Michael Royal

Bio: Michael Royal is an academic researcher from Washington University in St. Louis. The author has contributed to research in topics: Sitagliptin & Population. The author has an hindex of 6, co-authored 6 publications receiving 237 citations.

Alendronate, vitamin D, and calcium for the treatment of osteopenia/osteoporosis associated with HIV infection

Abstract: Background: Osteopenia and osteoporosis are frequent complications of HIV infection and/or its treatment. Alendronate is the only bisphosphonate approved for the treatment of osteoporosis in men and women. We conducted a 48-week prospective, randomized, open-label study to evaluate the effects of alendronate, vitamin D, and calcium supplementation on bone mineral density (BMD) in patients with HIV infection. Methods: Thirty-one HIV-infected subjects with lumbar spine BMD t-scores less than - 1.0 on antiretroviral therapy for a minimum of 6 months were randomized to receive (n = 15) or not to receive (n = 16) 70 mg of alendronate weekly for 48 weeks. All subjects received calcium (1000 mg daily as calcium carbonate) and vitamin D supplementation (400 IU daily). The study was powered to detect 3% changes in BMD in the lumbar spine within arms at 48 weeks. Results: Thirty-one patients were enrolled; most were male, with an average length of HIV infection of 8 years. Eighty-four percent had an HIV RNA load below 400 copies/mL, with a current median CD4 + T-cell count of 561 cells/mm 3 (median nadir CD4 cell count of 167 ceils/mm 3 ). At baseline, the median t-score in the lumbar spine was - 1.52 and the median t-score in the hip was -1.02. Alendronate in combination with vitamin D and calcium increased lumbar spine BMD by 5.2% (95% confidence interval [CI]: 1.3-6.4) at 48 weeks compared with an increase of 1.3% (95% CI: -2.4 to 4.0) in subjects receiving vitamin D and calcium alone. One subject discontinued treatment in each arm. There were no serious adverse events. Conclusions: Alendronate, vitamin D, and calcium are safe and potentially useful in the treatment of osteopenia/osteoporosis associated with HIV infection.

Dipeptidyl peptidase IV inhibition does not adversely affect immune or virological status in HIV infected men and women: a pilot safety study.

Abstract: Context: People infected with HIV have a higher risk for developing insulin resistance, diabetes, and cardiovascular disease than the general population. Dipeptidyl peptidase IV (DPP4) inhibitors are glucose-lowering medications with pleiotropic actions that may particularly benefit people with HIV, but the immune and virological safety of DPP4 inhibition in HIV is unknown. Objective: DPP4 inhibition will not reduce CD4+ T lymphocyte number or increase HIV viremia in HIV-positive adults. Design: This was a randomized, placebo-controlled, double-blind safety trial of sitagliptin in HIV-positive adults. Setting: The study was conducted at an academic medical center. Participants: Twenty nondiabetic HIV-positive men and women (9.8 ± 5.5 years of known HIV) taking antiretroviral therapy and with stable immune (625 ± 134 CD4+ T cells per microliter) and virological (<48 copies HIV RNA per milliliter) status. Intervention: The intervention included sitagliptin (100 mg/d) vs matching placebo for up to 24 weeks. ...

Sitagliptin Reduces Inflammation and Chronic Immune Cell Activation in HIV Adults With Impaired Glucose Tolerance

Abstract: Context: HIV infection is associated with a greater risk for fasting hyperinsulinemia, impaired glucose tolerance, and higher incidence rates for vascular disease, myocardial infarction, or stroke despite effective combination antiretroviral therapy (cART). The underlying mechanism(s) may involve chronic low-grade systemic inflammation and immune cell activation. Dipeptidyl peptidase-4 inhibitors (sitagliptin) improve glucose tolerance and may possess immunomodulatory effects because leukocyte CD26 cell surface receptors express dipeptidyl peptidase-4 activity. Objective: Sitagliptin will reduce inflammatory and immune cell activation markers known to be elevated in cART-treated HIV-infected (HIV+) adults with impaired glucose tolerance. Design: This was designed as a prospective, randomized, placebo-controlled, double-blind trial of sitagliptin in HIV+ adults. Setting: The setting was an academic medical center. Patients: Patients were cART-treated HIV+ men and women (n = 36) with stable HIV disease and ...

Durability of Response to Treatment among Antiretroviral-Experienced Subjects: 48-Week Results from AIDS Clinical Trials Group Protocol 359

Abstract: The 24-week extension of AIDS Clinical Trials Group Protocol 359, a study of human immunodeficiency virus (HIV)‐infected, indinavir-experienced patients, was designed to study the durability of “salvage” treatment regimens. Patients received saquinavir in combination with either ritonavir or nelfinavir and, in addition, delavirdine, adefovir, or both. Patients who demonstrated a virologic response at weeks 12‐16 were eligible to continue therapy in the extension through week 48. Of the 105 eligible subjects who were enrolled in the extension, 86 (82%) completed 48 weeks, and 49 (57%) of those 86 had HIV RNA levels 500 copies/ mL at week 48. For these 86 subjects who completed 48 weeks, the median change in CD4 cell count from baseline was +72 cells/mm 3 . Greater body weight, higher CD4 cell count, and greater degree of phenotypic susceptibility to indinavir and saquinavir at baseline were significantly associated with durable virologic suppression. These results show that some patients who experience treatment failure can demonstrate durable virologic and immunologic responses with salvage antiretroviral regimens. Current treatment guidelines recommend starting therapy for human immunodeficiency virus (HIV) infection with 2 nucleoside analogue reverse-transcriptase inhibitors in combination with 1 or 2 protease inhibitors or a nonnucleoside analogue reversetranscriptase inhibitor [1, 2]. However, 20%‐63% of patients from clinical cohorts experience virologic treatment failure while receiving combination antiretroviral therapy [3‐7]. Recent prospective studies have attempted to identify strategies for treatment of the treatment-experienced patient [8‐13], but these studies have focused primarily on 8‐24-week virologic responses to treatment. The durability of virologic and immunologic re

A lineage of myeloid cells independent of Myb and hematopoietic stem cells

Abstract: Macrophage Development Rewritten Macrophages provide protection against a wide variety of infections and critically shape the inflammatory environment in many tissues. These cells come in many flavors, as determined by differences in gene expression, cell surface phenotype and specific function. Schulz et al. (p. 86, published online 22 March) investigated whether adult macrophages all share a common developmental origin. Immune cells, including most macrophages, are widely thought to arise from hematopoietic stem cells (HSCs), which require the transcription factor Myb for their development. Analysis of Myb-deficient mice revealed that a population of yolk-sac–derived, tissue-resident macrophages was able to develop and persist in adult mice in the absence of HSCs. Importantly, yolk sac–derived macrophages also contributed substantially to the tissue macrophage pool even when HSCs were present. In mice, a population of tissue-resident macrophages arises independently of bone marrow–derived stem cells. Macrophages and dendritic cells (DCs) are key components of cellular immunity and are thought to originate and renew from hematopoietic stem cells (HSCs). However, some macrophages develop in the embryo before the appearance of definitive HSCs. We thus reinvestigated macrophage development. We found that the transcription factor Myb was required for development of HSCs and all CD11bhigh monocytes and macrophages, but was dispensable for yolk sac (YS) macrophages and for the development of YS-derived F4/80bright macrophages in several tissues, such as liver Kupffer cells, epidermal Langerhans cells, and microglia—cell populations that all can persist in adult mice independently of HSCs. These results define a lineage of tissue macrophages that derive from the YS and are genetically distinct from HSC progeny.

Pharmacology, Physiology, and Mechanisms of Action of Dipeptidyl Peptidase-4 Inhibitors

Abstract: Dipeptidyl peptidase-4 (DPP4) is a widely expressed enzyme transducing actions through an anchored transmembrane molecule and a soluble circulating protein. Both membrane-associated and soluble DPP4 exert catalytic activity, cleaving proteins containing a position 2 alanine or proline. DPP4-mediated enzymatic cleavage alternatively inactivates peptides or generates new bioactive moieties that may exert competing or novel activities. The widespread use of selective DPP4 inhibitors for the treatment of type 2 diabetes has heightened interest in the molecular mechanisms through which DPP4 inhibitors exert their pleiotropic actions. Here we review the biology of DPP4 with a focus on: 1) identification of pharmacological vs physiological DPP4 substrates; and 2) elucidation of mechanisms of actions of DPP4 in studies employing genetic elimination or chemical reduction of DPP4 activity. We review data identifying the roles of key DPP4 substrates in transducing the glucoregulatory, anti-inflammatory, and cardiometabolic actions of DPP4 inhibitors in both preclinical and clinical studies. Finally, we highlight experimental pitfalls and technical challenges encountered in studies designed to understand the mechanisms of action and downstream targets activated by inhibition of DPP4.

Bone Disease in HIV Infection: A Practical Review and Recommendations for HIV Care Providers

Abstract: Low bone mineral density (BMD) is prevalent in human immunodeficiency virus (HIV)-infected subjects. Initiation of antiretroviral therapy is associated with a 2%-6% decrease in BMD over the first 2 years, a decrease that is similar in magnitude to that sustained during the first 2 years of menopause. Recent studies have also described increased fracture rates in the HIV-infected population. The causes of low BMD in individuals with HIV infection appear to be multifactorial and likely represent a complex interaction between HIV infection, traditional osteoporosis risk factors, and antiretroviral-related factors. In this review, we make the point that HIV infection should be considered as a risk factor for bone disease. We recommend screening patients with fragility fractures, all HIV-infected post-menopausal women, and all HIV-infected men ⩾50 years of age. We also discuss the importance of considering secondary causes of osteoporosis. Finally, we discuss treatment of the more severe cases of bone disease, while outlining the caveats and gaps in our knowledge.

Coronavirus Infections and Type 2 Diabetes-Shared Pathways with Therapeutic Implications.

Abstract: Individuals with diabetes are at increased risk for bacterial, mycotic, parasitic, and viral infections. The severe acute respiratory syndrome (SARS)-CoV-2 (also referred to as COVID-19) coronavirus pandemic highlights the importance of understanding shared disease pathophysiology potentially informing therapeutic choices in individuals with type 2 diabetes (T2D). Two coronavirus receptor proteins, angiotensin-converting enzyme 2 (ACE2) and dipeptidyl peptidase-4 (DPP4) are also established transducers of metabolic signals and pathways regulating inflammation, renal and cardiovascular physiology, and glucose homeostasis. Moreover, glucose-lowering agents such as the DPP4 inhibitors, widely used in subjects with T2D, are known to modify the biological activities of multiple immunomodulatory substrates. Here, we review the basic and clinical science spanning the intersections of diabetes, coronavirus infections, ACE2, and DPP4 biology, highlighting clinical relevance and evolving areas of uncertainty underlying the pathophysiology and treatment of T2D in the context of coronavirus infection.