IL-6 Autoantibodies Predict Lower Platelet Counts and Altered Plasma Cytokine Profiles in Healthy Blood Donors: Results From the Danish Blood Donor Study.

Cytokine-specific autoantibodies (c-aAb) represent a novel type of immune dysfunction. Though they have been detected in both patient cohorts and healthy individuals, and have immunomodulatory properties, the full extent of their influence remains unknown. Based on the critical role of several cytokines in thrombopoiesis, we investigated if there is an association between c-aAb and platelet variables in healthy individuals, with a specific focus on c-aAb against a known thrombopoietic cytokine, IL-6. Using platelet count and mean platelet volume in 3,569 healthy participants of the Danish Blood Donor Study as dependent variables, we performed a series of multivariate regression analyses using five cytokine autoantibodies, including IL-6 c-aAb, as independent variables. In men, high titers of IL-6 c-aAb were negatively associated with platelet counts (ß = -24 *109/l (95% confidence interval -43 to -6), p = 0.008) and positively associated with mean platelet volume (ß = 0.4 fL (95% confidence interval 0.0-0.7) p = 0.043). These associations were exacerbated when adjusting for undetectable C-reactive protein levels, which we used as a proxy for c-aAb mediated IL-6 inhibition in vivo. Furthermore, in a smaller subgroup, individuals with high vs. low titer IL-6 c-aAb had different profiles of plasma IL-6, IL-10, TNFα and TPO, further suggesting a functional inhibition of IL-6 by high titers of circulating IL-6 c-aAb. We therefore speculate that in addition to their immunomodulatory potential IL-6 c-aAb may interfere with thrombopoiesis - directly or indirectly - under normal physiological conditions. This study is the first to suggest an influence of c-aAb on platelets in healthy individuals, beyond their apparent effects on immune competence.

Chronic inflammation markers and cytokine-specific autoantibodies in Danish blood donors with restless legs syndrome.

Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder negatively impacting sufferers' quality of sleep and health-related quality of life. The pathophysiology of RLS is poorly understood and research focusing on the link between RLS and inflammation has been limited. Our study aimed to investigate whether chronic inflammation markers C-reactive protein (CRP) and soluble urokinase-type plasminogen activator receptor (suPAR), as well plasma levels of five different cytokine-specific autoantibodies (c-aAb), i.e. modulators of inflammation, associate with RLS in otherwise healthy individuals. CRP, suPAR and c-aAb were measured in plasma samples of participants from the Danish Blood Donor Study in 2010. Returning donors between 2015 and 2018 completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment, resulting in datasets with RLS assessment and values for CRP (N = 3564), suPAR (N = 2546) and c-aAb (N = 1478). We performed logistic regression models using the CRP, suPAR or c-aAb as the independent variable and RLS status as the dependent variable, adjusted for appropriate covariates. Our study indicates that a high concentration of CRP is associated with RLS, while an increased probability of experiencing frequent RLS symptoms in those with an elevated plasma suPAR level appears to be mediated through lifestyle factors. We additionally report that a high titer of autoantibodies specific against the cytokine interferon-alpha was associated with RLS. Our results support the existence of links between systemic inflammation and RLS, though further RLS studies on CRP, suPAR and c-aAb in larger cohorts are warranted to confirm our findings and further reveal the hitherto underexplored links between RLS and inflammation.

Cytokine autoantibodies are stable throughout the haematopoietic stem cell transplantation course and are associated with distinct biomarker and blood cell profiles.

Cytokine-specific autoantibodies (c-aAbs) represent an emerging field in endogenous immunodeficiencies, and the immunomodulatory potential of c-aAbs is now well documented. Here, we investigated the hypothesis that c-aAbs affects inflammatory, immunoregulatory and injury-related processes and hence the clinical outcome of haematopoietic stem cell transplantation (HSCT). C-aAbs against IL-1α, IL-6, IL-10, IFNα, IFNγ and GM-CSF were measured in 131 HSCT recipients before and after (days + 7, + 14, + 28) HSCT and tested for associations with 33 different plasma biomarkers, leukocyte subsets, platelets and clinical outcomes, including engraftment, GvHD and infections. We found that c-aAb levels were stable over the course of HSCT, including at high titres, with few individuals seeming to acquire high-titre levels of c-aAbs. Both patients with stable and those with acquired high-titre c-aAb levels displayed significant differences in biomarker concentrations and blood cell counts pre-HSCT and at day 28, and the trajectories of these variables varied over the course of HSCT. No clinical outcomes were associated with high-titre c-aAbs. In this first study of c-aAbs in HSCT patients, we demonstrated that high-titre levels of c-aAb may both persist and emerge in patients over the course of HSCT and may be associated with altered immune biomarkers and cell profiles.

Disseminated Mycobacterium avium complex infection in a woman with anti-interferon-γ autoantibodies.

Defects in the interleukin-12/interferon-gamma (IFN-γ) pathway and anti-IFN-γ antibodies have been associated with severe nontuberculous mycobacteria (NTM) infections. Consequently, disseminated NTM infections should prompt investigations for immunodeficiency. Herein, we report a case of a treatment refractory and ultimately disseminated and fatal Mycobacterium avium complex infection in a 71-year-old woman of Thai origin. Simultaneously, she had recurrent Salmonella kentucky cultured from stool samples and chronic perianal HSV-2 lesions. Late in the course of disease, anti-IFN-γ autoantibodies were demonstrated. Clinical studies investigating immunomodulating therapy and treatment among patients with anti-IFN-γ autoantibodies are lacking and, in this case, treatment seemed of a more palliative nature.

Platelet and Red Blood Cell Transfusions and Risk of Acute Graft-versus-Host Disease after Myeloablative Allogeneic Hematopoietic Cell Transplantation.

Transfusion therapy is a critical part of supportive care early after allogeneic hematopoietic cell transplantation (allo-HCT). Platelet and RBC transfusions elicit immunomodulatory effects in the recipient, but if this impacts the risk of acute graft-versus-host disease (aGVHD) has only been scarcely investigated. We investigated if platelet and RBC transfusions were associated with the development of aGVHD following myeloablative allo-HCT in a cohort of 664 patients who underwent transplantation between 2000 and 2019. Data were further analyzed for the impact of blood donor age and sex and blood product storage time. Exploratory analyses were conducted to assess correlations between transfusion burden and plasma biomarkers of inflammation and endothelial activation and damage. Between day 0 and day +13, each patient received a median of 7 (IQR, 5 to 10) platelet transfusions and 3 (IQR, 2 to 6) RBC transfusions (Spearman's ρ = 0.49). The cumulative sums of platelet and RBC transfusions, respectively, received from day 0 to day +13 were associated with subsequent grade II-IV aGVHD in multivariable landmark Cox models (platelets: adjusted hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.06 to 1.51; RBCs: adjusted HR, 1.41; 95% CI, 1.09 to 1.82; both per 5 units; 184 events). For both platelet and RBC transfusions, we did not find support for a difference in the risk of aGVHD according to age or sex of the blood donor. Transfusion of RBCs with a storage time longer than the median of 8 days was inversely associated with aGVHD (HR per 5 units, 0.54; 95% CI, 0.30 to 0.96); however, when using an RBC storage time of ≥14 days as a cutoff, there was no longer evidence for an association with aGVHD (HR, 1.03 per 5 units; 95% CI, 0.53 to 2.00). For platelets, there was no clear association between storage time and the risk of aGVHD. The transfusion burdens of platelets and RBCs were positively correlated with plasma levels of TNF-α, IL-6, and soluble thrombomodulin at day +14. In conclusion, platelet and RBC transfusions in the first 2 weeks after myeloablative allo-HCT were associated with subsequent development of grade II-IV aGVHD. We did not find evidence of an impact of blood donor age or sex or blood product storage time on the risk of aGVHD. Our findings support restrictive transfusion strategies in allo-HCT recipients.

Identification of two different coagulation phenotypes in people living with HIV with undetectable viral replication.

Altered coagulation has been reported in people living with HIV (PLWH) with ongoing viral replication and may predispose to cardiovascular diseases. However, less is known about coagulation in PLWH with undetectable viral replication. In a cross-sectional observational study, we investigated whether HIV infection with undetectable viral replication is independently associated with activated partial thromboplastin time (APTT) and coagulation factor II-VII-X concentrations out of reference. Logistic regression analyses were used to assess the association of HIV infection with APTT and coagulation factor II-VII-X, after adjusting for age, sex, smoking status, alcohol consumption, BMI, diabetes and hsCRP. 936 PLWH with undetectable viral replication from the Copenhagen Co-morbidity in HIV infection study (COCOMO-study) and 2955 uninfected controls were included. Higher prevalence of short APTT was found in PLWH compared to controls (13.5% vs. 7.6%, P < 0.001). Furthermore, higher prevalence of low coagulation factor II-VII-X was found in PLWH than in controls (9.6% vs. 7.4%, P = 0.022). HIV was independently associated with short APTT (adjusted odds ratio (aOR) 2.3 (95% CI 1.7-2.9), P < 0.001) and low coagulation factor II-VII-X (aOR 1.4 (95% CI 1.0-1.9), P = 0.046). Few participants among PLWH and controls had both short APTT and low coagulation factor II-VII-X, 2.1% vs. 0.8%, respectively. We found evidence of both procoagulant (short APTT) and anticoagulant (low coagulation factor II-VII-X) alterations in PLWH with undetectable viral replication, and our findings suggest that two different coagulation phenotypes exist in participants with treated HIV infection.

Independent Association of Interleukin 6 With Low Dynamic Lung Function and Airflow Limitation in Well-Treated People With Human Immunodeficiency Virus.

BACKGROUND: Human immunodeficiency virus (HIV) infection is associated with an increased risk of chronic pulmonary diseases. We compared cytokine concentrations (interleukin 6 [IL-6], interleukin 1ß, 2, 4, 10, and 17A, tumor necrosis factor α, interferon γ, soluble CD14 [sCD14] and soluble CD163 [sCD163]) in people with HIV (PWH) and uninfected controls and investigated whether elevated cytokine concentrations were independently associated with lung function indices in PWH. METHODS: We performed spirometry and measured cytokine concentrations by Luminex immunoassays or enzyme-linked immunoassay in 951 PWH and 79 uninfected controls from the Copenhagen Comorbidity in HIV Infection study. Regression analyses were used to explore associations between elevated cytokine concentrations and lung function indices. RESULTS: PWH were predominantly male (84.6%) and 94.2% had undetectable viral replication. In PWH, elevated IL-6 was associated with lower forced expiratory volume in 1 second (-212 mL [95% confidence interval, -308 to -116 mL]), lower forced vital capacity (-208 mL [-322 to -93 mL]), and airflow limitation (aOR, 2.62 [1.58-4.36]) (all P < .001) in models adjusted for age, sex, ethnicity, smoking status, body mass index, and CD4 T-cell nadir. The association between IL-6 and dynamic lung function was modified by smoking (P for interaction = .005). CONCLUSION: IL-6 levels were elevated and independently associated with low dynamic lung function and airflow limitation in well-treated PWH, suggesting that systemic inflammation may contribute to the pathogenesis of chronic pulmonary diseases.

Trafficking, localization and degradation of the Na+,HCO3- co-transporter NBCn1 in kidney and breast epithelial cells.

The Na+;HCO3- co-transporter NBCn1 (SLC4A7) is a major regulator of intracellular pH yet its trafficking and turnover are essentially unstudied. Here, we used MDCK-II and MCF-7 cells to investigate these processes in epithelial cells. GFP-NBCn1 membrane localization was abolished by truncation of the full NBCn1 C-terminal tail (C-tail) yet did not require the C-terminal PDZ-binding motif (ETSL). Glutathione-S-Transferase-pulldown of the C-tail followed by mass spectrometry analysis revealed putative interactions with multiple sorting-, degradation- and retention factors, including the scaffolding protein RACK1. Pulldown of FLAG-tagged deletion constructs mapped the RACK1 interaction to the proximal NBCn1 C-tail. Proximity Ligation Assay and co-immunoprecipitation confirmed that native NBCn1 interacts with RACK1 in a cellular context. Consistent with a functional role of this complex, RACK1 knockdown reduced NBCn1 membrane localization without affecting total NBCn1 expression. Notably, only non-confluent cells exhibited detectable NBCn1-RACK1 plasma membrane co-localization, suggesting that RACK1 regulates the trafficking of NBCn1 to the membrane. Whereas total NBCn1 degradation was slow, with a half-life of more than 24 h, one-third of surface NBCn1 was constitutively endocytosed from the basolateral membrane within 60 min. This suggests that a fraction of NBCn1 exhibits recycling between the basolateral membrane and intracellular compartment(s). Our findings have important implications for understanding NBCn1 regulation as well as its dysregulation in disease.

Prevalence and correlation of cytokine-specific autoantibodies with epidemiological factors and C-reactive protein in 8,972 healthy individuals: Results from the Danish Blood Donor Study.

Natural cytokine-specific autoantibodies (c-aAb) have been measured in healthy and diseased individuals, and have been considered as both endogenous immune-regulators and pathogenic factors. Overall, the etiology and potential pathology of c-aAb are still undefined. To further characterize the sero-prevalence, predictors and consequences of high c-aAb levels, we performed the largest population-based study of c-aAb to date, using participants and epidemiological data from the Danish Blood Donor Study. Using a validated bead-based multiplex assay we assessed plasma levels of IL-1α, IL-6, IL-10, IFNα and GM-CSF-specific c-aAb in 8,972 healthy blood donors. Trace levels of at least one of the investigated c-aAb could be measured in 86% of the participants. The presence of high levels of potentially inhibitory c-aAb was generally associated with increasing age and male or female sex, depending on the c-aAb in question. A negative correlation between high levels of IL-6-specific c-aAb and plasma levels of C-reactive protein was observed, indicating cytokine-neutralizing levels of c-aAb in healthy blood donors. There was no substantial correlation between high levels of the five individual c-aAb investigated in this study. These data suggest that autoimmunity against endogenous cytokines is a relatively common phenomenon in healthy individuals, and that predictive factors for high, potentially neutralizing c-aAb levels vary depending on the cytokine in question, and may differ from predictors of general c-aAb presence.

Serum Anticytokine Autoantibody Levels Are Not Increased in Hidradenitis Suppurativa: A Case-Control Pilot Study.

BACKGROUND: Hidradenitis suppurativa is a skin disease of recurrent episodes of inflammatory nodules, abscesses, and scarring of the intertriginous regions, e.g. the axillae and groin. A dysregulated immune response to one or more unknown antigens in hidradenitis suppurativa has been suggested. One hypothetical element of this dysregulation may be the functionality of the cytokines. This study examines the serum level of anticytokine autoantibodies for interleukin (IL)-1α, IL-6, IL-10, IL-17A, IL-17E, IL-17F, and interferon-α. METHOD: Recombinant, carrier-free cytokines were coupled to microspheres. The coupled beads were incubated for 1 h in the dark with assay buffer-diluted sera, and subsequently for 30 min with polyclonal goat F(ab')2 anti-human IgG phycoerythrin-conjugated antibody. Data are presented as the median fluorescence intensity of samples. RESULTS: No difference in levels of anticytokine autoantibodies was demonstrated for any of the autoantibodies studied. DISCUSSION: The data suggest that endogenously produced autoantibodies only play a minor role, if any, in hidradenitis suppurativa.

A rapid, accurate and robust particle-based assay for the simultaneous screening of plasma samples for the presence of five different anti-cytokine autoantibodies.

PURPOSE: To establish and validate a rapid, cost-effective and accurate screening assay for the simultaneous testing of human naturally occurring anti-cytokine autoantibodies (c-aAb) targeting interleukin-1α (IL-1α), interleukin-6 (IL-6), interleukin-10 (IL-10), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interferon α (IFNα). Because the c-aAbs can be transferred to patients through blood transfusion, the assay was used to assess c-aAb levels in a cohort of patients who were receiving blood transfusions and subsequently presented with or without febrile reactions. MATERIALS AND METHODS: The microsphere-based Luminex platform was used. Recombinant forms of human IL-1α, IL-6, IL-10, GM-CSF, and IFNα were gently coupled to MAG-PLEX beads. Plasma IgG binding was measured with phycoerythrin (PE)-labeled secondary antibodies. Previously confirmed c-aAb positive and negative donor plasma samples and pooled normal immunoglobulin preparations were used to validate the assay. Plasma samples from 98 transfusion recipients, half of whom presented with febrile reactions, were tested by the assay. RESULTS: The assay detected specific and saturable immunoglobulin G (IgG) binding to each of the tested cytokines in previously confirmed c-aAb positive plasmas and in preparations of pooled normal immunoglobulin. Confirmed c-aAb negative plasmas gave no saturable binding. The detection limit of the cytokine autoantibodies was estimated to be between 1 pM and 10 pM. The recovery of confirmed cytokine autoantibodies quantities in the negative plasma samples ranged between 80% and 125%. The analytical intra- and inter-assay variations were 4% and 11%, respectively. Varying c-aAb levels were detectable in the transfusion recipients. There was no difference in c-aAb frequency between the patients with or without febrile transfusion reactions. The c-aAb level before and after the blood transfusions varied only slightly and in an irregular manner. CONCLUSION: This assay simultaneously detected up to five different c-aAbs in pooled human IgG and in plasma from individual blood donors, and it was deemed suitable for larger screenings. Based on confirmed antibody binding characteristics and the resultant reactivity in this multiplex assay, a classification of the c-aAb levels was suggested. The screening results of the recipients who received blood transfusions indicate that more studies are needed to clarify the role of antibodies, if any, in transfusion medicine and in high-dose immunoglobulin treatment.