Partial Degradation of Recombinant Antibody Functional Activity During Infant Gastrointestinal Digestion: Implications for Oral Antibody Supplementation

Ofatumumab-exposed breastfeeding in multiple sclerosis patients

BACKGROUND

In Europe, ofatumumab is approved for breastfeeding, but data on its transfer into breast milk and clinical experience are lacking.

OBJECTIVE

To analyze (1) health, development, and adverse events after live vaccination of ofatumumab-exposed breastfed infants and (2) detectability of ofatumumab in breast milk, and to calculate the relative infant dose (RID) using two methods, the traditional method and a second method considering maternal exposure to multiple ofatumumab doses and extended collection period.

METHODS

In this observational study, clinical data were collected by standardized telephone interviews up to 2 years postpartum. Breastmilk samples were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Twelve mothers started ofatumumab-exposed breastfeeding between 0.6 and 19.6 months postpartum. Infants showed neither abnormalities in infections, antibiotic use, or hospitalizations nor developmental delay. Five infants with available B cells had normal levels. Eight (66.7%) infants received live vaccines during/after exposed breastfeeding. None had complications. Ofatumumab concentration in breast milk varied widely between a median RID of average concentration 0.027% (range: 0.019%-0.115%) using method 1 and 2.912% (range: 1.301%-12.322%) using method 2.

CONCLUSION

Ofatumumab-exposed breastfeeding did not adversely affect infants' health or development. Despite higher RIDs using the more appropriate method 2, the risk of substantial antibody absorption by infants appears to be low.

Optimized Ultraviolet-C Processing Inactivates Pathogenic and Spoilage-Associated Bacteria while Preserving Bioactive Proteins, Vitamins, and Lipids in Human Milk

Holder pasteurization (HoP) enhances donor human milk microbiological safety but damages many bioactive milk proteins. Though ultraviolet-C irradiation (UV-C) can enhance safety while better preserving some milk proteins, it has not been optimized for dose or effect on a larger array of bioactive proteins. We determined the minimal UV-C parameters that provide >5-log reductions of relevant bacteria in human milk and how these treatments affect an array of bioactive proteins, vitamin E, and lipid oxidation. Treatment at 6000 and 12 000 J/L of UV-C resulted in >5-log reductions of all vegetative bacteria and bacterial spores, respectively. Both dosages improved retention of immunoglobulin A (IgA), IgG, IgM, lactoferrin, cathepsin D, and elastase and activities of bile-salt-stimulated lipase and lysozyme compared with HoP. These UV-C doses caused minor reductions in α-tocopherol but not γ-tocopherol and no increases in lipid oxidation products. UV-C treatment is a promising approach for donor human milk processing.

High accumulation of nivolumab in human breast milk: A case report

Nivolumab is an immunotherapeutic monoclonal antibody (mAb) that is used for the treatment of several types of cancer. The evidence on its use during lactation is lacking. Here, we report on a 39-year-old woman with metastasized melanoma who was treated with 480 mg nivolumab every four weeks during lactation. Breast milk samples were collected over the course of 34 days, including two cycles of nivolumab. The highest measured concentration of nivolumab during the first cycle was 503 ng/mL at day 13. The cumulative relative infant dose (RID) over the first cycle (28 days) was 9.8 %. The highest overall measured nivolumab concentration was 519 ng/mL at day 33, five days after administration of the second nivolumab cycle. Nivolumab seems to accumulate in breast milk over two consecutive cycles, hence the RIDs of consecutive cycles are expected to be higher. To draw further conclusions regarding safety of breastfeeding during nivolumab therapy, more information about the oral bioavailability of nivolumab in newborns, the nivolumab steady-state concentrations in breast milk and its pharmacodynamic effects are needed.

High-Pressure Processing of Human Milk: A Balance between Microbial Inactivation and Bioactive Protein Preservation

BACKGROUND

Donor human milk banks use Holder pasteurization (HoP; 62.5°C, 30 min) to reduce pathogens in donor human milk, but this process damages some bioactive milk proteins.

OBJECTIVES

We aimed to determine minimal parameters for high-pressure processing (HPP) to achieve >5-log reductions of relevant bacteria in human milk and how these parameters affect an array of bioactive proteins.

METHODS

Pooled raw human milk inoculated with relevant pathogens (Enterococcus faecium, Staphylococcus aureus, Listeria monocytogenes, Cronobacter sakazakii) or microbial quality indicators (Bacillus subtilis and Paenibacillus spp. spores) at 7 log CFU/mL was processed at 300-500 MPa at 16-19°C (due to adiabatic heating) for 1-9 min. Surviving microbes were enumerated using standard plate counting methods. For raw milk, and HPP-treated and HoP-treated milk, the immunoreactivity of an array of bioactive proteins was assessed via ELISA and the activity of bile salt-stimulated lipase (BSSL) was determined via a colorimetric substrate assay.

RESULTS

Treatment at 500 MPa for 9 min resulted in >5-log reductions of all vegetative bacteria, but <1-log reduction in B. subtilis and Paenibacillus spores. HoP decreased immunoglobulin A (IgA), immunoglobulin M (IgM), immunoglobulin G, lactoferrin, elastase and polymeric immunoglobulin receptor (PIGR) concentrations, and BSSL activity. The treatment at 500 MPa for 9 min preserved more IgA, IgM, elastase, lactoferrin, PIGR, and BSSL than HoP. HoP and HPP treatments up to 500 MPa for 9 min caused no losses in osteopontin, lysozyme, α-lactalbumin and vascular endothelial growth factor.

CONCLUSION

Compared with HoP, HPP at 500 MPa for 9 min provides >5-log reduction of tested vegetative neonatal pathogens with improved retention of IgA, IgM, lactoferrin, elastase, PIGR, and BSSL in human milk.

Formulation Studies to Develop Low-Cost, Orally-Delivered Secretory IgA Monoclonal Antibodies for Passive Immunization Against Enterotoxigenic Escherichia coli

Enterotoxigenic Escherichia coli (ETEC) is a common cause for diarrheal infections in children in low- and middle-income countries (LMICs). To date, no ETEC vaccine candidates have been approved. Passive immunization with low-cost, oral formulations of secretory IgA (sIgA) against ETEC is an alternative approach to protect high-risk populations in LMICs. Using a model sIgA monoclonal antibody (anti-LT sIgA2-mAb), the stability profiles of different formulations were assessed during storage and in in vitro digestion models (mimicking in vivo oral delivery). First, by employing various physicochemical techniques and a LT-antigen binding assay, three formulations with varying acid-neutralizing capacity (ANC) were evaluated to stabilize sIgA2-mAb during stress studies (freeze-thaw, agitation, elevated temperature) and during exposure to gastric phase digestion. Next, a low-volume, in vitro intestinal digestion model was developed to screen various additives to stabilize sIgA2-mAb in the intestinal phase. Finally, combinations of high ANC buffers and decoy proteins were assessed to collectively protect sIgA2-mAb during in vitro sequential (stomach to intestine) digestion. Based on the results, we demonstrate the feasibility of low-cost, 'single-vial', liquid formulations of sIgA-mAbs delivered orally after infant feeding for passive immunization, and we suggest future work based on a combination of in vitro and in vivo stability considerations.

Shaping infant development from the inside out: Bioactive factors in human milk

Human breast milk is the optimal nutrition for all infants and is comprised of many bioactive and immunomodulatory components. The components in human milk, such as probiotics, human milk oligosaccharides (HMOs), extracellular vesicles, peptides, immunoglobulins, growth factors, cytokines, and vitamins, play a critical role in guiding neonatal development beyond somatic growth. In this review, we will describe the bioactive factors in human milk and discuss how these factors shape neonatal immunity, the intestinal microbiome, intestinal development, and more from the inside out.

Persistence of Anti SARS-CoV-2 Antibodies in Breast Milk from Infected and Vaccinated Women after In Vitro-Simulated Gastrointestinal Digestion

Breastfeeding is key for infant development and growth. Breast milk contains different bioactive compounds including antibodies. Recent studies have demonstrated the presence of breast milk SARS-CoV-2 antibodies after maternal infection and vaccination. However, the potential impact on the infant has not been explored yet. As a first step, we aimed at assessing the potential persistence of SARS-CoV-2 IgA and IgG antibodies from infected and vaccinated women in the gastrointestinal tract of the infants by means of an in vitro-simulated gastrointestinal digestion approach. Breast milk samples from 10 lactating women receiving mRNA vaccination against SARS-CoV-2 (n = 5 with BNT162b2 mRNA and n = 5 with mRNA-1273) and also, COVID-19 infected (n = 5) were included. A control group with women with no exposure to the virus (n = 10 pre-pandemic) were also studied. The presence of IgA and IgG SARS-CoV-2 antibody levels was determined by ELISA after the gastric and intestinal stages. The impact of digested antibodies on infant gut microbiota was tested by simulating colonic fermentation with two different fecal inoculums: infants from vaccinated and non-vaccinated mothers. Specific gut microbial groups were tested by targeted qPCR. In vitro infant gastrointestinal digestion significantly decreased the levels of both anti-SARS-CoV-2 IgA and IgG. However, both remained resistant in all the study groups except in that evaluating breast milk samples from infected women, in which IgG was degraded below the cut-off values in the intestinal phase. No effect of the antibodies on microbiota were identified after digestion. In conclusion, antibody levels against SARS-CoV-2 are reduced after in vitro-simulated gastrointestinal tract but remain present, so a positive biological effect could be expected from this infant immunization pathway.

Effect of digestion on stability of palivizumab IgG1 in the infant gastrointestinal tract

BACKGROUND

Potentially, orally administered antibodies specific to enteric pathogens could be administered to infants to prevent diarrheal infections, particularly in developing countries where diarrhea is a major problem. However, to prevent infection, such antibodies would need to resist degradation within the gastrointestinal tract.

METHODS

Palivizumab, a recombinant antibody specific to respiratory syncytial virus (RSV), was used in this study as a model for examining the digestion of neutralizing antibodies to enteric pathogens in infants. The survival of this recombinant IgG1 across digestion in 11 infants was assayed via an anti-idiotype ELISA and RSV F protein-specific ELISA. Concentrations were controlled for any dilution or concentration that occurred in the digestive system using mass spectrometry-based quantification of co-administered, orally supplemented, indigestible polyethylene glycol (PEG-28).

RESULTS

Binding activity of Palivizumab IgG1 decreased (26-99%) across each phase of in vivo digestion as measured by both anti-idiotype and RSV F protein-specific ELISAs.

CONCLUSION

Antibodies generated for passive protection of the infant gastrointestinal tract from pathogens will need to be more resistant to digestion than the model antibody fed to infants in this study, or provided in higher doses to be most effective.

IMPACT

Binding activity of palivizumab IgG1 decreased (26-99%) across each phase of in vivo infant digestion as measured by both anti-idiotype and RSV F protein-specific ELISAs. Palivizumab was likely degraded by proteases and changes in pH introduced in the gut. Antibodies generated for passive protection of the infant gastrointestinal tract from pathogens will need to be more resistant to digestion than the model antibody fed to infants in this study, or provided in higher doses to be most effective. The monoclonal antibody IgG1 tested was not stable across the infant gastrointestinal tract. The observation of palivizumab reduction was unlikely due to dilution in the gastrointestinal tract. The results of this work hint that provision of antibody could be effective in preventing enteric pathogen infection in infants. Orally delivered recombinant antibodies will need to either be dosed at high levels to compensate for digestive losses or be engineered to better resist digestion. Provision of enteric pathogen-specific recombinant antibodies to at-risk infants could provide a new and previously unexplored pathway to reducing the infection in infants. The strategy of enteric recombinant antibodies deserves more investigation throughout medicine as a novel means for treatment of enteric disease targets.

Purification of Antibodies From Human Milk and Infant Digestates for Viral Inhibition Assays

Oral administration of enteric pathogen-specific immunoglobulins may be an ideal approach for preventing infectious diarrhea in infants and children. For oral administration to be effective, antibodies must survive functionally intact within the highly proteolytic digestive tract. As an initial step toward assessing the viability of this approach, we examined the survival of palivizumab, a recombinant monoclonal antibody (IgG1κ), across infant digestion and its ability to neutralize respiratory syncytial virus (RSV). Human milk and infant digestive samples contain substances known to interfere with the RSV neutralization assay (our selected functional test for antibody survival through digestion), therefore, antibody extraction from the matrix was required prior to performing the assay. The efficacy of various approaches for palivizumab purification from human milk, infant's gastric and intestinal digestates, including casein precipitation, salting out, molecular weight cut-off, and affinity chromatography (protein A and G) were compared. Affinity chromatography using protein G with high-salt elution followed by 30-kDa molecular weight cut-off centrifugal filtration was the most effective technique for purifying palivizumab from human milk and infant digestates with a high yield and reduced background interference for the viral neutralization assay. This work is broadly applicable to the optimal isolation of antibodies from human milk and infant digesta for viral neutralization assays, enables the examination of how digestion affects the viral neutralization capacity of antibodies within milk and digestive samples, and paves the way for assessment of the viability of oral administration of recombinant antibodies as a therapeutic approach to prevent enteric pathogen-induced infectious diarrhea in infants.