IL-2 produced by HBV-specific T cells as a biomarker of viral control and predictor of response to PD-1 therapy across clinical phases of chronic hepatitis B.

BACKGROUND: There are no immunological biomarkers that predict control of chronic hepatitis B (CHB). The lack of immune biomarkers raises concerns for therapies targeting PD-1/PD-L1 because they have the potential for immune-related adverse events. Defining specific immune functions associated with control of HBV replication could identify patients likely to respond to anti-PD-1/PD-L1 therapies and achieve a durable functional cure. METHODS: We enrolled immunotolerant, HBeAg+ immune-active (IA+), HBeAg- immune-active (IA-), inactive carriers, and functionally cured patients to test ex vivo PD-1 blockade on HBV-specific T cell functionality. Peripheral blood mononuclear cells were stimulated with overlapping peptides covering HBV proteins +/-α-PD-1 blockade. Functional T cells were measured using a 2-color FluoroSpot assay for interferon-γ and IL-2. Ex vivo functional restoration was compared to the interferon response capacity assay, which predicts overall survival in cancer patients receiving checkpoint inhibitors. RESULTS: Ex vivo interferon-γ+ responses did not differ across clinical phases. IL-2+ responses were significantly higher in patients with better viral control and preferentially restored with PD-1 blockade. Inactive carrier patients displayed the greatest increase in IL-2 production, which was dominated by CD4 T cell and response to the HBcAg. The interferon response capacity assay significantly correlated with the degree of HBV-specific T cell restoration. CONCLUSIONS: IL-2 production was associated with better HBV control and superior to interferon-γ as a marker of T cell restoration following ex vivo PD-1 blockade. Our study suggests that responsiveness to ex vivo PD-1 blockade, or the interferon response capacity assay, may support stratification for α-PD-1 therapies.

Reliability of histologic assessment for NAFLD and development of an expanded NAFLD activity score.

BACKGROUND AND AIMS: The NASH Clinical Research Network histologic scoring system, the gold-standard NASH histology assessment for clinical trials, has demonstrated intrarater and interrater variability. An expert panel in a previous systematic Research and Development/University of California Los Angeles (RAND/UCLA) study determined that existing histologic scoring systems do not fully capture NASH disease activity and fibrosis, and standardized definitions of histologic features are needed. We evaluated the reliability of existing and alternate histologic measures and their correlations with a disease activity visual analog scale to propose optimal components for an expanded NAFLD activity score (NAS). APPROACH AND RESULTS: Four liver pathologists who were involved in the prior RAND/UCLA study underwent standardized training and multiple discussions with the goal of improving agreement. They were blinded to clinical information and scored histologic measures twice, ≥2 weeks apart, for 40 liver biopsies representing the full spectrum of NAFLD. Index intraclass correlation coefficient (ICC) estimates demonstrated intrarater (0.80-0.85) and interrater (0.60-0.72) reliability. Hepatocyte ballooning items had similar interrater ICCs (0.68-0.79), including those extending scores from 0-2 to 0-4. Steatosis measures (interrater ICCs, 0.72-0.80) correlated poorly with disease activity. Correlations with disease activity were largest for hepatocyte ballooning and Mallory-Denk bodies (MDBs), with both used to develop the expanded NAS (intrarater ICC, 0.90; interrater ICC, 0.80). Fibrosis measures had ICCs of 0.70-0.87. CONCLUSIONS: After extensive preparation among a group of experienced pathologists, we demonstrated improved reliability of multiple existing histologic NAFLD indices and fibrosis staging systems. Hepatocyte ballooning and MDBs most strongly correlated with disease activity and were used for the expanded NAS. Further validation including evaluation of responsiveness is required.

Hepatic Secondary Syphilis Can Cause a Variety of Histologic Patterns and May Be Negative for Treponeme Immunohistochemistry.

The rate of syphilis in the United States has been increasing steadily in the past decade, but it remains an uncommon diagnosis in tissue biopsies. Most of the pathology literature on hepatic syphilis consists of older series or case reports. This study aimed to systematically characterize the histologic spectrum of hepatic syphilis in a contemporary cohort. Clinicopathologic features of 14 hepatic syphilis cases between 2012 and 2018 were analyzed to characterize the broad spectrum of histologic changes. Thirteen patients were men (age range: 19 to 59 y); 6 had known human immunodeficiency virus, 7 were men known to have sex with men, and no patient had known prior syphilis. Hepatic syphilis was the primary clinical suspicion in only 1 patient. Common symptoms included jaundice, rash, and abdominal pain. Thirteen had elevated transaminases, and 12 had elevated alkaline phosphatase. Pathologic changes were grouped into 5 histologic patterns: biliary-pattern injury (n=5), acute hepatitis (n=4), autoimmune hepatitis-like (n=1), fibroinflammatory mass-forming lesion (n=2), and no particular pattern (n=2). Nearly all showed portal and lobular lymphocytes and plasma cells; 12 had prominent histiocytes/Kupffer cells, 9 had ductular reaction, and 7 had duct inflammation. Occasional focal findings included dropout (n=7), phlebitis (n=7), and loose granulomata (n=5). Treponeme immunohistochemistry was positive in 10 and negative in 4, though treatment was given before biopsy in 3 of those 4. Thirteen patients had rapid plasma reagin testing either before or after biopsy, with 1:64 or higher titer. All patients who received treatment recovered. Hepatic syphilis is rare but likely underrecognized. It exhibits a variety of histologic appearances and therefore should be considered in several hepatic differential diagnoses, especially in men who have sex with men. Kupffer cells, granulomata, and phlebitis may suggest the diagnosis regardless of predominant histologic pattern. Negative treponeme immunohistochemical staining does not exclude the diagnosis, including in untreated patients.

Mimics of hepatocellular carcinoma: a review and an approach to avoiding histopathological diagnostic missteps.

Hepatocellular carcinoma (HCC) is one of the commonest carcinomas and leading causes of cancer-related death. Although, in patients with cirrhosis, radiologic diagnosis has improved significantly over the years, needle biopsy and histopathological assessment remains an important diagnostic modality. Most importantly, histopathological diagnosis is essential in patients with contending extrahepatic primaries, those with no known HCC risk factors, patients with ambiguous radiological features, and many other clinical contexts. Helpful features such as high serum alpha-fetoprotein (AFP) serologies are known to be present in many other tumor (including but not only HCC) and nontumor contexts and therefore not only lack sufficient diagnostic specificity for HCC but also create the potential to overlook non-HCC AFP-producing tumors, of which there are many. Therefore, using clinical examples and other examples from the medical literature, this review discusses several clinical and histological mimics of HCC and proffers an approach for practicing pathologists geared toward avoiding missteps.

Pharmacokinetics, tissue distribution and safety of gold nanoparticle/PKC Delta inhibitor peptide hybrid in rats.

Gold nanoparticles (GNPs) are extremely useful for drug delivery, due in part to their highly tunable nature. However, this variability has prevented a clear understanding of the pharmacokinetics and toxicity of GNPs for drug delivery. Here, we present the clearance, organ distribution and acute toxicity testing of our drug delivery system which uses GNPs and two penta-peptides, to deliver a rationally designed peptide drug. We found that with or without our therapeutic, the GNP/peptide hybrid cleared rapidly from the blood in rats and accumulated mostly in the liver and spleen, although it was also detectable in several other organs. There were subtle but detectable differences between the behavior of our GNP hybrids with or without the therapeutic peptide. The GNP/peptide hybrid showed no evidence of toxicity at single doses up to 16 times the therapeutic dose, as measured by a battery of tests including, blood cell makeup, levels of markers of liver, kidney and spleen function, organ mass indexes, and histology. These results underline the importance of testing the pharmacokinetics and toxicity of all GNP preparations, as even minor changes to the surface coatings of GNPs can influence their behavior. On the other hand, the results herein can help guide the design and use of similar GNP/peptide drug delivery systems.

Practical Application of Lineage-Specific Immunohistochemistry Markers: Transcription Factors (Sometimes) Behaving Badly.

CONTEXT.­: Transcription factors (TFs) are proteins that regulate gene expression and control RNA transcription from DNA. Lineage-specific TFs have increasingly been used by pathologists to determine tumor lineage, especially in the setting of metastatic tumors of unknown primary, among other uses. With experience gathered from its daily application and increasing pitfalls reported from immunohistochemical studies, these often-touted highly specific TFs are not as reliable as once thought. OBJECTIVES.­: To summarize the established roles of many of the commonly used TFs in clinical practice and to discuss known and potential sources for error (eg, false-positivity from cross-reactivity, aberrant, and overlap "lineage-specific" expression) in their application and interpretation. DATA SOURCES.­: Literature review and the authors' personal practice experience were used. Several examples selected from the University Health Network (Toronto, Ontario, Canada) are illustrated. CONCLUSIONS.­: The application of TF diagnostic immunohistochemistry has enabled pathologists to better assess the lineage/origin of primary and metastatic tumors. However, the awareness of potential pitfalls is essential to avoid misdiagnosis.

Standardising the interpretation of liver biopsies in non-alcoholic fatty liver disease clinical trials.

BACKGROUND: There is substantial variation in how histologic definitions and scoring systems of non-alcoholic fatty liver disease (NAFLD) are operationalised. AIM: To develop a consensus-based framework for standardising histologic assessment of liver biopsies in clinical trials of NAFLD. METHODS: An expert panel of 14 liver pathologists and three hepatologists was assembled. Using modified RAND/University of California Los Angeles appropriateness methodology, 130 items derived from literature review and expert opinion were rated by each panel member on a 1-9 scale. Disagreement was defined as ≥5 ratings in the lowest (1-3) and highest (7-9) categories. Items were classified as inappropriate (median 1-3.5 without disagreement), uncertain (median 3.5-6.5 or any median with disagreement) or appropriate (median 6.5-9 without disagreement). Survey results were discussed as a group before voting. RESULTS: Current measures of disease activity and fibrosis may not fully capture important features of non-alcoholic steatohepatitis (NASH). Alternative methods to evaluate ballooning degeneration are needed. Panellists were uncertain whether portal inflammation, degree of steatosis and Mallory-Denk bodies are important measures of disease activity. Furthermore, it was felt that current staging systems do not capture the full spectrum of fibrosis in NASH. A consensus definition and sub-stages for bridging fibrosis are needed. The severity of perisinusoidal fibrosis should be captured at all stages. Lastly, a method to evaluate features of fibrosis regression should be developed. CONCLUSION: The operating properties of the modifications proposed should be evaluated prospectively to determine reliability and responsiveness.

PPAR-gamma activation is associated with reduced liver ischemia-reperfusion injury and altered tissue-resident macrophages polarization in a mouse model.

BACKGROUND: PPAR-gamma (γ) is highly expressed in macrophages and its activation affects their polarization. The effect of PPAR-γ activation on Kupffer cells (KCs) and liver ischemia-reperfusion injury (IRI) has not yet been evaluated. We investigated the effect of PPAR-γ activation on KC-polarization and IRI. MATERIALS AND METHODS: Seventy percent (70%) liver ischemia was induced for 60mins. PPAR-γ-agonist or vehicle was administrated before reperfusion. PPAR-γ-antagonist was used to block PPAR-γ activation. Liver injury, necrosis, and apoptosis were assessed post-reperfusion. Flow-cytometry determined KC-phenotypes (pro-inflammatory Nitric Oxide +, anti-inflammatory CD206+ and anti-inflammatory IL-10+). RESULTS: Liver injury assessed by serum AST was significantly decreased in PPAR-γ-agonist versus control group at all time points post reperfusion (1hr: 3092±105 vs 4469±551; p = 0.042; 6hr: 7041±1160 vs 12193±1143; p = 0.015; 12hr: 5746±328 vs 8608±1259; p = 0.049). Furthermore, liver apoptosis measured by TUNEL-staining was significantly reduced in PPAR-γ-agonist versus control group post reperfusion (1hr:2.46±0.49 vs 6.90±0.85%;p = 0.001; 6hr:26.40±2.93 vs 50.13±8.29%; p = 0.048). H&E staining demonstrated less necrosis in PPAR-γ-agonist versus control group (24hr:26.66±4.78 vs 45.62±4.57%; p = 0.032). The percentage of pro-inflammatory NO+ KCs was significantly lower at all post reperfusion time points in the PPAR-γ-agonist versus control group (1hr:28.49±4.99 vs 53.54±9.15%; p = 0.040; 6hr:5.51±0.54 vs 31.12±9.58%; p = 0.009; 24hr:4.15±1.50 vs 17.10±4.77%; p = 0.043). In contrast, percentage of anti-inflammatory CD206+ KCs was significantly higher in PPAR-γ-agonist versus control group prior to IRI (8.62±0.96 vs 4.88 ±0.50%; p = 0.04). Administration of PPAR-γ-antagonist reversed the beneficial effects on AST, apoptosis, and pro-inflammatory NO+ KCs. CONCLUSION: PPAR-γ activation reduces IRI and decreases the pro-inflammatory NO+ Kupffer cells. PPAR-γ activation can become an important tool to improve outcomes in liver surgery through decreasing the pro-inflammatory phenotype of KCs and IRI.

Anti-inflammatory signaling during ex vivo liver perfusion improves the preservation of pig liver grafts before transplantation.

Normothermic ex vivo liver perfusion (NEVLP) improves graft preservation by avoiding cold ischemia injury. We investigated whether the protective effects of NEVLP can be further improved by applying strategies targeted on reducing the activation of proinflammatory cytokines during perfusion. Livers retrieved under heart-beating conditions were perfused for 4 hours. Following the preservation period, a pig liver transplantation was performed. In group 1 (n = 5), anti-inflammatory strategies (alprostadil, n-acetylcysteine, carbon monoxide, sevoflurane, and subnormothermic temperature [33°C]) were applied. This was compared with a perfused control group (group 2) where livers (n = 5) were perfused at 37°C without anti-inflammatory agents, similar to the setup used in current European clinical trials, and to a control group preserved with static cold storage (group 3). During 3-day follow-up, markers of reperfusion injury, bile duct injury, and liver function were examined. Aspartate aminotransferase (AST) levels during perfusion were significantly lower in the study versus control group at 1 hour (52 ± 6 versus 162 ± 86 U/L; P = 0.01), 2 hours (43 ± 5 versus 191 ± 111 U/L; P = 0.008), and 3 hours (24 ± 16 versus 218 ± 121 U/L; P = 0.009). During perfusion, group 1 versus group 2 had reduced interleukin (IL) 6, tumor necrosis factor α, and galactosidase levels and increased IL10 levels. After transplantation, group 1 had lower AST peak levels compared with group 2 and group 3 (1400 ± 653 versus 2097 ± 1071 versus 1747 ± 842 U/L; P = 0.47) without reaching significance. Bilirubin levels were significantly lower in group 1 versus group 2 at day 1 (3.6 ± 1.5 versus 6.60 ± 1.5 µmol/L; P = 0.02) and 3 (2 ± 1.1 versus 9.7 ± 7.6 µmol/L; P = 0.01). A trend toward decreased hyaluronic acid, as a marker of improved endothelial cell function, was observed at 1, 3, and 5 hours after reperfusion in group 1 versus group 2. Only 1 early death occurred in each group (80% survival). In conclusion, addition of anti-inflammatory strategies further improves warm perfused preservation. Liver Transplantation 22 1573-1583 2016 AASLD.

XB130 deficiency enhances lipopolysaccharide-induced septic response and acute lung injury.

XB130 is a novel oncoprotein that promotes cancer cell survival, proliferation and migration. Its physiological function in vivo is largely unknown. The objective of this study was to determine the role of XB130 in lipopolysaccharide (LPS)-induced septic responses and acute lung injury. LPS was intraperitoneally administrated to Xb130 knockout (KO) and wild type (WT) mice. There was a significant weight loss in KO mice at Day 2 and significantly higher disease scores during the 7 days of observation. The levels of tumor necrosis factor-alpha, monocyte chemoattractant protein-1, interleukin-6 and interleukin-10 in the serum were significantly higher in KO mice at Day 2. In KO mice there were a significantly higher lung injury score, higher wet/dry lung weight ratio, more apoptotic cells and less proliferative cells in the lung. Macrophage infiltration was significantly elevated in the lung of KO mice. There was significantly increased number of p-GSK-3ß positive cells in KO mice, which were mainly neutrophils and macrophages. XB130 is expressed in alveolar type I and type II cells in the lung. The expression in these cells was significantly reduced after LPS challenge. XB130 deficiency delayed the recovery from systemic septic responses, and the presence of XB130 in the alveolar epithelial cells may provide protective mechanisms by reducing cell death and promoting cell proliferation, and reducing pulmonary permeability.

Infiltrative (sinusoidal) and hepatitic patterns of injury in acute cellular rejection in liver allograft with clinical implications.

Acute cellular rejection post liver transplant occurs most commonly but not exclusively in the first year. In this study, we report two patterns: sinusoidal infiltrative and hepatitic, which are not considered in the Banff system. We describe their presentation, response to Solu-Medrol, and compare these to the typical moderate-severe acute cellular rejection. Patients transplanted from 2007 to 2012 at University Health Network, who had biopsy-proven rejection in the first year, were studied. Baseline transaminases and bilirubin, time of acute cellular rejection, follow-up, and treatment responses were analyzed. A total of 407 biopsies were received, of which 77 had diagnosis of acute cellular rejection with rejection activity index 5 or above; 49 from viral hepatitis patients were excluded. Twenty-eight were included; 15/28 (54%) had typical acute cellular rejection (tACR) using Banff criteria. Six (21%) had hepatitic acute cellular rejection overlapping with typical features of acute cellular rejection; seven (25%) had infiltrative acute cellular rejection (iACR) overlapping with typical features. The iACR occurred later than the tACR (124 versus 50 days; P = 0.032) and had a higher rise in baseline aspartate aminotransferase (ΔAST) compared with tACR (289 U/l versus 109 U/l; P=0.046). Only one out of seven patients with iACR (14 versus 40% in tACR) failed Solu-Medrol boluses and required thymoglobulin. Patients with hepatitic acute cellular rejection (hACR) had similar ΔAST (P = 0.12) but higher bilirubinemia than typical acute cellular rejection (tACR) (160 µmol/l versus 35 mol/l; P = 0.039) and required thymoglobulin in four out of six (67% versus 40%) instances. Patients with iACR had higher ΔAST than tACR but better Solu-Medrol response compared with both tACR and hACR. hACR is different from plasma cell-rich late-occurring cellular rejection in its pattern but similar in its poor Solu-Medrol response.

Abernethy malformation type II with nephrotic syndrome and other multisystemic presentation: an illustrative case for understanding pathogenesis of extrahepatic complication of congenital portosystemic shunt.

Abernethy malformation, an extrahepatic congenital portosystemic shunt, is more often diagnosed based on associated cardiac or pulmonary malformation. Although predominately a pediatric diagnosis, "late diagnoses" in adulthood have been reported especially in type II malformations that involve only a partial shunt of portal circulation directly into the inferior vena cava. Aside from the cardiac-related presentation, Abernethy malformation is also associated with multiple liver nodules, either benign or malignant, and pulmonary hypertension. In this report, we present immunoglobulin A glomerulonephritis with nephrotic syndrome as a hitherto unrecognized manifestation of this malformation outside the pediatric population, in a patient who also had pulmonary hypertension and multiple liver tumors. We also propose a pathogenetic basis for this multisystemic presentation that includes release into the systemic circulation of unfiltered bacteria, vasoactive substances, and immunoglobulin A-antigen complexes.

Pathology services in developing countries-the West African experience.

CONTEXT: Histopathology, like other branches of medicine in West Africa, has suffered largely from economic, political, social, and infrastructural problems, becoming a shadow of the top quality that had been obtained in the past. To address the prevailing problems, one needs to attempt defining them. OBJECTIVE: The existing structure of training and practice are discussed, highlighting the author's perception of the problems and suggesting practical ways to address these while identifying potential roles for North American pathology organizations. DESIGN: The author's past and ongoing association with pathology practice in Nigeria forms the basis for this review. RESULTS: Pathology practice is largely restricted to academic medical centers. The largest of academic centers each accession around 4000 or fewer surgical specimens per year to train 9 to 12 residents. Histopathology largely uses hematoxylin-eosin routine stains, sometimes with histochemistry but rarely immunohistochemistry. Pathologists depend largely on their skills in morphology (with its limitations) to classify and subclassify tumors on routine stains, including soft tissue and hematolymphoid malignancies. Immunofluorescence, intraoperative frozen section diagnosis, electronic laboratory system, and gross and microscopic imaging facilities are generally not available for clinical use. CONCLUSION: The existing facilities and infrastructure can be augmented with provision of material and professional assistance from other pathology associations in more developed countries and should, among other things, focus on supplementing residency education. Virtual residency programs, short-visit observerships, development of simple but practical laboratory information systems, and closer ties with pathologists in these countries are some of the suggested steps in achieving this goal.

Vascular and glomerular manifestations of viral hepatitis B and C: a review.

Secondary vasculopathies have varied etiologies that include paraneoplastic processes (eg, migratory thrombophlebitis, urticarial vasculitis); direct invasion by tumors (eg, superior and inferior vena cava syndrome); metabolic diseases (eg, diabetes mellitus); and infections, among others. The infective causes of vasculitides could result from direct involvement of vessels by a vasculo-tropic agent (eg, mucor infection); adjacent inflammation nonspecifically affecting nearby vessels; or from infection-induced immune-mediated vasculitis. Viruses represent a major group in the development of the latter, and many human viruses have been reported to cause vasculitis. The vasculitic lesions secondary to hepatitis B and hepatitis C viruses largely fall within the spectrum of immune-mediated secondary vascular injury and are discussed in this review.

Posttransplant adenoviral enteropathy in patients with small bowel transplantation.

Transplant patients on immunosuppression represent a risk group for opportunistic infections, including adenoviral infections. The clinical and histopathologic findings of posttransplant adenoviral enteropathy in 3 adult intestinal transplant patients are described. The histopathologic pitfalls for the differential diagnosis between intestinal adenoviral enteropathy and acute rejection are discussed. Adenoviral enteropathy is an opportunistic infection that may follow aggressive treatment for small bowel allograft rejection, but which may require no specific treatment. It is associated with mild mixed inflammation in the lamina propria and slight increase of crypt apoptosis, resembling low-grade acute rejection. The identification of characteristic viral inclusions in the surface or crypt epithelium points to the diagnosis of adenoviral enteropathy, in spite of the increased crypt apoptosis.

Real-time polymerase chain reaction and laser capture microdissection for the diagnosis of BK virus infection in renal allografts.

We used real-time polymerase chain reaction (PCR) technology to detect BK virus (BKV) in H and E-stained kidney biopsy sections, using laser capture microdissection. Renal allograft biopsy specimens from 4 patients with the histopathologic diagnosis of BKV-associated nephropathy (BKVAN; group 1) and 3 patients suspected to have BKVAN but without diagnostic histologic features (group 2) were retrieved. Diagnostic inclusion-bearing cells were microdissected by laser capture microscopy from group 1. Renal tubular epithelial cells were microdissected randomly in group 2. DNA was extracted and real-time amplification performed using primers targeting the large "T" and small "t" regions of the BKV and JC virus genomes. Tubular epithelial cells from a case without evidence of BKV infection were used as negative controls in a similar reaction. BKV presence was demonstrated only in epithelial cells containing typical viral inclusions. Group 2 and negative control samples were confirmed as negative for BKVAN. Real-time PCR technology can be used to detect BKV in H and E-stained, paraffin-embedded tissue sections. This technique detected BKV in tubular epithelial cells of renal allografts. To our knowledge, this is the first report of detecting BKV in laser capture microdissected renal biopsy specimens using real-time PCR.

CD154 on the surface of CD4+CD25+ regulatory T cells contributes to skin transplant tolerance.

BACKGROUND: It is known that the infusion of whole blood from donors (donor-specific transfusion) into recipients combined with anti-CD154 therapy can prolong allograft survival. It has generally been agreed that the effectiveness of anti-CD154 therapy is caused by the inactivation of alloreactive CD4+ and CD8+ effector T cells. The recent literature has implicated CD4+CD25+ regulatory T cells in the suppression of autoimmunity and graft rejection, and we therefore examined whether CD154 blockade is effective because of its blockade of inflammatory T-cell activation or because of a direct impact on the regulatory T cells. METHODS: RAG(-/-) mice were adoptively transfused with CD4+ T cells or a subset of the population (CD4+CD25+ or CD4+CD25- T cells) alone or in combination with donor-specific transfusion and anti-CD154 and given an allo-skin transplant. The longevity of the transplant was determined over time. CD154(-/-)CD4+ T cells were used to assess the importance of CD154 in graft rejection and acceptance. RESULTS: CD154 blockade (or loss of CD154) on CD4+CD25+ regulatory T cells enhanced their immunosuppressive activities and was a contributing factor to anti-CD154-induced immune suppression in vivo. In a model of allograft tolerance, suppression was elicited by antigen and anti-CD154 or antigen alone if the CD4+CD25+ regulatory T cells were deficient in CD154 expression. CONCLUSIONS: Neutralizing the function of CD154 on regulatory T cells upon antigen exposure induces heightened levels of suppressive activities and is likely a contributing factor to the long-lived therapeutic effects of anti-CD154 treatment.

Distinct mechanisms of action of anti-CD154 in early versus late treatment of murine lupus nephritis.

OBJECTIVE: Treatment with anti-CD154 antibody is known to ameliorate murine lupus nephritis when given early in the disease. The aims of this study were to identify the mechanism of this early effect, to determine whether late anti-CD154 treatment could halt established nephritis, and, if so, to examine potential mechanisms of late efficacy. METHODS: We studied the effects of anti-CD154 treatment on autoantibody production and immune complex deposition, renal pathology, survival, and renal cytokine and chemokine messenger RNA (mRNA) expression both in (NZB x NZW)F(1) mice (BW mice) and in NZM.2410 mice. RESULTS: Early treatment with anti-CD154 produced long-term survival in BW mice, with abrogation of renal immune complex deposition for months after treatment was stopped. Late anti-CD154 treatment, started after development of nephritis, could halt disease in approximately 40% of mice. In some mice, proteinuria could be reversed repeatedly with sequential courses of anti-CD154 antibody. The remissions induced by late treatment with anti-CD154 occurred despite ongoing renal immune complex deposition. In preliminary studies, responding mice had rapid reductions in renal mRNA for transforming growth factor beta, interleukin-10, and tumor necrosis factor alpha. CONCLUSION: Amelioration of murine lupus by anti-CD154 therapy is mediated by distinct mechanisms in early versus late intervention. We postulate that anti-CD154 therapy prevents autoantibody production and renal immune complex deposition in the early, induction phase and limits secondary tissue damage in situ in the late, effector phase. These data demonstrate that CD40-CD154 interactions are critical for the maintenance of autoimmunity and suggest a potential role for anti-CD154 as a therapeutic agent in established human lupus.