Srinu Reddi

Transepithelial transport of milk derived bioactive peptide VLPVPQK

The transepithelial transport of an antioxidative and ACE inhibitory peptide, VLPVPQK (named peptide C) derived from casein hydrolysates was investigated along with extensively studied opioid peptide β-casomorphin using a human intestinal cell (Caco-2) monolayer. The susceptibility to the brush-border peptidases and route of transepithelial transport were observed to be the primary factors influencing the transport of these peptides. The apical to basal transport mechanism was studied using bradykinin as control as it shows resistance to cellular peptidases and its route of transepithelial transport had been established. VLPVPQK and BCM 5 were hydrolyzed by cellular peptidases while bradykinin was found intact. The transport of VLPVPQK (1.0%) was found to be relatively much higher than BCM 5 (0.03%) and bradykinin (0.1%). Interestingly the effect of some inhibitors on the transport of VLPVPQK suggested involvement of PepT1 like transporters/SOPT2 while BCM 5, its hydrolytic product and bradykinin were suggested to be transported mainly via the intracellular transcytosis pathway.

Akt drives buffalo casein-derived novel peptide-mediated osteoblast differentiation

Milk is a potential nutraceutical with wide range of bioactive compounds that are antioxidative, antimicrobial, antithrombotic, immunomodulatory, opioid and antihypertensive. Various intervention studies with milk reflect its stupendous role in elevating bone mineral density. Milk and milk products have shown a preventive effect in bone loss during pre- and postmenopausal women. Since, milk is proved to have a vital role in bone health promotion, there is a need to identify bioactive compounds within it. Recently we have reported four novel peptides from milk casein for their osteoblast proliferation activity. Their role in differentiation and the signaling cascade evoked by them have not been studied. Thus, the present study has been designed to investigate the differentiation potential and signaling cascade of one of the novel peptides, that is, NAVPITPTL by analyzing osteoblast differentiation markers such as alkaline phosphatase activity, osteocalcin and mineral deposition. All the experimentations suggested a significant role of this peptide in osteoblast differentiation. The inhibitor studies, immunocytochemistry and immunoblotting have proven that the peptide-induced differentiation through pAkt signaling cascade as pAkt was observed in nucleus. Moreover, the peptide was found to be bioaccessible up to 1%.

Protective effects of casein-derived peptide VLPVPQK against hydrogen peroxide-induced dysfunction and cellular oxidative damage in rat osteoblastic cells.

Oxidative stress inhibits osteoblast differentiation and function that lead to the development of osteoporosis. Casein-derived peptide VLPVPQK (PEP), a potent antioxidant, was isolated from β-casein of buffalo milk. We used an in vitro oxidative stress model induced by hydrogen peroxide (H2O2) in rat osteoblastic cells to investigate the protective effects of PEP against H2O2-induced dysfunction and oxidative damage. Cells were pretreated with PEP (50–200 ng/mL) for 2, 7 or 21 days followed by 0.3 mM H2O2 treatment for 24 h and then markers of osteogenic development, oxidative damage and apoptosis were examined. PEP significantly increased the viability and differentiation markers of osteoblast cells such as alkaline phosphatase and calcium mineralization. Moreover, PEP suppressed the production of reactive oxygen species (ROS), lipid peroxidation and ameliorated H2O2-induced reduction in glutathione, superoxide dismutase and catalase activities. In addition, PEP partially inhibited caspase-9 and-3 activities and reduced propidium iodide–positive cells. Altogether, our results demonstrated that PEP could protect rat osteoblast against H2O2-induced dysfunction and oxidative damage by reduction of ROS production, lipid peroxidation and increased antioxidant enzyme activities. Thus, our data suggest that PEP might be a valuable protective agent against oxidative stress–related diseases such as osteoporosis.

Neutrophil gene dynamics and plasma cytokine levels in dairy cattle during peri-implantation period

Neutrophils being the first line of cellular defense show significant difference in their expression in pregnant (P) and non-pregnant (NP) cows during the peri-implantation period. To study these changes, blood samples were collected from cows coming in heat and brought for artificial insemination (AI) on day 0 (day of AI), 4, 8, 12, 14, 16, 18, 21, 24, 30 and 40 day post-AI. Pregnancy was confirmed by observing non-return of heat, progesterone assay and ultrasonography. Cows were then categorized into pregnant (n=10) and non-pregnant (n=10) groups. Blood neutrophils were isolated and plasma samples collected from both P and NP cows during this period. RNA from neutrophils was isolated and studied for gene expression of adhesion molecules (CD62L, CD11b), chemokine (IL-8), and interferon stimulated genes (ISG15, OAS1, MX1, MX2, IFI16 and IFI44) using qRT-PCR. Adhesion molecules along with IL-8 showed a higher expression in NP cows. Expression of IFI16 was up-regulated as early as day 8, whereas, that of ISG15, OAS1, MX1 and MX2 were up-regulated on days 12-21 post-AI in P cows. Highest expression was shown by OAS1 on day 18 and by ISG15 and MX2 on day 21 post-AI in P cows. Pro-inflammatory cytokines (TNFα and IL-8) were higher, whereas, anti-inflammatory cytokine (IL-10) levels were lower in plasma samples isolated from NP cows. Our study indicates that blood neutrophils are sensitive to implantation signals received from the conceptus and may play an important role in implantation of the developing conceptus.

Fermented milk with probiotic Lactobacillus rhamnosus S1K3 (MTCC5957) protects mice from salmonella by enhancing immune and nonimmune protection mechanisms at intestinal mucosal level.

We investigated the mechanism by which an Indian indigenous probiotic culture, Lactobacillus rhamnosus S1K3, could overcome the pathogenic strain Salmonella enterica with an emphasis on the response at the intestinal mucosal level after long-term (30days) consumption. S1K3 was able to produce antimicrobial compounds against the pathogens. The probiotic adhered strongly to intestinal epithelium and maintained its integrity in presence of Salmonella through stimulation of tight junction and antimicrobial peptide genes in vitro. Mice prefed for 30days with S1K3-fermented milk exhibited low incidence of pathogenic Salmonella at mucosal and systemic levels. The probiotic induced TLRs transcripts at the Peyers patches, followed by an increase in the Secretory-IgA in intestinal fluid, the IgA-secreting cells in lamina propria of small intestine and the IgA level in serum. Moreover, S1K3 maintained the protein level of IL-12, increased the IL-4 and reduced the TGF-β level in intestinal fluid/serum at the later stage of infection. All these actions concurred to lower the count of Salmonella in feces, its invasion in spleen, liver and intestine tissues and improved the health status of probiotic-fed group. In view of this performance, S1K3 appears to be a suitable candidate for the development of nutraceutical food.

Interferon-tau stimulated gene expression: A proxy to predict embryonic mortality in dairy cows

The embryonic mortality in cows is a growing concern for an ever-expanding dairy industry. The current study was an attempt to shorten the open period of dairy cows having suffered embryonic loss by diagnosing them at an earlier stage. The blood samples were collected from the Karan Fries (KF) cows on days 0 (day of AI/estrus), 4, 8, 12, 14, 16, 18, 21, 24, 28, 35 and 42 post insemination. The experimental animals were then categorized into pregnant (P), conception failure/early embryonic mortality (EEM) and late embryonic mortality cows (LEM), based on progesterone assay, ultrasonography and per-rectal palpation. There were 6 animals in each group. The plasma progesterone was higher in pregnant than EEM and LEM cows. Plasma Interferon-tau concentration was significantly (p < 0.05) lower in LEM than pregnant cows where it could be detected from day 14-21 but was non-detectable in EEM cows. The mRNA expression of ISG15, OAS1, MX1 and MX2 in blood neutrophils was significantly (p < 0.05) higher from day 8-42 as against day 0 in pregnant cows. The highest expression was observed around day 18-21 in pregnant cows. The ISG15, OAS1, MX1 and MX2 mRNA expression was significantly (p < 0.05) higher from day 4-42 as compared to day 0 in LEM cows, whereas in EEM cows the expression stayed close to that of day 0 (1.00 ± 0.00). The mRNA expression of ISG15, OAS1, MX1 and MX2 started to decline from day 24 onwards. The degree of expression of Interferon-tau stimulated genes was higher in pregnant and LEM cows than EEM cows. The study reveals that the Interferon tau stimulated gene expression in neutrophils can act as peripheral biomarkers for detecting the embryonic mortality in dairy cows.

Buffalo casein derived peptide can alleviates H2O2 induced cellular damage and necrosis in fibroblast cells

Oxidative stress is one of a critical pathogenic factor in the progression of aging and chronic diseases such as cancer, myocardial inflammation and diabetes. In the present scenario, peptides with short half life and more biological specificities are gaining much attention as prodrugs. Thus, the present investigation carried out to screen potential antioxidative peptide, VLPVPQK to cope with the cellular oxidative damage. Our results showed that treatment of rat fibroblast cells with 0.2mM H2O2 for 6h significantly declined different oxidative stress biomarkers such as SOD, CAT, GSH, and promoted LDH activity. In addition, ROS and TNF-α levels were also increased upon H2O2 exposure for 6h and thereby, it induced cell death. Amazingly, pretreatment of the peptide (VLPVPQK) significantly elevated cell survivability, by reversing all H2O2 induced alterations in fibroblast cells. Therefore, our results indicated that, the peptide (VLPVPQK) acted as a potential cytoprotective agent, who restored redox balance and cell homeostasis in cultured fibroblast cells, even after H2O2 exposure, suggesting that the peptide can be valuable as an effective remedy in treatment of oxidative stress related diseases and skin inflammation related disorders.