Autophagy modulates Borrelia burgdorferi-induced production of interleukin-1β (IL-1β)

Borrelia burgdorferi Engages Mammalian Type I IFN Responses via the cGAS-STING Pathway

Borrelia burgdorferi, the etiologic agent of Lyme disease, is a spirochete that modulates numerous host pathways to cause a chronic, multisystem inflammatory disease in humans. B. burgdorferi infection can lead to Lyme carditis, neurologic complications, and arthritis because of the ability of specific borrelial strains to disseminate, invade, and drive inflammation. B. burgdorferi elicits type I IFN (IFN-I) responses in mammalian cells and tissues that are associated with the development of severe arthritis or other Lyme-related complications. However, the innate immune sensors and signaling pathways controlling IFN-I induction remain unclear. In this study, we examined whether intracellular nucleic acid sensing is required for the induction of IFN-I to B. burgdorferi. Using fluorescence microscopy, we show that B. burgdorferi associates with mouse and human cells in culture, and we document that internalized spirochetes colocalize with the pattern recognition receptor cyclic GMP-AMP synthase (cGAS). Moreover, we report that IFN-I responses in mouse macrophages and murine embryonic fibroblasts are significantly attenuated in the absence of cGAS or its adaptor stimulator of IFN genes (STING), which function to sense and respond to intracellular DNA. Longitudinal in vivo tracking of bioluminescent B. burgdorferi revealed similar dissemination kinetics and borrelial load in C57BL/6J wild-type, cGAS-deficient, or STING-deficient mice. However, infection-associated tibiotarsal joint pathology and inflammation were modestly reduced in cGAS-deficient compared with wild-type mice. Collectively, these results indicate that the cGAS-STING pathway is a critical mediator of mammalian IFN-I signaling and innate immune responses to B. burgdorferi.

Increased expression of ELOVL7 contributes to production of inflammatory cytokines in THP-1 cell-derived M1-like macrophages

The elevation of intracellular very long-chain fatty acids (VLCFAs) augments pro-inflammatory activity of macrophages. VLCFAs are considered to function as regulators in macrophage inflammatory responses; however, the precise mechanism of regulating the production of VLCFAs is unclear. In this study, we focused on elongation of the very‑long‑chain fatty acid protein (ELOVL) family, rate-determining enzymes for VLCFA synthesis, in macrophages. ELOVL7 mRNA was upregulated in human monocytic THP-1 cell-derived M1-like macrophages. Metascape analysis using the RNA-seq data set showed the involvement of NF-κB and STAT1 in transcriptional regulation of ELOVL7 highly correlated genes. Gene ontology (GO) enrichment analysis suggested that ELOVL7 highly correlated genes were closely associated with multiple pro-inflammatory responses, including response to virus and positive regulation of NF-κB signaling. Consistent with RNA-seq analysis, the NF-κB inhibitor BAY11-7082, but not the STAT1 inhibitor fludarabine, canceled ELOVL7 upregulation in M1-like macrophages. ELOVL7 knockdown decreased interleukin (IL)-6 and IL-12/IL-23 p40 production. Moreover, RNA-seq analysis of plasmacytoid dendritic cells (pDCs) revealed that ELOVL7 was upregulated in pDCs treated with TLR7 and TLR9 agonists. In conclusion, we propose that ELOVL7 is a novel pro-inflammatory gene that is upregulated by inflammatory stimuli, and regulates M1-like macrophage and pDC functions.

Recent topics and advanced therapies in chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by the inability of phagocytes to produce reactive oxygen species (ROS) owing to a defect in any of the five components (CYBB/gp91phox, CYBA/p22phox, NCF1/p47phox, NCF2/p67phox, and NCF4/p40phox) and a concomitant regulatory component of Rac1/2 and CYBC1/Eros of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. Patients with CGD are at an increased risk of life-threatening infections caused by catalase-positive bacteria and fungi and of inflammatory complications such as CGD colitis. Antimicrobial and azole antifungal prophylaxes have considerably reduced the incidence and severity of bacterial and improved fungal infections and overall survival. CGD studies have revealed the precise epidemiology and role of NADPH oxidase in innate immunity which has led to a new understanding of the importance of phagocyte oxygen metabolism in various host-defense systems and the fields leading to cell death processes. Moreover, ROS plays central roles in the determination of cell fate as secondary messengers and by modifying of various signaling molecules. According to this increasing knowledge about the effects of ROS on the inflammasomal system, immunomodulatory treatments, such as IFN-γ and anti-IL-1 antibodies, have been established. This review covers the current topics in CGD and the relationship between ROS and ROS-mediated pathophysiological phenomena. In addition to the shirt summary of hematopoietic stem cell transplantation and gene therapy, we introduce a novel ROS-producing enzyme replacement therapy using PEG-fDAO to compensate for NADPH oxidase deficiency.

The NLRP3 inflammasome: regulation by metabolic signals

Macrophages undergo profound metabolic reprogramming upon sensing infectious and sterile stimuli. This metabolic shift supports and regulates essential innate immune functions, including activation of the NLRP3 inflammasome. Within distinct metabolic networks, key enzymes play pivotal roles to control flux restraining detrimental inflammasome signaling. However, depending on the metabolic cues, specific enzymes and metabolites result in inflammasome activation outcomes which contrast other metabolic steps in the pathway. We posit that understanding which metabolic steps commit to discrete inflammasome fates will broaden our understanding of metabolic checkpoints to maintain homeostasis and offer better therapeutic options in human disease.

Investigating immunoregulatory effects of myeloid cell autophagy in acute and chronic inflammation

Studies have highlighted a critical role for autophagy in the regulation of multiple cytokines. Autophagy inhibits the release of interleukin (IL)‐1 family cytokines, including IL‐1α, IL‐1β and IL‐18, by myeloid cells. This, in turn, impacts the release of other cytokines by myeloid cells, as well as other cells of the immune system, including IL‐22, IL‐23, IL‐17 and interferon‐γ. Here, we assessed the impact of genetic depletion of the autophagy gene Atg7 in myeloid cells on acute and chronic inflammation. In a model of acute lipopolysaccharide‐induced endotoxemia, loss of autophagy in myeloid cells resulted in increased release of proinflammatory cytokines, both locally and systemically. By contrast, loss of Atg7 in myeloid cells in the Lyn^−/− model of lupus‐like autoimmunity resulted in reduced systemic release of IL‐6 and IL‐10, with no effects on other cytokines observed. In addition, Lyn^−/− mice with autophagy‐deficient myeloid cells showed reduced expression of autoantibodies relevant to systemic lupus erythematosus, including anti‐histone and anti‐Smith protein. In vitro, loss of autophagy, through pharmacological inhibition or small interfering RNA against Becn1, inhibited IL‐10 release by human and mouse myeloid cells. This effect was evident at the level of Il10 messenger RNA expression. Our data highlight potentially important differences in the role of myeloid cell autophagy in acute and chronic inflammation and demonstrate a direct role for autophagy in the production and release of IL‐10 by macrophages.

A diagnostic classifier for gene expression-based identification of early Lyme disease

Background

Lyme disease is a tick-borne illness that causes an estimated 476,000 infections annually in the United States. New diagnostic tests are urgently needed, as existing antibody-based assays lack sufficient sensitivity and specificity.

Methods

Here we perform transcriptome profiling by RNA sequencing (RNA-Seq), targeted RNA-Seq, and/or machine learning-based classification of 263 peripheral blood mononuclear cell samples from 218 subjects, including 94 early Lyme disease patients, 48 uninfected control subjects, and 57 patients with other infections (influenza, bacteremia, or tuberculosis). Differentially expressed genes among the 25,278 in the reference database are selected based on ≥1.5-fold change, ≤0.05 p value, and ≤0.001 false-discovery rate cutoffs. After gene selection using a k-nearest neighbor algorithm, the comparative performance of ten different classifier models is evaluated using machine learning.

Results

We identify a 31-gene Lyme disease classifier (LDC) panel that can discriminate between early Lyme patients and controls, with 23 genes (74.2%) that have previously been described in association with clinical investigations of Lyme disease patients or in vitro cell culture and rodent studies of Borrelia burgdorferi infection. Evaluation of the LDC using an independent test set of samples from 63 subjects yields an overall sensitivity of 90.0%, specificity of 100%, and accuracy of 95.2%. The LDC test is positive in 85.7% of seronegative patients and found to persist for ≥3 weeks in 9 of 12 (75%) patients.

Conclusions

These results highlight the potential clinical utility of a gene expression classifier for diagnosis of early Lyme disease, including in patients negative by conventional serologic testing.

Xenophagy in cancer

Macroautophagy (herein autophagy) is an intracellular pathway in which cytoplasmic components are captured by double-membrane vesicles (autophagosomes) that eventually fuse with lysosomes to degrade the cargo. Basal levels of autophagy in all eukaryotic cells maintain cellular homeostasis and under conditions of stress, organelles and proteins not essential for survival are degraded. Apart from these functions, cargoes like aggregated proteins, damaged organelles and intracellular pathogens, which are otherwise harmful to cells, are also selectively captured by autophagy and are destined for degradation. In terms of infectious diseases, pathogens are cleared by a specific form of autophagy known as xenophagy. This lysosomal mediated degradation of pathogens also increases the antigen presentation of cells thereby inducing a further immune response. The process of xenophagy provides a broad spectrum of defense mechanism to capture bacterial, viral and protozoan pathogens. However, pathogens have developed ingenious mechanisms to modulate xenophagy to enhance their intracellular survival. Meanwhile, certain pathogens also induce deleterious effects such as chronic inflammation and overexpression of oncogenes in the host system. This over time can increase the susceptibility of the host for tumorigenesis. Hence targeting tumor through anti-microbial mechanisms like xenophagy could be a novel strategy for combinatorial anti-cancer therapy. The recent developments in understanding the role of xenophagy in combating cancer causing pathogens will be discussed in this review.

Borrelia burgdorferi hijacks cellular metabolism of immune cells: Consequences for host defense

Changes in cellular metabolism have proven to be important factors in driving cell behavior. It has been shown that cellular metabolism of immune cells changes when exposed to or infected by several pathogens: while this is often an adaptation of the host cells to the infection, sometimes it represents a mechanism through which the pathogens evade immune activation. Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis, is a pathogen that highly depends on the host to survive, as the bacterium lacks many central metabolic pathways to generate its own nutrients. It is therefore quite likely that the bacterium interacts with host cells to obtain these metabolites and thereby affects metabolism in the host. Previously, several studies have assessed metabolic pathways in B. burgdorferi s.l. and how it adapts to its different host species. However, few studies have looked into how the interaction with the bacterium might affect the host cell metabolism. In this review we present the major metabolic pathways activated during Lyme borreliosis, viewed from both bacterium and host metabolism, and we discuss how these pathways interact with each other, and how they influence pathogenesis of Lyme borreliosis.

Autophagy-associated immune responses and cancer immunotherapy

Autophagy is an evolutionarily conserved catabolic process by which cellular components are sequestered into a double-membrane vesicle and delivered to the lysosome for terminal degradation and recycling. Accumulating evidence suggests that autophagy plays a critical role in cell survival, senescence and homeostasis, and its dysregulation is associated with a variety of diseases including cancer, cardiovascular disease, neurodegeneration. Recent studies show that autophagy is also an important regulator of cell immune response. However, the mechanism by which autophagy regulates tumor immune responses remains elusive. In this review, we will describe the role of autophagy in immune regulation and summarize the possible molecular mechanisms that are currently well documented in the ability of autophagy to control cell immune response. In addition, the scientific and clinical hurdles regarding the potential role of autophagy in cancer immunotherapy will be discussed.

Uric acid priming in human monocytes is driven by the AKT-PRAS40 autophagy pathway

Metabolic triggers are important inducers of the inflammatory processes in gout. Whereas the high serum urate levels observed in patients with gout predispose them to the formation of monosodium urate (MSU) crystals, soluble urate also primes for inflammatory signals in cells responding to gout-related stimuli, but also in other common metabolic diseases. In this study, we investigated the mechanisms through which uric acid selectively lowers human blood monocyte production of the natural inhibitor IL-1 receptor antagonist (IL-1Ra) and shifts production toward the highly inflammatory IL-1β. Monocytes from healthy volunteers were first primed with uric acid for 24 h and then subjected to stimulation with lipopolysaccharide (LPS) in the presence or absence of MSU. Transcriptomic analysis revealed broad inflammatory pathways associated with uric acid priming, with NF-κB and mammalian target of rapamycin (mTOR) signaling strongly increased. Functional validation did not identify NF-κB or AMP-activated protein kinase phosphorylation, but uric acid priming induced phosphorylation of AKT and proline-rich AKT substrate 40 kDa (PRAS 40), which in turn activated mTOR. Subsequently, Western blot for the autophagic structure LC3-I and LC3-II (microtubule-associated protein 1A/1B-light chain 3) fractions, as well as fluorescence microscopy of LC3-GFP-overexpressing HeLa cells, revealed lower autophagic activity in cells exposed to uric acid compared with control conditions. Interestingly, reactive oxygen species production was diminished by uric acid priming. Thus, the Akt-PRAS40 pathway is activated by uric acid, which inhibits autophagy and recapitulates the uric acid-induced proinflammatory cytokine phenotype.

The Lyme Disease Pathogen Borrelia burgdorferi Infects Murine Bone and Induces Trabecular Bone Loss

Lyme disease is caused by members of the Borrelia burgdorferisensu lato species complex. Arthritis is a well-known late-stage pathology of Lyme disease, but the effects of B. burgdorferi infection on bone at sites other than articular surfaces are largely unknown. In this study, we investigated whether B. burgdorferi infection affects bone health in mice. In mice inoculated with B. burgdorferi or vehicle (mock infection), we measured the presence of B. burgdorferi DNA in bones, bone mineral density (BMD), bone formation rates, biomechanical properties, cellular composition, and two- and three-dimensional features of bone microarchitecture. B. burgdorferi DNA was detected in bone. In the long bones, increasing B. burgdorferi DNA copy number correlated with reductions in areal and trabecular volumetric BMDs. Trabecular regions of femora exhibited significant, copy number-correlated microarchitectural disruption, but BMD, microarchitectural, and biomechanical properties of cortical bone were not affected. Bone loss in tibiae was not due to increased osteoclast numbers or bone-resorbing surface area, but it was associated with reduced osteoblast numbers, implying that bone loss in long bones was due to impaired bone building. Osteoid-producing and mineralization activities of existing osteoblasts were unaffected by infection. Therefore, deterioration of trabecular bone was not dependent on inhibition of osteoblast function but was more likely caused by blockade of osteoblastogenesis, reduced osteoblast survival, and/or induction of osteoblast death. Together, these data represent the first evidence that B. burgdorferi infection induces bone loss in mice and suggest that this phenotype results from inhibition of bone building rather than increased bone resorption.

Crosstalk between autophagy and inflammatory signalling pathways: balancing defence and homeostasis

Autophagy has broad functions in immunity, ranging from cell-autonomous defence to coordination of complex multicellular immune responses. The successful resolution of infection and avoidance of autoimmunity necessitates efficient and timely communication between autophagy and pathways that sense the immune environment. The recent literature indicates that a variety of immune mediators induce or repress autophagy. It is also becoming increasingly clear that immune signalling cascades are subject to regulation by autophagy, and that a return to homeostasis following a robust immune response is critically dependent on this pathway. Importantly, examples of non-canonical forms of autophagy in mediating immunity are pervasive. In this article, the progress in elucidating mechanisms of crosstalk between autophagy and inflammatory signalling cascades is reviewed. Improved mechanistic understanding of the autophagy machinery offers hope for treating infectious and inflammatory diseases.

Differentiated THP-1 Cells Exposed to Pathogenic and Nonpathogenic Borrelia Species Demonstrate Minimal Differences in Production of Four Inflammatory Cytokines

Tick-borne borreliae include Lyme disease and relapsing fever agents, and they are transmitted primarily by ixodid (hard) and argasid (soft) tick vectors, respectively. Tick-host interactions during feeding are complex, with host immune responses influenced by biological differences in tick feeding and individual differences within and between host species. One of the first encounters for spirochetes entering vertebrate host skin is with local antigen-presenting cells, regardless of whether the tick-associated Borrelia sp. is pathogenic. In this study, we performed a basic comparison of cytokine responses in THP-1-derived macrophages after exposure to selected borreliae, including a nonpathogen. By using THP-1 cells, differentiated to macrophages, we eliminated variations in host response and reduced the system to an in vitro model to evaluate the extent to which the Borrelia spp. influence cytokine production. Differentiated THP-1 cells were exposed to four Borrelia spp., Borrelia hermsii (DAH), Borrelia burgdorferi (B31), B. burgdorferi (NC-2), or Borrelia lonestari (LS-1), or lipopolysaccharides (LPS) (activated) or media (no treatment) controls. Intracellular and secreted interferon (IFN)-γ, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α were measured using flow cytometric and Luminex-based assays, respectively, at 6, 24, and 48 h postexposure time points. Using a general linear model ANOVA for each cytokine, treatment (all Borrelia spp. and LPS compared to no treatment) had a significant effect on secreted TNF-α only. Time point had a significant effect on intracellular IFN-γ, TNF-α and IL-6. However, we did not see significant differences in selected cytokines among Borrelia spp.

TREATMENTS

Thus, in this model, we were unable to distinguish pathogenic from nonpathogenic borreliae using the limited array of selected cytokines. While unique immune profiles may be detectable in an in vitro model and may reveal predictors for pathogenicity in borreliae of unknown pathogenicity, a larger panel of cytokines would be desirable to test.

Bartonella quintana lipopolysaccharide (LPS): structure and characteristics of a potent TLR4 antagonist for in-vitro and in-vivo applications

The pattern recognition receptor TLR4 is well known as a crucial receptor during infection and inflammation. Several TLR4 antagonists have been reported to inhibit the function of TLR4. Both natural occurring antagonists, lipopolysaccharide (LPS) from Gram-negative bacteria as well as synthetic compounds based on the lipid A structure of LPS have been described as potent inhibitors of TLR4. Here, we have examined the characteristics of a natural TLR4 antagonist, isolated from Bartonella quintana bacterium by elucidating its chemical primary structure. We have found that this TLR4 antagonist is actually a lipooligosaccharide (LOS) instead of a LPS, and that it acts very effective, with a high inhibitory activity against triggering by the LPS-TLR4 system in the presence of a potent TLR4 agonist (E. coli LPS). Furthermore, we demonstrate that B. quintana LPS is not inactivated by polymyxin B, a classical cyclic cationic polypeptide antibiotic that bind the lipid A part of LPS, such as E. coli LPS. Using a murine LPS/D-galactosamine endotoxaemia model we showed that treatment with B. quintana LPS could improve the survival rate significantly. Since endogenous TLR4 ligands have been associated with several inflammatory- and immune-diseases, B. quintana LPS might be a novel therapeutic strategy for TLR4-driven pathologies.

Autophagy suppresses host adaptive immune responses toward Borrelia burgdorferi

We have previously demonstrated that inhibition of autophagy increased the Borrelia burgdorferi induced innate cytokine production in vitro, but little is known regarding the effect of autophagy on in vivo models of Borrelia infection. Here, we showed that ATG7-deficient mice that were intra-articular injected with Borrelia spirochetes displayed increased joint swelling, cell influx, and enhanced interleukin-1β and interleukin-6 production by inflamed synovial tissue. Because both interleukin-1β and interleukin-6 are linked to the development of adaptive immune responses, we examine the function of autophagy on Borrelia induced adaptive immunity. Human peripheral blood mononuclear cells treated with autophagy inhibitors showed an increase in interleukin-17, interleukin-22, and interferon-γ production in response to exposure to Borrelia burgdorferi. Increased IL-17 production was dependent on IL-1β release but, interestingly, not on interleukin-23 production. In addition, cytokine quantitative trait loci in ATG9B modulate the Borrelia induced interleukin-17 production. Because high levels of IL-17 have been found in patients with confirmed, severe, chronic borreliosis, we propose that the modulation of autophagy may be a potential target for anti-inflammatory therapy in patients with persistent Lyme disease.

Loss of autophagy enhances MIF/macrophage migration inhibitory factor release by macrophages

MIF (macrophage migration inhibitory factor [glycosylation-inhibiting factor]) is a pro-inflammatory cytokine expressed in multiple cells types, including macrophages. MIF plays a pathogenic role in a number of inflammatory diseases and has been linked to tumor progression in some cancers. Previous work has demonstrated that loss of autophagy in macrophages enhances secretion of IL1 family cytokines. Here, we demonstrate that loss of autophagy, by pharmacological inhibition or siRNA silencing of Atg5, enhances MIF secretion by monocytes and macrophages. We further demonstrate that this is dependent on mitochondrial reactive oxygen species (ROS). Induction of autophagy with MTOR inhibitors had no effect on MIF secretion, but amino acid starvation increased secretion. This was unaffected by Atg5 siRNA but was again dependent on mitochondrial ROS. Our data demonstrate that autophagic regulation of mitochondrial ROS plays a pivotal role in the regulation of inflammatory cytokine secretion in macrophages, with potential implications for the pathogenesis of inflammatory diseases and cancers.

ATG16L1 deficiency in macrophages drives clearance of uropathogenic E. coli in an IL-1β-dependent manner

Urinary tract infections (UTIs) are frequent, commonly recurrent, and costly. Deficiency in a key autophagy protein, ATG16L1, protects mice from infection with the predominant bacterial cause of UTIs, Uropathogenic E. coli (UPEC). Here, we report that loss of ATG16L1 in macrophages accounts for this protective phenotype. Compared with wild-type macrophages, macrophages deficient in ATG16L1 exhibit increased uptake of UPEC and enhanced secretion of interleukin-1β (IL-1β). The increased IL-1β production is dependent upon activation of the NLRP3 inflammasome and caspase-1. IL-1β secretion was also enhanced during UPEC infection of ATG16L1-deficient mice in vivo, and inhibition of IL-1β signaling abrogates the ATG16L1-dependent protection from UTIs. Our results argue that ATG16L1 normally suppresses a host-protective IL-1β response to UPEC by macrophages.

Early cytokine release in response to live Borrelia burgdorferi Sensu Lato Spirochetes is largely complement independent

Aim

Here we investigated the role of complement activation in phagocytosis and the release of cytokines and chemokines in response to two clinical isolates: Borrelia afzelii K78, which is resistant to complement-mediated lysis, and Borrelia garinii LU59, which is complement-sensitive.

Methods

Borrelia spirochetes were incubated in hirudin plasma, or hirudin-anticoagulated whole blood. Complement activation was measured as the generation of C3a and sC5b-9. Binding of the complement components C3, factor H, C4, and C4BP to the bacterial surfaces was analyzed. The importance of complement activation on phagocytosis, and on the release of cytokines and chemokines, was investigated using inhibitors acting at different levels of the complement cascade.

Results

1) Borrelia garinii LU59 induced significantly higher complement activation than did Borrelia afzelii K78. 2) Borrelia afzelii K78 recruited higher amounts of factor H resulting in significantly lower C3 binding. 3) Both Borrelia strains were efficiently phagocytized by granulocytes and monocytes, with substantial inhibition by complement blockade at the levels of C3 and C5. 4) The release of the pro-inflammatory cytokines and chemokines IL-1β, IL-6, TNF, CCL20, and CXCL8, together with the anti-inflammatory IL-10, were increased the most (by>10-fold after exposure to Borrelia). 5) Both strains induced a similar release of cytokines and chemokines, which in contrast to the phagocytosis, was almost totally unaffected by complement blockade.

Conclusions

Our results show that complement activation plays an important role in the process of phagocytosis but not in the subsequent cytokine release in response to live Borrelia spirochetes.

Association of autophagy-related 16-like 1 (ATG16L1) gene polymorphism with sepsis severity in patients with sepsis and ventilator-associated pneumonia

Autophagy is a highly conserved mechanism of eukaryotic cells implicated in cell homeostasis and elimination of intracellular pathogens. Functional polymorphisms in genes encoding for autophagy have been associated with susceptibility to inflammatory and infectious diseases, but data on severe infections are missing. The aim of the present study was to assess whether polymorphisms in genes encoding proteins involved in autophagy influence susceptibility to ventilator-associated pneumonia (VAP). Mechanically ventilated patients with VAP were studied. Genotyping for autophagy-related 16-like 1 (ATG16L1, rs2241880) functional polymorphism was performed using the TaqMan single-nucleotide assay. Monocytes were isolated from patients and stimulated with lipopolysaccharide (LPS). Tumor necrosis factor-α (TNF-α) was measured in the supernatants of monocytes using an enzyme-linked immunosorbent assay. Procalcitonin (PCT) was also measured in the serum of patients by an immuno-time-resolved amplified cryptate technology assay. A total of 155 patients with VAP were enrolled in the study. Carriage of the minor A allele of ATG16L1 was associated with septic shock with at least one organ failure (odds ratio (OR): 2.40, p: 0.036). TNF-α production was significantly greater among the carriers of the polymorphism presenting with at least one organ failure (p: 0.040). PCT was increased upon worsening to septic shock and organ failure only among carriers of the minor frequency A alleles. In a homogeneous cohort of septic patients with VAP, the carriage of autophagy polymorphisms predisposes to VAP severity and septic shock development. This may be related with predisposition to immunoparalysis.

Interleukin-1β in innate inflammation, autophagy and immunity

Although IL-1β is the master inflammatory cytokine in the IL-1 family, after more than ten years of continuous breeding, mice deficient in IL-1β exhibit no spontaneous disease. Therefore, one concludes that IL-1β is not needed for homeostasis. However, IL-1β-deficient mice are protected against local and systemic inflammation due to live infections, autoimmune processes, tumor metastasis and even chemical carcinogenesis. Based on a large number of preclinical studies, blocking IL-1β activity in humans with a broad spectrum of inflammatory conditions has reduced disease severity and for many, has lifted the burden of disease. Rare and common diseases are controlled by blocking IL-1β. Immunologically, IL-1β is a natural adjuvant for responses to antigen. Alone, IL-1β is not a growth factor for lymphocytes; rather in antigen activated immunocompetent cells, blocking IL-1 reduces IL-17 production. IL-1β markedly increases in the expansion of naive and memory CD4T cells in response to challenge with their cognate antigen. The response occurs when only specific CD4T cells respond to IL-1β and not to IL-6 or CD-28. A role for autophagy in production of IL-1β has emerged with deletion of the autophagy gene ATG16L1. Macrophages from ATG16L1-deficient mice produce higher levels of IL-1β after stimulation with TLR4 ligands via a mechanism of caspase-1 activation. The implications for increased IL-1β release in persons with defective autophagy may have clinical importance for disease.