Where does innate immunity stop and adaptive immunity begin?

The m6A epitranscriptome opens a new charter in immune system logic

N6-methyladenosine (m6A), the most prevalent RNA internal modification, is present in most eukaryotic species and prokaryotes. Studies have highlighted an intricate network architecture by which m6A epitranscriptome impacts on immune response and function. However, it was only until recently that the mechanisms underlying the involvement of m6A modification in immune system were uncovered. Here, we systematically review the m6A involvement in the regulation of innate and adaptive immune cells. Further, the interplay between m6A modification and anti-inflammatory, anti-viral and anti-tumour immunity is also comprehensively summarized. Finally, we focus on the future prospects of m6A modification in immune modulation. A better understanding of the crosstalk between m6A modification and immune system is of great significance to reveal new pathogenic pathways and to develop promising therapeutic targets of diseases.

Selective expression of a "correct cloud" of Dscam in crayfish survivors after second exposure to the same pathogen

Arthropod hypervariable Dscam (Down syndrome cell adhesion molecule) may be involved in adaptive-like immune characteristics, namely immune priming, enabling the host to "learn" and "remember" pathogens previously encountered in arthropods. However, expression of Dscam in immune-primed arthropods after a second challenge has apparently not been confirmed. Herein, working with Dscam of Australian freshwater crayfish (Cherax quadricarinatus, i.e. CqDscam), we further investigated whether immune priming is mediated by "clouds" of appropriate (or "correct") CqDscam isoforms. In crayfish that survived a first WSSV challenge (immune priming), long-lasting CqDscam expression remained higher after a second WSSV challenge. Selective CqDscam isoforms were also induced after both challenges. Based on pathogen binding assays, these WSSV-induced CqDscam isoforms had a higher WSSV binding ability, perhaps mainly mediated by Ig3-spliced variants. We therefore hypothesized that in these crayfish survivors, an unknown selection process was generating a "correct cloud" of CqDscam against a previously encountered pathogen.

Tumour necrosis factor, interferon-gamma and interleukins as predictive markers of antiprogrammed cell-death protein-1 treatment in advanced non-small cell lung cancer: a pragmatic approach in clinical practice

Background:

The emergence of novel antiprogrammed cell death protein-1 (PD-1) inhibitors in non-small cell lung cancers (NSCLC) has revolutionized the therapeutic landscape of this disease. Although overall survival (OS) has improved in the first- and second-line therapy settings for advanced NSCLC, the benefit is not universal. In a climate of global scrutiny for healthcare costs and potential for toxicities related to immunotherapy, appropriate patient selection is crucial. The aim of this study was to evaluate potential prognostic and predictive biomarkers interferon-gamma (IFN-γ), tumour necrosis factor-alpha (TNF-α) and a panel of interleukins (ILs) in the peripheral blood, and assess any correlation with response to anti-PD-1 inhibition, progression-free survival and OS in NSCLC patients.

Methods:

We prospectively studied 26 NSCLC patients that received immunotherapy (either pembrolizumab or nivolumab). IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10 and IL-12 were analyzed by flow cytometry at the time of diagnosis and at 3 months after initiation of anti-PD-1 inhibition.

Results:

Increased cytokine values (IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-6 and IL-8) at the time of diagnosis and at 3 months after initiation of treatment were significantly correlated with improved response to immunotherapy and prolonged OS. There was no correlation between cytokine levels and programmed cell death ligand-1 (PD-L1) expression.

Conclusions:

Increased IFN-γ, TNF-α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10 and IL-12 levels resulted in better response to NSCLC anti-PD-1 inhibition and longer survival, and this could potentially play an important role in selecting patients that would benefit from anti-PD-1 inhibitors.

Evolution of transgenerational immunity in invertebrates

Over a decade ago, the discovery of transgenerational immunity in invertebrates shifted existing paradigms on the lack of sophistication of their immune system. Nonetheless, the prevalence of this trait and the ecological factors driving its evolution in invertebrates remain poorly understood. Here, we develop a theoretical host-parasite model and predict that long lifespan and low dispersal should promote the evolution of transgenerational immunity. We also predict that in species that produce both philopatric and dispersing individuals, it may pay to have a plastic allocation strategy with a higher transgenerational immunity investment in philopatric offspring because they are more likely to encounter locally adapted pathogens. We review all experimental studies published to date, comprising 21 invertebrate species in nine different orders, and we show that, as expected, longevity and dispersal correlate with the transfer of immunity to offspring. The validity of our prediction regarding the plasticity of investment in transgenerational immunity remains to be tested in invertebrates, but also in vertebrate species. We discuss the implications of our work for the study of the evolution of immunity, and we suggest further avenues of research to expand our knowledge of the impact of transgenerational immune protection in host-parasite interactions.

Defending against pathogens - immunological priming and its molecular basis in a sea anemone, cnidarian

Cnidarians, in general, are long-lived organisms and hence may repeatedly encounter common pathogens during their lifespans. It remains unknown whether these early diverging animals possess some type of immunological reaction that strengthens the defense response upon repeated infections, such as that described in more evolutionary derived organisms. Here we show results that sea anemones that had previously encountered a pathogen under sub-lethal conditions had a higher survivorship during a subsequently lethal challenge than naïve anemones that encountered the pathogen for the first time. Anemones subjected to the lethal challenge two and four weeks after the sub-lethal exposure presented seven- and five-fold increases in survival, respectively, compared to the naïve anemones. However, anemones challenged six weeks after the sub-lethal exposure showed no increase in survivorship. We argue that this short-lasting priming of the defense response could be ecologically relevant if pathogen encounters are restricted to short seasons characterized by high stress. Furthermore, we discovered significant changes in proteomic profiles between naïve sea anemones and those primed after pathogen exposure suggesting a clear molecular signature associated with immunological priming in cnidarians. Our findings reveal that immunological priming may have evolved much earlier in the tree of life than previously thought.

Age and prior blood feeding of Anopheles gambiae influences their susceptibility and gene expression patterns to ivermectin-containing blood meals

Background

Ivermectin has been proposed as a novel malaria transmission control tool based on its insecticidal properties and unique route of acquisition through human blood. To maximize ivermectin’s effect and identify potential resistance/tolerance mechanisms, it is important to understand its effect on mosquito physiology and potential to shift mosquito population age-structure. We therefore investigated ivermectin susceptibility and gene expression changes in several age groups of female Anopheles gambiae mosquitoes.

Methods

The effect of aging on ivermectin susceptibility was analyzed in three age groups (2, 6, and 14-days) of colonized female Anopheles gambiae mosquitoes using standard survivorship assays. Gene expression patterns were then analyzed by transcriptome sequencing on an Illumina HiSeq 2500 platform. RT-qPCR was used to validate transcriptional changes and also to examine expression in a different, colonized strain and in wild mosquitoes, both of which blood fed naturally on an ivermectin-treated person.

Results

Mosquitoes of different ages and blood meal history died at different frequencies after ingesting ivermectin. Mortality was lowest in 2-day old mosquitoes exposed on their first blood meal and highest in 6-day old mosquitoes exposed on their second blood meal. Twenty-four hours following ivermectin ingestion, 101 and 187 genes were differentially-expressed relative to control blood-fed, in 2 and 6-day groups, respectively. Transcription patterns of select genes were similar in membrane-fed, colonized, and naturally-fed wild vectors. Transcripts from several unexpected functional classes were highly up-regulated, including Niemann-Pick Type C (NPC) genes, peritrophic matrix-associated genes, and immune-response genes, and these exhibited different transcription patterns between age groups, which may explain the observed susceptibility differences. Niemann-Pick Type 2 genes were the most highly up-regulated transcripts after ivermectin ingestion (up to 160 fold) and comparing phylogeny to transcriptional patterns revealed that NPCs have rapidly evolved and separate members respond to either blood meals or to ivermectin.

Conclusion

We present evidence of increased ivermectin susceptibility in older An. gambiae mosquitoes that had previously bloodfed. Differential expression analysis suggests complex midgut interactions resulting from ivermectin ingestion that likely involve blood meal digestion physiological responses, midgut microflora, and innate immune responses. Thus, the transcription of certain gene families is consistently affected by ivermectin ingestion, and may provide important clues to ivermectin’s broad effects on malaria vectors. These findings contribute to the growing understanding of ivermectin’s potential as a transmission control tool.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2029-8) contains supplementary material, which is available to authorized users.

A brief journey through the immune system

This review serves as an introduction to an Immunology Series for the Nephrologist published in CJASN. It provides a brief overview of the immune system, how it works, and why it matters to kidneys. This review describes in broad terms the main divisions of the immune system (innate and adaptive), their cellular and tissue components, and the ways by which they function and are regulated. The story is told through the prism of evolution in order to relay to the reader why the immune system does what it does and why imperfections in the system can lead to renal disease. Detailed descriptions of cell types, molecules, and other immunologic curiosities are avoided as much as possible in an effort to not detract from the importance of the broader concepts that define the immune system and its relationship to the kidney.

The surprisingly complex immune gene repertoire of a simple sponge, exemplified by the NLR genes: a capacity for specificity?

Most bacteria are not pathogenic to animals, and may instead serve beneficial functions. The requisite need for animals to differentiate between microbial friend and foe is likely borne from a deep evolutionary imperative to recognise self from non-self, a service ably provided by the innate immune system. Recent findings from an ancient lineage of simple animals - marine sponges - have revealed an unexpectedly large and diverse suite of genes belonging to one family of pattern recognition receptors, namely the NLR genes. Because NLRs can recognise a broad spectrum of microbial ligands, they may play a critical role in mediating the animal-bacterial crosstalk needed for sophisticated discrimination between microbes of various relationships. The building blocks for an advanced NLR-based immune specificity encoded in the genome of the coral reef sponge Amphimedon queenslandica may provide a specialisation and diversity of responses that equals, or even exceeds, that of vertebrate NLRs.

WSSV-induced crayfish Dscam shows durable immune behavior

One of the major gaps in our understanding of arthropod specific immune priming concerns the mechanism[s] by which the observed long-term (>2 weeks) protective effects might be mediated. Hypervariable Dscam (Down syndrome cell adhesion molecule) might support arthropod innate immunity with specificity for more extended periods. We show here that, in the relatively long-lived arthropod Cherax quadricarinatus, CqDscam does not behave like a typical, immediately-acting, short-lived innate immune factor: CqDscam was not induced within hours after challenge with a lethal virus, but instead was only up-regulated after 2-5 days. This initial response faded within ∼ 2 weeks, but another maximum was reached ∼ 1 month later. At around 2 months after the initial challenge, the virus-induced CqDscam bound to the virus virion and acted to neutralize the virus However, although CqDscam helped crayfish to survive during persistent infection, it nevertheless failed to provide any enhanced protection against a subsequent WSSV challenge. Thus, CqDscam is capable of supporting extended anti-virus immune memory in arthropods. Also, during a persistent virus infection, the balance of "immune firepower" in crayfish appears to be altered such that the general immune factors become depleted while CqDscam becomes relatively predominant.

The specifically enhanced cellular immune responses in Pacific oyster (Crassostrea gigas) against secondary challenge with Vibrio splendidus

The increasing experimental evidences suggest that there are some forms of specific acquired immunity in invertebrates, but the underlying mechanism is not fully understood. In the present study, Pacific oyster (Crassostrea gigas) stimulated primarily by heat-killed Vibrio splendidus displayed stronger immune responses at cellular and molecular levels when they encountered the secondary challenge of live V. splendidus. The total hemocyte counts (THC) increased significantly after the primary stimulation of heat-killed V. splendidus, and it increased even higher (p < 0.01) and reached the peak earlier (at 6 h) after the secondary challenge with live V. splendidus compared with that of the primary stimulation. The number of new generated circulating hemocytes increased dramatically (p < 0.01) at 6 h after the pre-stimulated oysters received the secondary stimulation with live V. splendidus, and the phagocytic rate was also enhanced significantly (p < 0.01) at 12 h after the secondary stimulation. Meanwhile, the enhanced phagocytosis of hemocytes was highly specific for V. splendidus and they could distinguish Vibrio anguillarum, Vibrio coralliilyticus, Yarrowia lipolytica, and Micrococcus luteus efficiently. In addition, the mRNA expression of 12 candidate genes related to phagocytosis and hematopoiesis were also monitored, and the expression levels of CgIntegrin, CgPI3K (phosphatidylinositol 3-kinase), CgRho J, CgMAPKK (mitogen-activated protein kinase kinase), CgRab32, CgNADPH (nicotinamide adenine dinucleotide phosphate) oxidase, CgRunx1 and CgBMP7 (bone morphogenetic protein 7) in the hemocytes of pre-stimulated oysters after the secondary stimulation of V. splendidus were higher (p < 0.01) than that after the primary stimulation, but there was no statistically significant changes for the genes of CgPKC (protein kinase C), CgMyosin, CgActin, and CgGATA 3. These results collectively suggested that the primary stimulation of V. splendidus led to immune priming in oyster with specifically enhanced phagocytosis and rapidly promoted regeneration of circulating hemocytes when the primed oysters encountered the secondary challenge with V. splendidus.

No more non-model species: the promise of next generation sequencing for comparative immunology

Next generation sequencing (NGS) allows for the rapid, comprehensive and cost effective analysis of entire genomes and transcriptomes. NGS provides approaches for immune response gene discovery, profiling gene expression over the course of parasitosis, studying mechanisms of diversification of immune receptors and investigating the role of epigenetic mechanisms in regulating immune gene expression and/or diversification. NGS will allow meaningful comparisons to be made between organisms from different taxa in an effort to understand the selection of diverse strategies for host defence under different environmental pathogen pressures. At the same time, it will reveal the shared and unique components of the immunological toolkit and basic functional aspects that are essential for immune defence throughout the living world. In this review, we argue that NGS will revolutionize our understanding of immune responses throughout the animal kingdom because the depth of information it provides will circumvent the need to concentrate on a few "model" species.

Mutations in components of antiviral or microbial defense as a basis for breast cancer

In-depth functional analyses of thousands of breast cancer gene mutations reveals vastly different sets of mutated genes in each of 21 different breast cancer genomes. Despite differences in which genes are mutated, innate immunity pathways and metabolic reactions supporting them are always damaged. These functions depend on many different genes. Mutations may be rare individually but each set of mutations affects some aspect of pathogen recognition and defense, especially those involving viruses. Some mutations cause a dysregulated immune response, which can also increase cancer risks. The frequency of an individual mutation may be less important than its effect on function. This work demonstrates that acquired immune deficiencies and immune dysregulation in cancer can occur because of mutations. Abnormal immune responses represent a hidden variable in breast cancer-viral association studies. Compensating for these abnormalities may open many new opportunities for cancer prevention and therapy.

Drosophila immune priming against Pseudomonas aeruginosa is short-lasting and depends on cellular and humoral immunity

Immune responses are traditionally divided into the innate and the adaptive arm, both of which are present in vertebrates, while only the innate arm is found in invertebrates. Immune priming experiments in Drosophila melanogaster and other invertebrates during the last decade have challenged this dogma, questioning the boundaries between innate and adaptive immunity. Studies on repeated inoculation of Drosophila with microbes reveal a long-lasting cellular immunity adaptation against particular microorganisms. Here we study the lasting effect of immune priming against infection with Pseudomonas aeruginosa, an opportunistic human pathogen that is lethal to the common fruit fly. Drosophila priming with heat-killed or low in virulence P. aeruginosa extends fly survival during a secondary lethal infection with a virulent strain of the same species. The protective immune response can last for more than 10 days after exposure to a persistent low-in-virulence live infection, but it is eliminated 7 days after the host is primed with heat-killed bacteria. Moreover, not only the cellular, but also the systemic NF-κB-mediated immune responses contribute to immune priming. Thus each microbe might elicit different mechanisms of immune priming that may or may not last for long.