Immune cells and interleukins play a crucial role in female-specific pain signaling. Interleukin 16 (IL-16) is a cytokine primarily associated with CD4+ T cell function. While previous studies have demonstrated the important role of spinal CD4+ T cells in neuropathic pain, the specific contribution of IL-16 to neuropathic pain remains unclear. In this study, by using a spinal nerve ligation (SNL)-induced neuropathic pain mice model, we found that SNL induced an increase in IL-16 mRNA levels, which persisted for a longer duration in female mice compared to male mice. Immunofluorescence analysis further confirmed enhanced IL-16- and CD4-positive signals in the spinal dorsal horn following SNL surgery in female mice. Knockdown of spinal IL-16 by siRNA or inhibition of CD4 by FGF22-IN-1, a CD4 inhibitor, attenuated established mechanical and thermal pain hypersensitivity induced by SNL. Furthermore, female mice injected with IL-16 intrathecally exhibited significant spontaneous pain, mechanical and thermal hyperalgesia, all of which could be alleviated by FGF22-IN-1 or a CD3 antibody. Additionally, IL-16 induced astrocyte activation but not microglial activation in the spinal dorsal horn of female mice. Meanwhile, astrocyte activation could be suppressed by the CD3 antibody. These results provide compelling evidence that IL-16 promotes astrocyte activation via CD4 on CD3+ T cells, which is critical for maintaining neuropathic pain in female mice.

Oxalate, a uremic toxin that accumulates in dialysis patients, is associated with cardiovascular disease. As oxalate crystals can activate immune cells, we tested the hypothesis that plasma oxalate would be associated with cytokine concentrations and cardiovascular outcomes in dialysis patients. In a cohort of 104 US patients with kidney failure requiring dialysis (cohort 1), we measured 21 inflammatory markers. As IL-16 was the only cytokine to correlate with oxalate, we focused further investigations on IL-16. We searched for associations between concentrations of IL-16 and mortality and cardiovascular events in the 4D cohort (1255 patients, cohort 2) and assessed further associations of IL-16 with other uremic toxins in this cohort. IL-16 levels were positively correlated with pOx concentrations (ρ = 0.39 in cohort 1, r = 0.35 in cohort 2) and were elevated in dialysis patients when compared to healthy individuals. No significant association could be found between IL-16 levels and cardiovascular events or mortality in the 4D cohort. We conclude that the cytokine IL-16 correlates with plasma oxalate concentrations and is substantially increased in patients with kidney failure on dialysis. However, no association could be detected between IL-16 concentrations and cardiovascular disease in the 4D cohort.

OBJECTIVE: Interleukin-16 (IL-16) has been reported to mediate left ventricular myocardial fibrosis and stiffening in patients with heart failure with preserved ejection fraction (HFpEF). We sought to elucidate whether IL-16 has a distinct impact on pathophysiology and prognosis across different subphenotypes of acute HFpEF.
RESULTS: We analysed 211 patients enrolled in a prospective multicentre registry of acute decompensated HFpEF for whom serum IL-16 levels after stabilization were available (53% female, median age 81 [interquartile range 75-85] years). We divided this sub-cohort into four phenogroups using our established clustering algorithm. The study endpoint was all-cause death. Patients were subclassified into phenogroup 1 (\'rhythm trouble\' [n = 69]), phenogroup 2 (\'ventricular-arterial uncoupling\' [n = 49]), phenogroup 3 (\'low output and systemic congestion\' [n = 41]), and phenogroup 4 (\'systemic failure\' [n = 52]). After a median follow-up of 640 days, 38 patients had died. Among the four phenogroups, phenogroup 2 had the highest IL-16 level. The IL-16 level showed significant associations with indices of cardiac hypertrophy, diastolic dysfunction, and congestion only in phenogroup 2. Furthermore, the IL-16 level had a significant predictive value for all-cause death only in phenogroup 2 (C-statistic 0.750, 95% confidence interval 0.606-0.863, P = 0.017), while there was no association between the IL-16 level and the endpoint in the other phenogroups.
CONCLUSIONS: Our results indicated that the serum IL-16 level had a significant association with indices that reflect the pathophysiology and prognosis of HFpEF in a specific phenogroup in acute HFpEF.

BACKGROUND: Prenatal air pollution exposure has been associated with individual inflammatory, cardiovascular, and metabolic biomarkers in mothers and neonates. However, studies of air pollution and a comprehensive panel of biomarkers across maternal and cord blood samples remain limited. Few studies used data-driven methods to identify biomarker groupings that converge biomarkers from multiple biological pathways. This study aims to investigate the impacts of prenatal air pollution on groups of biomarkers in maternal and cord blood samples.
METHODS: In the Maternal And Developmental Risks from Environmental and Social Stressors (MADRES) cohort, 87 biomarkers were quantified from 45 trimester 1 maternal blood and 55 cord blood samples. Pregnancy and trimester 1-averaged concentrations of particulate matter ≤2.5 μm and ≤10 μm in diameter (PM2.5 and PM10), nitrogen dioxide (NO2), and ozone (O3) were estimated, using inverse distance squared weighted spatial interpolation from regulatory air monitoring stations. Traffic-related NOx was assessed using California Line Source Dispersion Model: freeway/highway roads, non-freeway major roads, non-freeway minor roads, and their sum as total NOx. Elastic Net (EN) regression within the rexposome R package was used to group biomarkers and assess their associations with air pollution.
RESULTS: In maternal samples, trimester 1-averaged PM10 was associated with elevated inflammation biomarkers and lowered cardiovascular biomarkers. NO2 exhibited positive associations with cardiovascular and inflammation markers. O3 was inversely associated with inflammation, metabolic, and cardiovascular biomarkers. In cord blood, pregnancy-averaged PM2.5 was associated with higher cardiovascular biomarkers and lower metabolic biomarkers. PM10 was associated with lower inflammation and higher cardiovascular biomarkers. Total and major road NOx was associated with lower cardiovascular biomarkers.
CONCLUSIONS: Prenatal air pollution exposure was associated with changes in biomarkers related to inflammation, cardiovascular, metabolic, cancer, and neurological function in both mothers and neonates. This study shed light on mechanisms by which air pollution can influence biological function during pregnancy.

UNASSIGNED: Obesity is a chronic condition associated with low-grade inflammation mainly due to immune cell infiltration of white adipose tissue (WAT). WAT is distributed into two main depots: subcutaneous WAT (sWAT) and visceral WAT (vWAT), each with different biochemical features and metabolic roles. Proinflammatory cytokines including interleukin (IL)-16 are secreted by both adipocytes and infiltrated immune cells to upregulate inflammation. IL-16 has been widely studied in the peripheral proinflammatory immune response; however, little is known about its role in adipocytes in the context of obesity.
UNASSIGNED: We aimed to study the levels of IL-16 in WAT derived from sWAT and vWAT depots of humans with obesity and the role of this cytokine in palmitate-exposed 3T3-L1 adipocytes.
UNASSIGNED: The results demonstrated that IL-16 expression was higher in vWAT compared with sWAT in individuals with obesity. In addition, IL-16 serum levels were higher in patients with obesity compared with normal-weight individuals, increased at 6 months after bariatric surgery, and at 12 months after surgery decreased to levels similar to before the intervention. Our in vitro models showed that IL-16 could modulate markers of adipogenesis (Pref1), lipid metabolism (Plin1, Cd36, and Glut4), fibrosis (Hif1a, Col4a, Col6a, and Vegf), and inflammatory signaling (IL6) during adipogenesis and in mature adipocytes. In addition, lipid accumulation and glycerol release assays suggested lipolysis alteration.
UNASSIGNED: Our results suggest a potential role of IL-16 in adipogenesis, lipid and glucose homeostasis, fibrosis, and inflammation in an obesity context.

Endometriosis, affecting 6%-10% of women, often leads to pain and infertility and its underlying inflammatory mechanisms are poorly understood. We established endometriosis models in wild-type and IL16KO mice, revealing the driver function of IL-16 in initiating endometriosis-related inflammation. Using an in vitro system, we confirmed iron overload-induced GSDME-mediated pyroptosis as a key trigger for IL-16 activation and release. In addition, our research led to the development of Z30702029, a compound inhibiting GSDME-NTD-mediated pyroptosis, which shows promise as a therapeutic intervention for endometriosis. Importantly, our findings extend beyond endometriosis, highlighting GSDME-mediated pyroptosis as a broader pathway for IL-16 release and offering insights into potential treatments for various inflammatory conditions.

The discovery of promising cytokines and clarification of their immunological mechanisms in controlling the intracellular fate of Mycobacterium tuberculosis (Mtb) are necessary to identify effective diagnostic biomarkers and therapeutic targets. To escape immune clearance, Mtb can manipulate and inhibit the normal host process of phagosome maturation. Phagosome maturation arrest by Mtb involves multiple effectors and much remains unknown about this important aspect of Mtb pathogenesis. In this study, we found that interleukin 16 (IL-16) is elevated in the serum samples of Tuberculosis (TB) patients and can serve as a specific target for treatment TB. There was a significant difference in IL-16 levels among active TB, latent TB infection (LTBI), and non-TB patients. This study first revealed that macrophages are the major source of IL-16 production in response to Mtb infection, and elucidated that IL-16 can promote Mtb intracellular survival by inhibiting phagosome maturation and suppressing the expression of Rev-erbα which can inhibit IL-10 secretion. The experiments using zebrafish larvae infected with M. marinum and mice challenged with H37Rv demonstrated that reducing IL-16 levels resulted in less severe pathology and improved survival, respectively. In conclusion, this study provided direct evidence that Mtb hijacks the host macrophages-derived interleukin 16 to enhance intracellular growth. It is suggesting the immunosuppressive role of IL-16 during Mtb infection, supporting IL-16 as a promising therapeutic target.

Cancer cells can evade immune elimination by activating immunosuppressive signaling pathways in the tumor microenvironment (TME). Targeting immunosuppressive signaling pathways to promote antitumor immunity has become an attractive strategy for cancer therapy. Aurora-A is a well-known oncoprotein that plays a critical role in tumor progression, and its inhibition is considered a promising strategy for treating cancers. However, targeting Aurora-A has not yet got a breakthrough in clinical trials. Recent reports have indicated that inhibition of oncoproteins may reduce antitumor immunity, but the role of tumor-intrinsic Aurora-A in regulating antitumor immunity remains unclear. In this study, we demonstrated that in tumors with high lymphocyte infiltration (hot tumors), higher tumor-intrinsic Aurora-A expression is associated with a better prognosis in CRC patients. Mechanically, tumor-intrinsic Aurora-A promotes the cytotoxic activity of CD8+ T cells in immune hot CRC via negatively regulating interleukin-16 (IL-16), and the upregulation of IL-16 may impair the therapeutic effect of Aurora-A inhibition. Consequently, combination treatment with IL-16 neutralization improves the therapeutic response to Aurora-A inhibitors in immune hot CRC tumors. Our study provides evidence that tumor-intrinsic Aurora-A contributes to anti-tumor immunity depending on the status of lymphocyte infiltration, highlighting the importance of considering this aspect in cancer therapy targeting Aurora-A. Importantly, our results suggest that combining Aurora-A inhibitors with IL-16-neutralizing antibodies may represent a novel and effective approach for cancer therapy, particularly in tumors with high levels of lymphocyte infiltration.

BACKGROUND: The presence of Blood-Brain Barrier (BBB) dysfunction is defined by albumin quotient (QALB) and characterize a group of Multiple Sclerosis (MS) patients at clinical onset. We evaluated the concentration in cerebrospinal fluid (CSF) of 87 cytokines, to better characterize the CSF inflammatory pattern in presence of BBB damage.
METHODS: In an exploratory cohort, CSF cytokines were evaluated by means of Multiplex technology (Bio-Plex Pro-Human Cytokine, GF and Diabetes 27-Plex Panel, Bio-Plex Pro-Human Chemokines 40-Plex Panel, Bio-Plex Pro-Human Inflammation Assays 37-Plex Panel) in a cohort of Other Not Inflammatory Neurological Disorders (ONIND) and in cohort of patients with MS, stratified according to BBB damage into QALB+ and QALB- MS patients. In the validation cohort, we evaluated the relevant molecules in a cohort of MS patients, stratified again into QALB+ and QALB-, including also Neurofilament Light (NfL) and Chitinase 3-like 1 (CHI3L1) CSF concentration.
RESULTS: While MIP-1α, CXCL-13, and CCL-22 CSF concentrations were higher in both MS groups compared to ONIND, in QALB+ MS CSF concentrations of CXCL-9 (17.85 ± 4.69 pg/mL), CXCL-10 (476.5 ± 324.3 pg/mL), and IL-16 (96.08 ± 86.17 pg/mL) were higher than in QALB- MS (8.98 ± 5368 pg/mL, p < 0.005, 281.0 ± 180.9 pg/mL, p < 0.05, and 47.35 ± 36.87 pg/mL, p < 0.005, respectively) and ONIND (8.98 ± 5368 pg/mlL, p < 0.005, 281.0 ± 180.9 pg/mL, p < 0.005, and 47.35 ± 36.87 pg/mL, p < 0.001, respectively). A strong correlation was observed between CXCL-9 and CXCL-10 in all MS groups (all r>0.75, all p < 0.001). In the validation cohort again CXCL-10 CSF concentration were higher in QALB+ MS than in QALB- MS (94.25 ± 64.75 vs 153.8 ± 99.52, p < 0.05), while no difference was observed in serum. CSF NfL (1642 ± 1963 vs 3231 ± 3492 pg/mL, p < 0.05) and CHI3L1 (183.9 ± 86.62 vs 262 ± 137.5 ng/mL, p < 0.05) were increased in QALB+ MS.
CONCLUSIONS: BBB damage in MS is linked to a specific CSF cytokines pattern (CXCL-9, CXCL-10, IL-16), that are also involved in astrocyte-microglia interaction. To what extent their continuous production in the CNS may mark a more severe disease course merits to be investigated.

Increased peripheral cytokine levels have been observed in patients with psychotic disorders; however, large high-quality studies with individually matched healthy controls have been lacking regarding cytokines in cerebrospinal fluid (CSF) of individuals with psychotic disorders.
Patients diagnosed with a non-organic, non-affective psychotic disorder (ICD-10: F20/22-29) within a year prior to inclusion and individually age- and sex-matched healthy controls were included by identical in- and exclusion criteria\'s except for the psychiatric diagnoses. All participants were aged 18-50 years and individuals with neurological or immunological disorders were excluded. CSF cytokines were analyzed with MesoScale V-PLEX neuroinflammation panel. Co-primary outcomes were CSF interleukin-6 (IL-6) and IL-8.
We included 104 patients and 104 healthy controls, matching on age, sex and BMI. No significant differences were found for the primary outcomes IL-6 (relative mean difference (MD): 0.97, 95 %CI: 0.84-1.11, p = 0.637) or IL-8 (MD: 1.01, 95 %CI: 0.93-1.09, p = 0.895). Secondary analyses found patients to have higher IL-4 (MD: 1.30, 95 %CI: 1.04-1.61, p = 0.018), a trend towards higher IFN-γ (MD: 1.26, 95 %CI: 0.99-1.59, p = 0.056), and lower IL-16 (MD: 0.83, 95 %CI: 0.74-0.94, p = 0.004) than healthy controls, though not significant after correction for multiple testing. IL-8 and IL-16 were found positively associated with CSF white blood cells and CSF/serum albumin ratio. The study was limited by 77.9 % of the patients being on antipsychotic treatment at time of intervention, and that levels of nine of the 26 cytokines were below lower limit of detection (LLOD) in >50 % of samples; however, for the primary outcomes IL-6 and IL-8 more than 99.5 % of the samples were above LLOD and for IL-8 all samples exceeded the lower limit of quantification (LLOQ).
We found no evidence of increased IL-6 and IL-8 in patients with recent-onset psychotic disorders in contrary to previous findings in meta-analyses of CSF cytokines. Secondary analyses found indication of higher IL-4, decreased IL-16, and borderline increased IFN-γ in patients, neither of which have previously been reported on in CSF analyses of individuals with psychotic disorders.