Impact of treatment with direct-acting antivirals on inflammatory markers and autoantibodies in HIV/HCV co-infected individuals.

HCV infection could have extrahepatic manifestations due to an aberrant immune response. HCV/HIV co-infection increases such persistent immune activation. Aim of the present study is to describe the evolution of inflammatory markers used in clinical practice, mixed cryoglobulinemia (MC) and autoantibody reactivity in co-infected individuals who achieved sustained virological response (SVR) after DAA treatment. This prospective, observational study included all HIV/HCV co-infected subjects who started any DAA regimen from 2015 to 2020. Samples for laboratory measurements (ferritin, C reactive protein, C3 and C4 fractions, rheumatoid factor, MC, anti-thyroglobulin Ab, anti-thyroid peroxidase Ab, ANCA, ASMA, anti-LKM, anti-DNA, AMA, ANA, T CD4+ and CD8+ cell count, and CD4/CD8 ratio) were collected at baseline, after 4 weeks, at end of treatment, and at SVR12. The analysis included 129 individuals: 51.9% with a F0-F3 fibrosis and 48.1% with liver cirrhosis. Cryocrit, C3 fraction, and rheumatoid factor significantly improved at week 4; ferritin, anti-thyroglobulin Ab, and C4 fraction at EOT; total leukocytes count at SVR12. MC positivity decreased from 72.8% to 35.8% (p < .001). T CD4+ cell slightly increased at SVR12, but with an increase also in CD8+ resulting in stable CD4/CD8 ratio. Autoantibody reactivity did not change significantly. ANA rods and rings positivity increased from 14.8% to 28.6% (p = .099): they were observed in three subjects without exposure to RBV. DAA therapy may lead to improvement in inflammatory markers and MC clearance but without significant changes in autoantibodies reactivity and CD4/CD8 ratio over a follow up of 12 weeks.

The value of anti-rods and rings antibodies in Chinese population of Dalian City: A retrospective study.

The study aimed to investigate the clinical significance of anti-rods and rings (anti-RR) antibodies in antinuclear antibodies (ANAs) test samples retrospectively. The laboratory data and clinical details of patients with positive anti-RR antibodies were collected and analysed between December 2017 and May 2022 in the First Affiliated Hospital of Dalian Medical University. A total of 72 665 patients were tested for ANAs. There were 45 632 patients discovered with positive ANAs (62.80%), only 131 patients presented with anti-RR antibodies (0.18%), among which only 68 patients were hospitalized patients with a definitive diagnosis. Among the 68 patients with a definitive diagnosis, 8 of 68 (11.8%) had autoimmune diseases, and 19 of 68 (27.9%) had renal diseases. Other diseases included liver disease, pulmonary disease, cerebral ischemia, cerebral infarction, chronic cardiac failure and venous thromboembolism. The detection rate of high titre(≥1:1000) anti-RR antibodies is significantly higher in autoimmune diseases.

CTP synthase: the hissing of the cellular serpent.

CTP biosynthesis is carried out by two pathways: salvage and de novo. CTPsyn catalyzes the latter. The study of CTPsyn activity in mammalian cells began in the 1970s, and various fascinating discoveries were made regarding the role of CTPsyn in cancer and development. However, its ability to fit into a cellular serpent-like structure, termed 'cytoophidia,' was only discovered a decade ago by three independent groups of scientists. Although the self-assembly of CTPsyn into a filamentous structure is evolutionarily conserved, the enzyme activity upon this self-assembly varies in different species. CTPsyn is required for cellular development and homeostasis. Changes in the expression of CTPsyn cause developmental changes in Drosophila melanogaster. A high level of CTPsyn activity and formation of cytoophidia are often observed in rapidly proliferating cells such as in stem and cancer cells. Meanwhile, the deficiency of CTPsyn causes severe immunodeficiency leading to immunocompromised diseases caused by bacteria, viruses, and parasites, making CTPsyn an attractive therapeutic target. Here, we provide an overview of the role of CTPsyn in cellular and disease perspectives along with its potential as a drug target.

The value of anti-rods and rings antibodies in Western China population: A retrospective study.

The study aimed to retrospectively investigate the clinical significance of anti-rods and rings (anti-RR) antibodies in antinuclear antibodies (ANAs) test samples of western China. Between January 2016 and November 2018, the laboratory data and clinical details of patients with positive anti-RR antibodies were collected and analysed. The results showed that total of 197 227 patients tested, 109 453 patients presented with positive ANAs (55.50%), but only 107 patients with positive anti-RR antibodies (0.10%), including 51 females and 56 males. Diagnose were established in 51 of 107 patients: 25 were hepatopathy (HCV 8/25, HBV 12/25); 13 were autoimmune diseases (AID); and 7 were renal insufficiency; 6 were chronic obstructive pulmonary disease (COPD). We make the conclusions that anti-RR antibodies have a low prevalence, and there is no gender difference. Anti-RR antibodies exist other diseases besides hepatitis C, such as HBV, some autoimmune diseases, renal insufficiency and COPD, which we need further investigation.

Autoantibodies to cytoplasmic rods and rings in patients with hepatitis C virus infection treated with direct-acting antivirals: The role of prior treatment with interferon plus ribavirin.

INTRODUCTION: The cytoplasmic rods-rings (RR) pattern is found in hepatitis C (HCV) patients treated with interferon-ribavirin when studied with ANA-IIF. Ribavirin aggregates/induces antigenic changes in IMPDH-2, an enzyme necessary for ribavirin action. PATIENTS AND METHOD: Prospective search for anti-RR autoantibodies (HEp-2, INOVA) in patients treated with direct-acting antivirals (DAAs) from October 2015 to June 2017. HCV-negative patients from up to June 2016 acted as controls. Anti-RR was analyzed at baseline and, mainly, during treatment and follow-up. The Chi-square test, Student's t-test and a logistic regression analysis were performed. RESULTS: Between October 2015 and June 2016, 1258 men and 2389 women who were HCV-negative and 137 men and 112 women who were HCV-positive patients were studied. Approximately 22.9% of HCV-negative and 13.2% of HCV-positive were ANA-IIF-positive (p<0.05). Three HCV-negative (0.08%) and 23 (9.2%) HCV-positive patients had anti-RR (p<0.001). A total of 122 patients received DAAs; 30 received DAA+RBV; 46 pre-treated with IFN-RBV received DAA; 31 pre-treated with IFN-RBV received DAA+RBV; 16 received IFNpeg-RBV; and 24 received IFN-RBV-DAA. None of the 122 DAA-treated patients showed anti-RR; anti-RR were identified in 14.8% of those treated with DAA-RBV; in 25.9% of those pre-treated with IFN-RBV receiving DAA; in 22.2% of IFN-RBV-pre-treated patients who received DAA+RBV; in 7.4% of those treated with IFNpeg-RBV and in 29.6% of those treated with IFNpeg-RBV-DAA. The multivariate analysis showed significant associations between anti-RR and "Exposure to IFN" and "Time of exposure to RBV". CONCLUSIONS: Anti-RR autoantibodies were detected only in patients with current or past treatments with RBV, even in cases in which only DAAs were later administered.

PIK3R1 fusion drives chemoresistance in ovarian cancer by activating ERK1/2 and inducing rod and ring-like structures.

Gene fusions are common in high-grade serous ovarian cancer (HGSC). Such genetic lesions may promote tumorigenesis, but the pathogenic mechanisms are currently poorly understood. Here, we investigated the role of a PIK3R1-CCDC178 fusion identified from a patient with advanced HGSC. We show that the fusion induces HGSC cell migration by regulating ERK1/2 and increases resistance to platinum treatment. Platinum resistance was associated with rod and ring-like cellular structure formation. These structures contained, in addition to the fusion protein, CIN85, a key regulator of PI3K-AKT-mTOR signaling. Our data suggest that the fusion-driven structure formation induces a previously unrecognized cell survival and resistance mechanism, which depends on ERK1/2-activation.

Retrospective evaluation of "Rods and Rings" pattern detected in the anti-nuclear antibody (ANA) indirect immunofluorescence (IIF) test.

Introduction: Anti-rods and rings (anti-RR) antibodies have recently been described as a cytoplasmic pattern in IIF-based screening of autoantibodies on HEp-2 cells and ICAP has named it as AC-23. It is most frequently related to drug-induced antibody generation. This study aimed to investigate the clinical significance of AC-23 positivity and its relevance to the diagnosis and/or follow-up of the associated diseases and/or drug use. Methods: A multicenter retrospective study was conducted among 10 hospitals from six different provinces in Türkiye from January 2017 to December 2021. The laboratory data and clinical information of 600 patients with positive anti-RR antibodies out of 547.558 HEp-2 IIF ANA samples were analyzed. Results: The distribution of AC-23 positive patients by year indicated a steady increase between 2017-2021. Anti-RR prevalence in post-COVID-19 period was significantly higher than that of pre-COVID-19 period (p=0.00). Concomitant ANA positivity was detected in 56.5% of patients, the most common patterns being AC-4 and AC-5 (41.1%). The most frequent pathology among the anti-RR positive patients was an autoimmune disease (19.83%); 28.57% of which had rheumatoid arthritis and 17.65% autoimmune liver disease. Among the 600 patients, 65 (10.83%) were diagnosed as hepatitis C virus (HCV) infection. Available data for 38 of the HCV patients revealed that 71.05% of them had a history of interferon alfa+ribavirin and 28.95% of them had a history of NS3/4/5A/5B polymerase inhibitor or protease inhibitor drug use. Significant increase in the rate of anti-RR positivity was observed in the post-COVID-19 period when compared to pre-COVID-19 period (p:0.00). Discussion: This is the first multicenter study in Türkiye about the clinical association of anti-RR antibodies which may be ignored during routine HEp-2 IIF testing. Pathologies other than HCV should be taken into consideration in terms of the possible role of anti-RR in autoimmune diseases and other pathologies. The preliminary data obtained in this study suggest that anti-RR antibody development might also be associated to COVID-19, supporting the several previous data related to the potential of viruses triggering the formation of autoantibodies. Large-scale prospective studies should elucidate the clinical significance of RR pattern and determine its role in patient diagnosis and follow-up.

B7-H3 Associates with IMPDH2 and Regulates Cancer Cell Survival.

Lung cancer is one of the most common cancers worldwide, and despite improvements in treatment regimens, patient prognosis remains poor. Lung adenocarcinomas develop from the lung epithelia and understanding how specific genetic and environmental factors lead to oncogenic transformation in these cells is of great importance to define the pathways that contribute to tumorigenesis. The recent rise in the use of immunotherapy to treat different cancers has prompted the exploration of immune modulators in tumour cells that may provide new targets to manipulate this process. Of these, the B7 family of cell surface receptors, which includes PD-1, is of particular interest due to its role in modulating immune cell responses within the tumour microenvironment. B7-H3 (CD276) is one family member that is upregulated in many cancer types and suggested to contribute to tumour-immune interactions. However, the function and ligand(s) for this receptor in normal lung epithelia and the mechanisms through which the overexpression of B7-H3 regulate cancer progression in the absence of immune cell interactions remain unclear. Here, we present evidence that B7-H3 is associated with one of the key rate-limiting metabolic enzymes IMPDH2, and the localisation of this complex is altered in human lung cancer cells that express high levels of B7-H3. Mechanistically, the IMPDH2:B7-H3 complex provides a protective role in cancer cells to escape oxidative stress triggered by chemotherapy, thus leading to cell survival. We further demonstrate that the loss of B7-H3 in cancer cells has no effect on growth or migration in 2D but promotes the expansion of 3D spheroids in an IMPDH2-dependent manner. These findings provide new insights into the B7-H3 function in the metabolic homeostasis of normal and transformed lung cancer cells, and whilst this molecule remains an interesting target for immunotherapy, these findings caution against the use of anti-B7-H3 therapies in certain clinical settings.

Acute severe autoimmune hepatitis with anti-rods and rings autoantibodies; literature first evidence.

Autoimmune hepatitis (AIH) was defined as a progressive, chronic inflammatory autoimmune liver disease (ALD). The diagnosis of AIH requires the presence of characteristic clinical and laboratory features, and the exclusion of other clinical conditions that cause chronic hepatitis and cirrhosis. AIH can have an acute onset that mimics an acute viral or toxic hepatitis or an acute severe (fulminant, ASF) presentation that satisfies criteria for acute liver. Guidelines from the European Association for the Study of Liver Diseases define ALF with absence of pre-existing liver disease, acute onset of ≤ 26 weeks, coagulopathy (international normalised ratio (INR) ≥ 1.5), and presence of hepatic encephalopathy (HE). In recent years, autoantibodies (Aab) targeting subcellular structures described as the rods and rings (R&R) pattern in HEp-2 ANA have been presented as a unique and particular case of Aab generation. These R&R structures are composed of inosine monophosphate dehydrogenase type 2 (IMPDH2), and their formation can be induced in vitro by several small-molecule inhibitors. Aab targeting these relatively unknown structures has been observed in Hepatitis C virus (HCV) patients who have undergone treatment with pegylated interferona/ ribavirin (IFN/RBV) therapy. We presented and characterized a case patient with R&R and SMA Aab in AIH (ASF, fatal, without liver transplantation). To the best of our knowledge, this is the first evidence described in the Literature. Our early experience showed the R&R circulating Aab in one patient with Primary Biliary Cholangitis. This work now demonstrates that R&R Aab can also be present in AIH case.

Autoantibodies to intracellular "rods and rings" structures in two patients with autoimmune hepatitis treated with azathioprine.

In vitro, inhibition of the synthesis of guanosine monophosphate (GMP) by various drugs such as ribavirin, acyclovir, azathioprine, and mycophenolic acid leads to the formation of subcellular structures in cultured cells. Autoantibodies targeting these cellular structures can be detected as "rods and rings" (RR) patterns by immunofluorescence. In vivo, autoantibodies to RR have been almost exclusively associated with hepatitis C virus patients treated with pegylated interferon-α and ribavirin. However, longitudinal data for other patient groups are scarce. Here, we reviewed 276 sequential immunofluorescence results from 127 patients with autoimmune hepatitis for the presence of RR patterns. Of 102 patients exposed to drugs known to induce RR in vitro, two patients under long-term azathioprine therapy were positive for this pattern. This is the first report of anti-RR in patients with autoimmune hepatitis and in patients treated with azathioprine.

Anti-rods/rings autoantibody and IMPDH filaments: an update after fifteen years of discovery.

Autoantibodies to unknown subcellular rod and ring-shaped structures were first discovered in sera from hepatitis C patients in 2005. Early studies showed a strong association between these anti-rods/rings antibodies (anti-RR) and the standard of care interferon-α plus ribavirin combination therapy (IFN/RBV), suggesting that anti-RR are drug-induced autoantibodies. In the context of hepatitis C, anti-RR have been linked with relapse from or lack of response to IFN/RBV in some patient cohorts. However, examples of anti-RR in other diseases and healthy individuals have also been reported over the years, although anti-RR remains a rare autoantibody response in general. The advent of new direct-acting antiviral drugs for chronic hepatitis C and studies of anti-RR from different parts of the world are also beginning to change the perception of anti-RR. The nucleotide biosynthetic enzyme inosine monophosphate dehydrogenase (IMPDH) has been identified as the major autoantigen recognized by anti-RR. Coincidentally, the assembly of IMPDH into micron-scale rod and ring-shaped structures was discovered around the same time as anti-RR. Knowledge of the fundamental biological properties and cellular functions of these structures, referred to as "IMPDH filaments" by cell biologists, has advanced in parallel to anti-RR antibodies. Recent studies have revealed that IMPDH filament assembly is a mechanism to prevent feedback inhibition of IMPDH and is therefore important for the increased nucleotide production required in hyperproliferating cells, like activated T cells. Fifteen years later, we review the history and current knowledge in both the anti-RR autoantibody and IMPDH filament fields. TAKE-HOME MESSAGE: Anti-rods/rings are recognized as an example of a drug-induced autoantibody in hepatitis C patients treated with interferon and ribavirin, although new studies suggest anti-rods/rings may be detected in other contexts and may depend on unknown environmental or genetic factors in different populations. Recent data suggest that the assembly of IMPDH into rod and ring structures, the targets of anti-rods/rings autoantibody, is a mechanism for hyperproliferating cells, like activated T cells, to maintain increased guanine nucleotide levels to support rapid cell division.

Anti-rod and ring antibodies in patients with chronic hepatitis C using direct-acting antivirals.

Anti-rods and rings (anti-RR) antibody induction is related to the combination of interferon and ribavirin in the treatment of hepatitis C virus (HCV) infection. If the main factor leading to this autoimmune reaction is the combination of these drugs, is not well known, but in vitro studies shows that ribavirin alone can induce rods and rings structures. New direct-acting antivirals (DAAs) permit HCV treatment without needing interferon but may be associated with ribavirin in the most difficult-to-treat patients. The aim of this study is to evaluate the occurrence of anti-RR in patients with chronic HCV infection, before and after 12 weeks of treatment with DAAs, with and without ribavirin. From Jun 2016 to Oct 2017, 52 HCV-infected patients were screened for anti-RR before and after DAA therapy, including sofosbuvir, daclatasvir, simeprevir, and ribavirin. Serum samples were analyzed using indirect immunofluorescence. The anti-RR was present in 11 (21%) of the 52 patients (51.9% male and mean age of 59.1 years) before using DAAs. All of them had been previously treated and previous exposed to interferon/ribavirin, with exposure time to ribavirin associated with the presence of anti-RR. After 12 weeks of DAA treatment, 3 patients (5.7%) developed the antibody in low titers, and two of them (66%) were interferon/ribavirin experienced. Only one of the 29 naïve patients (3.44%) developed anti-RR during the current treatment. Anti-RR was present in patients previously treated with interferon/ribavirin and can emerge after DAA treatment probably at a lower frequency than after interferon/ribavirin treatment.

Association of Autoantibody to Rods and Rings with Hepatitis C Outcome and Viral Load.

Despite the current availability of more potent drugs, hepatitis C virus (HCV) infection is still treated with a combination of IFN-α and ribavirin in many countries. Interferon/ribavirin therapy can induce the appearance of autoantibodies to Rods and Rings (anti-RR), which have been associated to a poorer prognosis. The aim of this study was to investigate the prevalence of anti-RR antibodies before and after ribavirin therapy and to look for a possible association with HCV infection outcome. In this context, anti-RR antibodies were detected by IFI on HEp-2 cells in 142 patients under ribavirin therapy (G1: 74 patients with a positive posttreatment HCV-PCR and G2: 68 patients with a negative posttreatment HCV-PCR, matched in age and gender), 84 kidney transplant recipients (KTRs) under mycophenolate and 158 controls (30 with systemic lupus erythematosus, 37 with rheumatoid arthritis, and 91 healthy blood donors). No patient had anti-RR antibody before IFN-α/ribavirin therapy, while 27 (19%) developed the anti-RR pattern under treatment. The anti-RR antibody was absent in all KTRs and the 158 controls. The frequency of anti-RR antibody was significantly higher in G1 (27; 36.48%) than in G2 (0), p < 0.001. Moreover, and in G1, anti-RR antibody was more frequent in nonresponders (NR) patients (23, 56.1%) than in relapsers (REL) (4, 12.1%); p < 0.001, OR [95%CI] = 9.26 [2.75-31.18]. Moreover, anti-RR antibody titer was significantly higher in NR patients (3,200 [1,600-6,400]) comparatively to REL patients (800 [500-1,400]), p = 0.002. Likewise, log of viral load postribavirin therapy was significantly higher in anti-RR positive patients (6.24 ± 0.64) than in anti-RR negative (4.69 ± 1.06), p < 0.001. Based on these findings, ribavirin-induced anti-RR autoantibody seems to be associated with a more frequent nonresponse to IFN-α/ribavirin therapy with a significant higher HCV viral load.

Primary biliary cholangitis with contemporary presence of anti-mithocondrial and anti-rods and rings autoantibodies: literature first case.

Primary biliary cholangitis, previously known as primary biliary cirrhosis (PBC), is the most common autoimmune diseases of the liver (ALD). Patients with PBC may present with typical biliary pattern symptoms. Also the presence of anti-mitochondrial autoantibodies (AMAs) is the laboratory hallmark of PBC, which molecular target antigens are members of 2-oxoacid dehydrogenase complex of enzymes. In recent years, autoantibodies (Aab) targeting subcellular structures described as the rods and rings (R&R) pattern in HEp-2 ANA have been presented as a unique and particular case of Aab generation. These R&R structures are composed of inosine monophosphate dehydrogenase type 2 (IMPDH2), and their formation can be induced in vitro by several small-molecule inhibitors. Aab targeting these relatively unknown structures have been almost exclusively observed in hepatitis C virus (HCV) patients who have undergone treatment with pegylated interferon-a/ribavirin (IFN/RBV) therapy. Literature showed that anti-RR Aab have not been found in no treatment-naïve HCV patients or in patients from any other disease. Now we present and characterized a case patient with contemporary presence of AMAs and R&R Aab in PBC, without any laboratory evidence of HCV and/or other hepatic virus infection. For our knowledge, this is the first case described in the Literature. R&R Aab in patients without any clinical/laboratory signs or symptoms of Hepatitis virus and without pharmacological therapy open the window to the alternative scenario: the association of these Aab to ALD. Our work demonstrated that R&R Aab can be present in PBC case. The interesting idea suggested that R&R Aab may be present also in AMA-negative PBC and they can considered a new possible diagnostic tool in this specific clinical condition. Other study and cases are needed but the presence of R&R Aab linked with AMAs and PBC may be explained by alterations in immune regulation caused by autoimmunity in a particular genetic background.

Immune Response-Dependent Assembly of IMP Dehydrogenase Filaments.

Inosine monophosphate dehydrogenase (IMPDH) catalyzes the conversion of IMP to xanthosine monophosphate, the rate-limiting step in de novo guanosine monophosphate (GMP) synthesis. In cultured cells, IMPDH polymerizes into micron-scale filamentous structures when GMP synthesis is inhibited by depletion of purine precursors or by various drugs, including mycophenolic acid, ribavirin, and methotrexate. IMPDH filaments also spontaneously form in undifferentiated mouse embryonic stem cells and induced pluripotent stem cells, hinting they might function in various highly proliferative cell types. Therefore, we investigated IMPDH filament formation in human and murine T cells, which rely heavily on de novo guanine nucleotide synthesis to rapidly proliferate in response to antigenic challenge. We discovered extensive in vivo IMPDH filament formation in mature T cells, B cells, and other proliferating splenocytes of normal, adult B6 mice. Both cortical and medullary thymocytes in young and old mice also showed considerable assembly of IMPDH filaments. We then stimulated primary human peripheral blood mononuclear cells ex vivo with T cell mitogens phytohemagglutinin (PHA), concanavalin A (ConA), or antibodies to CD3 and CD28 for 72 h. We detected IMPDH filaments in 40-60% of T cells after activation compared to 0-10% of unstimulated T cells. Staining of activated T cells for the proliferation marker Ki-67 also showed an association between IMPDH filament formation and proliferation. Additionally, we transferred ovalbumin-specific CD4+ T cells from B6.OT-II mice into B6.Ly5a recipient mice, challenged these mice with ovalbumin, and harvested spleens 6 days later. In these spleens, we identified abundant IMPDH filaments in transferred T cells by immunofluorescence, indicating that IMPDH also polymerizes during in vivo antigen-specific T cell activation. Overall, our data indicate that IMPDH filament formation is a novel aspect of T cell activation and proliferation, and that filaments might be useful morphological markers for T cell activation. The data also suggest that in vivo IMPDH filament formation could be occurring in a variety of proliferating cell types throughout the body. We propose that T cell activation will be a valuable model for future experiments probing the molecular mechanisms that drive IMPDH polymerization, as well as how IMPDH filament formation affects cell function.

Anti-rods/rings autoantibody generation in hepatitis C patients during interferon-α/ribavirin therapy.

Chronic inflammation associated with hepatitis C virus (HCV) infection can lead to disabling liver diseases with progression to liver cirrhosis and hepatocellular carcinoma. Despite the recent availability of more effective and less toxic therapeutic options, in most parts of the world the standard treatment consists of a weekly injection of pegylated interferon α (IFN-α) together with a daily dose of ribavirin. HCV patients frequently present circulating non-organ-specific autoantibodies demonstrating a variety of staining patterns in the indirect immunofluorescence assay for antinuclear antibodies (ANA). Between 20% to 40% of HCV patients treated with IFN-α and ribavirin develop autoantibodies showing a peculiar ANA pattern characterized as rods and rings (RR) structures. The aim of this article is to review the recent reports regarding RR structures and anti-rods/rings (anti-RR) autoantibody production by HCV patients after IFN-α/ribavirin treatment. Anti-RR autoantibodies first appear around the sixth month of treatment and reach a plateau around the twelfth month. After treatment completion, anti-RR titers decrease/disappear in half the patients and remain steady in the other half. Some studies have observed a higher frequency of anti-RR antibodies in relapsers, i.e., patients in which circulating virus reappears after initially successful therapy. The main target of anti-RR autoantibodies in HCV patients is inosine-5'-monophosphate dehydrogenase 2 (IMPDH2), the rate-limiting enzyme involved in the guanosine triphosphate biosynthesis pathway. Ribavirin is a direct IMPDH2 inhibitor and is able to induce the formation of RR structures in vitro and in vivo. In conclusion, these observations led to the hypothesis that anti-RR autoantibody production is a human model of immunologic tolerance breakdown that allows us to explore the humoral autoimmune response from the beginning of the putative triggering event: exposure to ribavirin and interferon.

Anti-rods/rings autoantibody seropositivity does not affect response to telaprevir treatment for chronic hepatitis C infection.

PURPOSE: Autoantibodies to intracellular 'rods and rings' structures (anti-rods/rings or anti-RR) are strongly associated with hepatitis C (HCV) patients treated with interferon-α/ribavirin (IFN/RBV) and are linked with non-responsiveness to IFN/RBV or relapse, especially in Italian patients. This is the first study to determine whether there is any correlation of anti-RR with non-responsiveness to IFN/RBV treatment in patients also treated with telaprevir (TPV), one of several new therapies for chronic HCV recently implemented. METHODS: From 2013 to 2014, 52 HCV-infected patients were treated with IFN/RBV and TPV at five Italian clinics. Patient sera were collected and analyzed by indirect immunofluorescence for the presence of anti-RR antibodies. Patients were classified as anti-RR positive or anti-RR negative, and then various biological and clinical variables were analyzed to compare the two groups, including gender, age, HCV genotype, previous IFN/RBV treatment, and IFN/RBV/TPV treatment outcome. RESULTS: Of these 52 HCV patients treated with IFN/RBV/TPV, 10/32 (31%) who previously received IFN/RBV were anti-RR positive, compared to 0 of 20 treatment-naïve patients. Anti-RR-positive patients relapsed more than anti-RR-negative patients (3/10, 30% vs. 2/42, 5%; p < 0.05). However, zero anti-RR-positive patients were non-responsive, and frequencies of sustained virological response were similar (anti-RR positive: 7/10, 70% vs. anti-RR negative: 33/42, 79%). CONCLUSIONS: Overall, the data suggest that anti-RR seropositivity is not associated with resistance to TPV treatment in this patient cohort, but monitoring anti-RR-positive patients for relapse within the first 6 months after treatment may be useful.

Anti-rods/rings: a human model of drug-induced autoantibody generation.

In recent years, autoantibodies targeting subcellular structures described as the rods and rings pattern in HEp-2 ANA have been presented as a unique case of autoantibody generation. These rod and ring structures (RR) are at least partially composed of inosine monophosphate dehydrogenase type 2 (IMPDH2), and their formation can be induced in vitro by several small-molecule inhibitors, including some IMPDH2 inhibitors. Autoantibodies targeting these relatively unknown structures have been almost exclusively observed in hepatitis C virus (HCV) patients who have undergone treatment with pegylated interferon-α/ribavirin (IFN/RBV) combination therapy. To date, anti-RR antibodies have not been found in treatment-naïve HCV patients or in patients from any other disease groups, with few reported exceptions. Here, we describe recent advances in characterizing the RR structure and the strong association between anti-RR antibody response and HCV patients treated with IFN/RBV, detailing why anti-RR can be considered a human model of drug-induced autoantibody generation.

Induction of cytoplasmic pattern in the form of "rods and rings" through the treatment of hepatitis C: a case report.

Female patient, complaining of weakness and pain in hypogastric, was admitted to the emergency department of the University Hospital of the West of Paraná (HUOP). During the interview reported treatment of chronic infection with hepatitis C virus (HCV) with peginterferon and ribavirin. Among the laboratory tests ordered, the search for self-antibodies against cellular antigens, traditionally known as antinuclear factor, showed fluorescence shaped like rods and/or rings in the cytoplasm of cells. This study attempts to clarify the relationship between this pattern not yet completely understood and the clinical picture of the patient. This pattern is characterized by 3-10 µm rods or rings with 2-5 µm in diameter scattered throughout the cytoplasm of the cell. Therefore, this new standard has been designated as "rods and rings" (RR). The antigenic target of this reaction was identified as inosine-5'-monophosphate dehydrogenase type 2 (IMPDH2) which is a key enzyme in the synthesis of purine nucleotides. The IMPDH2 enzyme aggregated or modified shaped RR in those patients treated with ribavirin may become antigenic and induce an autoimmune response. It is possible that interferon alpha stimulates the occurrence of anti-RR reactivity apparently induced by ribavirin. So far it is not known why the standard RR in HEp2 cells occurs only in a fraction of patients with HCV. Previous studies presented in this paper allow affirming that these antibodies associated with the standard RR are strongly related to hepatitis C. Moreover, it can be stated that the occurrence of anti-RR reactivity is promoted by combination therapy with interferon and ribavirin.

Ultrastructure of cytoplasmic and nuclear inosine-5'-monophosphate dehydrogenase 2 "rods and rings" inclusions.

Inosine-5'-monophosphate dehydrogenase catalyzes the critical step in the de novo synthesis of guanosine nucleotides: the oxidation of inosine monophosphate to xanthosine monophosphate. This reaction can be inhibited by specific inhibitors, such as ribavirin or mycophenolic acid, which are widely used in clinical treatment when required to inhibit the proliferation of viruses or cells. However, it was recently found that such an inhibition affects the cells, leading to a redistribution of IMPDH2 and the appearance of IMPDH2 inclusions in the cytoplasm. According to their shape, these inclusions have been termed "Rods and Rings" (R&R). In this work, we focused on the subcellular localization of IMPDH2 protein and the ultrastructure of R&R inclusions. Using microscopy and western blot analysis, we show the presence of nuclear IMPDH2 in human cells. We also show that the nuclear pool has an ability to form Rod structures after inhibition by ribavirin. Concerning the ultrastructure, we observed that R&R inclusions in cellulo correspond to the accumulation of fibrous material that is not surrounded by a biological membrane. The individual fibers are composed of regularly repeating subunits with a length of approximately 11 nm. Together, our findings describe the localization of IMPDH2 inside the nucleus of human cells as well as the ultrastructure of R&R inclusions.