extract on alleviating lipopolysaccharide-induced acute mastitis in protecting the blood-milk barrier and reducing inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

According to ancient literature, Prunella vulgaris L. (P vulgaris) alleviates mastitis and has been used in China for many years; however, there are no relevant reports that confirm this or the mechanism of its efficacy.

AIM OF THE STUDY

To explore the anti-acute mastitis effect and potential mechanism of P vulgaris extract.

MATERIALS AND METHODS

First, the active ingredients and targets of P vulgaris against mastitis were predicted using network pharmacology. Next, the relevant active ingredients were enriched using macroporous resins and verified using UV and UPLC-Q-TOF-MS/MS. Lastly, a mouse model of acute mastitis was established by injecting lipopolysaccharides into the mammary gland and administering P vulgaris extract by oral gavage. The pathological changes in mammary tissue were observed by HE staining. Serum and tissue inflammatory factors were measured by ELISA method. MPO activity in mammary tissue was measured using colorimetry and MPO expression was detected by immunohistochemistry. The expression of tight junction proteins (ZO-1, claudin-3, and occludin) in mammary tissue was detected by immunofluorescence and Western blot. iNOS and COX-2 in mammary tissue were detected by Western blot. MAPK pathway and NF-κB pathway related proteins were also detected by Western blot.

RESULTS

Network pharmacology predicted that phenolic acids and flavonoids in P vulgaris had anti-mastitis effects. The contents of total flavonoids and total phenolic acids in P vulgaris extract were 64.5% and 29.4%, respectively. UPLC-Q-TOF-MS/MS confirmed that P vulgaris extract contained phenolic acids and flavonoids. The results of animal experiments showed that P vulgaris extract reduced lipopolysaccharide-induced inflammatory edema, inflammatory cell infiltration, and interstitial congestion of mammary tissue. It also reduced the levels of serum and tissue inflammatory factors TNF-α, IL-6, and IL-1β, and inhibited the activation of MPO. Furthermore, it downregulated the expression of MAPK and NF-κB pathway-related proteins. The expressions of ZO-1, occludin, and claudin-3 in mammary gland tissues were upregulated.

CONCLUSIONS

P vulgaris extract can maintain the integrity of mammary connective tissue and reduce its inflammatory response to prevent acute mastitis. Its mechanism probably involves regulating NF-κB and MAPK pathways.

Hesperetin regulates the intestinal flora and inhibits the TLR4/NF-κB signaling axis to protect the blood-milk barrier and prevent mastitis

The World Health Organization recommends breastfeeding for 6 months, but mastitis, a common disease during lactation, presents a major obstacle to fulfilling this recommendation. Maternal nutrient intake during lactation has been shown to be related to mastitis. Therefore, this study aimed to explore the effect of hesperetin, a phytonutrient, on mastitis. The oral administration of hesperetin to lipopolysaccharide (LPS)-induced mastitis mice alleviated their pathological damage, reduced the secretion of pro-inflammatory cytokines, and maintained the integrity of their blood-milk barrier. Moreover, our results showed that oral administration of hesperetin regulates the composition of the intestinal flora of mice. Fecal microbial transplantation (FMT) from the mice of hesperetin group alleviated LPS-induced mastitis in recipient mice. In additional, hesperetin attenuated the inflammatory response and increased the expression of tight junction proteins (TJs) in LPS-stimulated mouse mammary epithelial cells (mMECs). Through network pharmacological analysis and further research, we demonstrated hesperetin inhibits the expression of TLR4 and the activation of NF-κB signaling. In conclusion, hesperetin protects the blood-milk barrier and improve mastitis by regulating intestinal flora and inhibiting the activation of TLR4/NF-κB signaling axis. This study provides a theoretical basis for lactating females to consume hesperetin as a supplement to prevent mastitis and maintain mammary health.

Intramammary administration of lipopolysaccharides at parturition enhances immunoglobulin concentration in goat colostrum

In newborn ruminants, transfer of passive immunity is essential to obtain protection against pathogens. This study aimed to increase the permeability of the blood-milk barrier using intramammary lipopolysaccharides (LPS) in goats at parturition to modulate colostrum composition. Twenty multiparous Majorera dairy goats were randomly allocated in one of the two experimental groups. The LPS group (n = 10) received an intramammary administration (IA) of saline (2 mL) containing 50 µg of LPS from Escherichia coli (O55:B5) in each half udder at parturition. The control group (n = 10) received an IA of saline (2 mL). Rectal temperature (RT) was recorded, and a blood sample was collected at parturition (before IA). In addition, RT was measured, and blood and colostrum/milk samples were collected on day (d) 0.125 (3 hours), 0.5 (12 hours), 1, 2, 4, 7, 15 and 30 relative to the IA. Goat plasma immunoglobulin G (IgG) and M (IgM) and serum β-hydroxybutyrate, glucose, calcium, free fatty acids, lactate dehydrogenase and total protein concentrations were determined. Colostrum and milk yields as well as chemical composition, somatic cell count (SCC), IgG and IgM concentrations were measured. The MIXED procedure (SAS 9.4) was used, and the model included the IA, time, and the interaction between both fixed effects. Statistical significance was set as P < 0.05. Goats from the LPS group showed higher RT on d 0.125, 0.5 and 4 relative to the IA compared to the control group (PIA×Time = 0.007). Goat serum biochemical variables and plasma IgG and IgM concentrations were not affected by the IA. Colostrum and milk yield as well as chemical composition were not affected by the IA, except for milk lactose percentage that was lower in the LPS group compared to the control group (4.3 ± 0.08 and 4.6 ± 0.08%, respectively PIA = 0.026). Colostrum SCC was higher in the LPS group than in the control group (3.5 ± 0.09 and 3.1 ± 0.09 cells × 106/mL, respectively; PIA = 0.011). Similarly, milk SCC increased in the LPS group compared to the control group (PIA = 0.004). The LPS group showed higher IgG (PIA = 0.044) and IgM (PIA = 0.037) concentrations on colostrum than the control group (31.9 ± 4.8 and 19.0 ± 4.8 mg/mL, 0.8 ± 0.08 and 0.5 ± 0.08 mg/mL, respectively). No differences in milk IgG and IgM concentrations between groups were observed. In conclusion, the IA of LPS at parturition increases RT, SCC and IgG and IgM concentrations in colostrum without affecting either yield or chemical composition.

Taurine reduction of injury from neutrophil infiltration ameliorates Streptococcus uberis-induced mastitis

Mastitis is a common disease of dairy cows characterized by infiltration of leukocytes, especially neutrophils, resulting in increased permeability of the blood-milk barrier (BMB). Taurine, a functional nutrient, has been shown to have anti-inflammatory and antioxidant effects. Here, we investigated the regulatory effects and mechanisms of taurine on the complex immune network of the mammary gland in Streptococcus uberis (S. uberis) infection. We found that taurine had no direct effect on CXCL2-mediated neutrophil chemotaxis. However, it inhibited MAPK and NF-κB signalings by modulating the activity of TAK1 downstream of TLR2, thereby reducing CXCL2 expression in macrophages to reduce neutrophil recruitment in S. uberis infection. Further, the AMPK/Nrf2 signaling pathway was activated by taurine to help mitigate oxidative damage, apoptosis and disruption of tight junctions in mammary epithelial cells caused by hypochlorous acid, a strong oxidant produced by neutrophils, thus protecting the integrity of the mammary epithelial barrier. Taurine protects the BMB from damage caused by neutrophils via blocking the macrophage-CXCL2-neutrophil signaling axis and increasing the antioxidant capacity of mammary epithelial cells.

Phytosphingosine alleviates Staphylococcus aureus-induced mastitis by inhibiting inflammatory responses and improving the blood-milk barrier in mice

Mastitis is one of the common diseases in dairy cows which threatens the health of cows and impacts on economic benefits seriously. Recent studies have been showed that Subacute Ruminal Acidosis (SARA) increased the susceptibility of cow mastitis. SARA leads the disturbance of the rumen microbiota, and the rumen bacterial disordered community is an important endogenous factor of cow mastitis. That is to say, cows which suffer from SARA have a disordered rumen microbiota, a prolonged decline in ruminal PH and a high level of lipopolysaccharide (LPS) in the rumen, blood. Therefore, ruminal metabolism is closely related to the rumen microbiota. However, the specific mechanism of SARA and mastitis still not clear. We found an intestinal metabolite according to the metabonomics, which is correlated to inflammation. Phytophingosine (PS), a product from rumen fluid and milk of the cows which suffer from SARA and mastitis. It has the effect of killing bacteria and anti-inflammatory. Emerging evidences indicate that PS can alleviate inflammatory diseases. However, how PS affects mastitis is largely unknown. In this study, we explored the concrete role of PS on Staphylococcus aureus (S. aureus) -induced mastitis in mice. We found that PS obviously decreased the level of the proinflammatory cytokines. Meanwhile, PS also significantly relieved the mammary gland inflammation caused by S. aureus and restored the function of the blood-milk barrier. Here, we showed that PS increased the expression of the classic Tight-junctions (TJs) proteins including ZO-1, Occludin and Claudin-3. Moreover, PS improves S. aureus-induced mastitis by inhibiting the activation of the NF-κB and NLRP3 signaling pathways. These data indicated that PS relieved S. aureus-induced mastitis effectively. This also provides a reference for exploring the correlation between the intestinal metabolism and inflammation.

Maslinic acid alleviates LPS-induced mice mastitis by inhibiting inflammatory response, maintaining the integrity of the blood-milk barrier and regulating intestinal flora

Mastitis occurs frequently in breastfeeding women and not only affects the women's health but also hinders breastfeeding. Maslinic acid is a type of pentacyclic triterpenoid widely found in olives that has good anti-inflammatory activity. This study aims to discuss the protective function of maslinic acid against mastitis and its underlying mechanism. For this, mice models of mastitis were established using lipopolysaccharide (LPS). The results revealed that maslinic acid reduced the pathological lesions in the mammary gland. In addition, it reduced the generation of pro-inflammatory factors and enzymes (IL-6, IL-1β, TNF-α, iNOS, and COX2) in both mice mammary tissue and mammary epithelial cells. The high-throughput 16S rDNA sequencing of intestinal flora showed that in mice with mastitis, maslinic acid treatment altered β-diversity and regulated microbial structure by increasing the abundance of probiotics such as Enterobacteriaceae and downregulating harmful bacteria such as Streptococcaceae. In addition, maslinic acid protected the blood-milk barrier by maintaining tight-junction protein expression. Furthermore, maslinic acid downregulated mammary inflammation by inhibiting the activation of NLRP3 inflammasome, AKT/NF-κB, and MAPK signaling pathways. Thus, in a mice model of LPS-induced mastitis, maslinic acid can inhibit the inflammatory response, protect the blood-milk barrier, and regulate the constitution of intestinal flora.

Exposure to ZnO nanoparticles induced blood-milk barrier dysfunction by disrupting tight junctions and cell injury

Zinc oxide nanoparticles (ZnO-NPs) are one of the most widely used nanomaterials with excellent chemical and biological properties. However, their widespread application has led to increased risk to the natural environment and public health. A growing number of studies have shown that ZnO-NPs deposited in target organs interact with internal barriers to trigger injurious responses. The underlying mechanism of ZnO-NPs on the blood-milk barrier dysfunction remains to be understood. Our results revealed that excessive accumulation of ZnO-NPs induced histopathological injuries in the mammary gland, leading to the distribution of ZnO-NPs in the milk of lactating mice. A prominent diffusion of blood-milk barrier permeability marker, albumin-fluorescein isothiocyanate conjugate (FITC-albumin) was observed at cell-cell junction after ZnO-NPs exposure. Meanwhile, ZnO-NPs weakened the blood-milk barrier function by altering the expression of tight junction proteins. The excessive accumulation of ZnO-NPs also induced inflammatory response by activating the NF-κB and MAPK signaling pathways, leading to the dysfunctional blood-milk barrier. Furthermore, we found that ZnO-NPs led to increased iron accumulation and lipid oxidation, thus increasing oxidative injury and ferroptosis in mammary glands. These results indicated that ZnO-NPs weaken the integrity of the blood-milk barrier by directly affecting tight junctions and cellular injury in different ways.

Taurine protects blood-milk barrier integrity via limiting inflammatory response in Streptococcus uberis infections

Streptococcus uberis (S. uberis) is an important causative agent of mastitis, leading to significant economic losses to dairy industry. This research used a mouse mastitis model to investigate the protective effects of taurine on mammary inflammatory response and blood-milk barrier integrity in S. uberis challenge. The results showed that taurine attenuated S. uberis-induced mammary histopathological changes, especially neutrophil infiltration. The S. uberis-induced expression of pro-inflammatory mediators were decreased significantly by taurine. Further, we demonstrated that taurine limited the S. uberis-induced inflammatory responses via inhibiting the activation of NF-κB and MAPK signaling pathways. Inflammation usually disrupts the mammary barrier system. The recovery of claudin-3 and occludin expressions indicated that attenuation of inflammatory response by taurine can protect the integrity of blood-milk barrier in S. uberis infection. Taken together, our results reveal that the development of taurine as an effective prevention and control strategy for S. uberis-induced mastitis.

DNase I improves blood-milk barrier integrity and alleviates inflammation induced by Staphylococcus aureus during mastitis

Mastitis is an inflammation of mammary gland, which directly affects the milk production performance and causes huge economic losses in the dairy industry. During mastitis, the blood-milk barrier (BMB) loses its integrity and aggravates the severity of mastitis. Exogenous DNase I has been exerted protective effects in different model of tissue injury. Here, we designed a study to investigate the effects of DNase I on inflammation and BMB in a mice model of Staphylococcus aureus-induced mastitis. In the model, we found that DNase I treatment significantly alleviated the inflammatory response through decrease of inflammatory cells in mammary alveoli, MPO activity and cytokines in mammary gland. Furthermore, immunofluorescent staining and western blotting demonstrated that exogenous DNase I obviously reduced BMB permeability and changed the expression of tight junction proteins to support the re-establishment of the barrier integrity. Mechanismly, DNase I treatment inhibited NF-κB and enhanced AKT signaling pathways. Therefore, our results indicate that DNase I may be an effective treatment for attenuating mastitis.

Kynurenic acid protects against mastitis in mice by ameliorating inflammatory responses and enhancing blood-milk barrier integrity

Mastitis is one of the most serious diseases in humans and animals, especially in the modern dairy industry. Seeking safe and effective mastitis prevention strategies is urgent since food safety and drug residues in milk remain an enormous concern, despite the contribution of antibiotics to control mastitis. Kynurenic acid (KYNA), derived from the kynurenine pathway of tryptophan metabolism, has been shown to exhibit anti-inflammatory and immunomodulatory effects in many diseases. Recently, it was reported that impaired KYNA levels were associated with mastitis. However, the physiological role of KYNA in mastitis has not yet been elucidated. Therefore, the aim of this study was to investigate the protective role of KYNA in pathogen-induced mastitis in mice, as well as the underlying mechanism of this effect. We first evaluated the effects of KYNA on LPS-induced mastitis in mice. Additionally, the underlying anti-inflammatory mechanism of KYNA was investigated in mammary epithelial cells (MMECs). Furthermore, we examined the effects of KYNA on S. aureus and E. coli induced mastitis in mice. Our results demonstrated that KYNA alleviated LPS-induced mastitis by reducing inflammatory responses and enhancing blood-milk barrier integrity. The fundamental mechanisms involved the inhibition of NF-κB and activation of Nrf2/Ho-1, which is probably mediated by G protein-coupled receptor 35 but not aryl hydrocarbon receptor. Notably, KYNA also protected against S. aureus and E. coli induced mastitis in mice. In conclusion, our results highlight the role of KYNA in mastitis and serve as a basis for using endogenous metabolite as a novel preventative or therapeutic strategy for disease intervention.

Sodium propionate protect the blood-milk barrier integrity, relieve lipopolysaccharide-induced inflammatory injury and cells apoptosis

AIMS

Sodium propionate (SP) has been reported to possess an anti-inflammatory and anti-apoptotic potential by inhibiting certain signaling pathways and helps in reducing the pathological damages of the mammary gland. However, the effects of sodium propionate on attenuating Lipopolysaccharide (LPS)-induced inflammatory condition and cell damage in bovine mammary epithelial cells (bMECs) are not comprehensively studied yet. Therefore, the aim of the current investigation was to evaluate the protective effects of sodium propionate on LPS-induced inflammatory conditions and to clarify the possible underlying molecular mechanism in bMECs.

MAIN METHODS

The effects of increasing doses of SP on LPS-induced inflammation, oxidative stress and apoptosis was studied in vitro. Furthermore, the underlying protective mechanisms of SP on LPS-stimulated bMECs was investigated under different experimental conditions.

KEY FINDINGS

The results reveled that increased inflammatory cytokines, chemokines and those of tight junction's mRNA expression was significantly attenuated dose-dependently by propionate. Biochemical analysis revealed that propionate pretreatment modulated the LPS-induced intercellular reactive oxygen species (ROS) accumulation, oxidative and antioxidant factors and apoptosis rate. Furthermore, we investigated that the LPS activated nuclear factor-kB (NF-kB), caspase/Bax apoptotic pathways and Histone deacetylases (HDAC) was significantly attenuated by propionate in bMECs.

SIGNIFICANCE

Our results suggest that sodium propionate is a potent agent for ameliorating LPS-mediated cellular disruption and limiting detrimental inflammatory responses, partly via maintaining blood milk barrier integrity, inhibiting HDAC activity and NF-kB signaling pathway.

Toxic effects of TiO2 NPs in the blood-milk barrier of the maternal dams and growth of offspring

Titanium dioxide nanoparticles (TiO₂ NPs) are amongst the most frequently used nanomaterial in everyday consumer products, and their widespread applications have raised concerns of the consequent deleterious effects on human health, particularly to vulnerable populations, such as lactating females remains elusive. Therefore, this study was initiated to investigate the detrimental effects and toxic mechanisms induced by TiO₂ NPs in maternal dams and offspring during the lactation period. Dams were randomly divided into three groups. The water (Control; Group I) and TiO₂ NPs (100 mg/kg; Group II) were orally administered from postnatal day 1-20, respectively. The results indicated that TiO₂ NPs could cause toxicity in the dams, such as pathological damages to mammary gland tissues. The excessive accumulation of TiO₂ NPs could induce oxidative stress in the mammary gland, leading to the dysfunctional blood-milk barrier; besides, TiO₂ NPs could also be transferred to offspring via breastfeeding, causing abnormal development of infant. We further accessed the possible underlying molecular mechanism; for this, we orally administered TiO₂ NPs with vitamin E (100 mg/kg; Group III). The results revealed that toxicity induced by TiO₂ NPs was rescued. Collectively, this study presented the deleterious pathological effects of oral exposure to TiO₂ NPs in the mammary gland tissues and blood-milk barrier via the production of reactive oxygen species (ROS) in dams and developmental concerns in offspring. However, the administration of VE could mitigate the toxic effects induced by the TiO₂ NPs.

Dual effects of JNK activation in blood-milk barrier damage induced by zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) have been extensively applied in our daily life. Humans are at high risk of being exposed to ZnO-NPs, which induce potentially adverse health effects. Although a growing number of studies have investigated the toxic effects of ZnO-NPs, the available data concerning ZnO-NP interactions with the blood-milk barrier (BMB) remain highly limited. Herein, we systematically investigated the damage to BMB integrity induced by ZnO-NPs and the mechanisms involved. ZnO-NPs that were intravenously injected into lactating dams accumulated in the mammary gland and entered into the breast milk, inducing disruption to BMB integrity and changes in the tight junction (TJ) and adherens junction (AJ) components. Furthermore, using an in vitro BMB model composed of EpH4-Ev cells, we verified that ZnO-NP-triggered ROS generation and the activation of MKK4 and JNK are the main mechanism of cell-cell junction damage. More interestingly, JNK activation played different roles in inducing changes in the TJ and AJ complex, and these effects did not need to activate the downstream c-Jun. These data provide more information for understanding ZnO-NP interactions with the BMB and raise concern for the daily use and the intravenous use of ZnO-NPs by lactating mothers.

Gambogic acid alleviates inflammation and apoptosis and protects the blood-milk barrier in mastitis induced by LPS

Mastitis is one of the most common diseases among dairy cows. There is still much debate worldwide as to whether antibiotic therapy should be given to dairy cows, or if natural products should be taken as a substitute for antibacterial therapy. As the antibiotic treatment leads to the bacterial resistance and drug residue in milk, introducing natural products for mastitis is becoming a trend. This study investigates the mechanisms of the protective effects of the natural product gambogic acid (GA) in lipopolysaccharide (LPS)-induced mastitis. For in vitro treatments, it was found that GA reduced IL-6, TNF-α, and IL-1β levels by inhibiting the phosphorylation of proteins in the nuclear factor κB (NF-κB) and the mitogen-activated protein kinase (MAPK) pathway. GA also maintained a stable membrane mitochondrial potential and inhibited the overproduction of reactive oxygen species, which protected the cells from apoptosis. On the other hand, in vivo treatments with GA were found to reduce pathological symptoms markedly, and protected the blood-milk barrier from damage induced by LPS. The results demonstrate that GA plays a vital role in suppressing inflammation, alleviating the apoptosis effect, and protecting the blood-milk barrier in mastitis induced by LPS. Thus, these results suggest that the natural product GA plays a potential role in mastitis treatment.

Targeting gut microbiota as a possible therapy for mastitis

Mastitis, a disease that affects both dairy herds and humans, is recognized as the most common source of losses in the dairy industry. Antibiotics have been used for years as the primary treatment for mastitis. However, abuse of antibiotics has led to the emergence of resistant strains and the presence of drug residues and has increased the difficulty of curing this disease. In addition, antibiotics kill most of the microbes that are present in the digestive tract, leading to imbalances in the gut microbiome and destruction of the ecosystem that is normally present in the gut. Gut microbiota play an important role in the host's health and could be considered the "second brain" of the body. In recent years, the gut microbiota and their metabolites, including lipopolysaccharide (LPS) and short-chain fatty acids (SCFAs), have been shown to participate in the development of mastitis. LPS is the main component of the cell walls of gram-negative bacteria. Overproduction of rumen-derived LPS injures the rumen epithelium, resulting in the entry of LPS into the blood and damaged liver function; once in the blood, it circulates into the mammary gland, increasing blood-barrier permeability and leading to mammary gland inflammation. SCFAs, which are produced by gut microbiota as fermentation products, have a protective effect on mammary gland inflammatory responses and help maintain the function of the blood-milk barrier. Recently, increasing attention has been focused on the use of probiotics as a promising alternative for the treatment of mastitis. This review summarizes the effects of the gut microbiome and its metabolites on mastitis as well as the current of probiotics in mastitis. This work may provide a valuable theoretical foundation for the development of fresh ideas for the prevention and treatment of mastitis.