Mandakolathur R. Murali

Human lupus autoantibody–DNA complexes activate DCs through cooperation of CD32 and TLR9

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by pathogenic autoantibodies against nucleoproteins and DNA. Here we show that DNA-containing immune complexes (ICs) within lupus serum (SLE-ICs), but not protein-containing ICs from other autoimmune rheumatic diseases, stimulates plasmacytoid DCs (PDCs) to produce cytokines and chemokines via a cooperative interaction between Toll-like receptor 9 (TLR9) and FcgammaRIIa (CD32). SLE-ICs transiently colocalized to a subcellular compartment containing CD32 and TLR9, and CD32+, but not CD32-, PDCs internalized and responded to SLE-ICs. Our findings demonstrate a novel functional interaction between Fc receptors and TLRs, defining a pathway in which CD32 delivers SLE-ICs to intracellular lysosomes containing TLR9, inducing a signaling cascade leading to PDC activation. These data demonstrate that endogenous DNA-containing autoantibody complexes found in the serum of patients with SLE activate the innate immune system and suggest a novel mechanism whereby these ICs contribute to the pathogenesis of this autoimmune disease.

Functionally defective germline variants of sialic acid acetylesterase in autoimmunity

Sialic acid acetylesterase (SIAE) is an enzyme that negatively regulates B lymphocyte antigen receptor signalling and is required for the maintenance of immunological tolerance in mice. Heterozygous loss-of-function germline rare variants and a homozygous defective polymorphic variant of SIAE were identified in 24/923 subjects of European origin with relatively common autoimmune disorders and in 2/648 controls of European origin. All heterozygous loss-of-function SIAE mutations tested were capable of functioning in a dominant negative manner. A homozygous secretion-defective polymorphic variant of SIAE was catalytically active, lacked the ability to function in a dominant negative manner, and was seen in eight autoimmune subjects but in no control subjects. The odds ratio for inheriting defective SIAE alleles was 8.6 in all autoimmune subjects, 8.3 in subjects with rheumatoid arthritis, and 7.9 in subjects with type I diabetes. Functionally defective SIAE rare and polymorphic variants represent a strong genetic link to susceptibility in relatively common human autoimmune disorders.

Serum free light chain analysis.

In a variety of hematologic malignancies, immunoglobulin light chains (LC) are overproduced clonally and circulate without being linked by disulphide bonds to the immunoglobulin heavy chain. The recent development of a robust assay known as κ and λ “free” LC (FLC) to quantify the levels of these unbound LC in the serum, and thereby determine their ratio, has led to an explosion of studies that demonstrate its utility in a wide range of hematologic disorders. This article summarizes laboratory testing for serum FLC, with a particular focus on clinical applications for the test. Am. J. Hematol., 2010.

Laboratory testing for cryoglobulins

Cryoglobulins are immunoglobulins that precipitate below 37°C and can cause multiorgan damage. There are three types of cryoglobulins: Type I (also called simple), which is mostly associated with monoclonal gammopathy and/or other hematologic disorders and Type II and Type III (known as mixed cryoglobulins), which are associated with infectious and systemic diseases. Testing for cryoglobulins is complicated by lack of reference range, standards, and stringency in maintaining testing temperature conditions. Identification of cryoprecipitate can be critical for patient care; therefore, correct testing conditions are crucial for reliable cryoglobulin testing. The patients blood sample should be kept at 37°C initially to avoid premature precipitation of cryoglobulins and thereby decreasing the yield for subsequent identification. This could cause a false negative result. After warm centrifugation or warm cell precipitation, the clear serum is observed at 4°C for formation of cryoprecipitate. The cryoprecipitate is then washed in cold buffer, and the resulting precipitate is warmed to 37°C and subjected to further analysis by immunodiffusion and immunofixation. In addition to Meltzers triad of purpura, weakness and arthralgias, cryoglobulinemias have protean manifestations involving skin, joints, kidney, nervous system, as well as the hematopoietic system. The management of cryoglobulinemia especially in patients with organ damage remains difficult. Treatment of cryoglobulinemia focuses on management of the underlying lymphoproliferative disorder or infectious or systemic causes. Medical management may also include corticosteroids and other immunosuppressive agents and plasmapheresis. Rituximab therapy seems to abrogate the aberrant B cell response. Am. J.Hematol. 86:500–502, 2011.

EMLA cream–induced allergic contact dermatitis: a role for prilocaine as an immunogen

ical findings of marked autonomic dysregulation, and the thermogram, which confirmed the latter. Theories of RSD pathogenesis include central and peripheral nerve mechanisms: tissue injury produces nociceptive input to the spinal cord, which results in hyperexcitability of spinal cord neurons. Efferent sympathetic nerves are activated, and through an a-adrenergic mechanism, stimulate peripheral nociceptors, again completing a reflex loop? Treatment is aimed at blocking the sympathetic system to break the cycle and mobilizing the limb to restore normal function. In early or milder cases, limb mobilization may be sufficient to reverse the pathologic process. RSD after allergen immunotherapy has not been previously reported. We believe that trauma from the needle was the triggering stimulus for RSD, rather than an inflammatory response to the allergen. Future research may help answer questions about how cx-adrenergic activation of nociceptors takes place.

Immunologic Overlap of Helper T-Cell Subtypes 17 and 22 in Erythrodermic Psoriasis and Atopic Dermatitis.

IMPORTANCE Psoriasis and atopic dermatitis (AD) are inflammatory diseases thought to be mediated by helper T-cell subtypes 1 and 2 (TH1 and TH2), respectively. Although psoriasis and AD show histopathologic differences during chronic disease, they are difficult to distinguish histologically during erythrodermic exacerbations. OBJECTIVE To determine whether the immune phenotype of helper T cells can differentiate erythrodermic psoriasis and erythrodermic AD by studying skin biopsy specimens of patients with psoriasis and AD during erythrodermic and chronic disease phases. DESIGN, SETTING, AND PARTICIPANTS We conducted a retrospective study using biopsy samples of psoriasis, AD, and erythroderma belonging to the surgical pathology files of the James Homer Wright Pathology Laboratories, Massachusetts General Hospital, and collected from January 1, 2004, through December 31, 2011. Samples were obtained from patients with chronic psoriasis (n = 20), chronic AD (n = 20), erythroderma subsequently diagnosed as psoriasis (n = 7), and erythroderma subsequently diagnosed as AD (n = 5). We evaluated immunohistochemical stains for CD3 and dual stains for CD4 and T-bet, GATA binding protein 3 (GATA3), signal transducer and activator of transcription 3 (STAT3), or basonuclin 2 (BNC2), which are transcription factors reported to be specific and mutually exclusive for TH1, TH2, TH17, and TH22 cells, respectively. Two investigators independently counted CD3+ cells and dual-labeled CD4+/T-bet+, CD4+/GATA3+, CD4+/STAT3+, and CD4+/BNC2+ cells in 5 consecutive high-power fields. MAIN OUTCOMES AND MEASURES We evaluated the percentage of TH1, TH2, TH17, and TH22 cells in CD3+ T cells and the TH1:TH2 ratio in chronic psoriasis, chronic AD, erythrodermic psoriasis, and erythrodermic AD. RESULTS We found a significant difference in the TH1:TH2 ratio between chronic psoriasis and chronic AD (0.26 and 0.09, respectively; P = .005). However, we detected no significant difference in the percentage of TH1 (6.5% and 4.8%), TH2 (55.2% and 64.6%), TH17 (14.7% and 30.4%), and TH22 (3.8% and 3.3%) cells of CD3+ T cells or in the TH1:TH2 ratio (0.16 and 0.07) within biopsy specimens from patients with erythrodermic psoriasis and AD, respectively. CONCLUSIONS AND RELEVANCE This study confirms the TH1- and TH2-skewed phenotype of chronic psoriasis and chronic AD, respectively. However, the immune phenotype, as determined by immunohistochemical analysis, cannot discriminate between these inflammatory diseases in the erythrodermic phase. These findings advance our understanding of the pathophysiological characteristics of erythroderma, psoriasis, and AD and may influence therapeutic decisions.

Human Proteins with Affinity for Dermatan Sulfate Have the Propensity to Become Autoantigens

The mystery of why and how a small, seemingly disparate subset of all self molecules become functional autoantigens holds a key to understanding autoimmune diseases. Here and in a companion article in this issue, we show that affinity of self molecules to the glycosaminoglycan dermatan sulfate (DS) is a common property of autoantigens and leads to a specific autoreactive B-1a cell response. Autoimmune ANA/ENA reference sera react preferentially with DS affinity-fractionated cellular proteins. Studying patients with autoimmune diseases, we discovered patient-specific complex autoantigen patterns that are far richer and more diverse than previously thought, indicating significant pathological heterogeneity even within traditionally defined clinical entities, such as systemic lupus erythematosus. By shotgun sequencing of DS affinity-enriched proteomes extracted from cell lines, we identified approximately 200 autoantigens, both novel and previously linked to autoimmunity, including several well-known families of autoantigens related to the nucleosome, ribonucleoproteins, the cytoskeleton, and heat shock proteins. Using electron microscopy, we recognized direct interaction with dead cells as an origin of autoantigenic association of DS with self molecules. DS affinity may be a unifying property of the human autoantigen-ome (ie, totality of self molecules that can serve as functional autoantingens) and thus provides a promising tool for discovery of autoantigens, molecular diagnosis of autoimmune diseases, and development of cause-specific therapies.

Case records of the Massachusetts General Hospital. Case 9-2011. A 37-year-old man with flushing and hypotension.

From the Divisions of Rheumatology, Allergy, and Immunology (M.R.M.) and Cardiology (D.M.D.); and the Departments of Radiology (J.Y.S.) and Pathology (R.P.H.), Massachusetts General Hospital; the Division of Rheumatology, Allergy, and Immunology, Brigham and Women’s Hospital (M.C.C.); and the Departments of Medicine (M.R.M., M.C.C., D.M.D.), Radiology (J.Y.S.), and Pathology (R.P.H.), Harvard Medical School — all in Boston.

Identification of a Th2- and Th17-skewed immune phenotype in chronic urticaria with Th22 reduction dependent on autoimmunity and thyroid disease markers.

Chronic urticaria is a condition with many inciting factors and often presents a therapeutic challenge to clinicians. In addition to a central role for mast cells, an immune dysregulated state related to cytokine/chemokine alterations is increasingly being recognized.

Case records of the Massachusetts General Hospital. Case 2-2015. A 25-year-old man with abdominal pain, syncope, and hypotension.

Dr. Albert Yeh (Medicine): A 25-year-old man was admitted to this hospital because of abdominal pain, syncope, and hypotension. The patient had been well on the day of admission until, while lifting heavy boxes with a friend, he suddenly felt “a warm feeling” diffusely and had discomfort in his epigastrium and right upper quadrant that radiated throughout his abdomen, followed by tingling in his mouth, tongue, arms, and legs. Within the next few minutes, his vision blurred and darkened. He felt faint and lay down on the sidewalk. Within 5 minutes after the onset of symptoms, nonbloody, nonbilious vomiting occurred, and he lost consciousness. His friend held him in a sitting position and noticed he was shaking. Emergency medical services were called. On examination by emergency medical services personnel, the patient was lying on the sidewalk, unresponsive to verbal or painful stimuli, and had diaphoresis, shallow breathing, a clenched jaw, and urinary incontinence. A nasopharyngeal airway was placed, high-flow oxygen was administered, and ventilation with a bag-valve mask was performed at a rate of 10 breaths per minute. The Glasgow Coma Scale score was 3 (on a scale of 3 to 15, with lower scores indicating reduced levels of consciousness). The blood pressure was 53/27 mm Hg, and the pulse 90 beats per minute. A cardiac monitor recorded normal sinus rhythm. A bolus of normal saline was rapidly infused. Within 3 minutes, the pulse rose to 118 beats per minute, the blood pressure rose to 60/28 mm Hg, and spontaneous respirations resumed; high-flow oxygen was administered through a nonrebreather face mask. The level of capillary blood glucose was 73 mg per deciliter (4.05 mmol per liter). Naloxone was administered intravenously, without improvement. During transport to this hospital by ambulance, the patient opened his eyes in response to verbal stimuli. The blood pressure transiently rose to 102/73 mm Hg and then fell to 83/31 mm Hg, the pulse was 90 beats per minute, the respiratory rate was 17 to 21 breaths per minute, and the Glasgow Coma Scale score rose to 9. On arrival in the emergency department, approximately 30 minutes after the onset of symptoms, the patient was initially difficult to arouse, but his condition rapidly improved and then he was alert and responsive. He reported abdominal pain, which From the Departments of Medicine (M.R.M.), Radiology (J.W.U.), and Pa‐ thology (B.T.), Massachusetts General Hospital, and the Departments of Medi‐ cine (M.R.M.), Radiology (J.W.U.), and Pathology (B.T.), Harvard Medical School — both in Boston.