SARS-CoV-2/ACE2 Interaction Suppresses IRAK-M Expression and Promotes Pro-Inflammatory Cytokine Production in Macrophages

The major cause of death in SARS-CoV-2 infected patients is due to de-regulation of the innate immune system and development of cytokine storm. SARS-CoV-2 infects multiple cell types in the lung, including macrophages, by engagement of its spike (S) protein on angiotensin converting enzyme 2 (ACE2) receptor. ACE2 receptor initiates signals in macrophages that modulate their activation, including production of cytokines and chemokines. IL-1R-associated kinase (IRAK)-M is a central regulator of inflammatory responses regulating the magnitude of TLR responsiveness. Aim of the work was to investigate whether SARS-CoV-2 S protein-initiated signals modulate pro-inflammatory cytokine production in macrophages. For this purpose, we treated PMA-differentiated THP-1 human macrophages with SARS-CoV-2 S protein and measured the induction of inflammatory mediators including IL6, TNFα, IL8, CXCL5, and MIP1a. The results showed that SARS-CoV-2 S protein induced IL6, MIP1a and TNFα mRNA expression, while it had no effect on IL8 and CXCL5 mRNA levels. We further examined whether SARS-CoV-2 S protein altered the responsiveness of macrophages to TLR signals. Treatment of LPS-activated macrophages with SARS-CoV-2 S protein augmented IL6 and MIP1a mRNA, an effect that was evident at the protein level only for IL6. Similarly, treatment of PAM3csk4 stimulated macrophages with SARS-CoV-2 S protein resulted in increased mRNA of IL6, while TNFα and MIP1a were unaffected. The results were confirmed in primary human peripheral monocytic cells (PBMCs) and isolated CD14+ monocytes. Macrophage responsiveness to TLR ligands is regulated by IRAK-M, an inactive IRAK kinase isoform. Indeed, we found that SARS-CoV-2 S protein suppressed IRAK-M mRNA and protein expression both in THP1 macrophages and primary human PBMCs and CD14+ monocytes. Engagement of SARS-CoV-2 S protein with ACE2 results in internalization of ACE2 and suppression of its activity. Activation of ACE2 has been previously shown to induce anti-inflammatory responses in macrophages. Treatment of macrophages with the ACE2 activator DIZE suppressed the pro-inflammatory action of SARS-CoV-2. Our results demonstrated that SARS-CoV-2/ACE2 interaction rendered macrophages hyper-responsive to TLR signals, suppressed IRAK-M and promoted pro-inflammatory cytokine expression. Thus, activation of ACE2 may be a potential anti-inflammatory therapeutic strategy to eliminate the development of cytokine storm observed in COVID-19 patients

Surfactant proteins SP-A and SP-D modulate uterine contractile events in ULTR myometrial cell line

Pulmonary surfactant proteins SP-A and SP-D are pattern recognition innate immune molecules. However, there is extrapulmonary existence, especially in the amniotic fluid and at the feto-maternal interface. There is sufficient evidence to suggest that SP-A and SP-D are involved in the initiation of labour. This is of great importance given that preterm birth is associated with increased mortality and morbidity. In this study, we investigated the effects of recombinant forms of SP-A and SP-D (rhSP-A and rhSP-D, the comprising of trimeric lectin domain) on contractile events in vitro, using a human myometrial cell line (ULTR) as an experimental model. Treatment with rhSP-A or rhSP-D increased the cell velocity, distance travelled and displacement by ULTR cells. rhSP-A and rhSP-D also affected the contractile response of ULTRs when grown on collagen matrices showing reduced surface area. We investigated this effect further by measuring contractility-associated protein (CAP) genes. Treatment with rhSP-A and rhSP-D induced expression of oxytocin receptor (OXTR) and connexin 43 (CX43). In addition, rhSP-A and rhSP-D were able to induce secretion of GROα and IL-8. rhSP-D also induced the expression of IL-6 and IL-6 Ra. We provide evidence that SP-A and SP-D play a key role in modulating events prior to labour by reconditioning the human myometrium and in inducing CAP genes and pro-inflammatory cytokines thus shifting the uterus from a quiescent state to a contractile one

Role of Collectins and Complement Protein C1q in pregnancy and parturition

Collectins such as surfactant proteins SP-A, SP-D, and mannan-binding lectin (MBL), as well as complement protein C1q are evolutionarily conserved innate immune molecules. They are known to opsonize a range of microbial pathogens (bacteria, fungi, virus, and parasites) and trigger effector clearance mechanisms involving phagocytosis and/or complement activation. Collectins and C1q have also attracted attention in studies involving pregnancy as they are expressed in the female reproductive tissues during pregnancy; a unique state of immune suppression with increased susceptibility to infectious diseases. Recent studies are beginning to unravel their functional significance in implantation, placentation, pregnancy maintenance and parturition in normal and adverse pregnancies. Collectins and C1q, expressed in gestational tissues during pregnancy, might alter the status of mother’s immune response to the allogenic fetus and the microenvironment, thereby serving as important regulators of fetus-mother interaction. Here, we discuss the functional roles that have been assigned to SPA, SP-D, MBL and C1q in pregnancy and parturition

Evidence for genetic differences in the Africanized honey bee populations of South and North America

The arrival of Africanized honey bee Apis mellifera to the United States less than fifty years after its original release in Brazil is an interesting phenomenon. To better understand the population genetic aspects of this phenomenon, genetic variability and differentiation among Africanized honey bee populations were investigated. Mitochondrial and microsatellite DNA markers were used to compare the genetic composition of several populations of Africanized honey bees from Brazil, Central America, and Texas. Using mitochondrial DNA markers, three haplotypes were identified. One haplotype was European (C1) and the others were African (A1 and A4). A major shift in the frequencies of African mitochondrial DNA haplotypes A1 and A4 was detected across the range of Africanized honey bees. The A1 haplotype increased northward to Texas and largely replaced the A4 haplotype. The direction of the clinal distribution of A1-A4 in South America and perhaps even Africa appears opposite to the findings of the present study. It was reported that A1 was predominant in the more equatorial regions of Africa and South America, while the frequency of A4 increases in the more temperate (southern region). Selection along a temperature/climate gradient has been suggested as the reason for an observed A1-A4 cline in South America. However, in our study, the best explanation for the A1 northward incline would be selection for some geneotypes. The microsatellite DNA analysis revealed that the three populations displayed high genetic diversity with an average of expected heterozygosity per locus 0.82. Furthermore, private alleles found in the Texas population suggest ongoing hybridization with non-Africanized honey bees

EVIDENCE FOR GENETIC DIFFERENCES IN THE AFRICANIZED HONEY BEE POPULATIONS OF SOUTH AND NORTH AMERICA By

The members of the Committee appointed to examine the thesis of FATIMAH ALHAMLAN find it satisfactory and recommend that it be accepted Chair ii DEDICATION I would like to dedicate this work to my husband, Abdullah Assiri, for his understanding and assistance. His support and patience during the past two years did not go unnoticed or unappreciated. Without his strength and encouragement, I know I could not have accomplished this. Abdullah managed to hold our household together as I pursued the Master degree. He took on the job of housekeeper, cook and caregiver for our daughter in addition to his own busy schedule. His kindness, generosity, responsibility, and love were an essential part of this project. He is my partner and soul mate and his love and encouragement gave me the stamina to withstand the pressures and stress of graduate school. Thank you, Abdullah. iii ACKNOWLEDGEMENTS I am indebted to many people for their support of my Master program. I would like t

Containment of COVID-19: the unprecedented response of Saudi Arabia

The emergence of a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), from Wuhan, China, in December 2019 has challenged many countries. The current pandemic caused by this coronavirus has already negatively affected millions of people and the economies of countries worldwide. However, the challenges faced by Saudi Arabia during the Middle East respiratory syndrome coronavirus (MERS-CoV) epidemic that began in 2012 led to marked improvements in the government’s response to the current pandemic. Saudi Arabia is one of largest countries in the Middle East and is home to the holiest Muslim sites. Since the global risk of the virus was declared by the World Health Organization (WHO), Saudi Arabia has taken substantial public health measures to control the spread of the infection. This review reports on the transmission of SARS-COV-2 in Saudi Arabia and the proactive responses taken by the government, comparing the Saudi government’s actions and their effects with those of other countries. Although Saudi Arabia is currently experiencing the peak of the pandemic, their early precautionary responses have shortened the period of individual/family isolation, reduced the number of confirmed infections and infection-related fatality rates, and decreased the economic burden of the people and the country compared with other countries in the Middle East and elsewhere