Publications by authors named "Keith Fowke"

Introduction: Chronic immune activation is a hallmark of human immunodeficiency virus (HIV) infection that significantly impacts disease pathogenesis. However, in-depth studies characterizing the immunological landscape of the ectocervix during chronic HIV infection remain scarce despite the importance of this tissue site for HIV transmission.

Methods: Ectocervical tissue samples were obtained from antiretroviral-naïve HIV-seropositive and -seronegative Kenyan female sex workers.

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Chronic systemic immune activation significantly influences human immunodeficiency virus (HIV) disease progression. Despite evidence of a pro-inflammatory environment in the genital tract of HIV-infected women, comprehensive investigations into cervical tissue from this region remain limited. Similarly, the consequences of chronic HIV infection on the integrity of the female genital epithelium are poorly understood, despite its importance in HIV transmission and replication.

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Article Synopsis
  • The cervicovaginal epithelial barrier is vital for protecting the female reproductive tract from sexually transmitted infections, and its function is influenced by hormones like estradiol and progesterone.
  • A study involved collecting mucosal and blood samples from Kenyan female sex workers, analyzing them at different menstrual cycle phases to assess the hormones' impact on gene and protein expression in the ectocervical mucosa.
  • Findings indicated that during the follicular phase, higher estradiol levels were linked to better epithelial structure and increased barrier integrity, but there were no significant correlations involving progesterone or during the luteal phase.
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Background: LAG3 is an immune checkpoint molecule with emerging therapeutic use. Expression of LAG3 is well studied on T cells, but the proportion of LAG3-expressing cells varies greatly by study and its comparative expression between non-T cells is lacking.

Methods/objectives: This study uses flow cytometry to compare surface LAG3 expression between T cells, NK cells, B cells, pDCs and monocytes of healthy donors.

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We identified a cluster of mpox exposures among key populations in Kenya through retrospective serologic screening. We identified strong seropositivity among sex workers and gay, bisexual, and other men who have sex with men. These findings demonstrate the need for increased mpox surveillance among mpox-endemic and mpox-endemic-adjacent regions in Africa.

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Background: 1.5 million new HIV infections occurred in 2021, suggesting new prevention methods are needed. Inflammation increases the risk for HIV acquisition by attracting HIV target cells to the female genital tract (FGT).

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Currently, no effective vaccine to prevent human immunodeficiency virus (HIV) infection is available, and various platforms are being examined. The vesicular stomatitis virus (VSV) vaccine vehicle can induce robust humoral and cell-mediated immune responses, making it a suitable candidate for the development of an HIV vaccine. Here, we analyze the protective immunological impacts of recombinant VSV vaccine vectors that express chimeric HIV Envelope proteins (Env) in rhesus macaques.

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COVID-19 and influenza both cause enormous disease burdens, and vaccines are the primary measures for their control. Since these viral diseases are transmitted through the mucosal surface of the respiratory tract, developing an effective and convenient mucosal vaccine should be a high priority. We previously reported a recombinant vesicular stomatitis virus (rVSV)-based bivalent vaccine (v-EM2/SPΔC1) that protects animals from both SARS-CoV-2 and influenza viruses via intramuscular and intranasal immunization.

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Despite the human immunodeficiency virus (HIV) pandemic continuing worldwide for 40 years, no vaccine to combat the disease has been licenced for use in at risk populations. Here, we describe a novel recombinant vesicular stomatitis virus (rVSV) vector vaccine expressing modified HIV envelope glycoproteins and Ebola virus glycoprotein. Three heterologous immunizations successfully prevented infection by a different clade SHIV in 60% of non-human primates (NHPs).

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Article Synopsis
  • The study examines the effects of hydroxychloroquine (HCQ) on the immune response in healthy individuals, focusing on T cell activation and cytokine production.
  • Results showed that HCQ treatment significantly decreased T cell activation and responsiveness, which could be relevant for individuals with autoimmune diseases.
  • Although the study didn't specifically target COVID vaccine responses, it highlights potential impacts of HCQ on the immune system that might influence vaccine effectiveness in such patients.
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Invariant Natural Killer T (iNKT) cells undergo immune exhaustion during chronic activation caused by cancer and viral infections, such as HIV. Exhaustion is marked by cell dysfunction and increased expression of immune checkpoint proteins programmed cell-death-1 (PD-1) and lymphocyte-activation-gene-3 (LAG-3). We hypothesize that blockade of PD-1 and/or LAG-3 will enhance iNKT cell function.

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Some people remain healthier throughout life than others but the underlying reasons are poorly understood. Here we hypothesize this advantage is attributable in part to optimal immune resilience (IR), defined as the capacity to preserve and/or rapidly restore immune functions that promote disease resistance (immunocompetence) and control inflammation in infectious diseases as well as other causes of inflammatory stress. We gauge IR levels with two distinct peripheral blood metrics that quantify the balance between (i) CD8 and CD4 T-cell levels and (ii) gene expression signatures tracking longevity-associated immunocompetence and mortality-associated inflammation.

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Article Synopsis
  • The study focused on the tissue-adherent microbiota present in the ectocervical region of Kenyan female sex workers, revealing that these communities have distinct characteristics compared to luminal microbiota.
  • The researchers found a higher diversity in the tissue-adherent microbiome, with key genera including Gardnerella and Lactobacillus, and noted different associations with gene expression and host protein profiles.
  • The findings indicate that these tissue-adherent communities could play significant roles in health and disease, particularly regarding inflammatory responses and epithelial barrier stability.
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Background: Serological surveys are used to ascertain influenza infection and immunity, but evidence for the utility of mucosal immunoglobulin A (IgA) as a correlate of infection or protection is limited.

Methods: We performed influenza-like illness (ILI) surveillance on 220 individuals living or working in a retirement community in Gainesville, Florida from January to May 2018, and took pre- and postseason nasal samples of 11 individuals with polymerase chain reaction (PCR)-confirmed influenza infection and 60 randomly selected controls. Mucosal IgA against 10 strains of influenza was measured from nasal samples.

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  • Hormonal changes during the menstrual cycle influence immune responses in the cervicovaginal area, with varying concentrations of immune mediators like cytokines and immunoglobulins across different phases.
  • A systematic review and meta-analysis of studies revealed that many immune mediators have lower concentrations in the luteal phase compared to the follicular phase, with only a few, like IL-1α and HBD-2, showing elevated levels during luteal phase.
  • The research compiled data from over 39,000 measurements, indicating a moderate to high strength of evidence for these immunological shifts throughout the menstrual cycle, highlighting a need for more comprehensive understanding due to previous inconsistent study results.
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COVID-19 and influenza are both highly contagious respiratory diseases that have been serious threats to global public health. It is necessary to develop a bivalent vaccine to control these two infectious diseases simultaneously. In this study, we generated three attenuated replicating recombinant vesicular stomatitis virus (rVSV)-based vaccine candidates against both SARS-CoV-2 and influenza viruses.

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Depot medroxyprogesterone acetate (DMPA) is an injectable hormonal contraceptive used by millions of women worldwide. However, experimental studies have associated DMPA use with genital epithelial barrier disruption and mucosal influx of human immunodeficiency virus (HIV) target cells. We explored the underlying molecular mechanisms of these findings.

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Background: Mucosa-associated invariant T (MAIT) cells are innate-like T cells with specialized antimicrobial functions. Circulating MAIT cells are depleted in chronic human immunodeficiency virus (HIV) infection, but studies examining this effect in peripheral tissues, such as the female genital tract, are lacking.

Methods: Flow cytometry was used to investigate circulating MAIT cells in a cohort of HIV-seropositive (HIV+) and HIV-seronegative (HIV-) female sex workers (FSWs), and HIV- lower-risk women (LRW).

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Introduction: Acetylsalicylic acid (ASA) is a well-known and safe anti-inflammatory. At low-dose, it is prescribed to prevent secondary cardiovascular events in those with pre-existing conditions and to prevent preeclampsia. Little is known about how low-dose ASA affects the immune response.

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Background: Invariant Natural Killer T (iNKT) cells are innate lymphocytes bridging the innate and adaptive immune systems and are critical first responders against cancer and infectious diseases. iNKT cell phenotype and functionality are studied using in vitro stimulation assays assessing cytokine response and proliferation capabilities. The most common stimulant is the glycolipid α-Galactosyl Ceramide (α-GalCer), which stimulates iNKT cells when presented by CD1d, an MHC class I-like molecule expressed by antigen-presenting cells (APC).

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Immunological correlates of natural resistance to HIV have been identified in HIV-exposed seronegative (HESN) individuals and include a low-inflammatory genital mucosal status. The cervicovaginal epithelium has not been studied for such correlates despite constituting an important barrier against sexual HIV transmission. To fill this gap in knowledge, we collected samples of blood, cervical mononuclear cells, cervicovaginal lavage, and ectocervical tissue from Kenyan HESN sex workers (n = 29) and controls (n = 33).

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Article Synopsis
  • Depot Medroxyprogesterone Acetate (DMPA) is a common contraceptive in Sub-Saharan Africa and its impact on HIV risk and immune activation among women, particularly sex workers, was studied.
  • The study involved DMPA-using female sex workers and non-sex workers, comparing their immune responses with control groups not using hormonal contraception.
  • Results indicated that while DMPA increased inflammation and activation markers in non-sex workers, it seemed to negate the lower immune activation typically seen in sex workers, highlighting DMPA's role as a significant immune modulator.
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LAG3 is an important immune checkpoint with relevance in cancer, infectious disease and autoimmunity. However, despite LAG3's role in immune exhaustion and the great potential of LAG3 inhibition as treatment, much remains unknown about its biology, particularly its mechanism of action. This review describes the knowns, unknowns and controversies surrounding LAG3.

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Background: The hormonal contraceptive depot medroxyprogesterone acetate (DMPA) may be associated with an increased risk of acquiring human immunodeficiency virus (HIV). We hypothesize that DMPA use influences the ectocervical tissue architecture and HIV target cell localization.

Methods: Quantitative image analysis workflows were developed to assess ectocervical tissue samples collected from DMPA users and control subjects not using hormonal contraception.

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Article Synopsis
  • The COVID-19 pandemic has triggered serious health, social, and economic challenges globally, with significant negative impacts particularly in lower- and middle-income countries.
  • In Kenya, the response to the pandemic, including daily curfews and economic loss, has severely affected impoverished populations like sex workers who depend on informal income for survival.
  • Despite these hardships, communities and programs in Kenya have shown resilience and creativity in adapting to disruptions caused by the pandemic, aiming to recover health and stability as the crisis continues.
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