Identification of a Vitamin-D Receptor Antagonist, MeTC7, which Inhibits the Growth of Xenograft and Transgenic Tumors In Vivo

Vitamin-D receptor (VDR) mRNA is overexpressed in neuroblastoma and carcinomas of lung, pancreas, and ovaries and predicts poor prognoses. VDR antagonists may be able to inhibit tumors that overexpress VDR. However, the current antagonists are arduous to synthesize and are only partial antagonists, limiting their use. Here, we show that the VDR antagonist MeTC7 (5), which can be synthesized from 7-dehydrocholesterol (6) in two steps, inhibits VDR selectively, suppresses the viability of cancer cell-lines, and reduces the growth of the spontaneous transgenic TH-MYCN neuroblastoma and xenografts in vivo. The VDR selectivity of 5 against RXRα and PPAR-γ was confirmed, and docking studies using VDR-LBD indicated that 5 induces major changes in the binding motifs, which potentially result in VDR antagonistic effects. These data highlight the therapeutic benefits of targeting VDR for the treatment of malignancies and demonstrate the creation of selective VDR antagonists that are easy to synthesize.

Potential for Further Mismanagement of Fever During COVID-19 Pandemic: Possible Causes and Impacts

Fever remains an integral part of acute infectious diseases management, especially for those without effective therapeutics, but the widespread myths about "fevers" and the presence of confusing guidelines from different agencies, which have heightened during the coronavirus disease 2019 (COVID-19) pandemic and are open to alternate interpretation, could deny whole populations the benefits of fever. Guidelines suggesting antipyresis for 37.8-39°C fever are concerning as 39°C boosts the protective heat-shock and immune response (humoral, cell-mediated, and nutritional) whereas ≥40°C initiates/enhances the antiviral responses and restricts high-temperature adapted pathogens, e.g., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), strains of influenza, and measles. Urgent attention is accordingly needed to address the situation because of the potential public health consequences of the existence of conflicting guidelines in the public domain. We have in this article attempted to restate the benefits of fever in disease resolution, dispel myths, and underline the need for alignment of national treatment guidelines with that of the WHO, to promote appropriate practices and reduce the morbidity and mortality from infectious diseases, such as COVID-19.

The complete genome sequence of Indian sheeppox vaccine virus and comparative analysis with other capripoxviruses

Sheeppox virus (SPPV) is responsible for a significant economic loss to sheep husbandry in enzootic regions of Africa, the Middle East, and Asia including the Indian subcontinent. In this study, we present the complete genome sequence of SPPV vaccine strain SPPV-Srin38/00 from India determined by next-generation sequencing (NGS) using Illumina technology. The attenuated Srinagar vaccine strain of SPPV (SPPV-Srin38/00) was developed by serial passaging the virus initially in lamb testes (LT) cells followed by Vero cell line. The SPPV-Srin38/00 virus has a genome size of 150, 103 bp, which encodes for 147 functional putative genes and consists of a central coding region flanked by two identical 2353 bp inverted terminal repeats (ITRs). Comparative phylogenetic analysis based on complete genome sequences of Capripoxviruses formed three distinct groups each for SPPV, GTPV, and LSDV with clustering of SPPV-Srin38/00 strain with SPPV-A strain. Nine ORFs of SPPV-Srin38/00 namely SPPV-Srin_002/SPPV-Srin_155, SPPV-Srin_004/SPPV-Srin_153, SPPV-Srin_009, SPPV-Srin_013, SPPV-Srin_026, SPPV-Srin_132, and SPPV-Srin_136 were found to be fragmented as compared to LSDV, whereas only one ORF (such as SPPV-Srin_136) was found to be fragmented as compared to GTPV. SPPV genomes, including the SPPV-Srin38/00 strain, shared 99.78-99.98% intraspecies nucleotide identity, indicating that SPPV strains have extremely low genetic diversity. The strain shared 96.80-97.08% and 97.11-97.61% nt identity with GTPV and LSDV strains, respectively. Its ORFs 016, 021, 022, 130 and 138 are the least identical ORFs among three species of the genus Capripoxvirus with 72.5-93% aa identity to GTPV and LSDV strains and may be potentially used for differentiation of CaPV species. This study may contribute to a better understanding of the epidemiology and evolution of capripoxviruses as well as the development of specific detection methods, better expression vectors, and vaccines with improved safety and efficacy.

CD300a Receptor Blocking Enhances Early Clearance of Leishmania donovani From Its Mammalian Host Through Modulation of Effector Functions of Phagocytic and Antigen Experienced T Cells

The parasites of the genus Leishmania survive and proliferate in the host phagocytic cells by taking control over their microbicidal functions. The parasite also promotes differentiation of antigen-specific anti-inflammatory cytokines producing effector T cells, which eventually results in disease pathogenesis. The mechanisms that parasites employ to dominate host adaptive immunity are largely unknown. For the first time, we report that L. donovani, which causes visceral leishmaniasis in the Indian subcontinent, upregulates the expression of an immune inhibitory receptor i.e., CD300a on antigen presenting and phagocytic cells to dampen their effector functions. The blocking of CD300a signals in leishmania antigens activated macrophages and dendritic cells enhanced the production of nitric oxide, pro-inflammatory cytokines along with MHCI/II genes expression, and reduced parasitic uptake. Further, the abrogation of CD300a signals in Leishmania infected mice benefited antigen-experienced, i.e., CD4⁺CD44⁺ and CD8⁺CD44⁺ T cells to acquire more pro-inflammatory cytokines producing phenotypes and helped in the early clearance of parasites from their visceral organs. The CD300a receptor blocking also enhanced the conversion of CD4⁺ T effectors cells to their memory phenotypes i.e., CCR7^high CD62L^high up to 1.6 and 1.9 fold after 14 and 21 days post-infection, respectively. These findings implicate that CD300a is an important determinant of host phagocytic cells functions and T cells differentiation against Leishmania antigens.

Differential expression profile of CXC-receptor-2 ligands as potential biomarkers in pancreatic ductal adenocarcinoma

The discovery of early detection markers of pancreatic cancer (PC) disease is highly warranted. We analyzed the expression profile of different CXC-receptor-2 (CXCR2) ligands in PC cases for the potential of biomarker candidates. Analysis of different PDAC microarray datasets with matched normal and pancreatic tumor samples and next-generation sequenced transcriptomics data using an online portal showed significantly high expression of CXCL-1, 3, 5, 6, 8 in the tumors of PC patients. High CXCL5 expression was correlated to poor PC patient survival. Interestingly, mRNA and protein expression analysis of human PC cell lines showed higher CXCL2, 3, and 5 expressions in cell lines derived from metastatic sites than primary tumors. Furthermore, we utilized immunohistochemistry (IHC) to evaluate the expression of CXCR2 ligands in the human PC tumors and observed positive staining for CXCL1, 3, and 8 with a higher average IHC composite score of CXCL3 in the PC tissue specimens than the normal pancreas. We also observed an increase in the expression of mouse CXCL1, 3, and 5 in the pre-cancerous lesions of tumors and metastasis tissues derived from the PDX-cre-LSL-Kras^G12D mouse model. Together, our data suggest that different CXCR2 ligands show the potential of being utilized as a diagnostic biomarker in PC patients.

Clinical Features and Outcome of Stroke with COVID-19. COVID-19 Stroke Study Group (CSSG), India

Background and Purpose:

Occurrence of stroke has been reported among patients with COVID-19. The present study compares clinical features and outcomes of stroke patients with and without COVID-19.

Methods:

The COVID-19 Stroke Study Group (CSSG) is a multicentric study in 18 sites across India to observe and compare the clinical characteristics of patients with stroke admitted during the current pandemic period and a similar epoch in 2019. The present study reports patients of stroke with and without COVID-19 (CoVS and non-CoVS, respectively) seen between February 2020 and July 2020. Demographic, clinical, treatment, and outcome details of patients were collected.

Results:

The mean age and gender were comparable between the two groups. CoVS patients had higher stroke severity and extent of cerebral involvement on imaging. In-hospital complications and death were higher among CoVS patients (53.06% vs. 17.51%; P < 0.001) and (42.31% vs. 7.6%; P < 0.001), respectively. At 3 months, higher mortality was observed among CoVS patients (67.65% vs. 13.43%; P < 0.001) and good outcome (modified Rankin score [mRS]: 0–2) was seen more often in non-CoVS patients (68.86% vs. 33.33%; P < 0.001). The presence of COVID-19 and baseline stroke severity were independent predictors of mortality.

Conclusions:

CoVS is associated with higher severity, poor outcome, and increased mortality. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and baseline stroke severity are independent predictors of mortality.

Isolation and genetic characterization of canine adenovirus type 2 from a domestic dog showing neurological symptoms

Canine adenoviruses (CAVs) are of two types: canine adenovirus type 1 (CAV-1), which causes infectious canine hepatitis, and canine adenovirus type 2 (CAV-2), which is mainly associated with the respiratory type of disease in dogs. Due to the widespread use of modified live vaccines to control canine adenoviral infections and subsequently reduced disease incidence, CAVs are often neglected by clinicians. Although a number of studies are available about CAV-1 prevalence in India, only meagre information is available about CAV-2. This study reports the CAV-2 infection in a vaccinated dog with neurological and respiratory symptoms which was found negative for other canine pathogens like canine distemper virus and canine parvovirus. The virus was successfully isolated from rectal swab in MDCK cells and characterized by immunofluorescence assay and virus neutralization test. On phylogenetic analysis of partial E3 region, the Indian CAV-2 grouped in a separate clade different from established subgroups. An insertion of "G" nucleotide was reported at nucleotide (nt.) position 1077 in the E3 gene of Indian CAV-2 isolates which led to a frameshift in the coding region of E3 gene thereby imparting additional eleven amino acids to its C-terminal end in comparison to isolates from other parts of the world. This may have an implication on the functional role of E3 protein inside the cell. This study reinforces the unique signature insertion in the E3 gene of Indian CAV-2 and is the second study in the world to report the association of CAV-2 with neurological disease in dogs.

Mechanical Counterbalance of Kinesin and Dynein Motors in a Microtubular Network Regulates Cell Mechanics, 3D Architecture, and Mechanosensing

Microtubules (MTs) and MT motor proteins form active 3D networks made of unstretchable cables with rod-like bending mechanics that provide cells with a dynamically changing structural scaffold. In this study, we report an antagonistic mechanical balance within the dynein-kinesin microtubular motor system. Dynein activity drives the microtubular network inward compaction, while isolated activity of kinesins bundles and expands MTs into giant circular bands that deform the cell cortex into discoids. Furthermore, we show that dyneins recruit MTs to sites of cell adhesion, increasing the topographic contact guidance of cells, while kinesins antagonize it via retraction of MTs from sites of cell adhesion. Actin-to-microtubule translocation of septin-9 enhances kinesin-MT interactions, outbalances the activity of kinesins over that of dyneins, and induces the discoid architecture of cells. These orthogonal mechanisms of MT network reorganization highlight the existence of an intricate mechanical balance between motor activities of kinesins and dyneins that controls cell 3D architecture, mechanics, and cell-microenvironment interactions.

Role of toll-like receptors in modulation of cytokine storm signaling in SARS-CoV-2-induced COVID-19

Balanced immune regulation is crucial for recognizing an invading pathogen, its killing, and elimination. Toll‐like receptors (TLRs) are the key regulators of the innate immune system. It helps in identifying between self and nonself‐molecule and eventually eliminates the nonself. Endosomal TLR, mainly TLR3, TLR7, TLR8, and membrane‐bound TLR4, has a role in the induction of cytokine storms. TLR7/8 recognizes the ssRNA SARS‐COV‐2 and when it replicates to dsRNA, it is recognized by TLR3 and drives the TRIF‐mediated inflammatory signaling like NF‐κB, MAPK. Such signaling leads to significant transcription and translation of pro‐inflammatory genes, releasing inflammatory molecules into the systemic circulation, causing an imbalance in the system. So, whenever an imbalance occurs, a surge in the pro‐inflammatory mediators is observed in the blood, including cytokines like interleukin (IL)‐2, IL‐4, IL‐6, IL‐1β, IL‐8, interferon (IFN)‐γ, tumor necrosis factor (TNF)‐α. IL‐6 and IL‐1β are one of the driving factors for bringing the cytokine storm into the systemic circulation, which migrates into the other organs, causing multiple organ failures leading to the death of the individual with severe illness.

The imbalanced and hyper responsive immune system leads to a surge leading to death of the infected patients in COVID‐19.

It has been observed that cytokine surge is TLR induced, mainly through activation of TLR3, TLR4, TLR7, TLR8 receptors.

The cytokine storm migrates into the other organ through systemic circulation. The inflammation and the organ damage occur due to the TLR mediated NF‐κB, MAPK pathway. Hence blocking these specific TLRs may alleviate the chance of SARS‐COV‐2 infection.

Proteome Modulation in Peripheral Blood Mononuclear Cells of Peste des Petits Ruminants Vaccinated Goats and Sheep

In the present study, healthy goats and sheep (n = 5) that were confirmed negative for peste des petits ruminants virus (PPRV) antibodies by monoclonal antibody-based competitive ELISA and by serum neutralization test and for PPRV antigen by s-ELISA were vaccinated with Sungri/96. A quantitative study was carried out to compare the proteome of peripheral blood mononuclear cells (PBMCs) of vaccinated goat and sheep [5 days post-vaccination (dpv) and 14 dpv] vs. unvaccinated (0 day) to divulge the alteration in protein expression following vaccination. A total of 232 and 915 proteins were differentially expressed at 5 and 14 dpv, respectively, in goats. Similarly, 167 and 207 proteins were differentially expressed at 5 and 14 dpv, respectively, in sheep. Network generated by Ingenuity Pathway Analysis was “infectious diseases, antimicrobial response, and inflammatory response,” which includes the highest number of focus molecules. The bio functions, cell-mediated immune response, and humoral immune response were highly enriched in goats at 5 dpv and at 14 dpv. At the molecular level, the immune response produced by the PPRV vaccine virus in goats is effectively coordinated and stronger than that in sheep, though the vaccine provides protection from virulent virus challenge in both. The altered expression of certain PBMC proteins especially ISG15 and IRF7 induces marked changes in cellular signaling pathways to coordinate host immune responses.

Nutritional Immunity, Zinc Sufficiency, and COVID-19 Mortality in Socially Similar European Populations

The impact of zinc (Zn) sufficiency/supplementation on COVID-19-associated mortality and incidence (SARS-CoV-2 infections) remains unknown. During an infection, the levels of free Zn are reduced as part of “nutritional immunity” to limit the growth and replication of pathogen and the ensuing inflammatory damage. Considering its key role in immune competency and frequently recorded deficiency in large sections of different populations, Zn has been prescribed for both prophylactic and therapeutic purposes in COVID-19 without any corroborating evidence for its protective role. Multiple trials are underway evaluating the effect of Zn supplementation on COVID-19 outcome in patients getting standard of care treatment. However, the trial designs presumably lack the power to identify negative effects of Zn supplementation, especially in the vulnerable groups of elderly and patients with comorbidities (contributing 9 out of 10 deaths; up to >8,000-fold higher mortality). In this study, we have analyzed COVID-19 mortality and incidence (case) data from 23 socially similar European populations with comparable confounders (population: 522.47 million; experiencing up to >150-fold difference in death rates) and at the matching stage of the pandemic (March 12 to June 26, 2020; first wave of COVID-19 incidence and mortality). Our results suggest a positive correlation between populations’ Zn-sufficiency status and COVID-19 mortality [r (23): 0.7893–0.6849, p-value < 0.0003] as well as incidence [r (23):0.8084–0.5658; p-value < 0.005]. The observed association is contrary to what would be expected if Zn sufficiency was protective in COVID-19. Thus, controlled trials or retrospective analyses of the adverse event patients’ data should be undertaken to correctly guide the practice of Zn supplementation in COVID-19.

Clinical profile and outcome of non-COVID strokes during pandemic and the pre pandemic period: COVID-Stroke Study Group (CSSG) India

Background

As the health systems around the world struggled to meet the challenges of COVID-19 pandemic, care of many non-COVID emergencies was affected.

Aims

The present study examined differences in the diagnosis, evaluation and management of stroke patients during a defined period in the ongoing pandemic in 2020 when compared to a similar epoch in year 2019.

Methods

The COVID stroke study group (CSSG) India, included 18 stroke centres spread across the country. Data was collected prospectively between February and July 2020 and retrospectively for the same period in 2019. Details of demographics, stroke evaluation, treatment, in-hospital and three months outcomes were collected and compared between these two time points.

Results

A total of 2549 patients were seen in both study periods; 1237 patients (48.53%) in 2019 and 1312 (51.47%) in 2020. Although the overall number of stroke patients and rates of thrombolysis were comparable, a significant decline was observed in the month of April 2020, during the initial period of the pandemic and lockdown. Endovascular treatment reduced significantly and longer door to needle and CT to needle times were observed in 2020. Although mortality was higher in 2020, proportion of patients with good outcome were similar in both the study periods.

Conclusions

Although stroke admissions and rates of thrombolysis were comparable, some work flow metrics were delayed, endovascular stroke treatment rates declined and mortality was higher during the pandemic study period. Reorganization of stroke treatment pathways during the pandemic has likely improved the stroke care delivery across the globe.

Recent Trends in the Management of Alzheimer's Disease: Current Therapeutic Options and Drug Repurposing Approaches

Alzheimer's disease is one of the most progressive forms of dementia, ultimately leading to death in aged populations. The major hallmarks of Alzheimer's disease include deposition of extracellular amyloid senile plaques and intracellular neurofibrillary tangles in brain neuronal cells. Although there are classical therapeutic options available for the treatment of the diseases, however, they provide only a symptomatic relief and do not modify the molecular pathophysiological course of the disease. Recent research advances in Alzheimer's disease have highlighted the potential role of anti-amyloid, anti-tau, and anti-inflammatory therapies. However, these therapies are still in different phases of pre-clinical/clinical development. In addition, drug repositioning/repurposing is another interesting and promising approach to explore rationalized options for the treatment of Alzheimer's disease. This review discusses the different aspects of the pathophysiological mechanism involved in the progression of Alzheimer's disease along with the limitations of current therapies. Furthermore, this review also highlights emerging investigational drugs along with recent drug repurposing approaches for Alzheimer's disease.

Abstract 1087: CXCR2 and its ligands modulate chemotherapy resistance in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has one of the lowest survival rates of cancers, with a five-year relative survival of 9%. The significant factor contributing to low survivorship is the intrinsic resistance to chemotherapy. In the present study, we elucidate a targetable pathway that facilitates resistance in these cells. One inflammatory pathway used in cancer progression is CXCR2, which binds chemokines CXCL 1-3 and 5-8. Our group and others have shown an association of CXCR2 with tumor progression, angiogenesis and metastasis in PDAC, and chemotherapy resistance in other cancers. In this study, we test the hypothesis that CXCR2 is integral in PDAC chemotherapy resistance. We generated gemcitabine resistant cell lines (GemR) from the parent cell lines of T3M4 (WT KRAS) and CD18/HPAF (Mutant KRAS) with 40- and 67-fold higher resistance in comparison to the parent cell lines, respectively. Using qRT-PCR and ELISA, we profiled chemokines' expression, CXCL1, 5, and 8, on parent- and GemR-cell lines. We observed a higher basal level expression of CXCL1, 5, and 8 ligands in GemR cells than the parent cell lines. Further treatment with gemcitabine, the parent cell lines had a higher increase in CXCL1 and 8 ligand expression in comparison with GemR cell lines. With further investigation of T3M4, we found a dose-dependent and time-dependent increase for CXCL1 and CXCL8. CXCL5 had a constant high expression with all doses of gemcitabine. With our initial observations of gemcitabine treatment enhancing CXCR2 ligands in PDAC cells, we evaluated the effects of the small molecule CXCR2 antagonist SCH 479833 (SCH 47) in combination with gemcitabine treatment on the parent and GemR cell lines. We used the relative IC50 and half the relative IC50 for both the gemcitabine and SCH 47 treatment doses. We observed that a lower concentration of gemcitabine in the presence of the SCH 47 was more effective than the higher concentration of gemcitabine without SCH 47 for the GemR-cell lines. Together, our observations show chemotherapy-resistant PDAC cell lines express higher CXCR2 ligand levels at baseline, with parent cell lines increasing expression with chemotherapy treatment. We also show an advantageous combination treatment of CXCR2 antagonist with lower gemcitabine concentration. Overall, these results show a promising future for CXCR2 antagonism in the treatment of resistant PDAC tumors.

Citation Format: Caitlin Molczyk, Dipakkumar R. Prajapati, Sugandha Saxena, Paran Goel, Michelle Varney, Rakesh K. Singh. CXCR2 and its ligands modulate chemotherapy resistance in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1087.