Frequency of IRF5+ dendritic cells is associated with the TLR7-induced inflammatory cytokine response in SARS-CoV-2 infection.

The SARS-CoV-2 infection leads to enhanced inflammation driven by innate immune responses. Upon TLR7 stimulation, dendritic cells (DC) mediate the production of inflammatory cytokines, and in particular of type I interferons (IFN). Especially in DCs, IRF5 is a key transcription factor that regulates pathogen-induced immune responses via activation of the MyD88-dependent TLR signaling pathway. In the current study, the frequencies of IRF5+ DCs and the association with innate cytokine responses in SARS-CoV-2 infected individuals with different disease courses were investigated. In addition to a decreased number of mDC and pDC subsets, we could show reduced relative IRF5+ frequencies in mDCs of SARS-CoV-2 infected individuals compared with healthy donors. Functionally, mDCs of COVID-19 patients produced lower levels of IL-6 in response to in vitro TLR7 stimulation. IRF5+ mDCs more frequently produced IL-6 and TNF-α compared to their IRF5- counterparts upon TLR7 ligation. The correlation of IRF5+ mDCs with the frequencies of IL-6 and TNF-α producing mDCs were indicators for a role of IRF5 in the regulation of cytokine responses in mDCs. In conclusion, our data provide further insights into the underlying mechanisms of TLR7-dependent immune dysfunction and identify IRF5 as a potential immunomodulatory target in SARS-CoV-2 infection.

Liver damage promotes pro-inflammatory T-cell responses against apolipoprotein B-100.

OBJECTIVES: Liver-derived apolipoprotein B-100 (ApoB100) is an autoantigen that is recognized by atherogenic CD4+ T cells in cardiovascular disease (CVD). CVD is a major mortality risk for patients with chronic inflammatory liver diseases. However, the impact of liver damage for ApoB100-specific T-cell responses is unknown. METHODS: We identified ApoB100-specific T cells in blood from healthy controls, nonalcoholic fatty liver disease (NAFLD) patients, and CVD patients by activation-induced marker expression and analyzed their differentiation pattern in correlation to the lipid profile and liver damage parameters in a cross-sectional study. To assess the induction of extrahepatic ApoB100-specific T cells upon transient liver damage in vivo, we performed hydrodynamic tail vein injections with diphtheria toxin A (DTA)-encoding plasmid in human ApoB100-transgenic mice. RESULTS: Utilizing immunodominant ApoB100-derived peptides, we found increased ApoB100-specific T-cell populations in NAFLD and CVD patients compared to healthy controls. In a peptide-specific manner, ApoB100 reactivity in healthy controls was accompanied by expression of the regulatory T (Treg)-cell transcription factor FOXP3. In contrast, FOXP3 expression decreased, whereas expression of pro-inflammatory cytokine interleukin (IL)-17A increased in ApoB100-specific T cells from NAFLD and CVD patients. Dyslipidemia and liver damage parameters in blood correlated with reduced FOXP3 expression and elevated IL-17A production in ApoB100-specific T-cell populations, respectively. Moreover, DTA-mediated transient liver damage in human ApoB100-transgenic mice accumulated IL-17a-expressing ApoB100-specific T cells in the periphery. CONCLUSION: Our results show that liver damage promotes pro-inflammatory ApoB100-specific T-cell populations, thereby providing a cellular mechanism for the increased CVD risk in liver disease patients.

Human pDCs display sex-specific differences in type I interferon subtypes and interferon α/ß receptor expression.

The outcomes of many diseases differ between women and men, with women experiencing a higher incidence and more severe pathogenesis of autoimmune and some infectious diseases. It has been suggested that this is partially due to activation of plasmacytoid dendritic cells (pDCs), the main producers of interferon (IFN)-α, in response to toll-like receptor (TLR)7 stimulation. We investigated the induction of type I IFN (IFN-I) subtypes upon TLR7 stimulation on isolated pDCs. Our data revealed a sex-specific differential expression of IFN-Is, with pDCs from females showing a significantly higher mRNA expression of all 13 IFN-α subtypes. In addition, pDCs from females had higher levels of IFN-ß mRNA after stimulation, indicating that sex differences in IFN-I production by pDCs were mediated by a signaling event upstream of the first loop of IFN-I mRNA transcription. Furthermore, the surface expression levels of the common IFN-α/ß receptor subunit 2 were significantly higher on pDCs from females in comparison to males. These data indicate that higher IFN-α production is already established at the mRNA level and propose a contribution of higher IFN-α/ß receptor 2 expression on pDCs to the immunological differences in IFN-I production observed between females and males.

TLR7-mediated activation of XBP1 correlates with the IFNα production in humans.

The transcription factor X-box binding protein 1 (XBP1) represents a key component of the endoplasmatic reticulum (ER) stress response and is required for the production of several pro-inflammatory cytokines. XBP1 is furthermore essential for the development and survival of plasmacytoid dendritic cells (pDCs), and has recently been suggested to be involved in toll-like receptor (TLR) 2/4 signaling. Activation of TLR7 on pDCs results in an upregulation of pro-inflammatory cytokines, such as type I interferons (IFN-I), and has been implicated in several autoimmune and inflammatory diseases, but the role of XBP1 in this process remains unknown. Here, we show that signaling via TLR7 leads to an upregulation of XBP1 and IFNα-production. XBP1 mRNA expression levels positively correlated with the production of IFNα, while blocking of XBP1 mRNA splicing significantly reduced mRNA transcripts of IFNα. In conclusion, these data suggest a central role of XBP1 in TLR7-induced IFNα production and identify XBP1 as a potential novel therapeutic target in IFNα-driven autoimmune and inflammatory diseases.

Sex Differences in Plasmacytoid Dendritic Cell Levels of IRF5 Drive Higher IFN-α Production in Women.

Increased IFN-α production contributes to the pathogenesis of infectious and autoimmune diseases. Plasmacytoid dendritic cells (pDCs) from females produce more IFN-α upon TLR7 stimulation than pDCs from males, yet the mechanisms underlying this difference remain unclear. In this article, we show that basal levels of IFN regulatory factor (IRF) 5 in pDCs were significantly higher in females compared with males and positively correlated with the percentage of IFN-α-secreting pDCs. Delivery of recombinant IRF5 protein into human primary pDCs increased TLR7-mediated IFN-α secretion. In mice, genetic ablation of the estrogen receptor 1 (Esr1) gene in the hematopoietic compartment or DC lineage reduced Irf5 mRNA expression in pDCs and IFN-α production. IRF5 mRNA levels furthermore correlated with ESR1 mRNA levels in human pDCs, consistent with IRF5 regulation at the transcriptional level by ESR1. Taken together, these data demonstrate a critical mechanism by which sex differences in basal pDC IRF5 expression lead to higher IFN-α production upon TLR7 stimulation in females and provide novel targets for the modulation of immune responses and inflammation.

Infections complicating severe alcoholic hepatitis: Enterococcus species represent the most frequently identified pathogen.

BACKGROUND: Patients with acute alcoholic steatohepatitis are at a high risk for infections. To date, neither disease-specific pathogen patterns, nor typical sites of infection, nor antibiotic treatment strategies have been established for AH. AIMS: To characterize incidence of infections, pathogen spectrum, sites of infection, and related mortality of patients with AH under steroid therapy. METHODS: We retrospectively analyzed clinical data of 73 patients with severe alcoholic hepatitis (MELD ≥ 20). RESULTS: Infections were detected in 45 patients (73%). Patients who developed an infection after initiation of corticosteroid therapy had a higher 6-month mortality than patients without onset of infection after initiation of corticosteroid treatment (44% versus 24%, p = 0.116). The pathogen identified most frequently was Enterococcus species. DISCUSSION: Infections frequently complicate severe alcoholic hepatitis and affect survival. The high rate of Enterococcus infections suggests that commonly used antibiotics, such as cephalosporins and quinolones, may represent an ineffective choice of empiric antibiotic treatment for complicated AH.

German cohort of HCV mono-infected and HCV/HIV co-infected patients reveals relative under-treatment of co-infected patients.

BACKGROUND: Current German and European HIV guidelines recommend early evaluation of HCV treatment in all HIV/HCV co-infected patients. However, there are still considerable barriers to initiate HCV therapy in everyday clinical practice. This study evaluates baseline characteristics, "intention-to-treat" pattern and outcome of therapy of HCV/HIV co-infected patients in direct comparison to HCV mono-infected patients in a "real-life" setting. METHODS: A large, single-center cohort of 172 unselected HCV patients seen at the Infectious Diseases Unit at the University Medical Center Hamburg-Eppendorf from 2000-2011, 88 of whom HCV/HIV co-infected, was retrospectively analyzed by chart review with special focus on demographic, clinical and virologic aspects as well as treatment outcome. RESULTS: Antiviral HCV combination therapy with PEG-interferon plus weight-adapted ribavirin was initiated in 88/172 (52%) patients of the entire cohort and in n = 36 (40%) of all HCV/HIV co-infected patients (group A) compared to n = 52 (61%) of the HCV mono-infected group (group B) (p = 0.006). There were no significant differences of the demographics or severity of the liver disease between the two groups with the exception of slightly higher baseline viral loads in group A. A sustained virologic response (SVR) was observed in 50% (n = 18) of all treated HIV/HCV co-infected patients versus 52% (n = 27) of all treated HCV mono-infected patients (p = 0.859). Genotype 1 was the most frequent genotype in both groups (group A: n = 37, group B: n = 49) and the SVR rates for these patients were only slightly lower in the group of co-infected patients (group A: n = 33%, group B: 40% p = 0.626). During the course of treatment HCV/HIV co-infected patients received less ribavirin than mono-infected patients. CONCLUSION: Overall, treatment was only initiated in half of the patients of the entire cohort and in an even smaller proportion of HCV/HIV co-infected patients despite comparable outcome (SVR) and similar baseline characteristics. In the light of newer treatment options, greater efforts to remove the barriers to treatment that still exist for a great proportion of patients especially with HIV/HCV co-infection have to be undertaken.

Hepatitis C virus and hepatocellular carcinoma: carcinogenesis in the era of direct-acting antivirals.

Chronic hepatitis C virus (HCV) infection is a major cause of hepatic fibrosis and cirrhosis, with a risk for the development of hepatocellular carcinoma (HCC). Although highly effective direct-acting antivirals (DAAs) are available, the incidence, morbidity, and mortality of HCV-associated HCC are still high. This article reviews the current knowledge of the mechanisms of HCV-induced carcinogenesis with a special focus on those processes that continue after virus clearance and outlines implications for patient surveillance after DAA treatment.

Sex differences in the percentage of IRF5 positive B cells are associated with higher production of TNF-α in women in response to TLR9 in humans.

BACKGROUND: The clinical course and outcome of many diseases differ between women and men, with women experiencing a higher prevalence and more severe pathogenesis of autoimmune diseases. The precise mechanisms underlying these sex differences still remain to be fully understood. IRF5 is a master transcription factor that regulates TLR/MyD88-mediated responses to pathogen-associated molecular patterns (PAMPS) in DCs and B cells. B cells are central effector cells involved in autoimmune diseases via the production of antibodies and pro-inflammatory cytokines as well as mediating T cell help. Dysregulation of IRF5 expression has been reported in autoimmune diseases, including systemic lupus erythematosus, primary Sjögren syndrome, and rheumatoid arthritis. METHODS: In the current study, we analyzed whether the percentage of IRF5 positive B cells differs between women and men and assessed the resulting consequences for the production of inflammatory cytokines after TLR7- or TLR9 stimulation. RESULTS: The percentage of IRF5 positive B cells was significantly higher in B cells of women compared to men in both unstimulated and TLR7- or TLR9-stimulated B cells. B cells of women produced higher levels of TNF-α in response to TLR9 stimulation. CONCLUSIONS: Taken together, our data contribute to the understanding of sex differences in immune responses and may identify IRF5 as a potential therapeutic target to reduce harmful B cell-mediated immune responses in women.

Transcriptional Pattern Analysis of Virus-Specific CD8+ T Cells in Hepatitis C Infection: Increased Expression of TOX and Eomesodermin During and After Persistent Antigen Recognition.

Thymocyte selection-associated high mobility group box (TOX) has been described to be a key regulator in the formation of CD8+ T cell exhaustion. Hepatitis C virus (HCV) infection with different lengths of antigen exposure in acute, chronic, and after resolution of HCV infection is the ideal immunological model to study the expression of TOX in HCV-specific CD8+ T cells with different exposure to antigen. HCV-specific CD8+ T cells from 35 HLA-A*01:01, HLA-A*02:01, and HLA-A*24:02 positive patients were analyzed with a 16-color FACS-panel evaluating the surface expression of lineage markers (CD3, CD8), ectoenzymes (CD39, CD73), markers of differentiation (CD45RO, CCR7, CD127), and markers of exhaustion and activation (TIGIT, PD-1, KLRG1, CD226) and transcription factors (TOX, Eomesodermin, T-bet). Here, we defined on-target T cells as T cells against epitopes without escape mutations and off-target T cells as those against a "historical" antigen mutated in the autologous sequence. TOX+HCV-specific CD8+ T cells from patients with chronic HCV and on-target T cells displayed co-expression of Eomesodermin and were associated with the formation of terminally exhausted CD127-PD1hi, CD39hi, CD73low CD8+ T cells. In contrast, TOX+HCV-specific CD8+ T cells in patients with off-target T cells represented a progenitor memory Tex phenotype characterized by CD127hi expression and a CD39low and CD73hi phenotype. TOX+HCV-specified CD8+ T cells in patients with a sustained virologic response were characterized by a memory phenotype (CD127+, CD73hi) and co-expression of immune checkpoints and Eomesodermin, indicating a key structure in priming of HCV-specific CD8+ T cells in the chronic stage, which persisted as a residual after therapy. Overall, the occurrence of TOX+HCV-specific CD8+ T cells was revealed at each disease stage, which impacted the development of progenitor Tex, intermediate Tex, and terminally exhausted T cell through an individual molecular footprint. In sum, TOX is induced early during acute infection but is modulated by changes in viral sequence and antigen recognition. In the case of antigen persistence, the interaction with Eomesodermin leads to the formation of terminally exhausted virus-specific CD8+ T cells, and there was a direct correlation of the co-expression of TOX and Eomes and terminally exhausted phenotype of virus-specific CD8+ T cells.

High and Sustained Ex Vivo Frequency but Altered Phenotype of SARS-CoV-2-Specific CD4+ T-Cells in an Anti-CD20-Treated Patient with Prolonged COVID-19.

Here, we longitudinally assessed the ex vivo frequency and phenotype of SARS-CoV-2 membrane protein (aa145-164) epitope-specific CD4+ T-cells of an anti-CD20-treated patient with prolonged viral positivity in direct comparison to an immunocompetent patient through an MHC class II DRB1*11:01 Tetramer analysis. We detected a high and stable SARS-CoV-2 membrane-specific CD4+ T-cell response in both patients, with higher frequencies of virus-specific CD4+ T-cells in the B-cell-depleted patient. However, we found an altered virus-specific CD4+ T-cell memory phenotype in the B-cell-depleted patient that was skewed towards late differentiated memory T-cells, as well as reduced frequencies of SARS-CoV-2-specific CD4+ T-cells with CD45RA- CXCR5+ PD-1+ circulating T follicular helper cell (cTFH) phenotype. Furthermore, we observed a delayed contraction of CD127- virus-specific effector cells. The expression of the co-inhibitory receptors TIGIT and LAG-3 fluctuated on the virus-specific CD4+ T-cells of the patient, but were associated with the inflammation markers IL-6 and CRP. Our findings indicate that, despite B-cell depletion and a lack of B-cell-T-cell interaction, a robust virus-specific CD4+ T-cell response can be primed that helps to control the viral replication, but which is not sufficient to fully abrogate the infection.

Clinical Presentation and Disease Course of 37 Consecutive Cases of Progressive Multifocal Leukoencephalopathy (PML) at a German Tertiary-Care Hospital: A Retrospective Observational Study.

Background: Progressive multifocal leukoencephalopathy (PML) caused by JCV is a rare but frequently fatal disease of the central nervous system, usually affecting immunocompromised individuals. Our study aims to expand the data on patient characteristics, diagnosis, clinical course, possible PML-directed treatment, and outcome of patients with PML at a German tertiary-care hospital. Methods:In this single-center observational cohort study, 37 consecutive patients with a confirmed diagnosis of PML seen at the University Medical Center Hamburg-Eppendorf from 2013 until 2019 were retrospectively analyzed by chart review with a special focus on demographics, risk factors, and clinical aspects as well as PML-directed treatment and survival. Results:We identified 37 patients with definite, probable, and possible PML diagnosis. 36 patients (97%) had underlying immunosuppressive disorders such as HIV/AIDS (n = 17; 46%), previous treatment with monoclonal antibodies (n = 6; 16%), hematological or oncological malignancies (n = 6; 16%), sarcoidosis (n = 5; 14%), solid organ transplantation (n = 1; 3%), and diagnosis of mixed connective tissue disease (n = 1; 3%). In only one patient no evident immunocompromised condition was detected (n = 1; 3%). Treatment attempts to improve the outcome of PML were reported in 13 patients (n = 13; 35%). Twenty seven percent of patients were lost to follow-up (n = 10). Twenty four-month survival rate after diagnosis of PML was 56% (n = 15). Conclusion: This interdisciplinary retrospective study describes epidemiology, risk factors, clinical course, and treatment trials in patients with PML at a German tertiary-care hospital. Acquired immunosuppression due to HIV-1 constituted the leading cause of PML in this monocenter cohort.

B cell analysis in SARS-CoV-2 versus malaria: Increased frequencies of plasmablasts and atypical memory B cells in COVID-19.

B cells play a central role in antiviral and antiparasitic immunity, not only as producers of antibodies, but also as APCs and mediators of inflammation. In this study, we used 16-color flow cytometry analysis to investigate the frequency, differentiation, and activation status of peripheral B cells of patients with SARS-CoV-2 infection or acute Plasmodium falciparum malaria compared with the healthy individuals. As a main result, we observed an increase of the frequency of (CD27-, CD21-) atypical memory B cells and (CD19+, CD27+, CD38+) plasmablasts in malaria and COVID-19 patients. Additionally, CD86, PD-1, CXCR3, and CD39 expression was up-regulated, whereas CD73 was down-regulated on plasmablasts of COVID-19 and malaria patients compared with the bulk B cell population. In particular, there was a more pronounced loss of CD73+ B cells in malaria. The frequency of plasmablasts positively correlated with serum levels of CRP, IL-6, and LDH of COVID-19 patients. In the longitudinal course of COVID-19, a rapid normalization of the frequency of atypical memory B cells was observed. The role and function of plasmablasts and atypical memory B cells in COVID-19 and other acute infections remain to be further investigated. The role of B cells as either "driver or passenger" of hyperinflammation during COVID-19 needs to be clarified.

Seroconversion of HBsAG coincides with hepatitis A super-infection: A case report.

BACKGROUND: Hepatitis B virus (HBV) is a hepatotropic virus that can cause acute and chronic liver damage. According to the world health organization 257 million people are infected with chronic HBV infection worldwide. Super-infection with other hepadnaviruses, including hepatitis A virus (HAV), hepatitis C virus, hepatitis D virus, and hepatitis E virus is associated with increased risk of acute liver failure in patients with chronic HBV. CASE SUMMARY: Here, we report a case of a 47-year old male patient with HBV-related compensated Child A cirrhosis, who presented with general fatigue, malaise and laboratory signs of acute hepatitis. Although the patient was regularly seen at a specialized university liver unit, the HAV vaccination status was unclear. Acute HAV super-infection was diagnosed by positive serological and polymerase chain reaction analysis. Following acute HAV super-infection, spontaneous HBsAg elimination and development of an anti-HBs titer were observed. CONCLUSION: This case illustrates the importance of carefully checking the vaccination status. In our patient, unspecific immunological responses to HAV led to functional cure of HBV.

Down-regulation of CD73 on B cells of patients with viremic HIV correlates with B cell activation and disease progression.

Recently, alterations of the T cell expression of the ectonucleotidases, CD39 and CD73, during HIV infection have been described. Here, peripheral (n = 70) and lymph nodal B cells (n = 10) of patients with HIV at different stages of disease as well as uninfected individuals were analyzed via multicolor flow cytometry with regard to expression of CD39 and CD73 and differentiation, proliferation, and exhaustion status. Patients with chronic, untreated HIV showed a significantly decreased frequency of CD73-expressing B cells (P < 0.001) compared with healthy controls. Decreased frequencies of CD39+CD73+ B cells in patients with HIV correlated with low CD4+ counts (P < 0.0256) as well as increased proliferation and exhaustion status as determined by Ki-67 and programmed death-1 expression. Down-regulation of CD73 was observed in naive and memory B cells as determined by CD27 and CD21. Neither HIV elite controller patients nor antiretroviral therapy-treated patients had significantly lower CD39 and CD73 expression on B cells compared with healthy controls. Of importance, low CD73+ expression on B cells was associated with modulated in vitro B cell function. Further in vivo studies are warranted to evaluate the in vivo role of phenotypic loss of CD73 in B cell dysregulation in HIV.

[Sex differences in infectious diseases and their clinical consequences]. / Geschlechtsunterschiede bei Infektionserkrankungen.

Differences between women and men range from their anatomy, their natural social behavior to their susceptibility and response to different pathologies, including infectious diseases. The underlying mechanisms of sex differences in infectious diseases are manifold, including differences in exposure to common pathogens, genetic factors that modulate immune responses against pathogens and hormonal factors that may alter susceptibility or disease progression, and responsiveness to treatment. On one hand, these mechanisms lead to higher innate and adaptive immune responses in females, which result in faster clearance of acute infections and higher antibody responses to several vaccines, on the other hand this contributes to an increased susceptibility to chronic inflammatory diseases. In this review we summarize the underlying causes of sex differences in prevalence, clinical course of disease and treatment outcome of infectious diseases. In order to develop individualized treatment concepts, a fair balance between the sexes should be maintained in basic science, preclinical and clinical studies.

Association of autoimmune hepatitis and systemic lupus erythematodes: a case series and review of the literature.

Liver test abnormalities have been described in up to 60% of patients with systemic lupus erythematodes (SLE) at some point during the course of their disease. Prior treatment with potentially hepatotoxic drugs or viral hepatitis is commonly considered to be the main cause of liver disease in SLE patients. However, in rare cases elevated liver enzymes may be due to concurrent autoimmune hepatitis (AIH). To distinguish whether the patient has primary liver disease with associated autoimmune clinical and laboratory features resembling SLE - such as AIH - or the elevation of liver enzymes is a manifestation of SLE remains a difficult challenge for the treating physician. Here, we present six female patients with complex autoimmune disorders and hepatitis. Patient charts were reviewed in order to investigate the complex relationship between SLE and AIH. All patients had coexisting autoimmune disease in their medical history. At the time of diagnosis of AIH, patients presented with arthralgia, abdominal complaints, cutaneous involvement and fatigue as common symptoms. All patients fulfilled the current diagnostic criteria of both, AIH and SLE. Remission of acute hepatitis was achieved in all cases after the initiation of immunosuppressive therapy. In addition to this case study a literature review was conducted.