Cutting edge: IL-6 is a marker of inflammation with no direct role in inflammasome-mediated mouse models

Lipopolysaccharide and lipotheicoic acid differentially modulate epididymal cytokine and chemokine profiles and sperm parameters in experimental acute epididymitis

Bacterial infections are the most prevalent etiological factors of epididymitis, a commonly diagnosed inflammatory disease in the investigation of male infertility factors. The influence of early pathogenic mechanisms at play during bacterial epididymitis on reproductive outcomes is little understood. We report here that experimental epididymitis induced in rats by Gram-negative (LPS) and Gram-positive (LTA) bacterial products resulted in differential patterns of acute inflammation in the cauda epididymis. LPS elicited a strong inflammatory reaction, as reflected by upregulation of levels of mRNA for seven inflammatory mediators (Il1b, Tnf, Il6, Ifng, Il10, Nos2 and Nfkbia), and tissue concentration of six cytokines/chemokines (IL1A, IL1B, IL6, IL10, CXCL2 and CCL2) within the first 24 h post-treatment. Conversely, LTA induced downregulation of one (Nfkbia) and upregulation of six (Il1b, Il6, Nos2, Il4 Il10 and Ptgs1) inflammatory gene transcripts, whereas increased the tissue concentration of three cytokines/chemokines (IL10, CXCL2 and CCL2). The stronger acute inflammatory response induced by LPS correlated with a reduction of epididymal sperm count and transit time that occurred at 1, 7, and 15 days post-treatment. Our study provides evidence that early epididymal inflammatory signaling events to bacterial activators of innate immunity may contribute to the detrimental effects of epididymitis upon male fertility.

Increased Neutrophil Secretion Induced by NLRP3 Mutation Links the Inflammasome to Azurophilic Granule Exocytosis

Heterozygous mutations in the NLRP3 gene in patients with cryopyrin associated periodic syndrome (CAPS) lead to hyper-responsive inflammasome function. CAPS is a systemic auto-inflammatory syndrome characterized by the activation of the innate immune system induced by elevated pro-inflammatory cytokines, but the involvement of selective innate immune cells in this process is not fully understood. Neutrophil secretion and the toxic components of their granules are mediators of inflammation associated with several human diseases and inflammatory conditions. Here, using the Nlrp3^A350V inducible mouse model (MWS CreT) that recapitulates human patients with the A352V mutation in NLRP3 observed in the Muckle-Wells sub-phenotype of CAPS, we studied the relationship between hyper-activation of the inflammasome and neutrophil exocytosis. Using a flow cytometry approach, we show that Nlrp3^A350V (MWS) neutrophils express normal basal levels of CD11b at the plasma membrane and that the upregulation of CD11b from secretory vesicles in response to several plasma membrane or endocytic agonist including the bacterial-derived mimetic peptide formyl-Leu-Met-Phe (fMLF) and the unmethylated oligonucleotide CpG is normal in MWS neutrophils. Significant but modest CD11b upregulation in MWS neutrophils compared to wild type was only observed in response to GM-CSF and CpG. The same pattern was observed for the secretion of matrix metalloproteinase-9 (MMP-9) from gelatinase granules in that MMP-9 secretion in MWS neutrophils was not different from that observed in wild-type neutrophils except when stimulated with GM-CSF and CpG. In contrast, azurophilic granule secretion, whose cargoes constitute the most toxic secretory and pro-inflammatory factors of the neutrophil, was markedly dysregulated in MWS neutrophils under both basal and stimulated conditions. This could not be attributed to paracrine effects of secretory cytokines because IL-1β secretion by neutrophils was undetectable under these experimental conditions. The increased azurophilic granule exocytosis in MWS neutrophils was attenuated by treatment with the neutrophil exocytosis inhibitor Nexinhib20. In agreement with a possible neutrophil contribution to systemic inflammation in CAPS, the levels of neutrophil secretory proteins were significantly elevated in the plasma from Nlrp3^A350V mice. Altogether, our data indicates an azurophilic granule-selective dysregulation of neutrophil exocytosis in CAPS.

NaoXinTong Enhances Atorvastatin-induced Plaque Stability While Ameliorating Atorvastatin-induced Hepatic Inflammation

Buchang NaoXinTong (NXT) is a Chinese medicine that has been used for many years for treatment of patients with coronary heart disease (CHD) in China. Statins substantially reduce hypercholesterolemia and CHD mortality and morbidity. However, there is still a lot of CHD patients who do not respond well to statin therapy. Herein, we report the effects of NXT on atorvastatin-inhibited atherosclerosis and atorvastatin-induced hepatic side effects. After 10 weeks of high-fat diet (HFD) feeding, apoE-deficient mice were randomly divided into 4 groups and received the following treatment for another 8 weeks: group 1, HFD; group 2, HFD containing NXT; group 3, HFD containing atorvastatin; and group 4, HFD containing both NXT and atorvastatin. After treatment, serum lipid profiles, atherosclerotic lesions, and hepatic lipid content and inflammation were determined. NXT moderately increased high-density lipoprotein cholesterol levels, although had little effect on atorvastatin-induced reduction of low-density lipoprotein cholesterol levels. Both NXT and atorvastatin reduced en face lesions and sinus lesions of aortic root. In addition, NXT enhanced atorvastatin-induced lesion plaque stability by increasing smooth muscle cell/collagen content and reducing macrophage accumulation and calcification in lesion areas. The co-treatment of NXT and atorvastatin further reduced hepatic triglyceride levels by downregulating acyl-CoA:diacylglycerol acyltransferase 1 while activating hormone-sensitive lipase, adipose triglyceride lipase, and comparative gene identification-58 expression. The AMPKα pathway was also further activated by the co-treatment. More importantly, the liver injuries caused by atorvastatin, such as hepatic inflammation and elevated serum aminotransferase activities, were substantially attenuated by NXT. Therefore, our study demonstrates that NXT enhances atorvastatin-induced plaque stability and ameliorates atorvastatin-induced hepatic side effects.

TNF regulates transcription of NLRP3 inflammasome components and inflammatory molecules in cryopyrinopathies

The NLRP3 inflammasome is a protein complex responsible for caspase-1-dependent maturation of the proinflammatory cytokines IL-1β and IL-18. Gain-of-function missense mutations in NLRP3 cause the disease spectrum known as the cryopyrin-associated periodic syndromes (CAPS). In this study, we generated Nlrp3-knockin mice on various KO backgrounds including Il1b/Il18-, caspase-1-, caspase-11- (Casp1/11-), and Tnf-deficient strains. The Nlrp3L351P Il1b-/- Il18-/- mutant mice survived and grew normally until adulthood and, at 6 months of age, exhibited marked splenomegaly and leukophilia. Injection of these mice with low-dose LPS resulted in elevated serum TNF levels compared with Nlrp3L351P Casp1/11-/- mice and Il1b-/- Il18-/- littermates. Treatment of Nlrp3A350V mice with the TNF inhibitor etanercept resulted in all pups surviving to adulthood, with normal body and spleen/body weight ratios. Nlrp3A350V Tnf-/- mice showed a similar phenotypic rescue, with marked reductions in serum IL-1β and IL-18, reduced myeloid inflammatory infiltrate in the skin and spleen, and substantial decreases in splenic mRNA expression of both inflammasome components (Nlrp3, Pycard, pro-Casp1) and pro-cytokines (Il1b, Il18). Likewise, we observed a reduction in the expression of both pro-Casp1 and pro-Il1b in cultured Nlrp3A350V Tnf-/- BM-derived DCs. Our data show that TNF is an important transcriptional regulator of NLRP3 inflammasome components in murine inflammasomopathies. Moreover, these results may have therapeutic implications for CAPS patients with partial responses to IL-1-targeted therapies.

Regulation and Sensing of Inflammasomes and Their Impact on Intestinal Health

Pattern recognition receptors such as nucleotide-binding oligomerization domain (NOD)-containing protein receptors (NLRs) and the pyrin and hematopoitic interferon-inducible nuclear protein (HIN) domain (PYHIN) receptors initiate the inflammatory response following cell stress or pathogenic challenge. When activated, some of these receptors oligomerize to form the structural backbone of a signalling platform known as an inflammasome. Inflammasomes promote the activation of caspase-1 and the maturation of the proinflammatory cytokines, interleukin (IL)-1β and IL-18. The gut dysregulation of the inflammasome complex is thought to be a contributing factor in the development of inflammatory bowel diseases (IBD), such as ulcerative colitis (UC) and Crohn's disease (CD). The importance of inflammasomes to intestinal health has been emphasized by various inflammasome-deficient mice in dextran sulphate sodium (DSS) models of intestinal inflammation and by the identification of novel potential candidate genes in population-based human studies. In this review, we summarise the most recent findings with regard to the formation, sensing, and regulation of the inflammasome complex and highlight their importance in maintaining intestinal health.

Rewiring monocyte glucose metabolism via C-type lectin signaling protects against disseminated candidiasis

Monocytes are innate immune cells that play a pivotal role in antifungal immunity, but little is known regarding the cellular metabolic events that regulate their function during infection. Using complementary transcriptomic and immunological studies in human primary monocytes, we show that activation of monocytes by Candida albicans yeast and hyphae was accompanied by metabolic rewiring induced through C-type lectin-signaling pathways. We describe that the innate immune responses against Candida yeast are energy-demanding processes that lead to the mobilization of intracellular metabolite pools and require induction of glucose metabolism, oxidative phosphorylation and glutaminolysis, while responses to hyphae primarily rely on glycolysis. Experimental models of systemic candidiasis models validated a central role for glucose metabolism in anti-Candida immunity, as the impairment of glycolysis led to increased susceptibility in mice. Collectively, these data highlight the importance of understanding the complex network of metabolic responses triggered during infections, and unveil new potential targets for therapeutic approaches against fungal diseases.

Fungal infections are a major health concern for immunocompromised individuals due to the lack of success of the currently available antifungal therapies. Unveiling the metabolic processes involved in the immune function offers a promising opportunity for the development of new therapeutic approaches against these infections. In this report, we describe how changes in monocyte glucose metabolism are crucial for host defense against infections caused by the opportunistic pathogenic yeast Candida albicans. We report how the participation of various metabolic routes, such as glycolysis, oxidative phosphorylation and the pentose phosphate pathway, were differentially required after yeast or hyphal exposure, depending on the cellular energy requirements for each response. The proper control of metabolic reprogramming of immune cells was crucial to afford protection against fungal infections in vivo.

Airway and serum biochemical correlates of refractory neutrophilic asthma

Background

Despite progress in the diagnosis and management of asthma, many patients have poorly controlled or refractory asthma (RA). The mechanism of this RA is not well understood.

Objective

We sought to explore the relationship between neutrophils and other biomarkers of RA.

Method

Sixty patients with RA, 30 patients with nonrefractory asthma (NRA), and 20 healthy subjects were enrolled. We performed a comprehensive characterization of these study subjects, which included laboratory and pulmonary function studies, chest computed tomography, and bronchoscopy with bronchoalveolar lavage (BAL). We analyzed BAL fluid and serum for a total of 244 biomolecules using a multiplex assay and correlated them with clinical and other laboratory parameters.

Results

RA was significantly different from NRA with regard to pulmonary function indices, bronchial basement membrane thickness, and BAL fluid neutrophil and lymphocyte counts but not eosinophil counts. BAL fluid neutrophil counts negatively and positively correlated with forced vital capacity and age, respectively. Of the 244 biomolecules studied, 52 and 14 biomolecules from BAL fluid and serum, respectively, were significantly different among the study groups. Thirteen of these 52 molecules correlated with BAL fluid neutrophil counts. BAL fluid from 40% of patients with RA was positive for a pathogenic microbe. Infection-negative neutrophilic RA was associated with an increase in levels of select biomarkers of inflammation in the serum, suggesting the presence of systemic inflammation.

Conclusions

RA was associated with increased numbers of neutrophils and proneutrophilic biomolecules in the airways. Subclinical infection was present in 40% of patients with RA, which likely contributed to neutrophilic inflammation. A subgroup of patients with noninfected neutrophilic RA was associated with systemic inflammation.

Calcium-sensing receptor, proinflammatory cytokines and calcium homeostasis

The calcium-sensing receptor (CaSR) expressed in the parathyroid gland and the kidney tubule acts as the calciostat and orchestrates blood calcium homeostasis by modulating production and release of parathyroid hormone (PTH) and active vitamin D that influence Ca(2+) fluxes across the bone, kidney and intestine. Here we consider the role of the CaSR as a responder to proinflammatory cytokines released as part of the innate immune response to tissue injury and inflammation with resetting of the calciostat on the one hand and as a promoter and mediator of the initial inflammatory response on the other. The importance of the CaSR in systemic calcium homeostasis is exemplified by the fact that inactivating and activating mutations in the gene result in hypercalcemia and hypocalcemia, respectively. Proinflammatory cytokines interleukin-1β and interleukin-6 upregulate CaSR expression in parathyroid and kidney and do this through defined response elements in the CASR gene promoters. This results in decreased serum PTH and 1,25-dihydroxyvitamin D and calcium levels. This is likely to underlie the hypocalcemia that commonly occurs in critically ill patients, those with burn injury and sepsis, for example. The level of calcium in extracellular fluid bathing necrotic cells is often elevated and acts as a chemokine to attract monocytes/macrophages that express the CaSR to sites of tissue injury. Elevated levels of calcium acting via the CaSR can function as a danger signal that stimulates assembly of myeloid cell cytosolic multiprotein inflammasomes resulting in maturation of the proinflammatory cytokine IL-1β by caspase-1. Thus the CaSR is both promoter of and responder to the inflammation.

Tr1 Cells, but Not Foxp3+ Regulatory T Cells, Suppress NLRP3 Inflammasome Activation via an IL-10-Dependent Mechanism

The two best-characterized types of CD4(+) regulatory T cells (Tregs) are Foxp3(+) Tregs and Foxp3(-) type 1 regulatory (Tr1) cells. The ability of Foxp3(+) Tregs and Tr1 cells to suppress adaptive immune responses is well known, but how these cells regulate innate immunity is less defined. We discovered that CD44(hi)Foxp3(-) T cells from unmanipulated mice are enriched in Tr1 cell precursors, enabling differentiation of cells that express IL-10, as well as Tr1-associated cell surface markers, CD49b and LAG-3, and transcription factors, cMaf, Blimp-1, and AhR. We compared the ability of Tr1 cells versus Foxp3(+) Tregs to suppress IL-1β production from macrophages following LPS and ATP stimulation. Surprisingly, Tr1 cells, but not Foxp3(+) Tregs, inhibited the transcription of pro-IL-1β mRNA, inflammasome-mediated activation of caspase-1, and secretion of mature IL-1β. Consistent with the role for IL-10 in Tr1 cell-mediated suppression, inhibition of inflammasome activation and IL-1β secretion was abrogated in IL-10R-deficient macrophages. Moreover, IL-1β production from macrophages derived from Nlrp3(A350V) knockin mice, which carry a mutation found in cryopyrin-associated periodic syndrome patients, was suppressed by Tr1 cells but not Foxp3(+) Tregs. Using an adoptive transfer model, we found a direct correlation between Tr1 cell engraftment and protection from weight loss in mice expressing a gain-of-function NLRP3. Collectively, these data provide the first evidence for a differential role of Tr1 cells and Foxp3(+) Tregs in regulating innate immune responses. Through their capacity to produce high amounts of IL-10, Tr1 cells may have unique therapeutic effects in disease-associated inflammasome activation.

Independent roles of the priming and the triggering of the NLRP3 inflammasome in the heart

AIMS

The NLRP3 inflammasome is activated in the ischaemic heart promoting caspase-1 activation, inflammation, and cell death. Ischaemic injury establishes both a priming signal (transcription of inflammasome components) and a trigger (NLRP3 activation). Whether NLRP3 activation, without priming, induces cardiac dysfunction and/or failure is unknown. The aim of this study was to assess the independent and complementary roles of the priming and the triggering signals in the heart, in the absence of ischaemia or myocardial injury.

METHODS AND RESULTS

We used mice with mutant NLRP3 (constitutively active), NLRP3-A350V, under the control of tamoxifen-driven expression of the Cre recombinase (Nlrp3-A350V/CreT mice). The mice were treated for 10 days with tamoxifen before measuring the activity of caspase-1, the effector enzyme in the inflammasome. Tamoxifen treatment induced the inflammasome in the spleen but not in the heart, despite expression of the mutant NLRP3-A350V. The components of the inflammasome were significantly less expressed in the heart compared with the spleen. Subclinical low-dose lipopolysaccharide (LPS; 2 mg/kg) in Nlrp3-A350V/CreT mice induced the expression of the components of the inflammasome (priming), measured using real-time PCR and western blot, leading to the formation of an active inflammasome (caspase-1 activation) in the heart and LV systolic dysfunction while low-dose LPS was insufficient to induce LV systolic dysfunction in wild-type mice (all P < 0.01 for mutant vs. wild-type mice).

CONCLUSION

The signalling pathway governing the inflammasome formation in the heart requires a priming signal in order for an active NLRP3 to induce caspase-1 activation and LV dysfunction.

Involvement of purinergic receptors and NOD-like receptor-family protein 3-inflammasome pathway in the adenosine triphosphate-induced cytokine release from macrophages

Adenosine triphosphate (ATP) has been described as a danger signal activating the NOD-like receptor-family protein 3 (NLRP3)-inflammasome leading to the pro-inflammatory cytokine, interleukin (IL)-1β, release in the lung. The NLRP3-inflammasome pathway has been previously described to be involved in experimental collagen deposition and the development of pulmonary fibrosis. The aim of the present study was to investigate the role of the NLRP3 inflammasome pathway and P2X7 purinergic receptor in the activation of human macrophages in vitro by ATP. We showed that adenosine 5'-[γ-thio]triphosphate tetralithium salt (ATPγS) and 2',3'-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP), two stable analogs of ATP, are able to potentiate the release of IL-1β from human monocyte-derived macrophages induced by low concentration of lipopolysaccharide (LPS). However, in the same conditions no increase in IL-1α and IL-6 was observed. Immunochemistry has shown that human macrophages natively express NLRP3 and purinergic P2X7 receptors (P2X7 R). NLRP3 and IL-1β mRNA expression were induced from LPS-primed macrophages, but also after 5-h treatment of BzATP as analysed by reverse transcription quantitative polymerase chain reaction. However, other inflammasome pathways (NLRP1, NLRP2, NLRC4, NLRP6 and AIM2) and P2X7 R were not induced by BzATP. We observed that P2X7 R antagonists, A-438079 and A-740003, were able to reduce the release of IL-1β, but not of IL-1α and IL-6 from macrophages stimulated by ATPγS or BzATP. The present results showed the involvement of the P2X7 R-NLRP3 inflammasome pathway in the secretion of IL-1β from ATP-stimulated human macrophages, and suggest that P2X7 R were not involved in IL-1α and IL-6 release. This study also points out that repression of the P2X7 R represents a novel potential therapeutic approach to control fibrosis in lung injury.

Inflammasomes in neuroinflammation and changes in brain function: a focused review

Recent literature has pointed to the existence of inflammasome-mediated inflammatory pathways in central nervous system (CNS) disorders and associated changes in behavior. Neuroinflammation, which is an innate immune response in the CNS against harmful and irritable stimuli such as pathogens and metabolic toxic waste, as well as to chronic mild stress, is mediated by protein complexes known as inflammasomes. Inflammasomes activate pro-inflammatory caspases 1 and 5, which then cleave the precursor forms of pro-inflammatory cytokines IL-1β, IL-18, and IL-33 into their active forms. These pro-inflammatory cytokines have been shown to promote a variety of innate immune processes associated with infection, inflammation, and autoimmunity, and thereby play an instrumental role in the instigation of neuroinflammation during old age and subsequent occurrence of neurodegenerative diseases, cognitive impairment, and dementia. In particular, NLRP inflammasomes may also have a role in the etiologies of depression, Alzheimer's disease (AD) and in metabolic disorders, such as Type II diabetes, obesity and cardiovascular diseases that have been shown to be co-morbid with psychiatric illnesses. It has been reported that while these inflammasomes may be activated through TNF-α dependent pathways, other cytokines, like IFN-γ, may assist in inhibiting their activation and thus delay disease progression. Furthermore, some other cytokines, including IL-6, may not have a direct role in inflammasome-mediated diseases. An array of recent research suggests that NLRP inflammasomes targeted therapies could be used for alleviating neuroinflammation and for treatment of associated psychiatric illnesses, although this still remains a challenge and necessitates further extensive research. This review examines the complex inflammatory signaling pathways involved in the activation of NLRP inflammasomes and the role they play in promoting neuroinflammation and subsequent behavioral changes.

Inflammatory responses in the Japanese pufferfish (Takifugu rubripes) head kidney cells stimulated with an inflammasome-inducing agent, nigericin

A cytosolic receptor complex called inflammasome is responsible for mounting inflammatory response by releasing pro-inflammatory cytokines, interleukin (IL)-1β and IL-18. However, inflammatory cascades mediated by the inflammasome are unknown in a lower vertebrate like fish. Therefore, in an in vitro experiment, in order to obtain a preliminary information, we conducted transcriptomic analysis of 18 cytokines including pro-inflammatory cytokines in the Japanese pufferfish (Takifugu rubripes) head kidney (HK) cells stimulated with an inflammasome-inducing agent, nigericin, and a combination of nigericin and LPS by a multiplex RT-PCR assay (GenomeLab Genetic Analysis System, GeXPS; Beckman Coulter Inc.). Furthermore, expression of IL-1β, IL-6, IL-18, nuclear factor (NF)-κB, nucleotide-binding oligomerization domain 2 (NOD2) and NOD-like receptor X1 (NLRX1) genes was examined in HK cells by a quantitative real-time PCR. Additionally, to confirm functionality of activated inflammatory immunity, we also assessed phagocytic activity, superoxide anion production (NBT assay) and lysozyme activity in the nigericin-stimulated HK cells. An increased gene expression of pro-inflammatory cytokines (IL-1β and IL-18), NF-κB and NOD2 was recorded in nigericin and combined nigericin+LPS- stimulated HK cells. Enhanced cellular (phagocytic activity and NBT assay) and humoral (lysozyme activity) immune parameters in the stimulated cells confirmed induction of inflammatory response. Results suggested probable activation of inflammasome components for processing of the inflammatory cytokines in the Japanese pufferfish.

NLRP3 inflammasome activation is required for fibrosis development in NAFLD

NLR inflammasomes, caspase 1 activation platforms critical for processing key pro-inflammatory cytokines, have been implicated in the development of nonalcoholic fatty liver disease (NAFLD). As the direct role of the NLRP3 inflammasome remains unclear, we tested effects of persistent NLRP3 activation as a contributor to NAFLD development and, in particular, as a modulator of progression from benign hepatic steatosis to steatohepatitis during diet-induced NAFLD. Gain of function tamoxifen-inducible Nlrp3 knock-in mice allowing for in vivo temporal control of NLRP3 activation and loss of function Nlrp3 knockout mice were placed on short-term choline-deficient amino acid-defined (CDAA) diet, to induce isolated hepatic steatosis or long-term CDAA exposure, to induce severe steatohepatitis and fibrosis, respectively. Expression of NLRP3 associated proteins was assessed in liver biopsies of a well-characterized group of patients with the full spectrum of NAFLD. Nlrp3(-/-) mice were protected from long-term feeding CDAA-induced hepatomegaly, liver injury, and infiltration of activated macrophages. More importantly, Nlrp3(-/-) mice showed marked protection from CDAA-induced liver fibrosis. After 4 weeks on CDAA diet, wild-type (WT) animals showed isolated hepatic steatosis while Nlrp3 knock-in mice showed severe liver inflammation, with increased infiltration of activated macrophages and early signs of liver fibrosis. In the liver samples of patients with NAFLD, inflammasome components were significantly increased in those patients with nonalcoholic steatohepatitis (NASH) when compared to those with non-NASH NAFLD with mRNA levels of pro-IL1 beta correlated to levels of COL1A1. Our study uncovers a crucial role for the NLRP3 inflammasome in the development of NAFLD. These findings may lead to novel therapeutic strategies aimed at halting the progression of hepatic steatosis to the more severe forms of this disease. Key message: Mice with NLRP3 inflammasome loss of function are protected from diet-induced steatohepatitis. NLRP3 inflammasome gain of function leads to early and severe onset of diet-induced steatohepatitis in mice. Patients with severe NAFLD exhibit increased levels of NLRP3 inflammasome components and levels of pro-IL1β mRNA correlate with the expression of COL1A1.

Divergence of IL-1, IL-18, and cell death in NLRP3 inflammasomopathies

The inflammasome is a cytoplasmic multiprotein complex that promotes proinflammatory cytokine maturation in response to host- and pathogen-derived signals. Missense mutations in cryopyrin (NLRP3) result in a hyperactive inflammasome that drives overproduction of the proinflammatory cytokines IL-1β and IL-18, leading to the cryopyrin-associated periodic syndromes (CAPS) disease spectrum. Mouse lines harboring CAPS-associated mutations in Nlrp3 have elevated levels of IL-1β and IL-18 and closely mimic human disease. To examine the role of inflammasome-driven IL-18 in murine CAPS, we bred Nlrp3 mutations onto an Il18r-null background. Deletion of Il18r resulted in partial phenotypic rescue that abolished skin and visceral disease in young mice and normalized serum cytokines to a greater extent than breeding to Il1r-null mice. Significant systemic inflammation developed in aging Nlrp3 mutant Il18r-null mice, indicating that IL-1 and IL-18 drive pathology at different stages of the disease process. Ongoing inflammation in double-cytokine knockout CAPS mice implicated a role for caspase-1-mediated pyroptosis and confirmed that CAPS is inflammasome dependent. Our results have important implications for patients with CAPS and residual disease, emphasizing the need to explore other NLRP3-mediated pathways and the potential for inflammasome-targeted therapy.

Primary vitamin D target genes allow a categorization of possible benefits of vitamin D₃ supplementation

Vitamin D deficiency has been associated with an increased risk of developing a number of diseases. Here we investigated samples from 71 pre-diabetic individuals of the VitDmet study, a 5-month high dose vitamin D3 intervention trial during Finnish winter, for their changes in serum 25-hydroxyvitamin D3 (25(OH)D3) concentrations and the expression of primary vitamin D target genes in peripheral blood mononuclear cells and adipose tissue. A negative correlation between serum concentrations of parathyroid hormone and 25(OH)D3 suggested an overall normal physiological vitamin D response among the participants. The genes CD14 and thrombomodulin (THBD) are up-regulated primary vitamin D targets and showed to be suitable gene expression markers for vitamin D signaling in both primary tissues. However, in a ranking of the samples concerning their expected response to vitamin D only the top half showed a positive correlation between the changes of CD14 or THBD mRNA and serum 25(OH)D3 concentrations. Interestingly, this categorization allows unmasking a negative correlation between changes in serum concentrations of 25(OH)D3 and the inflammation marker interleukin 6. We propose the genes CD14 and THBD as transcriptomic biomarkers, from which the effects of a vitamin D3 supplementation can be evaluated. These biomarkers allow the classification of subjects into those, who might benefit from a vitamin D3 supplementation, and others who do not.