Milk modulates macrophage polarization in vitro

Effects of human donor milk on gut barrier function and inflammation: in vitro study of the beneficial properties to the newborn

Introduction

The gastrointestinal and immune systems of premature infants are not fully developed, rendering them more vulnerable to severe complications like necrotizing enterocolitis. Human milk offers a rich array of bioactive factors that collectively contribute to reducing the incidence of gut infections and inflammatory conditions. When a mother's milk is unavailable, preterm infants are often provided with donor human milk processed in Human Milk Banks. However, it remains uncertain whether pasteurized milk confers the same level of risk reduction as unprocessed milk. This uncertainty may stem from the well-documented adverse effects of heat treatment on milk composition. Yet, our understanding of the comprehensive impact on protective mechanisms is limited.

Methods

In this study, we conducted a comparative analysis of the effects of raw versus pasteurized milk and colostrum versus mature milk on cellular functions associated with the gut epithelial barrier and responses to inflammatory stimuli. We utilized THP-1 and HT-29 cell lines, representing monocyte/macrophages and gut epithelial cells, respectively.

Results

Our observations revealed that all milk types stimulated epithelial cell proliferation. However, only raw colostrum increased cell migration and interfered with the interaction between E. coli and epithelial cells. Furthermore, the response of epithelial and macrophage cells to lipopolysaccharide (LPS) was enhanced solely by raw colostrum, with a milder effect observed with mature milk. In contrast, both raw and pasteurized milk diminished the LPS induced response in monocytes. Lastly, we examined how milk affected the differentiation of monocytes into macrophages, finding that milk reduced the subsequent inflammatory response of macrophages to LPS.

Discussion

Our study sheds light on the impact of human milk on certain mechanisms that potentially account for its protective effects against necrotizing enterocolitis, highlighting the detrimental influence of pasteurization on some of these mechanisms. Our findings emphasize the urgency of developing alternative pasteurization methods to better preserve milk properties. Moreover, identifying the key components critically affected by these protective mechanisms could enable their inclusion in donor milk or formula, thereby enhancing immunological benefits for vulnerable newborns.

Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.

Flavonoids from Dalbergia cochinchinensis: Impact on osteoclastogenesis

Background/purpose

Dalbergia cochinchinensi has been widely used in traditional medicine because of its flavonoids. This study examined which components in D. cochinchinensis were capable of reducing or even stimulating the formation of bone-resorbing osteoclasts.

Materials and methods

We have isolated subfamilies of chalcones (isoliquiritigenin, butein), flavones (7-hydroxy-6-methoxyflavone) and neoflavanoids (5-methoxylatifolin), and performed an in vitro bioassay on osteoclastogenesis. The flavonoids were tested for their potential to change the expression of tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CTSK) in murine bone marrow cultures being exposed to RANKL, M-CSF and TGF-β1 using RT-PCR, histochemistry and immunoassay.

Results

We could confirm that isoliquiritigenin and butein significantly lower the expression of TRAP and CTSK in this setting. Moreover, histochemistry supported the decrease of TRAP by the chalcones. We further observed a trend towards an increase of osteoclastogenesis in the presence of 5-methoxylatifolin and 7-hydroxy-6-methoxyflavone, particular in bone marrow cultures being exposed to RANKL and M-CSF. Consistently, the anti-inflammatory activity was restricted to isoliquiritigenin and butein in murine RAW 264.7 inflammatory macrophages stimulated by lipopolysaccharide (LPS). With respect to osteoblastogenesis, neither of the flavonoids but butyrate, a short chain fatty acid, increased the osteogenic differentiation marker alkaline phosphatase activity in ST2 murine mesenchymal cells.

Conclusion

We have identified two flavonoids from D. cochinchinensis with a potential pro-osteoclastogenic activity and confirm the anti-osteoclastogenic activity of isoliquiritigenin and butein.

TGF-β Signalling Mediates the Anti-Inflammatory Activity of Enamel Matrix Derivative In Vitro

Enamel matrix derivative (EMD) prepared from extracted porcine fetal tooth material can support the regrow of periodontal tissues. Previous findings suggest that EMD has anti-inflammatory properties and TGF-β activity in vitro. However, the anti-inflammatory activity of EMD is mediated via TGF-β has not been considered. To this aim, we first established a bioassay to confirm the anti-inflammatory activity of EMD. The bioassay was based on the RAW 264.7 macrophage cell line and proven with primary macrophages where EMD significantly reduced the forced expression of IL-6. We then confirmed the presence of TGF-β1 in EMD by immunoassay and by provoking the Smad2/3 nuclear translocation in RAW 264.7 macrophages. Next, we took advantage of the TGF-β receptor type I kinase-inhibitor SB431542 to block the respective signalling pathway. SB431542 reversed the anti-inflammatory activity of EMD and TGF-β in a bioassay when IL-6 and CXCL2 expression was driven by the LPS stimulation of RAW 264.7 macrophages. This central observation was supported by showing that SB431542 reversed the anti-inflammatory activity of EMD using IL-1β and TNF-α-stimulated ST2 bone marrow stromal cells. Together, these findings implicate that the TGF-β activity mediates at least part of the anti-inflammatory activity of EMD in vitro.

Damaged Mesenchymal Cells Dampen the Inflammatory Response of Macrophages and the Formation of Osteoclasts

Damage to mesenchymal cells occurs by dental implant drills as a consequence of shear forces and heat generation. However, how the damaged mesenchymal cells can affect the polarization of macrophages and their differentiation into osteoclastogenesis is not fully understood. To simulate cell damage, we exposed suspended ST2 murine bone marrow stromal cells to freeze/thawing or sonication cycles, followed by centrifugation. We then evaluated the lysates for their capacity to modulate lipopolysaccharide-induced macrophage polarization and RANKL-MCSF-TGF-β-induced osteoclastogenesis. We report that lysates of ST2, particularly when sonicated, greatly diminished the expression of inflammatory IL6 and COX2 as well as moderately increased arginase 1 in primary macrophages. That was confirmed by lysates obtained from the osteocytic cell line IDG-SW3. Moreover, the ST2 lysate lowered the phosphorylation of p65 and p38 as well as the nuclear translocation of p65. We further show herein that lysates of damaged ST2 reduced the formation of osteoclast-like cells characterized by their multinuclearity and the expression of tartrate-resistant phosphatase and cathepsin K. Taken together, our data suggest that thermal and mechanical damage of mesenchymal cells causes the release of as-yet-to-be-defined molecules that dampen an inflammatory response and the formation of osteoclasts in vitro.

Dalbergiones lower the inflammatory response in oral cells in vitro

Objectives

Periodontitis is a global health burden that underlines the demand for anti-inflammatory treatment. Dalbergia melanoxylon being a rich source of flavonoids has been widely used in traditional medicine but the potential anti-inflammatory activity of its dalbergiones remains to be shown.

Material and methods

We have isolated 3′-hydroxy-4,4′-dimethoxydalbergione, 4-methoxydalbergione, and 4′-hydroxy-4-methoxydalbergione from Dalbergia melanoxylon and tested their potential anti-inflammatory activity.

Results

All dalbergiones are potent inhibitors of an LPS-induced inflammatory response of RAW 264.7 macrophages. This is specified by IL1β and IL6 production, and the p65 nuclear translocation. Consistently, in primary macrophages, the dalbergiones caused an M1-to-M2 polarization switch indicated by the decreased ration of IL1β and IL6 versus arginase 1 and YM1 expression. To implement oral cells, we have used gingival fibroblasts exposed to IL1β and TNFα. Consistently, all dalbergiones reduced the expression of IL6 and IL8 as well as the nuclear translocation of p65.

Conclusion

These findings increase the accumulating knowledge on dalbergiones and extend it towards its capacity to lower the inflammatory response of oral cells.

Clinical relevance

These findings are another piece of evidence that supports the use of herbal medicine to potentially lower inflammatory events related to dentistry.

Heartwood of Dalbergia cochinchinensis: 4,7,2'-Trihydroxy-4'-methoxyisoflavanol and 6,4'-Dihydroxy-7-methoxyflavane Reduce Cytokine and Chemokine Expression In Vitro

Dalbergia cochinchinensis has been widely used in traditional medicine because of its flavonoids; however, the impact of the flavonoids to modulate the inflammatory response to oral cells remains to be described. For this aim, we isolated 4,7,2'-trihydroxy-4'-methoxyisoflavanol (472T4MIF) and 6,4'-dihydroxy-7-methoxyflavane (64D7MF) from the heartwood of D. cochinchinensis and confirmed the chemical structure by nuclear magnetic resonance. We show here that both flavonoids are inhibitors of an inflammatory response of murine RAW 264.7 inflammatory macrophages stimulated by LPS. This is indicated by interleukin (IL)1, IL6, and chemokine CCL2 production besides the phosphorylation of p65. Consistently, in primary murine macrophages, both flavonoids decreased the inflammatory response by lowering LPS-induced IL1 and IL6 expression. To introduce oral cells, we have used human gingival fibroblasts and provoked the inflammatory response by exposing them to IL1β and TNFα. Under these conditions, 472T4MIF, but not 64D7MF, reduced the expression of chemokines CXCL1 and CXCL2. Taken together, we identified two flavonoids that can reduce the expression of cytokines and chemokines in macrophages and fibroblastic cells.

Anti-Inflammatory Activity of a Demineralized Bone Matrix: An In Vitro Pilot Study

Demineralized bone matrix (DBM) is commonly used for the reconstruction of bone defects. Early graft consolidation involves a transient inflammatory process. It is, however, unclear whether DBM can modulate this process. To test this possibility, we prepared acid lysates of demineralized ground cortical (DGC) and moldable demineralized fibers (MDF). Murine RAW 264.7 and primary bone marrow macrophages were exposed to acid lysates of DGC and MFD prior to provoking an inflammatory response with lipopolysaccharide (LPS). Similarly, murine ST2 mesenchymal cells were exposed to DGC and MFD with and without interleukin 1β (IL1) and TNFα. We show here that acid lysates of DGC and MFD reduced the expression of IL1 and IL6 in RAW 264.7 macrophages, as determined by RT-PCR and, for IL6, by immunoassay. This response was confirmed with primary macrophages. Likewise, desalted acid lysates exert anti-inflammatory properties on RAW 264.7 cells and in ST2 cells, the forced expression of IL6, inducible nitric oxide synthase (iNOS) and chemokine ligand 5 (CCL5) was reduced. These in vitro findings suggest that DGC and MFD lower the inflammation-induced expression of inflammatory mediators in murine cell-based bioassays.

RNAseq of TGF-β receptor type I kinase-dependent genes in oral fibroblast exposed to milk

Background

Milk is a rich source of natural growth factors that may support oral tissue homeostasis and wound healing. We had shown earlier that blocking TGF-β receptor type I kinase with the inhibitor SB431542 abolished the expression of IL11 and other genes in human gingival fibroblasts exposed to the aqueous fraction of milk. Our aim was to identify the entire signature of TGF-β receptor type I kinase-dependent genes regulated by the aqueous fraction of human milk.

Result

RNAseq revealed 99 genes being strongly regulated by milk requiring activation of the SB431542-dependent TGF-β receptor type I kinase. Among the SB431542-dependent genes is IL11 but also cadherins, claudins, collagens, potassium channels, keratins, solute carrier family proteins, transcription factors, transmembrane proteins, tumor necrosis factor ligand superfamily members, and tetraspanin family members. When focusing on our candidate gene, we could identify D609 to suppress IL11 expression, independent of phospholipase C, sphinosine-1 phosphate synthesis, and Smad-3 phosphorylation and its nuclear translocation. In contrast, genistein and blocking phosphoinositide 3-kinases by wortmannin and LY294002 increased the milk-induced IL11 expression in gingival fibroblasts.

Conclusion

Taken together, our data revealed TGF-β receptor type I kinase signaling to cause major changes of the genetic signature of gingival fibroblasts exposed to aqueous fraction of human milk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01913-5.

Classical Dichotomy of Macrophages and Alternative Activation Models Proposed with Technological Progress

Macrophages are important immune cells that participate in the regulation of inflammation in implant dentistry, and their activation/polarization state is considered to be the basis for their functions. The classic dichotomy activation model is commonly accepted, however, due to the discovery of macrophage heterogeneity and more functional and iconic exploration at different technologies; some studies have discovered the shortcomings of the dichotomy model and have put forward the concept of alternative activation models through the application of advanced technologies such as cytometry by time-of-flight (CyTOF), single-cell RNA-seq (scRNA-seq), and hyperspectral image (HSI). These alternative models have great potential to help macrophages divide phenotypes and functional genes.

Macrophages and the maintenance of homeostasis

There have been many chapters written about macrophage polarization. These chapters generally focus on the role of macrophages in orchestrating immune responses by highlighting the T-cell-derived cytokines that shape these polarizing responses. This bias toward immunity is understandable, given the importance of macrophages to host defense. However, macrophages are ubiquitous and are involved in many different cellular processes, and describing them as immune cells is undoubtedly an oversimplification. It disregards their important roles in development, tissue remodeling, wound healing, angiogenesis, and metabolism, to name just a few processes. In this chapter, we propose that macrophages function as transducers in the body. According to Wikipedia, “A transducer is a device that converts energy from one form to another.” The word transducer is a term used to describe both the “sensor,” which can interpret a wide range of energy forms, and the “actuator,” which can switch voltages or currents to affect the environment. Macrophages are able to sense a seemingly endless variety of inputs from their environment and transduce these inputs into a variety of different response outcomes. Thus, rather than functioning as immune cells, they should be considered more broadly as cellular transducers that interpret microenvironmental changes and actuate vital tissue responses. In this chapter, we will describe some of the sensory stimuli that macrophages perceive and the responses they make to these stimuli to achieve their prime directive, which is the maintenance of homeostasis.