Mythily Srinivasan

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https://hdl.handle.net/1805/17678

Targeting Neuroinflammation Using Novel Glucorticoid-Induced Leucine Zipper Analogs

Unresolved inflammation and altered immune signals contribute to the pathology of many chronic diseases. Dr. Srinivasan's research includes the design and development of immunotherapeutic peptides using motif-mediated protein-protein interactions as drug targets.

Recently, she investigated approaches to suppress neuroinflammation in Alzheimer's disease, the most common cause of dementia that is projected to affect over seven million individuals in the United States by 2025. These studies resulted from earlier observations that the blockade of T cell co-receptor CD28 by CD80 competitive antagonist peptides unregulated glucocorticoid-induced leucine zipper (GILZ)-an anti-inflammatory molecule that directly inhibits the pro-inflammatory transcription factor, nuclear factor-kappa B (NF-kB).

Adopting data from the GILZ and NF-kB interaction complex, Dr. Srinivasan developed modified analogs of the p65 binding motif of GIlZ. Efficacy studies, in collaboration with Dr. Debomoy Lahiri, Professor of Neuroscience, and Dr. Deborah Hickman of the IU School of Medicine, suggested that the novel therapeutics exhibited suppressive potential in cellular and animal models of Alzheimer's disease.

Together with the Indiana University Research and Technology Corporation, Dr. Srinivasan initiated a startup venture, Provaidya LLC, to develop the patented GILZ analogs as investigational new drugs and received phase I funding from the National Institutes of Aging.

Dr. Srinivasan's work to develop peptide therapeutics to suppress neuroinflammation is another example of how IUPUI faculty are TRANSLATING RESEARCH INTO PRACTICE.

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Now showing 1 - 10 of 27

A nuclear factor-kappa B inhibiting peptide suppresses innate immune receptors and gliosis in a transgenic mouse model of Alzheimer’s disease
(Elsevier, 2021-06) Lindsay, Alison; Hickman, Deborah; Srinivasan, Mythily; Oral Pathology, Medicine and Radiology, School of Dentistry
A disproportionate increase in activated nuclear factor-kappa B (NF-κB) has been shown to drive the Aβ deposition, neuroinflammation and neurodegeneration in Alzheimer’s disease (AD). Hence, selective targeting of activated p65 represents an attractive therapeutic approach for AD. Glucocorticoid induced leucine zipper (GILZ) is a NF-κB interactant that binds and sequesters the activated p65 in the cytoplasm. The p65 binding domain of GILZ adopts a polyproline type II helical conformation, a motif that acts as an adaptable glove in the interface with the binding partner and constitutes an excellent template for drug design. Previously, peptide analogs of the p65 binding domain of GILZ, referred to as GA have been shown to suppress pathology in the lipopolysaccharide induced model of neuroinflammation. In this study, we investigated the CNS delivery of labeled GA administered intraperitoneally in adult mice for a period of upto 24 h. Further, we evaluated the suppressive potential of GA in 5xFAD mice, an aggressive model with five genetic mutations closely associated with human AD. Groups of 5xFAD mice administered GA or control peptide intraperitoneally on alternate days for six weeks were evaluated for Aβ deposition, microglia, inflammation and innate immune responses by immunohistochemistry and real time polymerase reaction. GA was observed in proximity with NeuN positive neurons suggesting that the compound crossed the blood brain barrier to reach the brain parenchyma. Further, GA treatment decreased Aβ load, reduced Iba1 + microglia and glial fibrillary acidic protein (GFAP)+ astrocytes, inhibited inflammatory cytokines and suppressed toll like receptor (TLR-2, TLR-4) expressions in 5xFAD mice.
Psychometric Characteristics of Oral Pathology Test Items in the Dental Hygiene Curriculum—A Longitudinal Analysis
(MDPI, 2021-05-13) Srinivasan, Mythily; Oral Pathology, Medicine and Radiology, School of Dentistry
As the landscape of oral healthcare and the delivery of services continue to undergo change, the dental hygienist plays an increasing role in assisting dentists with oral diagnosis and preventive strategies. Hence, the dental hygiene curriculum standards require biomedical science instructions, including general and oral pathology. Student learning and cognitive competencies are often measured using multiple-choice questions (MCQs). The objectives of this study were to perform a longitudinal analysis of test items and to evaluate their relation to the absolute grades of the oral pathology course in the dental hygiene curriculum. A total of 1033 MCQs covering different concepts of oral pathology administered from 2015 through 2019 were analyzed for difficulty and discriminatory indices, and the differences between the years were determined by one-way ANOVA. Test reliability as determined by the average KR-20 value was 0.7 or higher for each exam. The mean difficulty index for all exams was 0.73 +/− 0.05, and that of the discriminatory index was 0.33 +/− 0.05. Wide variations were observed in the discriminatory indices of test items with approximately the same difficulty index, as well as in the grade distribution in each cohort. Furthermore, longitudinal data analyses identified low achieving cohorts amongst the groups evaluated for the same knowledge domain, taught with the same instruction, and using similar test tools. This suggest that comparative analyses of tests could offer feedback not only on student learning attributes, but also potentially on the admission processes to the dental hygiene program.
Can Salivary Innate Immune Molecules Provide Clue on Taste Dysfunction in COVID-19?
(Frontiers, 2021-10) Ermel, Aaron; Thyvalikakath, Thankam Paul; Foroud, Tatiana; Khan, Babar; Srinivasan, Mythily; Medicine, School of Medicine
Emerging concerns following the severe acute respiratory syndrome coronavirus-2 (SARS-CoV2) pandemic are the long-term effects of coronavirus disease (COVID)-19. Dysgeusia in COVID-19 is supported by the abundant expression of the entry receptor, angiotensin-converting enzyme-2 (ACE2), in the oral mucosa. The invading virus perturbs the commensal biofilm and regulates the host responses that permit or suppress viral infection. We correlated the microbial recognition receptors and soluble ACE2 (sACE2) with the SARS-CoV2 measures in the saliva of COVID-19 patients. Data indicate that the toll-like receptor-4, peptidoglycan recognition protein, and sACE2 are elevated in COVID-19 saliva and correlate moderately with the viral load.
Taste Dysfunction and Long COVID-19
(Frontiers, 2021-07-14) Srinivasan, Mythily; Oral Pathology, Medicine and Radiology, School of Dentistry
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent for the coronavirus disease 2019 (COVID-19), has imposed unprecedented morbidity and mortality worldwide. As of June 2021, globally over 163 million individuals are infected and nearly 3.4 million individuals have died. Emerging concerns include complaints of persistent symptoms for extended periods in recovered individuals. Cellular damage due to disease and/or treatment, prolonged viral shedding, chronic immune inflammatory response, and pro-coagulant state induced by SARS-CoV-2 infection are suggested mechanisms contributing to the symptom sequelae.
COVID-19 and saliva: A primer for dental health care professionals
(Wiley, 2020-08-23) Srinivasan, Mythily; Thyvalikakath, Thankam P.; Cook, Blaine N.; Zero, Domenick T.; Oral Pathology, Medicine and Radiology, School of Dentistry
To contain the COVID‐19 pandemic, it is essential to find methods that can be used by a wide range of health care professionals to identify the virus. The less potential contagious nature of the collection process, the ease of collection and the convenience of frequent collection for real‐time monitoring makes saliva an excellent specimen for home‐based collection for epidemiological investigations. With respect to COVID‐19, the use of saliva offers the added advantages of greater sensitivity and potential for detection at an early stage of infection. However, the advantages from a diagnostic perspective also reflect the potential risk to dental professionals from saliva from infected patients. Although not validated in COVID‐19 patients, but by extension from studies of SARS‐CoV‐1 studies, it is suggested that using antimicrobial mouthrinses such as chlorhexidine, hydrogen peroxide or sodium hypochlorite solutions could reduce the viral load in saliva droplets and reduce the risk of direct transmission. Because large saliva droplets could deposit on inanimate surfaces, changing the personal protective equipment including the clinical gown, gloves, masks, protective eye wear and face shield between patients, as well as decontamination of the work surfaces in the clinic, could reduce the risk of indirect contact transmission.
Oral epithelial expression of angiotensin converting enzyme-2: Implications for COVID-19 diagnosis and prognosis
(2020-06-23) Srinivasan, Mythily; Zunt, Susan L.; Goldblatt, Lawrence I.; Oral Pathology, Medicine and Radiology, School of Dentistry
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) uses the angiotensin converting enzyme (ACE)-2 as the host receptor for target cell entry. The extent and distribution of ACE-2 has been associated with the clinical symptoms of coronavirus disease (COVID)-19. Here we show by immunofluorescence analysis that the ACE2 is abundantly expressed in oral mucosa, particularly in the surface epithelial cells suggesting that these cells could represent sites of entry for SARS-CoV-2. Further, together with the reports on ACE2 ectodomain shedding, we discuss the rationale for the hypothesis that the ACE-2 measurement in saliva could be a marker for COVID-19 infection during early phase following SARS-CoV-2 exposure.
Glucocorticoid Induced Leucine Zipper in Lipopolysaccharide Induced Neuroinflammation
(Frontiers, 2019-01-25) Witek, Emily; Hickman, Debra; Lahiri, Debomoy K.; Srinivasan, Mythily; Psychiatry, School of Medicine
Glucocorticoids (GCs) are steroid hormones secreted as the end-product of the neuroendocrine stress cascade. Both absence and elevated GC mediate neurotoxic responses, suggesting that a narrow window ranging from physiological to slightly high GC mediate protective responses. The beneficial effects of GC are attributed to the transactivation of regulatory proteins and inhibition mediated by glucocorticoid receptor (GR) interactions with other co-factors. The glucocorticoid induced leucine zipper (GILZ) is a gene strongly upregulated by GC and mediates many of the anti-inflammatory and anti-proliferative effects of GC. Although GILZ is constitutively expressed in many tissues including the brain, the expression has been shown to occur with varying dynamics suggesting that the local milieu modulates its expression with consequent effects on cellular responses. Here we investigated the expression profile of GILZ in lipopolysaccharide (LPS) mediated neuroinflammation model of Alzheimer’s disease (AD). Our data suggest that the GILZ expression is downregulated in neuroinflammation correlating inversely with the pro-inflammatory cytokines and innate immune responses.
Mechanisms of NF-κB p65 and strategies for therapeutic manipulation
(Dove Medical Press, 2018-10-30) Giridharan, Sivagami; Srinivasan, Mythily; Oral Pathology, Medicine and Radiology, School of Dentistry
The transcription factor NF-κB is a critical regulator of immune and inflammatory responses. In mammals, the NF-κB/Rel family comprises five members: p50, p52, p65 (Rel-A), c-Rel, and Rel-B proteins, which form homo- or heterodimers and remain as an inactive complex with the inhibitory molecules called IκB proteins in resting cells. Two distinct NF-κB signaling pathways have been described: 1) the canonical pathway primarily activated by pathogens and inflammatory mediators, and 2) the noncanonical pathway mostly activated by developmental cues. The most abundant form of NF-κB activated by pathologic stimuli via the canonical pathway is the p65:p50 heterodimer. Disproportionate increase in activated p65 and subsequent transactivation of effector molecules is integral to the pathogenesis of many chronic diseases such as the rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, and even neurodegenerative pathologies. Hence, the NF-κB p65 signaling pathway has been a pivotal point for intense drug discovery and development. This review begins with an overview of p65-mediated signaling followed by discussion of strategies that directly target NF-κB p65 in the context of chronic inflammation.
Differential profiles of soluble and cellular toll like receptor (TLR)-2 and 4 in chronic periodontitis
(PLOS, 2018-12-20) AlQallaf, Hawra; Hamada, Yusuke; Blanchard, Steven; Shin, Daniel; Gregory, Richard; Srinivasan, Mythily; Periodontology, School of Dentistry
Chronic periodontitis is a common inflammatory disease initiated by a complex microbial biofilm and mediated by the host response causing destruction of the supporting tissues of the teeth. Host recognition of pathogens is mediated by toll-like receptors (TLRs) that bind conserved molecular patterns shared by large groups of microorganisms. The oral epithelial cells respond to most periodontopathic bacteria via TLR-2 and TLR-4. In addition to the membrane-associated receptors, soluble forms of TLR-2 (sTLR-2) and TLR-4 (sTLR-4) have been identified and are thought to play a regulatory role by binding microbial ligands. sTLR-2 has been shown to arise from ectodomain shedding of the extracellular domain of the membrane receptor and sTLR-4 is thought to be an alternate spliced form. Many studies have previously reported the presence of elevated numbers of viable exfoliated epithelial cells in the saliva of patients with chronic periodontitis. The objective of this study was to investigate the potential value of salivary sTLR-2 and sTLR-4 together with the paired epithelial cell-associated TLR-2/4 mRNA as diagnostic markers for chronic periodontitis. Unstimulated whole saliva was collected after obtaining informed consent from 40 individuals with either periodontitis or gingivitis. The sTLR-2 and sTLR4 in saliva was measured by enzyme-linked immunosorbent assay. The TLR-2 and TLR-4 transcript in the epithelial cells in saliva was measured by real time polymerase chain reaction. While levels of sTLR-2 exhibited an inverse correlation, sTLR-4 positively correlated with clinical parameters in the gingivitis cohort. Interestingly, both correlations were lost in the periodontitis cohort indicating a dysregulated host response. On the other hand, while the sTLR-2 and the paired epithelial cell associated TLR-2 mRNA exhibited a direct correlation (r2 = 0.62), that of sTLR4 and TLR-4 mRNA exhibited an inverse correlation (r2 = 0.53) in the periodontitis cohort. Collectively, assessments of salivary sTLR2 and sTLR4 together with the respective transcripts in the epithelial cells could provide clinically relevant markers of disease progression from gingivitis to periodontitis.
Nuclear factor-kappa B: Glucocorticoid-induced leucine zipper interface analogs suppress pathology in an Alzheimer's disease model
(Elsevier, 2018-01-01) Srinivasan, Mythily; Lahiri, Niloy; Thyagarajan, Anish; Witek, Emily; Hickman, Debra; Lahiri, Debomoy K.; Oral Pathology, Medicine and Radiology, School of Dentistry
Introduction Glucocorticoid-induced leucine zipper is a regulatory protein that sequesters activated nuclear factor-kappa B p65. Previously, we showed that rationally designed analogs of the p65-binding domain of glucocorticoid-induced leucine zipper, referred to as glucocorticoid-induced leucine zipper analogs (GAs), inhibited amyloid β–induced metabolic activity and inflammatory cytokines in mixed brain cell cultures. Here, we investigate the therapeutic efficacy of GA in an Alzheimer's disease model. Methods GA and control peptides were synthesized covalently as peptide amides with the cell-penetrating agent. C57Bl/6J mice induced with lipopolysaccharide-mediated neuroinflammation (250 mg/kg i.p/day for six days) were treated on alternate days with GA-1, GA-2, or control peptides (25 mg/kg i.v). Brain tissues were assessed for gliosis, cytokines, and antiapoptotic factors. Results The brain tissues of GA-1– and GA-2–treated mice exhibited significantly reduced gliosis, suppressed inflammatory cytokines, and elevated antiapoptotic factors. Discussion The antineuroinflammatory effects of GA suggest potential therapeutic application for Alzheimer's disease.

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