Background and Purpose: Escherichia coli is a common mastitis-causing pathogens and is destructive to the blood-milk barrier. Oral administration of Lactobacillus casei Zhang (LCZ) could alleviate mice mastitis. However, its prophylactic effect and mechanism through intramammary injection on E. coli-induced mastitis is unclear now. Here, we investigate this using E. coli-induced mastitis model. Experimental Approach: Prophylactic effects and mechanism of intramammary injection of LCZ on blood-milk barrier and inflammation were studied in both bovine mammary epithelial cells (BMECs) and pregnant mice. Key Results: In vitro tests revealed that LCZ significantly inhibited the adhesion of E. coli to monolayer cells, reduce the damage of cell desmosomes, up-regulated the expression of tight junction proteins (claudin-1, claudin-4, occludin, and ZO-1), and down-regulated the expression of inflammatory cytokines (TNF-α, IL-1β, and IL-6) thereby enhancing the trans-epithelial electric resistance of monolayer BMECs and effectively protecting cells from damage caused by E. coli. In vivo experiments suggested that LCZ significantly promoted the expression of tight junction proteins (claudin-3, occludin, and ZO-1) but significantly inhibited the expression of inflammatory cytokines (TNF-α, IL-1β, and IL-6) in mouse mammary tissue, thereby decreased disruption in mammary tissues, infiltration of inflammatory cells in E. coli-induced mastitis. Conclusions and Implications: In our study, LCZ ameliorates blood-milk barrier disruption and suppresses the inflammatory response during E. coli-induced mastitis, indicating LCZ may serve as a effective prophylactic agent to preserve the blood-milk barrier function during mastitis.

Objectives: The current study was carried out to explore the knowledge, attitude, and practices towards Brucellosis in the people of Khyber Pukhtun Khwa Province, Pakistan. Study design: Cross-sectional study Material and methods: Total of 1600 participants belong to different professions, education level, locality and nature of contact with animals were selected by random sample method. The samples were selected from the Khyber Pakhtun Khwa province of Pakistan. Results: The findings of this study documented poor knowledge regarding brucellosis in the selected participants of current study. Although human and animal health professionals had sufficient knowledge about brucellosis, however no serious trends to control brucellosis were noticed even in health professionals. The unhygienic approach was observed in farmers regarding the handling animal and their products. Self medication approach was also documented in many participants which create antibiotic resistance. Conclusions: Based on the findings we noticed a lack of information regarding zoonotic diseases, health facilities and a weak bond between health and non-health professionals in KPK. Proper education and awareness is highly recommended on zoonotic diseases. Keywords: Zoonotic diseases, Brucellosis, Knowledge, Practices, Attitude

Letter to editor It has been demonstrated that the latest outbreak-causing novel coronavirus pneumonia (COVID-19) virus (2019-nCoV, SARS-CoV-2) invades human alveolar epithelial cells primarily by angiotensin-converting enzyme 2 ACE2 (Zhou et al., 2020). The SARS-CoV engages ACE2 for cellular entry to produce final infection (Hoffmann et al., 2020). Furthermore, Zhao et al documented that in human lungs, ACE2 is found primarily in alveolar epithelial cells of type II (AT2), indicating that this virus activates ACE2-positive AT2 cells to cause pneumonia (Zhao et al., 2020). Recently an epidemiological research indicated that certain patients with SARS-CoV-2 exhibit symptoms of severe liver injury (Chen et al., 2020). The investigators also established that ACE2 is significantly enriched in cholangiocytes by studying stable liver cells at single-cell resolution (Chai et al., 2020), depicting that the virus may bind ACE2-positive cholangiocytes directly causes dis-regulation result in liver function. Now the main question arises that why ACE2 is crucial for COVID-19 control and treatment strategies? Normally, ACE2 catalyzing the transformation of angiotensin-II into angiotensin-1–7. Angiotensin-II acts on angiotensin receptor-1(AT1) and controls the processes of vasoconstriction, apoptosis, proinflammatory changes, and fibrosis cycle, while angiotensin 1–7 acts on Mas receptors induces contrary symptoms (Paz Ocaranza et al., 2020 ). Thus any loss in the activity of ACE2 in the alveolar cells may increase the level of angiotensin II and result in acute respiratory distress. The expression of ACE2 is comparatively higher in lung and a study documented the protective role of ACE2 in lung injury (Imai et al., 2005). It was proved in a mice model that acidic gas inhaled by mice downregulated ACE2 and increased the level of Ang II in the lung and plasma of wild-type mice, and the levels of Ang II in the lung. Further, the research team found that recombinant human ACE2 (rhACE2) protein action may reduce the plasma Ang II levels and reduce the risk of acute lung injury in ACE2 Knockout mice. The binding mode of COVID-19 virus with ACE2 and the clinical importance of renin-angiotensin System, revealed that this system is extensively involved in the pathology of COVID-19 (Gurwitz, 2020; Vaduganathan et al., 2020). Mostly the COVID-19 patients develop fever, inflammatory changes, and respiratory distress. It can be hypothesized that these changes might be due to lack of ACE2 and imbalance in renin-angiotensin system in the pulmonary interstitium. Furthermore, Gurwitz suggested that telmisartan as an alternative choice for treating COVID19 before the respiratory distress develops. Interestingly, Zhang et al. noticed a low fatality rate in COVID-19 hypertensive patients that were exposed to Angiotensin converting enzyme inhibitors (ACEIs) and Angiotensin receptor blockers (ARBs) than control ones (Zhang et al., 2020). Hoffmann and his co-workers proved that protease inhibitor-mediated blocking of Ace2 and Tmprss2 might be a target in the prevention and treatment of COVID-19 (Hoffmann et al., 2020).Based on the above findings, we can speculate that the treatment strategies for COVID-19 may include recombinant ACE2 therapy, hormones such as estradiol, which increases the level of ACE2, and drugs that decrease the level of angiotensin II.Keywords: ACE2, Angiotensin II, Zoonosis, COVID19, therapeutic purpose