Association of recurrent candidal vaginitis with inheritance of Lewis blood group antigens

ABO blood group antigens and differential glycan expression: Perspective on the evolution of common human enzyme deficiencies

Enzymes catalyze biochemical reactions and play critical roles in human health and disease. Enzyme variants and deficiencies can lead to variable expression of glycans, which can affect physiology, influence predilection for disease, and/or directly contribute to disease pathogenesis. Although certain well-characterized enzyme deficiencies result in overt disease, some of the most common enzyme deficiencies in humans form the basis of blood groups. These carbohydrate blood groups impact fundamental areas of clinical medicine, including the risk of infection and severity of infectious disease, bleeding risk, transfusion medicine, and tissue/organ transplantation. In this review, we examine the enzymes responsible for carbohydrate-based blood group antigen biosynthesis and their expression within the human population. We also consider the evolutionary selective pressures, e.g. malaria, that may account for the variation in carbohydrate structures and the implications of this biology for human disease.

Microbial lectome versus host glycolipidome: How pathogens exploit glycosphingolipids to invade, dupe or kill

Glycosphingolipids (GSLs) are ubiquitous components of the cell membranes, found across several kingdoms of life, from bacteria to mammals, including humans. GSLs are a subclass of major glycolipids occurring in animal lipid membranes in clusters named “lipid rafts.” The most crucial functions of GSLs include signal transduction and regulation as well as participation in cell proliferation. Despite the mainstream view that pathogens rely on protein–protein interactions to survive and thrive in their hosts, many also target the host lipids. In particular, multiple pathogens produce adhesion molecules or toxins that bind GSLs. Attachment of pathogens to cell surface receptors is the initial step in infections. Many mammalian pathogens have evolved to recognize GSL-derived receptors. Animal glycosphingolipidomes consist of multiple types of GSLs differing in terminal glycan and ceramide structures in a cell or tissue-specific manner. Interspecies differences in GSLs dictate host specificity as well as cell and tissue tropisms. Evolutionary pressure exerted by pathogens on their hosts drives changes in cell surface glycoconjugates, including GSLs, and has produced a vast number of molecules and interaction mechanisms. Despite that abundance, the role of GSLs as pathogen receptors has been largely overlooked or only cursorily discussed. In this review, we take a closer look at GSLs and their role in the recognition, cellular entry, and toxicity of multiple bacterial, viral and fungal pathogens.

Vulvovaginal Candidosis: Current Concepts, Challenges and Perspectives

Vulvovaginal candidosis (VVC) is a frequently occurring infection of the lower female genital tract, mostly affecting immuno-competent women at childbearing age. Candida albicans is the most prevalent pathogenic yeast—apart from other non-albicans species—related to this fungal infection. Different virulence factors of C. albicans have been identified, which increase the risk of developing VVC. To initiate treatment and positively influence the disease course, fast and reliable diagnosis is crucial. In this narrative review, we cover the existing state of understanding of the epidemiology, pathogenesis and diagnosis of VVC. However, treatment recommendations should follow current guidelines.

Advances in Understanding Human Genetic Variations That Influence Innate Immunity to Fungi

Fungi are ubiquitous. Yet, despite our frequent exposure to commensal fungi of the normal mammalian microbiota and environmental fungi, serious, systemic fungal infections are rare in the general population. Few, if any, fungi are obligate pathogens that rely on infection of mammalian hosts to complete their lifecycle; however, many fungal species are able to cause disease under select conditions. The distinction between fungal saprophyte, commensal, and pathogen is artificial and heavily determined by the ability of an individual host's immune system to limit infection. Dramatic examples of commensal fungi acting as opportunistic pathogens are seen in hosts that are immune compromised due to congenital or acquired immune deficiency. Genetic variants that lead to immunological susceptibility to fungi have long been sought and recognized. Decreased myeloperoxidase activity in neutrophils was first reported as a mechanism for susceptibility to Candida infection in 1969. The ability to detect genetic variants and mutations that lead to rare or subtle susceptibilities has improved with techniques such as single nucleotide polymorphism (SNP) microarrays, whole exome sequencing (WES), and whole genome sequencing (WGS). Still, these approaches have been limited by logistical considerations and cost, and they have been applied primarily to Mendelian impairments in anti-fungal responses. For example, loss-of-function mutations in CARD9 were discovered by studying an extended family with a history of fungal infection. While discovery of such mutations furthers the understanding of human antifungal immunity, major Mendelian susceptibility loci are unlikely to explain genetic disparities in the rate or severity of fungal infection on the population level. Recent work using unbiased techniques has revealed, for example, polygenic mechanisms contributing to candidiasis. Understanding the genetic underpinnings of susceptibility to fungal infections will be a powerful tool in the age of personalized medicine. Future application of this knowledge may enable targeted health interventions for susceptible individuals, and guide clinical decision making based on a patient's individual susceptibility profile.

Vulvovaginal candidiasis: Epidemiology, microbiology and risk factors

Vulvovaginal candidiasis (VVC) is an infection caused by Candida species that affects millions of women every year. Although Candida albicans is the main cause of VVC, the identification of non-Candida albicans Candida (NCAC) species, especially Candida glabrata, as the cause of this infection, appears to be increasing. The development of VVC is usually attributed to the disturbance of the balance between Candida vaginal colonization and host environment by physiological or nonphysiological changes. Several host-related and behavioral risk factors have been proposed as predisposing factors for VVC. Host-related factors include pregnancy, hormone replacement, uncontrolled diabetes, immunosuppression, antibiotics, glucocorticoids use and genetic predispositions. Behavioral risk factors include use of oral contraceptives, intrauterine device, spermicides and condoms and some habits of hygiene, clothing and sexual practices. Despite a growing list of recognized risk factors, much remains to be elucidated as the role of host versus microorganisms, in inducing VVC and its recurrence. Thus, this review provides information about the current state of knowledge on the risk factors that predispose to VVC, also including a revision of the epidemiology and microbiology of VVC, as well as of Candida virulence factors associated with vaginal pathogenicity.

Blood Groups in Infection and Host Susceptibility

Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome.

Variation in microbiologic profiles among pregnant women with bacterial vaginosis

OBJECTIVE

The purpose of this study was to determine if clinical findings and sociodemographic variables among bacterial vaginosis (BV)-positive pregnant women are associated with different microbiologic profiles.

STUDY DESIGN

Pregnant women were assessed for BV by Nugent criteria. BV+ women were separated into 6 mutually exclusive microbiologic groups. In unadjusted analyses, we compared (1) sociodemographic and behavioral characteristics, and (2) 3 clinical characteristics among BV+ women with and without Mobiluncus (M+ vs M-). Unadjusted data were analyzed using the chi-square test. Multiple logistic regression was used to assess the likelihood of having clinical signs of BV in women with and without Mobiluncus spp while controlling for confounders.

RESULTS

A total of 1756 BV+ pregnant women were followed. The M+ group (n=702) was significantly more likely than the M- group (n=1054) to be non-Hispanic black (80.9% vs 66.2%; P < .0001), older than 21 years (61.7% vs 48.7%; P < .0001), and to have had more than 3 lifetime sexual partners (66.4% vs 54.9%; P < .0001). The M+ group was also more likely to have clue cells on wet mount (63.9% vs 47.2%; P < .0001) and a positive amine odor after addition of KOH (57.2% vs 45.0%; P=.001). There was no difference in other demographic variables or physician diagnosis of abnormal vaginal discharge. In the adjusted analyses for each clinical outcome, all findings were consistent with the unadjusted analyses.

CONCLUSION

BV+ pregnant women with Mobiluncus spp are more likely to have clue cells present on wet mount, a positive amine odor after KOH preparation, and to be older, non-Hispanic black, and have had more lifetime sexual partners compared to BV+ women without any Mobiluncus species.

Genetic susceptibility to vaginal candidiasis

To enable future studies on host resistance factors and therapy, inbred and outbred mouse strains were tested for susceptibility to vaginal candidiasis. Groups of mice were given 0.5 mg estradiol 3 days before and 4 days after intravaginal challenge with a suspension of Candida albicans. On day 1 after challenge, a swab was used to quantitate infection in all groups and to assure equivalent infection levels. On day 6, this was repeated and the experiment was terminated. BALB/c, the reference strain in repeated experiments, was susceptible, showing persistent infection with levels of cfu at day 6 falling within a range between a twofold decrease and a fourfold increase in relation to day 1 levels. CD-1 outbred mice were markedly resistant, with day 6 cfu levels showing a 74- to 87-fold decrease with respect to day 1 levels, whereas other outbred strains (CF-1, SW, ICR) were susceptible. A BALB/c substrain (ByJ) was also susceptible. With exception of CBA/J, which showed modest resistance, all inbred strains were similarly susceptible, including DBA/2, AKR/J, C3H/HeN, A/J and C57BL/6. The differences between CD-1 and BALB/c mice were also seen with a second C. albicans isolate. Our results show susceptibility to vaginal candidiasis is independent of the major histocompatibility locus H2 haplotype and any effect ascribable to use of particular commercial mouse suppliers. Differences among mouse strains in susceptibility to C. albicans, as seen in previous studies involving nonvaginal challenge routes, are not reflected in this vaginal candidiasis model; in general, such resistance patterns appear specific to the route of challenge administration. The resistance seen in mouse strain CD-1 is of particular interest in that CD-1 is known to be resistant to endocrine disruption by estrogen. Our results suggest this estrogen insensitivity may have broad-ranging effects on processes other than gametogenesis, including vaginal susceptibility to candidiasis.

Determination of Duffy genotypes in three populations of African descent using PCR and sequence-specific oligonucleotides

The expression of the Duffy Antigen/Receptor for Chemokines (DARC) on red blood cells (RBC) has been commonly determined using hemagglutination tests. Because the vast majority of African individuals are Duffy-negative, screening for DARC expression on RBC is a valuable tool to assess Caucasian admixture in populations of African descent. Furthermore, blood group antigens have been frequently tested as potential risk factors for complex diseases. We established a dot-blotting protocol using sequence-specific oligonucleotides (SSOs) for the DARC-46T ("Duffy-positive") and -46C ("Duffy-negative") alleles. With this method, but not with serological methods, Duffy-positive individuals can be further characterized as homozygous or heterozygous for the dominant Duffy-positive allele, allowing more precise estimation of allele frequencies and admixture in heterogeneous populations. In unrelated African American (n = 235), Afro-Caribbean (n = 90) and Colombian (n = 93) subjects, the frequency of the -46T allele was 21.7%, 12.2% and 74.7%, respectively. The percentage of Duffy-positive individuals (homozygous or heterozygous for the -46T allele) in each population was in accordance with published frequencies. As expected, the -46C allele was not detected in 20 Caucasian subjects. This sensitive and specific method allows for the rapid and inexpensive screening of large samples for Duffy genotypes using small quantities of genomic DNA.

Host genes and infectious diseases. HIV, other pathogens, and a public health perspective

INTRODUCTION

The global impact of infectious diseases is tremendous. In 1996, the 17 million deaths from infectious diseases accounted for one third of all deaths worldwide, while the acute and chronic morbidity from infectious diseases adds an additional great burden on global health. Multiple factors, host and nonhost, influence the susceptibility of individuals and populations to infectious diseases, as well as the severity of the illness once infected.

METHODS

We review the influence of host genes on the susceptibility to and severity of viral, bacterial, parasitic and fungal infectious diseases, on vaccine responsiveness and on treatments for infections. HIV/AIDS is discussed in detail because it is an example of an infectious disease influenced by multiple host genes and because of its impact. Although the HIV/AIDS pandemic dates only since the late 1970s, it has claimed the lives of 11 million people worldwide and, today, more than 30 million people are estimated to be HIV infected.

CONCLUSION

Our greater understanding of the genetic factors that influence morbidity and mortality of infectious disease leads to new avenues of prevention and treatment that can improve the health of individuals and populations.