Effects of Helminth Eradication on the Immune System

Cytokine Gene Expression Profiles during HIV and Helminth Coinfection in Underprivileged Peri-Urban South African Adults

BACKGROUND

Intestinal helminth parasites are potent stimulators of T helper type 2 (Th2) and regulatory Th3 anti-inflammatory immune responses, while human immunodeficiency virus (HIV) infections are activators of predominantly T helper type 1(Th1) pro-inflammatory responses. Studies investigating the immune profiles of individuals coinfected with helminths and HIV are scarce. Although it is well known that helminths cause a type 2 immune response during the chronic stage of infection that is characterised by Th2 cell differentiation, eosinophil recruitment, and alternative macrophage activation, the immune mechanisms that regulate tissue damage at the time of parasite invasion are poorly understood.

AIM

The aim of the study was to determine the cytokine gene expression profiles during HIV and helminth coinfection in underprivileged South African adults living in a peri-urban area with poor sanitary conditions and a lack of clean water supply.

METHOD

Study participants (n = 164) were subdivided into uninfected controls, HIV-infected, helminth-infected, and HIV and helminth-coinfected groups. The Kato-Katz and Mini Parasep techniques and Ascaris lumbricoides-specific Immunoglobulin E (IgE) and Immunoglobulin G4 (IgG4) levels were used to detect helminth infections. Participants' HIV status was determined using two HIV1/2 antibody test kits. RNA was isolated from white blood cells for cytokine (Th1-, Th2-, and Th17-related) and transcription factor gene expression profiling using real-time PCR.

RESULTS

Multivariate regression data were adjusted for age, gender, BMI, antiretroviral treatment (ART), and nutritional supplement intake. The HIV and helminth-coinfected group had significantly higher tumour necrosis factor alpha (TNF-α) (adjusted β = 0.53, p = 0.036), interleukin 2 (IL-2) (adjusted β = 6.48, p = 0.008), and interleukin 17 (IL-17) (adjusted β = 1.16, p = 0.001) levels and lower GATA binding protein 3 (GATA3) levels (adjusted β = -0.77, p = 0.018) compared to the uninfected controls. No statistical significance was noted for Th2-related cytokines.

CONCLUSION

The coinfected group had higher proinflammatory Th1- and Th17-related cytokine gene expression profiles compared to the uninfected controls. The findings suggest that pro-inflammatory responses are elevated during coinfection, which supports the hypothesis that helminths have a deleterious effect on HIV immune responses.

Memories that last: Dynamics of memory T cells throughout the body

Memory T cells form an essential part of immunological memory, which can last for years or even a lifetime. Much experimental work has shown that the individual cells that make up the memory T-cell pool are in fact relatively short-lived. Memory T cells isolated from the blood of humans, or the lymph nodes and spleen of mice, live about 5-10 fold shorter than naive T cells, and much shorter than the immunological memory they convey. The commonly accepted view is, therefore, that long-term T-cell memory is maintained dynamically rather than by long-lived cells. This view is largely based on memory T cells in the circulation, identified using rather broad phenotypic markers, and on research in mice living in overly clean conditions. We wondered to what extent there may be heterogeneity in the dynamics and lifespans of memory T cells. We here review what is currently known about the dynamics of memory T cells in different memory subsets, locations in the body and conditions of microbial exposure, and discuss how this may be related to immunometabolism and how this knowledge can be used in various clinical settings.

Immunological Interactions between Intestinal Helminth Infections and Tuberculosis

Helminth infections are among the neglected tropical diseases affecting billions of people globally, predominantly in developing countries. Helminths’ effects are augmented by coincident tuberculosis disease, which infects a third of the world’s population. The role of helminth infections on the pathogenesis and pathology of active tuberculosis (T.B.) remains controversial. Parasite-induced suppression of the efficacy of Bacille Calmette-Guerin (BCG) has been widely reported in helminth-endemic areas worldwide. T.B. immune response is predominantly proinflammatory T-helper type 1 (Th1)-dependent. On the other hand, helminth infections induce an opposing anti-inflammatory Th2 and Th3 immune-regulatory response. This review summarizes the literature focusing on host immune response profiles during single-helminth, T.B. and dual infections. It also aims to necessitate investigations into the complexity of immunity in helminth/T.B. coinfected patients since the research data are limited and contradictory. Helminths overlap geographically with T.B., particularly in Sub-Saharan Africa. Each disease elicits a response which may skew the immune responses. However, these effects are helminth species-dependent, where some parasites have no impact on the immune responses to concurrent T.B. The implications for the complex immunological interactions that occur during coinfection are highlighted to inform government treatment policies and encourage the development of high-efficacy T.B. vaccines in areas where helminths are prevalent.

Trained immunity in type 2 immune responses

Immunological memory of innate immune cells, also termed "trained immunity", allows for cross-protection against distinct pathogens, but may also drive chronic inflammation. Recent studies have shown that memory responses associated with type 2 immunity do not solely rely on adaptive immune cells, such as T- and B cells, but also involve the innate immune system and epithelial cells. Memory responses have been described for monocytes, macrophages and airway epithelial cells of asthmatic patients as well as for macrophages and group 2 innate lymphoid cells (ILC2) from allergen-sensitized or helminth-infected mice. The metabolic and epigenetic mechanisms that mediate allergen- or helminth-induced reprogramming of innate immune cells are only beginning to be uncovered. Trained immunity has been implicated in helminth-driven immune regulation and allergen-specific immunotherapy, suggesting its exploitation in future therapies. Here, we discuss recent advances and key remaining questions regarding the mechanisms and functions of trained type 2 immunity in infection and inflammation.

Infectious diseases among Ethiopian immigrants in Israel: a descriptive literature review

The mass immigration of Ethiopian Jews to Israel began in the 1980s. For most of these immigrants this was a time of sharp transition from a village life with very basic living conditions, in most cases without a regular supply of water, electricity, or healthcare services, to a modern Western urban society. The aim of this review was to search the medical literature on the characteristics of infectious diseases that are typical in Ethiopian immigrants (EI), using relevant keywords. There has been success in coping with diseases among EI, that are rare although recognized in Israel, in terms of screening and early identification. TB was common in Ethiopia over all the years of immigration to Israel. In contrast, HIV appeared in EI from 1999 when they had long stayovers in transition camps in Gondar and Addis Ababa where there was a high risk of infection with sexually transmitted diseases. There were often delays in diagnosing 'exotic' diseases that are endemic in Africa, but not well known in Israel, such as Onchocerciasis, Schistosomiasis, Strongyloidiasis, and Bartonella endocarditis, which cause severe morbidity and mortality among EI. We describe the effect on general morbidity in Israel, and how the healthcare services coped with these diseases, including obstacles, and failures and successes. In light of the ongoing immigration of African refugees to the United States and Europe, the Israeli experience can be of value to healthcare policy makers in developing strategies for the effective management by medical staff treating these immigrants.