Peptide Characterization and Functional Stability of a Partially Hydrolyzed Whey-Based Formula over Time.

Human clinical trials have shown that a specific partially hydrolyzed 100% whey-based infant formula (pHF-W) reduces AD risk in the first yeast of life. Meta-analyses with a specific pHF-W (pHF-W1) confirm a protective effect while other meta-analyses pooling different pHF-W show conflicting results. Here we investigated the molecular composition and functional properties of the specific pHF-W1 as well as the stability of its manufacturing process over time. This specific pHF-W1 was compared with other pHF-Ws. We used size exclusion chromatography to characterize the peptide molecular weight (MW), a rat basophil degranulation assay to assess the relative level of beta-lactoglobulin (BLG) allergenicity and a preclinical model of oral tolerance induction to test prevention of allergic sensitization. To analyze the exact peptide sequences before and after an HLA binding assay, a mass cytometry approach was used. Peptide size allergenicity and oral tolerance induction were conserved across pHF-W1 batches of production and time. The median MW of the 37 samples of pHF-W1 tested was 800 ± 400 Da. Further oral tolerance induction was observed using 10 different batches of the pHF-W1 with a mean reduction of BLG-specific IgE levels of 0.76 log (95% CI = -0.95; -0.57). When comparing pHF-W1 with three other formulas (pHF-W2 3 and 4), peptide size was not necessarily associated with allergenicity reduction in vitro nor oral tolerance induction in vivo as measured by specific IgE level (p < 0.05 for pHF-W1 and 2 and p = 0.271 and p = 0.189 for pHF-W3 and 4 respectively). Peptide composition showed a limited overlap between the formulas tested ranging from 11.7% to 24.2%. Furthermore nine regions in the BLG sequence were identified as binding HLA-DR. In conclusion, not all pHF-Ws tested have the same peptide size distribution decreased allergenicity and ability to induce oral tolerance. Specific peptides are released during the different processes used by different infant formula producers.

Partially Hydrolysed Whey-Based Infant Formula Improves Skin Barrier Function.

Specific partially hydrolysed whey-based infant formulas (pHF-W) have been shown to decrease the risk of atopic dermatitis (AD) in infants. Historically, AD has been associated primarily with milk allergy; however, defective skin barrier function can be a primary cause of AD. We aimed to ascertain whether oral supplementation with pHF-W can improve skin barrier function. The effect of pHF-W was assessed on transepidermal water loss (TEWL) and antibody productions in mice epicutaneously exposed to Aspergillus fumigatus. Human primary keratinocytes were stimulated in vitro, and the expression of genes related to skin barrier function was measured. Supplementation with pHF-W in neonatal mice led to a significant decrease in TEWL and total IgE, but not in allergen-specific antibody levels. The whey hydrolysate was sufficient to decrease both TEWL and total IgE. Aquaporin-3 gene expression, linked with skin hydration, was modulated in the skin of mice and human primary keratinocytes following protein hydrolysate exposure. Skin barrier improvement may be an additional mechanism by which pHF-W may potentially reduce the risk of AD development in infants. Further human studies are warranted to confirm the clinical efficacy of these observations.

Systemic delivery of SapC-DOPS has antiangiogenic and antitumor effects against glioblastoma.

Saposin C-dioleoylphosphatidylserine (SapC-DOPS) nanovesicles are a nanotherapeutic which effectively target and destroy cancer cells. Here, we explore the systemic use of SapC-DOPS in several models of brain cancer, including glioblastoma multiforme (GBM), and the molecular mechanism behind its tumor-selective targeting specificity. Using two validated spontaneous brain tumor models, we demonstrate the ability of SapC-DOPS to selectively and effectively cross the blood-brain tumor barrier (BBTB) to target brain tumors in vivo and reveal the targeting to be contingent on the exposure of the anionic phospholipid phosphatidylserine (PtdSer). Increased cell surface expression of PtdSer levels was found to correlate with SapC-DOPS-induced killing efficacy, and tumor targeting in vivo was inhibited by blocking PtdSer exposed on cells. Apart from cancer cell killing, SapC-DOPS also exerted a strong antiangiogenic activity in vitro and in vivo. Interestingly, unlike traditional chemotherapy, hypoxic cells were sensitized to SapC-DOPS-mediated killing. This study emphasizes the importance of PtdSer exposure for SapC-DOPS targeting and supports the further development of SapC-DOPS as a novel antitumor and antiangiogenic agent for brain tumors.

Loss of T cell and B cell quiescence precedes the onset of microbial flora-dependent wasting disease and intestinal inflammation in Gimap5-deficient mice.

Homeostatic control of the immune system involves mechanisms that ensure the self-tolerance, survival and quiescence of hematopoietic-derived cells. In this study, we demonstrate that the GTPase of immunity associated protein (Gimap)5 regulates these processes in lymphocytes and hematopoietic progenitor cells. As a consequence of a recessive N-ethyl-N-nitrosourea-induced germline mutation in the P-loop of Gimap5, lymphopenia, hepatic extramedullary hematopoiesis, weight loss, and intestinal inflammation occur in homozygous mutant mice. Irradiated fetal liver chimeric mice reconstituted with Gimap5-deficient cells lose weight and become lymphopenic, demonstrating a hematopoietic cell-intrinsic function for Gimap5. Although Gimap5-deficient CD4(+) T cells and B cells appear to undergo normal development, they fail to proliferate upon Ag-receptor stimulation although NF-kappaB, MAP kinase and Akt activation occur normally. In addition, in Gimap5-deficient mice, CD4(+) T cells adopt a CD44(high)CD62L(low)CD69(low) phenotype and show reduced IL-7ralpha expression, and T-dependent and T-independent B cell responses are abrogated. Thus, Gimap5-deficiency affects a noncanonical signaling pathway required for Ag-receptor-induced proliferation and lymphocyte quiescence. Antibiotic-treatment or the adoptive transfer of Rag-sufficient splenocytes ameliorates intestinal inflammation and weight loss, suggesting that immune responses triggered by microbial flora causes the morbidity in Gimap5-deficient mice. These data establish Gimap5 as a key regulator of hematopoietic integrity and lymphocyte homeostasis.

Gfi1 integrates progenitor versus granulocytic transcriptional programming.

In patients with severe congenital neutropenia (SCN) and mice with growth factor independent-1 (Gfi1) loss of function, arrested myeloid progenitors accumulate, whereas terminal granulopoiesis is blocked. One might assume that Gfi-null progenitors accumulate because they lack the ability to differentiate. Instead, our data indicate that Gfi1 loss of function deregulates 2 separable transcriptional programs, one of which controls the accumulation and lineage specification of myeloid progenitors, but not terminal granulopoiesis. We demonstrate that Gfi1 directly represses HoxA9, Pbx1, and Meis1 during normal myelopoiesis. Gfi1-/- progenitors exhibit elevated levels of HoxA9, Pbx1 and Meis1, exaggerated HoxA9-Pbx1-Meis1 activity, and progenitor transformation in collaboration with oncogenic K-Ras. Limiting HoxA9 alleles corrects, in a dose-dependent manner, in vivo and in vitro phenotypes observed with loss of Gfi1 in myeloid progenitor cells but did not rescue Gfi1-/- blocked granulopoiesis. Thus, Gfi1 integrates 2 events during normal myeloid differentiation; the suppression of a HoxA9-Pbx1-Meis1 progenitor program and the induction of a granulopoietic transcription program.

Mutations in growth factor independent-1 associated with human neutropenia block murine granulopoiesis through colony stimulating factor-1.

Severe congenital neutropenia (SCN) is characterized by a deficiency of mature neutrophils, leading to recurrent bacterial and fungal infections. Although mutations in Elastase-2, neutrophil (ELA2) predominate in human SCN, mutation of Ela2 in mice does not recapitulate SCN. The growth factor independent-1 (GFI1) transcription factor regulates ELA2. Mutations in GFI1 are associated with human SCN, and genetic deletion of Gfi1 results in murine neutropenia. We examined whether human SCN-associated GFI1N382S mutant proteins are causal in SCN and found that GFI1 functions as a rate-limiting granulopoietic molecular switch. The N382S mutation inhibited GFI1 DNA binding and resulted in a dominant-negative block to murine granulopoiesis. Moreover, Gfi1N382S selectively derepressed the monopoietic cytokine CSF1 and its receptor. Gfi1N382S-expressing Csf1-/- cells formed neutrophils. These results reveal a common transcriptional program that underlies both human and murine myelopoiesis, and that is central to the pathogenesis of SCN associated with mutations in GFI1. This shared transcriptional pathway may provide new avenues for understanding SCN caused by mutations in other genes and for clinical intervention into human neutropenias.

Bim/Bcl-2 balance is critical for maintaining naive and memory T cell homeostasis.

We examined the role of the antiapoptotic molecule Bcl-2 in combating the proapoptotic molecule Bim in control of naive and memory T cell homeostasis using Bcl-2(-/-) mice that were additionally deficient in one or both alleles of Bim. Naive T cells were significantly decreased in Bim(+/-)Bcl-2(-/-) mice, but were largely restored in Bim(-/-)Bcl-2(-/-) mice. Similarly, a synthetic Bcl-2 inhibitor killed wild-type, but not Bim(-/-), T cells. Further, T cells from Bim(+/-)Bcl-2(-/-) mice died rapidly ex vivo and were refractory to cytokine-driven survival in vitro. In vivo, naive CD8(+) T cells required Bcl-2 to combat Bim to maintain peripheral survival, whereas naive CD4(+) T cells did not. In contrast, Bim(+/-)Bcl-2(-/-) mice generated relatively normal numbers of memory T cells after lymphocytic choriomeningitis virus infection. Accumulation of memory T cells in Bim(+/-)Bcl-2(-/-) mice was likely caused by their increased proliferative renewal because of the lymphopenic environment of the mice. Collectively, these data demonstrate a critical role for a balance between Bim and Bcl-2 in controlling homeostasis of naive and memory T cells.