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The expression of Bruton tyrosine kinase (BTK) in B cells and innate immune cells provides essential downstream signaling for BCR, Fc receptors, and other innate immune cell pathways. The topical covalent BTK inhibitor PRN473 has shown durable, reversible BTK occupancy with rapid on-rate and slow off-rate binding kinetics and long residence time, resulting in prolonged, localized efficacy with low systemic exposure in vivo. Mechanisms of PRN473 include inhibition of IgE (FcεR)–mediated activation of mast cells and basophils, IgG (FcγR)–mediated activation of monocytes, and neutrophil migration. In vivo, oral PRN473 was efficacious and well tolerated in the treatment of canine pemphigus foliaceus. In this study, we evaluated in vitro selectivity and functionality, in vivo skin Ab inflammatory responses, and systemic pharmacology with topically administered PRN473. Significant dose-dependent inhibition of IgG-mediated passive Arthus reaction in rats was observed with topical PRN473 and was maintained when given 16 h prior to challenge, reinforcing extended activity with once-daily administration. Similarly, topical PRN473 resulted in significant dose-dependent inhibition of the mouse passive cutaneous anaphylaxis IgE-mediated reaction. Multiday treatment with topical PRN473 in rodents resulted in low-to-no systemic accumulation, suggesting that efficacy was mainly due to localized exposure. Reduced skin Ab inflammatory activity was also confirmed with oral PRN473. These preclinical studies provide a strong biologic basis for targeting innate immune cell responses locally in the skin, with rapid onset of action following once-daily topical PRN473 administration and minimal systemic exposure. Dose-dependent inhibition in these preclinical models of immune-mediated skin diseases support future clinical studies.

Zizyphus mauritiana Lam. seeds (ZMS) have been used medicinally as sedative or hypnotic drugs in most of Asian countries. ZMS has significant benefits to the human health. Therefore, we have evaluated immunomodulatory effect of lectin extracted from these ZMSL in both in vitro and in vivo study. Anaphylaxis is a severe life-threatening allergic reaction and Arthus reaction is deposition of immune complex and complement system activation, so we hypothesized that if ZMSL can protect these severe allergic diseases. We have studied the effect of ZMSL on macrophages and Wistar albino rats and confirmed its protective effect against anaphylaxis and Arthus reaction. Results of this study suggest ZMSL have immunostimulatory and antiallergic activity.

Although neutrophils play important roles in immunity and inflammation, their analysis is strongly hindered by their short-lived and terminally differentiated nature. Prior studies reported conditional immortalization of myeloid progenitors using retroviral expression of an estrogen-dependent fusion protein of the HoxB8 transcription factor. This approach allowed the long-term culture of mouse myeloid progenitors (HoxB8 progenitors) in estrogen-containing media, followed by differentiation toward neutrophils upon estrogen withdrawal. Although several reports confirmed the in vitro functional responsiveness of the resulting differentiated cells (HoxB8 neutrophils), little is known about their capacity to perform in vivo neutrophil functions. We have addressed this issue by an in vivo transplantation approach. In vitro–generated HoxB8 neutrophils showed a neutrophil-like phenotype and were able to perform conventional neutrophil functions, like respiratory burst, chemotaxis, and phagocytosis. The i.v. injection of HoxB8 progenitors into lethally irradiated recipients resulted in the appearance of circulating donor-derived HoxB8 neutrophils. In vivo–differentiated HoxB8 neutrophils were able to migrate to the inflamed peritoneum and to phagocytose heat-killed Candida particles. The reverse passive Arthus reaction could be induced in HoxB8 chimeras but not in irradiated, nontransplanted control animals. Repeated injection of HoxB8 progenitors also allowed us to maintain stable circulating HoxB8 neutrophil counts for several days. Injection of arthritogenic K/B×N serum triggered robust arthritis in HoxB8 chimeras, but not in irradiated, nontransplanted control mice. Taken together, our results indicate that HoxB8 progenitor–derived neutrophils are capable of performing various in vivo neutrophil functions, providing a framework for using the HoxB8 system for the in vivo analysis of neutrophil function.

The formation and deposition of immune complexes (IC) containing immunoglobulin (Ig)G antibodies induces an acute inflammatory response with tissue injury. One of the experimental models of IC-related vasculitis is the cutaneous reverse passive Arthus reaction, in which IgG antibodies are injected i.d., followed immediately by the i.v. application of the corresponding antigen. This reaction is characterized by edema, hemorrhage and neutrophil infiltration. To assess the role of the anti-inflammatory cytokine interleukin (IL)-10 in IC-related vasculitis, we investigated the cutaneous Arthus reaction using IL-10 knockout (IL-10KO) mice. Edema, which was quantified macroscopically by measuring the vascular leakage of Evans blue dye at 4 h after IC challenge, was significantly increased in IL-10KO mice compared with wild-type mice. In addition, hemorrhage, which was assessed by the average diameter of purpuric spots at 8 h after IC challenge, was enhanced significantly in IL-10KO mice compared with wild-type mice. Histological examination showed that the number of extravascular neutrophils was significantly increased in IL-10KO mice compared with wild-type mice at 4 and 8 h after IC challenge. Analysis of pro-inflammatory cytokine mRNA expression showed that IL-6 mRNA levels were significantly increased in IL-10KO mice compared with wild-type mice at 4 and 8 h after IC challenge. These results showed that IC-induced inflammation and vascular damage were significantly enhanced in the absence of IL-10. Thus, IL-10 may limit tissue disruption by suppressing the excessive infiltration of neutrophils and cytokine expression in a mouse model of type III vasculitis.

This Pillars of Immunology article is a commentary on “Fc receptors initiate the Arthus reaction: redefining the inflammatory cascade,” a pivotal article written by D. L. Sylvestre and J. V. Ravetch, and published in Science, in 1994. https://www.science.org/doi/10.1126/science.8066448.

The Arthus reaction is a rare adverse reaction that usually occurs after vaccination with large and more severe local reactions, belonging to type Ⅲ hypersensitivity reaction. This reaction is characterized by pain, swelling, induration (Tissue that becomes firm) and edema, even accompanied by severe necrosis or ulceration at the injection sites. However, most of mild cases generally can be cured without treatment, and only severe cases need to be treated with anti-allergy. Therefore, this adverse reaction is often ignored by people. We searched PubMed, Web of Science and Chinese database (CNKI database and Wan Fang database) for published studies using the terms “Arthus reaction” or “Arthus phenomenon”, combined with “vaccine”, with no date or language restrictions for all publications before January 28, 2019. Only 30 cases of Arthus reaction were found, of which only one case died.4 cases of Arthus reaction post-dose-1 were reported in the review. The proportion of Arthus reaction occurred after the first, second and third injections in those case reports was 13.3%, 50.0%, and 23.3%, respectively. Arthus reaction was determined according to the clinical symptoms (The symptoms which were observed by the researchers, such as red, swelling and painful with itching at or around the injection sites). The specific causes of Arthus reaction after one dose of vaccination are not described in detail in literatures. Therefore, it could be hypothesized that the case has a pre-existing specific IgG (Such as pre-existing antibody, etc.) to cause the Arthus reaction. And 17 reported cases were observed in children younger than 6 y. In addition, we collected only 18 cases of bacterial vaccine-induced Arthus reaction and 12 cases of viral vaccines. However, there are no other data (Such as the total number and incidence rate of vaccination) in literatures, so we cannot compare statistically significant differences. At presents, no previous reviews of vaccine-induced Arthus reaction have been found. Thus, a systematic review about vaccine-associated Arthus reaction is urgently needed to deepen people‘s understanding and concern of this phenomenon. In this manuscript, we retrospectively reviewed the description of the discovery process and mechanisms of Arthus reaction, a description of the characteristics of Arthus reaction cases, reporting the Arthus reaction cases in China during 2010–2015, diagnostic criteria and general treatment, preventive measures of Arthus reaction, and challenges remaining to be investigated in the future.

Objective Immune complex (IC) deposition activates polymorphonuclear neutrophils (PMNs), increases vascular permeability, and leads to organ damage in systemic lupus erythematosus and rheumatoid arthritis. The bioactive lipid sphingosine 1-phosphate (S1P), acting via S1P receptor 1 (S1P1 ), is a key regulator of endothelial cell (EC) barrier function. This study was undertaken to investigate whether augmenting EC integrity via S1P1 signaling attenuates inflammatory injury mediated by ICs. Methods In vitro barrier function was assessed in human umbilical vein endothelial cells (HUVECs) by electrical cell-substrate impedance sensing. Phosphorylation of myosin light chain 2 (p-MLC-2) and VE-cadherin staining in HUVECs were assessed by immunofluorescence. A reverse Arthus reaction (RAR) was induced in the skin and lungs of mice with S1P1 deleted from ECs (S1P1 EC-knockout [ECKO] mice) and mice treated with S1P1 agonists and antagonists. Results S1P1 agonists prevented loss of barrier function in HUVECs treated with IC-activated PMNs. S1P1 ECKO and wild-type (WT) mice treated with S1P1 antagonists had amplified RAR, whereas specific S1P1 agonists attenuated skin and lung RAR in WT mice. ApoM-Fc, a novel S1P chaperone, mitigated EC cell barrier dysfunction induced by activated PMNs in vitro and attenuated lung RAR. Expression levels of p-MLC-2 and disruption of VE-cadherin, each representing manifestations of cell contraction and destabilization of adherens junctions, respectively, that were induced by activated PMNs, were markedly reduced by treatment with S1P1 agonists and ApoM-Fc. Conclusion Our findings indicate that S1P1 signaling in ECs modulates vascular responses to IC deposition. S1P1 agonists and ApoM-Fc enhance the EC barrier, limit leukocyte escape from capillaries, and provide protection against inflammatory injury. The S1P/S1P1 axis is a newly identified target to attenuate tissue responses to IC deposition and mitigate end-organ damage.

Platelets regulate inflammation as well as hemostasis. Inflammatory insults often induce hemostatic function through mechanisms that are not always understood. The triggering receptor expressed in myeloid cells (TREM)-like transcript 1 (TLT-1) is an abundantly expressed platelet receptor and its deletion leads to hemorrhage and edema after lipopolysaccharide and TNF-α treatment. To define a role for TLT-1 in immune derived bleeding we used a CXCL-2 mediated local inflammatory reaction in the vessels of the cremaster muscle of treml1 -/- and wild type mice. Our whole mount immunofluorescent staining of the cremaster muscle demonstrated a 50% reduction in clot size and increased extravasation of plasma molecules in treml1 -/- mice compared to wild type. We demonstrate that the decreased clotting in treml1 -/- mice is associated with a 2X reduction in integrin β3 phosphorylation on residue Y773 after platelet activation, which is consistent with treml1 -/- mice displaying reduced outside-in signaling and smaller thrombi. We further substantiate TLT-1's role in the regulation of immune derived bleeding using the reverse arthus reaction and demonstrate TLT-1's role in thrombosis using the thromboplastin initiated and collagen/epinephrine models of pulmonary embolism. Thus, the data presented here demonstrate that TLT-1 regulates early clot formation though the stabilization of αIIbβ3 outside-in signaling.

Chikungunya virus (CHIKV) was first isolated in humans in 1952, following an epidemic in Tanzania. The origin of the name means "to bend forward or become contorted," in reference to the posture adopted by patients due to the joint pain that occurs during the infection. Epidemiology data suggest that by the end of 2015, about 1.6 million people had been infected with CHIKV. The acute period of the disease is characterized by high fever, myalgia, joint pain, and severe and disabling polyarthritis, sometimes accompanied by headache, backache, and maculopapular rash, predominantly on the thorax. Around half of the patients will progress to the subacute and chronic phases, that is manifested by persistent polyarthritis/polyarthralgia, accompanied by morning stiffness and fatigue, which could remain for years. Oral features may include gingivitis possibly as a consequence of arthralgia of the hands leading to limited oral health measures as well as burning sensation and oral mucosal ulceration. Treatment in the acute phase includes acetaminophen, and weak opioids (tramadol or codeine) should be used in cases of severe or refractory pain. For patients who have progressed to the subacute stage and who have not had notable benefit from common analgesics or opioids, NSAIDs, or adjunctive pain medications (anticonvulsants or antidepressants) may be of benefit. In patients with moderate-to-severe musculoskeletal pain or in those who cannot be given or tolerate NSIADs or opiates, prednisolone should be prescribed.

Store-operated calcium entry (SOCE) is the most common mode of calcium influx in non-excitable cells, including immune cells. The two STIM isoforms mediate SOCE as well as Fc receptor (FcR)-downstream activation of macrophages and mast cells-which appears to be relevant in vivo, in models of antibody-dependent tissue injury and allergy. Hence, the pathway of SOCE may be a therapeutic target for treatment of immune complex (IC)-mediated autoimmunity and allergic asthma. The pyrazole derivative, BTP2 is an efficient inhibitor of SOCE, which has already been shown to attenuate allergic inflammation. However, its effect on Fc gamma receptor (FcγR) signaling and IC-induced tissue injury had not yet been studied. Here, we show that BTP2 is a potent inhibitor of SOCE in primary macrophages, blocking FcγR-mediated responses. To investigate the effect of inhibition of SOCE in IC-mediated tissue injury, we induced reverse passive Arthus reaction to IgG immune complexes in the skin and lungs of BTP2- or control-treated mice. Treatment with BTP2 resulted in markedly attenuated inflammation in both the skin and the lungs. Our findings indicate the involvement of SOCE in FcγR-mediated responses in vitro and in vivo and suggest that BTP2-mediated inhibition of SOCE may have a therapeutic potential on IC-mediated autoimmunity.

The present study reports the evaluation of immunomodulatory and therapeutic potential of a purified Aspergillus panamensis lectin. The immunomodulatory potential of the purified lectin was determined in swiss albino mice by studying its effect on anaphylaxis reaction, arthus reaction, respiratory burst activity, nitric oxide production and quantification of cytokine levels. The therapeutic potential of the lectin was evaluated in male wistar rat models by studying its curative effect on ulcerative colitis. The purified lectin inhibited systemic anaphylaxis and arthus reaction. It enhanced the functional ability of macrophages which was evident from increase in reduction of nitroblue tetrazolium dye and nitric oxide production. It also stimulated the production of Th-1 cytokine IFN-γ and Th-2 cytokine IL-6. Maximum immunomodulatory effect was seen at lectin concentration of 1.5 mg/kg body weight. The lectin also showed curative effect against trinitrobenzene sulphonic acid induced ulcerative colitis. The results of this study adequately reflect the role of purified A. panamensis lectin in improving the immune status of mice models. They also show the effect of lectin in reducing the severity of incidence and decrease in clinical symptoms of ulcerative colitis.

Two 31-year-old women who had abused ketamine, 1 for 8 years and 1 for 5 years, presented with ketamine-induced vesicopathy with urinary frequency, decreased bladder capacity, and detrusor overactivity. An enterocystoplasty was performed in both cases. The pathology of the urinary bladders in both women showed ulcerative cystitis and fibrinoid necrosis of vessels; the latter was confirmed by Masson trichrome staining. Fibrinoid necrosis of vessels is a kind of immune complex-mediated vasculitis that induces the release of inflammatory mediators, with subsequent thrombosis, ischemic injury, and eventual tissue necrosis in localized areas, the so-called Arthus reaction. The new finding of fibrinoid necrosis in the urinary bladders of ketamine abusers may provide a new clue to the pathogenesis of ketamine-induced vesicopathy.

Background:IgG4-related disease (IgG4-RD) is an immune-mediated disorder causing fibro-inflammatory lesions. Although the cause remains unknown, it may be driven by interactions between B lymphocytes and CD4+ cytotoxic and regulatory T cells and is characterized by an increase in short-lived plasmablasts, circulating antibodies, and macrophages. Standard therapy mainly includes glucocorticoids (GC), limited by toxicity with long-term use (> 6 mo), and to a lesser extent, immunosuppressives (eg, rituximab). Bruton tyrosine kinase (BTK) plays an important role in the activation of multiple immune effector cells such as B cells, mast cells, eosinophils, basophils, monocytes/macrophages, and neutrophils. Dysregulation of the activation of these immune cells results in autoimmune inflammation, tissue damage, and development of fibrosis. Rilzabrutinib is a highly selective oral BTK inhibitor that targets multiple pathways of innate and adaptive immunity (with direct effects on B-cell and FcR pathways) and has the potential to inhibit antigen presentation to autoreactive T cells.Objectives:To provide the biological rationale for rilzabrutinib in IgG4-RD.Methods:Rilzabrutinib has been evaluated in biochemical, in vitro studies, and in vivo models of inflammatory diseases. Additional support is provided by the phase 2 trial for oral rilzabrutinib in patients with pemphigus vulgaris and the phase 2 trial for oral rilzabrutinib in patients with immune thrombocytopenia (ITP).Results:Rilzabrutinib inhibited the activity of BTK and B-cell receptor in B cells (IC50 5-123 nM) and Fc gamma receptor in IgG/Fc gamma receptor-stimulated monocytes (IC50 56 nM) and blocked IgG- and IgM-mediated antibody production in enriched B cells when stimulated in T-cell dependent (anti-CD40+IL-21) and T-cell independent (TLR-9/CpG and TNP-LPS) pathways. The impact of rilzabrutinib on innate cell pathways was further confirmed by significant dose-dependent inhibition of macrophage and neutrophil-driven passive rat Arthus reaction (P < 0.01 vs vehicle) and antibody-induced murine ITP (P < 0.05 vs vehicle). In a 12-week phase 2 pemphigus vulgaris trial, 54% of patients achieved the primary endpoint, control of disease activity (CDA) on low-dose corticosteroids by week 4, and 73% achieved it by week 12. In the phase 2 trial of ITP patients (median 6 prior therapies), rilzabrutinib 400 mg bid showed rapid and sustained improvement in platelet counts and only grade 1/2-related adverse events1. In responders, platelet counts increased as early as day 8, potentially due to innate immune mechanisms. Collectively, results in both B and innate immune cells provide an initial basis for evaluating rilzabrutinib in IgG4-RD. The ongoing phase 2a study (NCT04520451) is investigating rilzabrutinib 400 mg bid (+tapered GC) vs GC control (3:1) for 12 weeks in IgG4-RD patients refractory to rituximab. The primary objective is to evaluate the safety and ability of rilzabrutinib to induce GC-free remission at week 12. Coupled with known preclinical/clinical findings, mechanistic analyses in this ongoing IgG4-RD study will profile B and other immune cell effects pre-/post-rilzabrutinib dosing to enhance the clinical understanding of rilzabrutinib in IgG4-RD.Conclusion:Studies of rilzabrutinib that show beneficial effects on both B-cell and innate cell pathways provide support for its therapeutic role in immune-mediated diseases and for targeting the underlying pathophysiological effects of IgG4-RD. Effective and safe therapies that rapidly induce and maintain clinical responses, while minimizing the need for continuous GC treatment, remain an unmet need for patients with IgG4-RD.References:[1]Kuter et al. Res Pract Thromb Haemost. 2020;4(suppl 1): PB1318.Disclosure of Interests:Li Long Employee of: Principia Biopharma, a Sanofi Company, Matthew Baker: None declared, Mollie Carruthers: None declared, Alireza Meysami: None declared, Robert Spiera Consultant of: research funding and personal fees for consulting from Chemocentryx, Formation Biologics, Roche-Genentech, and Sanofi, Grant/research support from: research funding fees from BMS, Boehringer Ingelheim, Corbus, GSK, and Inflarx; personal fees from AbbVie, CSL Behring, GSK, and Janssen, Mamatha Reddy Employee of: Principia Biopharma, a Sanofi Company, Marianne Kavanagh Employee of: Principia Biopharma, a Sanofi Company, Michelle Francesco Employee of: Principia Biopharma, a Sanofi Company, Claire Langrish Employee of: Principia Biopharma, a Sanofi Company, Ann Neale Employee of: Principia Biopharma, a Sanofi Company, Puneet Arora Employee of: Principia Biopharma, a Sanofi Company, John H. Stone Consultant of: research funding and personal fees for consulting from Principia and Sanofi

Background: Beta-sitosterol (BS) is a compound discovered to be present in numerous plants. A number of interesting biomedical properties have been attributed to BS, including immuno-modulating and anti-inflammatory activities. Therefore, the aim of this report was to evaluate its anti-inflammatory capacity by applying various rodent experimental tests.Methods. To carry out the objective of the study we applied the methods indicated here. Two of the adopted methods were based on the passive reverse Arthus reaction: the rat paw edema test and the rat pleurisy assay. We also applied two methods related with the non-specific acute inflammation: the mouse ear edema test, and the mouse mieloperoxidase activity assay.Results. The results obtained in all tests established a significant anti-inflammatory potential of BS. In the rat paw edema test we found an inhibitory effect which goes from 50-70%; in the rat pleurisy assay our findings with respect to the volume of pleural exuded showed a reduction of 46%, as well as a 20% low amount of neutrophils in comparison with the level of the control group. In the mouse ear edema test we found a mean inflammatory inhibition of 75%, and with respect to mieloproxidase activity the results showed a significant inhibition induced by the three doses of BS.Conclusions. In the present study we determined a potent anti-inflammatory capacity of BS in specific and nonspecific types of acute inflammation in rodents.Keywords: Beta-sitosterol, anti-inflammatory assays, mouse, rat

Deposition of immune complexes (ICs) in tissues triggers acute inflammatory pathology characterized by massive neutrophil influx leading to edema and hemorrhage, and is especially associated with vasculitis of the skin, but the mechanisms that regulate this type III hypersensitivity process remain poorly understood. Here, using a combination of multiphoton intravital microscopy and genomic approaches, we re-examined the cutaneous reverse passive Arthus reaction and observed that IC-activated neutrophils underwent transmigration, triggered further IC formation, and transported these ICs into the interstitium, whereas neutrophil depletion drastically reduced IC formation and ameliorated vascular leakage in vivo. Thereafter, we show that these neutrophils expressed high levels of CXCL2, which further amplified neutrophil recruitment and activation in an autocrine and/or paracrine manner. Notably, CXCL1 expression was restricted to tissue-resident cell types, but IC-activated neutrophils may also indirectly, via soluble factors, modulate macrophage CXCL1 expression. Consistent with their distinct cellular origins and localization, only neutralization of CXCL2 but not CXCL1 in the interstitium effectively reduced neutrophil recruitment. In summary, our study establishes that neutrophils are able to self-regulate their own recruitment and responses during IC-mediated inflammation through a CXCL2-driven feed forward loop.

Kohli N and Chauhan RS (2020). Type III Hypersensitivity-Related Disorders in Animals. Journal of Immunology Immunopathology, 22(1): 48-55.

Background Local type III hypersensitivity reactions are acute inflammatory events induced by immune complex (IC) deposition. CD22 and CD72 are B cell-specific cell surface molecules that negatively regulate B cell function. Objective To elucidate the roles of CD22 and CD72 in the development of IgG-mediated type III hypersensitivity reactions. Method The reverse Arthus reaction model in the skin was induced in mice lacking CD22 (CD22 -/- ), CD72 (CD72 -/- ), and both of them (CD22 -/- /CD72 -/- ). Edema at 4 hours and hemorrhage at 8 hours after IC challenge were evaluated. Inflammatory cell infiltration and cytokine and chemokine expression were also examined. Results Edema and hemorrhage were significantly reduced in CD22 -/- /CD72 -/- mice compared with wild-type mice. The loss of both membrane proteins resulted in a greater decrease in edema at 4 hours, but not hemorrhage at 8 hours, than the loss of each protein alone. Infiltration of neutrophils, macrophages, and T cells, and the expression of TNF-α, IL-6, MIP-1α, and CCR5 mRNA were also diminished in the knockout mice compared to wild-type mice, and most significantly reduced in CD22 -/- /CD72 -/- mice. Regulatory T (Treg) cells in the spleen were significantly increased in all knockout mice at 4 hours. Significant differences in the severity of edema and hemorrhage between wild-type and knockout mice were lost when Treg cells were depleted in the knockout mice. Conclusion These results demonstrate that CD22 and CD72 expression contribute to the development of the reverse Arthus reaction model and CD22 and CD72 might be therapeutic targets for human IC-mediated diseases.

Autoimmune diseases are caused by immune complex-induced activation of the complement system and subsequent inflammation. Recent studies have revealed an association between autoimmune diseases and worse survival in patients with cancer; however, the underlying mechanism is still unknown. The C5a-C5a receptor (C5aR) system has been shown to enhance cancer activity and recruit myeloid-derived suppressor cells (MDSCs) that suppress the anti-tumor immune response. The Arthus reaction is inflammation caused by complement system activation by the immune complex and thus is a model of autoimmune diseases. To explore the effect of the Arthus reaction on cancer progression, mouse cancer cells were inoculated in syngeneic mouse skin, where the Arthus reaction was induced simultaneously. The Arthus reaction enhanced invasion and tumor growth of C5aR-positive cancer cells, but not control cells, and induced MDSC recruitment. Intravenous injection of C5a-stimulated C5aR-positive cancer cells into nude mice resulted in more lung nodules than injection of nontreated C5aR-positive cells and C5a-stimulated C5aR-negative cells, supporting C5a-C5aR-mediated enhancement of cancer growth. C5aR expression in uterine cervical carcinoma stage I cells, which invade into the deeper tissues, was significantly higher than that in CIN3 cells, which remain in the epithelium. These results indicate that cancer promotion by the C5a-C5aR system may underlie poor prognosis in cancer patients with autoimmune diseases, particularly in patients with C5aR-positive cancer, and may be associated with cervical cancer invasion. The enhancement of cancer cell invasion and growth by the C5a-C5aR system suggests that this system is a possible target of cancer therapy.

Vaccines are important for providing protection from infectious diseases. Vaccination initiates a process that stimulates development of a robust and long-lived immune response to the disease agents in the vaccine. Side effects are sometimes associated with vaccination. These vary from development of acute hypersensitivity responses to vaccine components to local tissue reactions that are annoying but not significantly detrimental to the patient. The pathogenesis of these responses and the consequent clinical outcomes are discussed. Overstimulation of the immune response and the potential relationship to autoimmunity is evaluated in relation to genetic predisposition.

An allergy may sometimes be very dangerous and one of the main factors responsible for allergy is the complement system which can lead to a life-threatening reaction called anaphylaxis. Cycloxygenase-1 (COX-1), Cycloxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) trigger allergic and inflammatory reactions. A number of anti-allergic synthetic drugs are available but are costly and show many side effects. Hence, the ancient traditional system of medication mentioned in Ayurveda finds an edge over various synthetic drugs. Zizyphus mauritiana is referred to as the store house of phytochemicals in Ayurveda. The stem and root barks of Zizyphus mauritiana were dried and powdered under controlled conditions. Extractions of the dried powders were performed separately in different solvents in increasing order of their polarity and were tested for their ability to inhibit the complement system. The aqueous extract of the root bark was found to be more effective in inhibiting the complement system. Fractionation of the aqueous extract resulted in the isolation of the Most Active Fraction (MAF) which inhibited the complement system, COX-1, COX-2, and 5-LOX with IC50 values of 0.006 μg ml(-1), 0.065 μg ml(-1), 0.008 μg ml(-1), and 0.083 μg ml(-1), respectively. The MAF was proven to be successful in down-regulating pro-inflammatory mediators like TNF-α, COX-2, and iNOS when tested on a RAW 264.7 cell line. In vivo, the MAF was found to be preventive against anaphylactic shock and the Arthus reaction, when orally administered daily to Wistar rats. Phytochemical analysis of the MAF has indicated that it is rich in tannins. Results indicate that the MAF, a fraction isolated from the aqueous extract of the root bark of Zizyphus mauritiana, has potent anti-allergic and anti-inflammatory properties.

Aryl hydrocarbon receptor (AhR), which was discovered as a receptor for environmental concomitants, plays an important role widely in the immune system. In this study, we assessed AhR involvement in immune-complex-mediated vascular injury by examining the reverse-passive Arthus reaction in AhR heterozygous knockout (AhR+/−) mice. In the cutaneous Arthus reaction, dermal edema was severer in AhR+/− mice than in wild-type mice. The number of infiltrating neutrophils and mRNA expression levels of CXC chemokine ligand 1 and IL-6 were also increased in AhR+/− mice. Similarly, in the peritoneal Arthus reaction, infiltration of neutrophils was increased in AhR+/− mice. Peritoneal macrophages from AhR+/− mice expressed higher levels of Fcγ receptor III and produced higher levels of CXC chemokine ligand 1 and IL-6 after immune complex treatment. In addition, AhR occupied the promoter regions of Fcγ receptor III gene in peritoneal macrophages in a ligand-dependent manner. Depletion of macrophages reduced the cutaneous Arthus reaction in AhR+/− mice, and adoptive transfer of AhR+/− mice macrophages into wild-type mice exacerbated the peritoneal Arthus reaction. Furthermore, AhR expression was decreased and Fcγ receptor III expression was increased in CD14+ monocytes in peripheral blood from patients with immune-complex-mediated vasculitis compared with those from healthy controls. These results suggest that downregulation of AhR is associated with the exacerbation of immune-complex-mediated vascular injury.

Neutrophils are the most abundant leukocytes in the blood. In the recent decades, their crucial roles in host defense, immune regulation and tissue damage have been studied in a deeper dimension. In this protocol, we described a mouse model of immune complex-mediated vasculitis in the dorsal skin induced by Arthus reaction, and the subsequent analysis of edema, hemorrhage and tissue damage due to neutrophil activation by means of Evans blue area analysis, histology, and immunofluorescence. This protocol could facilitate the investigation of cellular therapy strategy against over-activated neutrophil-mediated tissue damage.

Immune complex (IC) deposition causes significant tissue injury associated with various autoimmune diseases such as vasculitis. In the cascade of inflammation, cell-to-cell and cell-to-matrix adhesion via adhesion molecules are essential. To assess the role of αE and β7 integrin in IC-mediated tissue injury, peritoneal and cutaneous reverse-passive Arthus reaction was examined in mice lacking αE integrin (αE−/−) or β7 integrin (β7−/−). Both αE−/− and β7−/− mice exhibited significantly attenuated neutrophil infiltration in the peritoneal and cutaneous Arthus reaction. β7 integrin deficiency, not αE integrin deficiency, significantly reduced the number of mast cells in the peritoneal cavity, which was consistent with the result that mast cells expressed only α4β7 integrin, not αEβ7 integrin. αE−/− mice instead revealed the reduction of CD8+ T cells in the peritoneal cavity, and nearly half of them in wild-type mice expressed αE integrin. These αE+CD8+ T cells produced more proinflammatory cytokines than αE−CD8+ T cells, and adoptive transfer of αE+CD8+ T cell into αE−/− recipients restored cutaneous and peritoneal Arthus reaction. These results suggest that in the peritoneal and cutaneous reverse-passive Arthus reaction, α4β7 integrin is involved in the migration of mast cells for initial IC recognition. αEβ7 integrin, in contrast, contributes by recruiting αE+CD8+ T cells, which produce more proinflammatory cytokines than αE−CD8+ T cells and amplify IC-mediated inflammation.

We aimed to study the inhibitory effects of topical cyclosporine A (CsA) 0.05 % on immune-mediated corneal neovascularization, and to compare its efficacy with those of dexamethasone 0.1 % and bevacizumab 0.5 %. Immune-mediated corneal neovascularization was created in 36 right eyes of 36 rabbits. The rabbits were then randomized into four groups. Group I received CsA 0.05 %, Group II received dexamethasone 0.1 %, Group III received bevacizumab 0.5 %, and Group IV received isotonic saline twice a day for 14 days. The corneal surface covered with neovascular vessels was measured on the photographs. The rabbits were then sacrificed and the corneas excised. Paraffin-embedded sections were stained with hematoxylin-eosin and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. The means of percent area of corneal neovascularization in Group I, II, III, and IV were 24.4 %, 5.9 %, 37.1 %, and 44.1 %, respectively. The inhibitory effect of CsA 0.05 % was found to be better than the effect found in the bevacizumab 0.5 % and control groups (p = 0.03 and p = 0.02, respectively). CsA 0.05 % was found to have significantly lesser inhibitory effects on corneal neovascularization than dexamethasone 0.1 % (p

A type III hypersensitivity reaction induced by an immune complex, such as leukocytoclastic vasculitis, is mediated by inflammatory cell infiltration that is highly regulated by multiple adhesion molecules. CX3CL1, a ligand for CX3C chemokine receptor 1 (CX3CR1), has recently been identified as a key mediator of leukocyte adhesion that functions without the recruitment of integrins or selectin-mediated rolling. To elucidate the role of CX3CL1 and CX3CR1 in the development of leukocytoclastic vasculitis, the cutaneous and peritoneal reverse Arthus reactions, classic experimental models for immune complex-mediated tissue injury, were examined in mice lacking CX3CR1. CX3CL1 expression in sera and lesional skin of patients with polyarteritis nodosa (PN) and healthy controls was also examined. Edema and hemorrhage were significantly reduced in CX3CR1(-/-) mice compared with wild-type mice. Infiltration of neutrophils and mast cells and expression of IL-6 and tumor necrosis factor-α were also decreased in CX3CR1(-/-) mice. CX3CL1 was expressed in endothelial cells during the cutaneous reverse Arthus reactions. Furthermore, serum CX3CL1 levels were significantly higher in patients with PN than in healthy controls. Endothelial cells in lesional skin of patients with PN strongly expressed CX3CL1. These results suggest that interactions between CX3CL1 and CX3CR1 may contribute to the development of leukocytoclastic vasculitis by regulating neutrophil and mast cell recruitment and cytokine expression.

H2S donor attenuates inflammatory responses through the L-selectin involved pathway, in the cutaneous reverse passive Arthus reaction. H2S has been highlighted recently as an endogenous, gaseous signaling molecule, especially in inflammations. The deposition of IC induces an acute inflammatory response with tissue injury. To assess the roles of H2S in the IC-induced diseases, the cutaneous, reverse passive Arthus reaction was conducted using NaHS as a H2S donor. Furthermore, we conducted similar experiments using selectin−/− mice to determine the involvement of selectin molecules in the H2S-mediated pathway. Exogenous application of NaHS dramatically attenuated inflammatory reactions in WT mice associated with Arthus reaction. Namely, mRNA expressions of TNF-α, IFN-γ, and neutrophil numbers were reduced significantly in the lesional skins of NaHS-treated WT mice relative to untreated ones. NaHS treatment significantly reduced these three parameters in the lesional skins of E- and P-selectin−/− mice but not in those of L-selectin−/− mice. Quite similar results were obtained in the blocking study using WT mice injected with mAb to E-, P-, and L-selectin. Our results indicated that the exogenous application of NaHS attenuates inflammatory responses in reverse passive Arthus reaction through a L-selectin-involved pathway but not through E- or P-selectin pathways.

Lectins are non-immune proteins or glycoproteins with the ability to induce cell agglutination and mediate cellular and molecular recognition processes in a variety of biological interactions. Recently, several mushroom lectins have been reported to show immunomodulatory activities. The immunomodulatory potential of purified A. gorakhpurensis lectin was determined by evaluating its effect on systemic anaphylaxis reaction, arthus reaction, respiratory burst activity, nitric oxide production and levels of cytokines IFN-γ and IL-6. Administration of different doses of purified lectin was found to stimulate immunological activity. Lectin prevented BSA induced Arthus reaction and systemic anaphylaxis. The enhanced functional ability of macrophages was evident from respiratory burst activity and nitric oxide production in splenocyte cultures. Interferon-γ and interleukin-6 levels were significantly up-regulated in lectin treated groups. Maximum modulatory effect was observed at the lectin dose of 3.0 mg/kg body weight. The results of the experiments conducted adequately reflect the immunostimulatory effect of purified A. gorakhpurensis lectin.

IgG antibodies are potent inducers of proinflammatory responses by cross-linking Fc receptors on innate immune effector cells resulting in tissue injury. The recently discovered enzymes endoglycosidase S (EndoS) and IgG-degrading enzyme (IdeS) of Streptococcus pyogenes are able to modulate the interaction between IgG antibodies and the Fc receptors, by hydrolysis of the glycan associated with the heavy chain of the IgG molecule (EndoS), or cleavage in the hinge region of the heavy IgG chain (IdeS). In this work, we investigated their ability to inhibit damage mediated by skin-bound antibodies in vivo in two different experimental models, the Arthus reaction, and epidermolysis bullosa acquisita, an autoimmune blistering skin disease associated with autoantibodies against type VII collagen. We demonstrate that both enzymes efficiently interfere with IgG-mediated proinflammatory processes, offering a great asset to specifically target pathological IgG antibodies in the skin and holding great promise for future applications in human therapy.

von Willebrand disease (VWD)-type 2B is characterized by gain-of-function mutations in the von Willebrand factor (VWF) A1-domain, leading to increased affinity for its platelet-receptor, glycoprotein Ibα. We engineered the first knock-in (KI) murine model for VWD-type 2B by introducing the p.V1316M mutation in murine VWF. Homozygous KI-mice replicated human VWD-type 2B with macrothrombocytopenia (platelet counts reduced by 55%, platelet volume increased by 44%), circulating platelet-aggregates and a severe bleeding tendency. Also, vessel occlusion was deficient in the FeCl3-induced thrombosis model. Platelet aggregation induced by thrombin or collagen was defective for KI-mice at all doses. KI-mice manifested a loss of high molecular weight multimers and increased multimer degradation. In a model of VWF-string formation, the number of platelets/string and string-lifetime were surprisingly enhanced in KI-mice, suggesting that proteolysis of VWF/p.V1316M is differentially regulated in the circulation versus the endothelial surface. Furthermore, we observed increased leukocyte recruitment during an inflammatory response induced by the reverse passive Arthus reaction. This points to an active role of VWF/p.V1316M in the exfiltration of leukocytes under inflammatory conditions. In conclusion, our genetically-engineered VWD-type 2B mice represent an original model to study the consequences of spontaneous VWF-platelet interactions and the physiopathology of this human disease.

Objective: Lectins are complex and heterogenous group of carbohydrate binding proteins, commonly found in all types of organisms with striking biological activities. Many anti-inflammatory synthetic medicines are available, but they show many side effects. In this context, anti-inflammatory compounds free from any adverse effects are the requirement of time. In the present study, the most active lectin isolated from seeds of Zizyphus oenoplia is tested for its anti-allergic and anti-inflammatory activities. Methods: The most active lectin was isolated from seeds of Zizyphus oenoplia. The procedure of isolation involved extraction of lectins from dried seeds in sodium phosphate buffered saline (0.02 M, pH 7) followed by precipitation with ammonium sulphate (20%-60%) and dialysis. Later, affinity chromatography and ion-exchange chromatography were performed for further purification. The purified fraction was estimated for homogeneity and molecular weight determination on 10% SDS-PAGE. The isolated most active lectin was named as ZOSL (Zizyphus oenoplia seed lectin) and was tested for its anti-allergic and anti-inflammatory activity in vivo through Arthus reaction and anaphylactic shock on Wistar albino rats. Results: ZOSL was found to be monomeric with molecular weight 25 kD. It was seen that regular oral administration of ZOSL to Wistar rats can prevent anaphylactic shock as well as Arthus reaction. Conclusion: A novel monomeric lectin (ZOSL), with anti-allergic and anti-inflammatory activity, was isolated from the seeds of Zizyphus oenoplia.

Neutrophil recruitment to the inflammatory sites is regulated by a variety of adhesion molecules including β2 integrins. The dependency of neutrophil recruitment on β2 integrins is variable in different tissues, but has not yet been verified in the cutaneous passive reverse Arthus reaction. We examined this question and also evaluated the impact of isoflurane on neutrophil recruitment to the skin because we previously showed in vitro that isoflurane binds and inhibits β2 integrins. The dependency on β2 integrins in neutrophil recruitment to the skin in the Arthus reaction was examined using αL, αM and β2 knockout mice. Then, we evaluated the effect of isoflurane on neutrophil recruitment to the skin. In addition, the effects of isoflurane on neutrophil binding to intercellular adhesion molecule-1 (ICAM-1), one of the β2 integrin ligands, were studied in vitro using cell adhesion assays. Neutrophil recruitment to the skin in the Arthus reaction model was totally dependent on β2 integrins, as β2 knockout mice completely abolished it. However, the defect of only one of the β2 integrins was not sufficient to abolish neutrophil recruitment. Isoflurane reduced neutrophil recruitment to the skin by approximately 90 %. Also, isoflurane inhibited neutrophil adhesion to β2 integrin ligand ICAM-1. We demonstrated that (1) neutrophil recruitment to the skin was totally dependent on β2 integrins, and (2) isoflurane significantly impaired neutrophil recruitment. Based on the previous studies on the contribution of other adhesion molecules in neutrophil recruitment, it is likely that isoflurane at least partially affects on β2 integrins in this model.

IC-mediated vasculitis (ICV) can be life threatening. The cellular and immune mechanisms controlling ICV are poorly understood. Therefore, we investigated the role of α-1-antitrypsin (α1AT) and IFN-γ in reducing the severity of ICV in a mouse model in vivo. To induce ICV, mice were challenged with the reverse passive Arthus reaction (RPA), the prototypic in vivo model for leukocytoclastic vasculitis (LcV), and the modulation of vascular permeability, edema formation, and leukocyte recruitment was studied. To further analyze the dynamics of RPA, we applied intravital microscopy in the dorsal skinfold chamber. α1AT continuously led to reduced leukocyte recruitment. α1AT interfered with neutrophil recruitment through a KC-dependent mechanism and reduced KC-elicited neutrophil activation. In contrast to α1AT, IFN-γ-reduced leukocyte recruitment during RPA was clearly independent of KC. We also revealed that the recruitment of neutrophils during RPA was a prerequisite for full KC expression. Thus, therapeutic administration of α1AT and IFN-γ might be beneficial for limiting the duration and severity of ICV.

Background The pathogenic role of IgE has been implicated in a variety of allergic and inflammatory diseases. We have previously established an IgE-mediated cutaneous reverse passive Arthus model in which eosinophil infiltration is a prominent feature. This uniquely provides a model of type III hypersensitivity in which Fc classes of Ig that forms immune complex differentially determine the disease manifestation. Objective To investigate the mechanisms of how mast cells and basophils regulate this IgE-mediated Arthus reaction. Methods IgE-mediated cutaneous reverse passive Arthus reaction was induced in wild-type C57BL/6 or WBB6F1-+/+ mice and mast-cell-deficient WBB6F1-W/W v mice by intradermal injection of IgE anti-trinitrophenyl antibodies followed immediately by intravenous administration of trinitrophenyl bovine serum albumin. Basophils were depleted in vivo using anti-CD200R3 monoclonal antibody prior to the IC challenge. Results Hemorrhage and infiltration of eosinophils, neutrophils, and basophils were significantly reduced but were not completely abrogated in WBB6F1-W/W v mice compared with those in wild-type WBB6F1-+/+ mice. Wild-type C57BL/6 mice treated by basophil-depleting mAb also showed significantly decreased hemorrhage and inflammatory cell infiltration, especially that of eosinophils, compared with control mice. Furthermore, basophil depletion in WBB6F1-W/W v mice led to nearly complete inhibition of eosinophil recruitment. By contrast, basophil depletion did not further decrease neutrophil infiltration in WBB6F1-W/W v mice. Conclusion While mast cells play a central role, basophils also have an important function, especially for eosinophil recruitment, in IgE-mediated cutaneous reverse passive Arthus reaction.

Therapeutic use and function of recombinant molecules can be studied by the expression of foreign genes in mice. In this study, we have expressed human Fcγ receptor-Ig fusion molecules (FcγR-Igs) in mice by administering FcγR-Ig plasmid DNAs hydrodynamically and compared their effectiveness with purified molecules in blocking immune-complex (IC)-mediated inflammation in mice. The concentration of hydrodynamically expressed FcγR-Igs (CD16A(F)-Ig, CD32A(R)-Ig and CD32A(H)-Ig) reached a maximum of 130 μg ml(-1) of blood within 24 h after plasmid DNA administration. The in vivo half-life of FcγR-Igs was found to be 9-16 days and western blot analysis showed that the FcγR-Igs were expressed as a homodimer. The hydrodynamically expressed FcγR-Igs blocked 50-80% of IC-mediated inflammation up to 3 days in a reverse passive Arthus reaction model. Comparative analysis with purified molecules showed that hydrodynamically expressed FcγR-Igs are more efficient than purified molecules in blocking IC-mediated inflammation and had a higher half-life. In summary, these results suggest that the administration of a plasmid vector with the FcγR-Ig gene can be used to study the consequences of blocking IC binding to FcγRs during the development of inflammatory diseases. This approach may have potential therapeutic value in treating IC-mediated inflammatory autoimmune diseases such as lupus, arthritis and autoimmune vasculitis.

The lead optimisation of the diaminopyrimidine carboxamide series of spleen tyrosine kinase inhibitors is described. The medicinal chemistry strategy was focused on optimising the human whole blood activity whilst achieving a sufficient margin over liability kinases and hERG activity. GSK143 is a potent and highly selective SYK inhibitor showing good efficacy in the rat Arthus model.

Lectins bind to surface receptors on target cells, and activate a cascade of events, eventually leading to altered immune status of host. The immunomodulatory potential of purified lectin from Aspergillus nidulans was evaluated in Swiss albino mice treated intraperitoneally with seven different doses of purified lectin. Lectin prevented BSA-induced Arthus reaction and systemic anaphylaxis. The enhanced functional ability of macrophages was evident from respiratory burst activity and nitric oxide production in splenocyte cultures. Interferon-gamma and interleukin-6 levels were significantly up-regulated in treated groups. Maximum stimulatory effect was observed at the dose of 1.5 mg/kg body weight. Therapeutic potential of A. nidulans lectin was assessed against trinitrobenzene sulfonic acid-induced ulcerative colitis in male Wistar rats. Rats pre-treated with 80 mg/kg body weight of purified lectin intraperitoneally prior to colitis induction showed lesser disease severity and recovery within 7 days, while rats post-treated with the same dose showed recovery in 11 days. The results demonstrate immunomodulatory effects of A. nidulans lectin in Swiss albino mice, resulting in improved immune status of the animals and unfold its curative effect against ulcerative colitis in rat model. This is the first report on immunomodulatory and therapeutic potential of a lectin from microfungi.

Bruton tyrosine kinase (Btk) is essential for B cell development and function and also appears to be important for myeloid cells. The bone marrow of Btk-deficient mice shows enhanced granulopoiesis compared with that of wild-type mice. In purified granulocyte-monocyte-progenitors (GMP) from Btk-deficient mice, the development of granulocytes is favored at the expense of monocytes. However, Btk-deficient neutrophils are impaired in maturation and function. Using bone marrow chimeras, we show that this defect is cell-intrinsic to neutrophils. In GMP and neutrophils, Btk plays a role in GM-CSF– and Toll-like receptor–induced differentiation. Molecular analyses revealed that expression of the lineage-determining transcription factors C/EBPα, C/EBPβ, and PU.1, depends on Btk. In addition, expression of several granule proteins, including myeloperoxidase, neutrophilic granule protein, gelatinase and neutrophil elastase, is Btk-dependent. In the Arthus reaction, an acute inflammatory response, neutrophil migration into tissues, edema formation, and hemorrhage are significantly reduced in Btk-deficient animals. Together, our findings implicate Btk as an important regulator of neutrophilic granulocyte maturation and function in vivo.

FcγRIV is a relatively new IgG Fc receptor (FcγR) that is reported to contribute to the pathogenesis of autoimmune diseases, although its specific role in relation to FcγRIII, complement and IgG2 subclasses remains uncertain. Here we define FcγRIV on macrophages as a receptor for soluble IgG2a/b complexes but not for cellular bound IgG2a and show that simultaneous activation of FcγRIV and FcγRIII is critical to mediate certain type II/III autoimmune responses. FcγRIII-deficient mice display compensatory enhanced FcγRIV expression, are protected from lung inflammation after deposition of IgG complexes, and show reduced sensitivity to IgG2a/b-mediated hemolytic anemia, indicating that increased FcγRIV alone is not sufficient to trigger these diseases in the absence of FcγRIII. Importantly, however, blockade of FcγRIV is also effective in inhibiting phagocytosis and cytokine production in IgG2b-induced anemia and acute lung injury, processes that display a further dependence on C5a anaphylatoxin receptor. Using gene deletion and functional inhibition studies, we found that FcγRIII and FcγRIV are each essential to trigger an FcRγ-linker for activation of T-cell-dependent signal that drives C5a production in the Arthus reaction. Together, the results demonstrate a combined requirement for FcγRIII and FcγRIV in autoimmune injury, and identify the linker for activation of T cells adaptor as an integral component of linked FcγR and C5a anaphylatoxin receptor activation to generate inflammation.

Guinea-pigs injected with guinea-pig thyroglobulin intradermally and rabbit antiserum to guinea-pig thyroglobulin intravenously, showed inflammatory reactions both in the thyroid and in the skin. However, while the eosinophil granulocyte was the predominating cell of the inflammatory infiltrate in the thyroid, neutrophil granulocytes and mononuclear cells prevailed in the skin. Indirect evidence suggested that the reason for this difference might be the larger number of mast cells in the thyroid.

Antibody-antigen complex mediated inflammation is integral to the pathogenesis of many autoimmune diseases. Mice deficient in the γ-chain of Fc-receptors are protected in IgG-mediated glomerulonephritis and the Arthus reaction and FcR-bearing mast cells and macrophages have been assigned primary roles in these processes. Here we demonstrate that neutrophil selective transgenic expression of the two uniquely human activating FcγRs, FcγRIIA and FcγRIIIB was sufficient to restore susceptibility to progressive anti-glomerular basement membrane (GBM) nephritis and the cutaneous Reverse Passive Arthus (RPA) reaction in γ-chain deficient mice. Both FcγRIIA and FcγRIIIB mediated robust neutrophil accumulation in tissues suggesting direct roles for these human receptors in IC-induced neutrophil recruitment, while FcγRIIA alone mediated organ injury. In an acute model of anti-GBM nephritis, both FcγRIIIB and FcγRIIA promoted initial neutrophil recruitment to glomerular immune-complexes (ICs) accessible to circulating cells, while FcγRIIA further sustained accumulation. In a model of soluble ICs deposited strictly within the post-capillary venules of the cremaster muscle, FcγRIIIB was solely responsible for converting initial selectin-dependent tethers to slow rolling and adhesion. However, in the cremaster RPA reaction, dependent on vascular and tissue accumulation of soluble ICs, FcγRIIA predominated in neutrophil recruitment that was dependent on G-protein coupled receptor activation. Thus, human FcγRs on neutrophils serve as the primary molecular links between ICs and immunological disease with FcγRIIA promoting tissue injury, and FcγRIIIB and FcγRIIA displaying specialized context-dependent functions in IC-induced neutrophil recruitment.

The deposition of immune complexes (IC) induces an acute inflammatory response with tissue injury, for which the involvement of nitric oxide (NO) and carbon monoxide (CO) has been suggested. NO is induced by NO synthase (NOS) and CO is generated by haeme oxygenase (HO). Among HO isoenzymes, HO-1 is an induced type. To assess the role of NO and CO in the pathogenic process, the cutaneous reverse passive Arthus reaction was examined using NOS inhibitor, HO-1 stimulator and HO-1 inhibitor. To evaluate the reaction we considered oedema, tumour necrosis factor-alpha, interleukin-6, and neutrophil number. The values of these four parameters were significantly reduced in mice treated with HO-1 stimulator as compared with the positive control mice. Quite the reverse was observed in mice treated with HO-1 inhibitor. These results suggest that the HO-1/CO signalling pathway is a therapeutic target for human IC-mediated disease., Clinical and experimental immunology, 153(2), pp.245-257; 2008

Antigen-antibody (Ab) interactions that lead to the formation of immune complexes (ICs) are subtle biochemical processes determining health or disease according to the outcome. Good laboratory practice (GLP)-acknowledged IC detection methods reveal that plasma levels of up to 15 microg/mL heat-aggregated immunoglobulin G (IgG) equivalents are normal, indicating the physiological role of ICs. Among the major variables that influence the equilibrium association constant Ka, are specificity and epitope density of the antigen, Ig class/subclass of the Ab, IC complement (C)-activating capacity, Fc receptor (FcR) interaction, and cytokine activation pattern. The Ka of antigen-Ab binding at approximately 20 degrees C ranges from low affinity (105) to high affinity (107-1011). Beneficial ICs serve to remove and/or neutralize infectious or toxic antigens, following an infectious attack in immune and vaccinated hosts. Circulating ICs are more prone for benefit than tissue-bound ICs, which reflect in situ formation and/or undesired deposition in tissues due to overflow from insufficient reticuloendothelial system (RES) removal. The classical textbook topic on ICs still holds true but is under revision because of the improved knowledge of effector systems, such as C, cytokine, and FcR apparatus. Therapeutic options to treat IC-associated diseases include intravenous immunoglobulins (IVIG) at their onset and monoclonal antibodies (mAb) directed at C activation products and/or cytokines.

Objectives: Systemic lupus erythematosus (SLE) is a classical autoimmune disorder characterised by the production of IgG autoantibodies against double-stranded DNA (dsDNA). Activation of FcγR-bearing effector cells by immune complexes (ICs) is a key event in SLE pathogenesis as lupus-prone NZB/NZW F 1 hybrids lacking activating Fcγ receptors (FcγR) are protected against inflammatory kidney damage despite glomerular deposition of ICs. Moreover, soluble FcγRs inhibit IC-caused Arthus reaction in vivo . Therefore, recombinant human soluble FcγRII (CD32) was evaluated as a novel therapeutic strategy in lupus-like disease in NZB/NZW F 1 hybrids. Methods: Binding of husCD32 to murine IgG was studied in vitro by binding to IgG-coated erythrocytes and inhibition of phagocytosis of IgG-opsonised murine erythrocytes. In order to examine therapeutic impact of husCD32 in vivo , female NZB/NZW F 1 mice were treated either from week 16 to 20 (“prophylactic”, 150 μg/week husCD32) or continuously from week 24 (“therapeutic”; 100 μg/week husCD32) by subcutaneous injections. Controls received buffered saline. Results: In vitro investigations of husCD32 revealed binding to murine erythrocytes coated with murine IgG. Moreover, husCD32 substantially diminished phagocytosis of murine IgG-opsonised murine red blood cells by peritoneal macrophages indicating disruption of IgG–FcγR interaction. There was a therapeutic efficacy of husCD32 to attenuate lupus pathology indicated by significantly delayed onset of proteinuria and weight loss, reduced histopathological findings, delayed development of anaemia and improved survival by prophylactical application. Therapeutic treatment did not reverse nephritis but significantly prolonged survival despite apparent kidney damage. B cell count, concentration of IgG anti-dsDNA autoantibodies and deposition of glomerular ICs was not significantly affected by the application of husCD32. Conclusions: The results demonstrate binding properties of husCD32 to ICs in vitro and as a proof-of-principle therapeutic efficacy in inhibiting chronic murine lupus pathology in vivo .

On October 20, 1997, the U.S. Food and Drug Administration (FDA) licensed Purified Chick Embryo Cell (PCEC, RabAvert®) vaccine against rabies in humans following clinical trials demonstrating safety and efficacy. From October 1997 through December 2005, the Vaccine Adverse Event Reporting System (VAERS) received 336 reports of adverse events (AEs) following vaccination with PCEC vaccine in the U.S.; there were no death reports. Serious events, including 20 hospitalizations and 13 neurological events, were described in 24 (7%) reports. There was no pattern among the 13 neurological AEs suggesting a plausible relationship to vaccination. A total of 20 AEs, 3 serious, were classified as possible anaphylaxis. There were 312 non-serious AEs (93%). Nineteen reports (6%) described that the vaccination series was discontinued because of non-serious AEs. Most reported AEs are non-serious and consistent with pre-licensure safety data. The rabies risk must be carefully considered before vaccine discontinuation.

金沢大学大学院医学系研究科血管分子科学, Immune complex (IC)-induced inflammation is mediated by inflammatory cell infiltration, a process that is highly regulated by expression of multiple adhesion molecules. The roles and interactions of ICAM-1 and VCAM-1, the major regulators of leukocyte firm adhesion, were examined in the cutaneous reverse-passive Arthus reaction using ICAM-1-deficient (ICAM-1-/-) mice and blocking mAb against VCAM-1. Within 8 h, IC challenge of wild-type mice induced edema, hemorrhage, interstitial accumulation of neutrophils and mast cells, as well as production of TNF-α and IL-6. All of these inflammatory parameters were reduced significantly in ICAM-1-/- mice. The blockade of VCAM-1 in wild-type mice did not affect any inflammatory parameters. In contrast, ICAM-1-/- mice treated with anti-VCAM-1 mAb had significantly reduced edema, hemorrhage, and neutrophil infiltration. Furthermore, VCAM-1 blockade in ICAM-1-/- mice suppressed cutaneous TNF-α and IL-6 production. Thus, VCAM-1 plays a complementary role to ICAM-1 in the cutaneous Arthus reaction by regulating leukocyte accumulation and proinflammatory cytokine production. © Society for Leukocyte Biology.

BACKGROUND Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is a pro-inflammatory cytokine, which is closely associated with the pathogenesis of various types of cutaneous vasculitis (CV). AIM To investigate the therapeutic effects of an anti-TWEAK monoclonal antibody (mAb) in a mouse model of cutaneous reverse passive Arthus (RPA) reaction. METHODS Cutaneous RPA reaction was induced in BALB/c mice by intradermal injection of anti-ovalbumin IgG into the left ear followed immediately by intravenous injection of chicken ovalbumin. After treatment, haemorrhagic lesions in the mouse skin were scored semiquantitatively. The amount of extravasated fluorescein isothiocyanate (FITC)-labelled bovine serum albumin (BSA) in the ears was detected spectrophotometrically. Expression of myeloperoxidase (MPO) was detected by immunohistochemical staining, while mRNA expression of TNF-α and interleukin (IL)-6 in lesional skin was detected by real-time quantitative (q)PCR. RESULTS Our results indicated that anti-TWEAK mAb significantly attenuated the clinical and histopathological changes in immune complex (IC)-induced mice, and also reduced the semiquantitative haemorrhage score, FITC-labelled BSA extravasation and MPO activity. Real-time qPCR showed that anti-TWEAK mAb significantly inhibited mRNA expression of TNF-α and IL-6 in lesional skin from IC-induced mice. CONCLUSION These data suggest that anti-TWEAK mAb can block vascular damage and leucocyte infiltration in IC-induced mice. TWEAK might be a candidate immunotherapeutic medicine for suppression of IC-induced CV.

Low-molecular-weight heparins (LMWHs) have some effects on cell proliferation and inflammation beyond mere anticoagulation. They have been tried on treatment of a few dermatological disorders such as lichen planus, skin wound healing, recurrent aphtous stomatitis, chronic urticaria, and contact hypersensitivity. LMWHs are generally well-tolerated drugs, rarely can lead to severe reactions. In this article, we will review the novel indications of LMWHs in dermatology practice and common skin reactions associated with their use.