacology and toxicology studies. To further refine LCGA-17 for eventual tests in clinical trials, the researchers are taking advantage of their Reptide platform, an AI-powered system that makes small modifications to the natural milk-derived peptide to optimize it for stability, solubility, and other factors.

“We strongly hope that we can bring LCGA-17 as a new way to any person who experiences a lot of stress,” said Malyshev. “You can fully enjoy your life, your work, your relationships.”

A spoonful of sugar

Rather than go after milk proteins, Martinez and his team of researchers at Intrinsic Medicine are all about the sugars: human milk oligosaccharides (HMOs). In children, HMOs from breast milk help establish the infant immune system and gut microbiome as well as prevent infections (9). Martinez wondered if these safe and shelf-stable compounds might also benefit adult humans, particularly as an untapped source of therapeutics for complex diseases.

“We could look to nature, and perhaps we can look in an evolutionary context to identify compounds capable of modulating some of these underlying drivers of these disorders,” said Martinez.

He and the researchers at Intrinsic Medicine identified three promising HMOs for their potential to treat various complex disorders including irritable bowel syndrome, arthritis, atopic dermatitis, autism, and pain.

The researchers focus on two HMOs in particular, compounds they named OM001 and OM003, for their ability to relieve the social stress associated with autism. Preclinical data suggest that these two HMOs might act by affecting gut bacteria, which communicate with the brain via gut-nervous system connections. Martinez and his team are eager to explore the potential of these molecules further.

Until recent advances in technology enabled isolating and producing large quantities of them, it was difficult for scientists studying HMOs to get enough material to perform the experiments they needed to do. But new analytical tools and technologies have accelerated the pace of HMO research. 

“Our scientific understanding of human biology is really enabling a second look at compounds that have been explored for nearly a century,” said Martinez. “This gives us a new lens to view human milk oligosaccharides and to really fully understand their natural adaptive context, and I think it's really always exciting when evolution helps you understand your own biology.”

A lipid just for neonates

When his wife went into labor three months early, Eric Benner, now a neonatologist and neuroscientist at Duke University and cofounder of Tellus Therapeutics, had never even heard of the Neonatal Intensive Care Unit (NICU). That harrowing family event ignited his interest in neonatal health and improving outcomes for this vulnerable population of children.

Because preterm babies have not finished developing by the time they are born, they can suffer from severe complications. For example, babies in the NICU have strokes at same rate as adults do, but because they’re still developing, strokes affect preemies differently.

When Benner told one of the faculty members leading his neonatal-perinatal fellowship his goals for his neonatal research, “he just kind of chuckled and said, ‘You know, we don't do novel drug development in babies. We get hand-me-down drugs.’ And so I went back to the call room and went into a rapid state of depression thinking that I'd completely messed up my career. Nothing I was going to do in the lab was ever going to be translated into children,” said Benner.

Determined to find a way to develop new treatments for this vulnerable population, Benner focused on the main concern for neonatal treatment: safety. He started looking at everything infants were regularly exposed to, and he realized that breast milk was the perfect place to start. Numerous studies demonstrated that breastfeeding improved neurodevelopmental outcomes in premature newborns (4, 10), so Benner and his team at Duke started investigating the potential therapeutic effects of breast milk components.

They started with white matter injury, which results in a loss of myelination in the brain and is the most common brain injury in preterm infants. The injury has no treatment and can only be diagnosed by magnetic resonance imaging. Because of this, the earliest a doctor can diagnose white matter injury is when the baby reaches term (37 weeks of gestational age). Often, though, doctors only catch white matter injury when babies fail to reach their four-to-six-month developmental milestones.

“It's a double hit for the parents. Not only do they have to survive the NICU, which is a traumatic experience in and of itself — they may very well leave the NICU thinking that they dodged a bullet,” said Benner. “Then to find out six months later that they didn't escape that bullet that they thought they did, I think can be very traumatic for families.”

White matter injury typically occurs before 32 weeks gestation when immature oligodendrocytes, the cells that myelinate neurons in the brain, are very sensitive to inflammation and oxidative stress. If the oligodendrocytes encounter inflammation, they degenerate, leaving the child with low numbers of these cells. Often the oligodendrocytes that remain have difficulty maturing and properly myelinating neurons.

During this same developmental period, preterm infants possess many neural stem cells in the brain. Benner came across research from other groups showing that derivatives of cholesterol called oxysterols, which are natural components of breast milk, activate the Sonic hedgehog signaling pathway (11). 

“An endogenous cholesterol derivative that could stimulate the Sonic hedgehog pathway had, at least on paper, the potential to improve myelination in babies,” said Benner.

Benner teamed up with his friend and fellow neuroscientist, Jason Kralic, to found Tellus Therapeutics to develop TT-20, their breast milk-derived cholesterol derivative, into the first therapy designed specifically for neonates.

“Our therapy is targeting those neural stem cells, and it really triggers those neural stem cells to produce new waves of oligodendrocytes,” said Benner. “If babies have an inflammatory disease that eliminates a lot of those oligodendrocytes, then afterwards, we can treat them with a compound that generates essentially replacement oligodendrocytes.”

The researchers at Tellus Therapeutics have tested TT-20 in numerous animal models, and they’re excited about the results they have so far. They are working on pharmacology, toxicology, and pharmacokinetics studies with the plan to file an investigational new drug application within the next year and a half.

Benner hopes that other research groups will see the unmet need for treatments in the neonatal population and develop therapies for diseases that affect children from birth throughout their entire lives.

“My hope as a neonatologist is that this will be a new era in neonatal medicine,” said Benner. “Instead of just supporting carers, supporting babies, and crossing our fingers and hoping for the best, we'll be able to do things that increase the chance of good outcomes in these kids.”

References

1. Ballard, O. & Morrow, A. L. Human Milk Composition. Pediatric Clinics of North America  60, 49-74 (2013).
2. Meinzen-Derr, J. et al. Role of human milk in extremely low birth weight infants’ risk of necrotizing enterocolitis or death. J Perinatol  29, 57-62 (2009).
3. Bernardo L. Horta. Breastfeeding: Investing in the Future. Breastfeeding Medicine S-11-12 (2019).
4. Blesa, M. et al. Early breast milk exposure modifies brain connectivity in preterm infants. NeuroImage  184, 431-439 (2019).
5. Takeuchi, T. et al. Opioid mediated suppressive effect of milk-derived lactoferrin on distress induced by maternal separation in rat pups. Brain Research  979, 216-224 (2003).
6. Kamemori, N. et al. Suppressive effects of milk-derived lactoferrin on psychological stress in adult rats. Brain Research  1029, 34-40 (2004).
7. Malyshev, A.V. et al. In silico Screening and Behavioral Validation of a Novel Peptide, LCGA-17, With Anxiolytic-Like Properties. Frontiers in Neuroscience15 (2021).
8. Malyshev, A.V. et al. Peptide LCGA-17 Attenuates Behavioral and Neurochemical Deficits in Rodent Models of PTSD and Depression. Pharmaceuticals15, 462 (2022).
9. Wici?ski, M. et al. Human Milk Oligosaccharides: Health Benefits, Potential Applications in Infant Formulas, and Pharmacology. Nutrients  12, 266 (2020).
10. Vohr, B.R. et al. Beneficial Effects of Breast Milk in the Neonatal Intensive Care Unit on the Developmental Outcome of Extremely Low Birth Weight Infants at 18 Months of Age. Pediatrics 118, e115-e123 (2006).
11. Corcoran, R.B. & Scott, M.P. Oxysterols stimulate Sonic hedgehog signal transduction and proliferation of medulloblastoma cells. Proc Natl Acad Sci U S A 103, 8408-13 (2006).