Transcobalamin receptor antibodies in autoimmune vitamin B12 central deficiency.

Vitamin B12 is critical for hematopoiesis and myelination. Deficiency can cause neurologic deficits including loss of coordination and cognitive decline. However, diagnosis relies on measurement of vitamin B12 in the blood, which may not accurately reflect the concentration in the brain. Using programmable phage display, we identified an autoantibody targeting the transcobalamin receptor (CD320) in a patient with progressive tremor, ataxia, and scanning speech. Anti-CD320 impaired cellular uptake of cobalamin (B12) in vitro by depleting its target from the cell surface. Despite a normal serum concentration, B12 was nearly undetectable in her cerebrospinal fluid (CSF). Immunosuppressive treatment and high-dose systemic B12 supplementation were associated with increased B12 in the CSF and clinical improvement. Optofluidic screening enabled isolation of a patient-derived monoclonal antibody that impaired B12 transport across an in vitro model of the blood-brain barrier (BBB). Autoantibodies targeting the same epitope of CD320 were identified in seven other patients with neurologic deficits of unknown etiology, 6% of healthy controls, and 21.4% of a cohort of patients with neuropsychiatric lupus. In 132 paired serum and CSF samples, detection of anti-CD320 in the blood predicted B12 deficiency in the brain. However, these individuals did not display any hematologic signs of B12 deficiency despite systemic CD320 impairment. Using a genome-wide CRISPR screen, we found that the low-density lipoprotein receptor serves as an alternative B12 uptake pathway in hematopoietic cells. These findings dissect the tissue specificity of B12 transport and elucidate an autoimmune neurologic condition that may be amenable to immunomodulatory treatment and nutritional supplementation.

Vitamin B12 deficiency among asymptomatic healthy infants: its impact on the immune system.

BACKGROUND: The immunomodulatory effects of vitamin B12 deficiency in children have not yet been established in the literature. In the current study, the effects of vitamin B12 on the immune system in asymptomatic and otherwise healthy infants have been studied. METHODS: The study was conducted at Marmara University, "well-child" outpatient clinic. Vitamin B12 level was measured in a cohort of 611 healthy term infants, followed regularly for at least 6 months. Immunoglobulin measurements, lymphocyte subset analysis, cytokine production analysis, lymphocyte proliferation assays and evaluation of lymphocyte apoptosis were performed in a subset of 60 infants. RESULTS: In this cohort, one out of three babies displayed vitamin B12 deficiency. The percentage of CD4+CD25+ regulatory T cells (Tregs) was lower in vitamin B12 deficient babies than in controls. Although the percentage of Tregs increased after treatment, the change was not significant. There was no difference of cytokine levels between vitamin B12 deficient and control groups. However, proinflammatory cytokines were reduced after treatment. No significant difference was observed for immunoglobulins, early apoptosis and lymphocyte proliferation. CONCLUSIONS: Vitamin B12 deficiency is an underestimated health problem among the developing countries. The clinical consequences of the decreased percentage of Tregs associated with vitamin B12 deficiency, and reduction of proinflammatory cytokines after vitamin supplementation needs to be further studied, especially in terms of emerging allergies, autoimmune disorders and anti-inflammatory effects.

Immunodeficiency and inborn disorders of vitamin B12 and folate metabolism.

PURPOSE OF REVIEW: Immune dysfunction, including severe combined immunodeficiency, has been described in genetic disorders affecting the metabolism of the vitamins cobalamin (vitamin B12) and folate. We have reviewed reports of clinical findings in patients with a number of inborn errors of cobalamin or folate metabolism, specifically looking for immune problems. RECENT FINDINGS: There is little evidence that immune function is affected in most of the disorders. Exceptions are Imerslund-Gräsbeck syndrome and hereditary folate malabsorption (affecting intestinal absorption of cobalamin and folate, respectively), transcobalamin deficiency (affecting transport of cobalamin in blood and cellular cobalamin uptake), and methylenetetrahydrofolate dehydrogenase 1 deficiency (catalyzing cytoplasmic interconversion of reduced folate coenzyme derivatives). SUMMARY: Although some inborn errors of cobalamin or folate can be associated with immune dysfunction, the degree and type of immune dysfunction vary with no obvious pattern.

High frequency of anti-parietal cell antibody (APCA) and intrinsic factor blocking antibody (IFBA) in individuals with severe vitamin B12 deficiency - an observational study in primary care patients.

Background Vitamin B12 deficiency is common worldwide and is also linked to several diseases including autoimmune atrophic gastritis (AAG). The presence of anti-parietal cell antibodies (APCA) and/or intrinsic factor blocking antibodies (IFBA) is indicative of AAG that may develop into pernicious anemia. Both conditions are known to be associated with an increased risk of gastric carcinoma. The aim of this study was to estimate the frequency of individuals positive for APCA and IFBA antibodies in primary care patients with severe vitamin B12 deficiency. Methods An observational study was designed and 5468 consecutive patients from primary care with a request for vitamin B12 status were included and add-on testing for APCA and IFBA that were automatically registered if severe vitamin B12 deficiency was identified (<73.8 pmol/L). For patients included in the intervention, study demographic data, mean corpuscular volume (MCV) and hemoglobin values were collected. Results Seventy-seven patients with severe vitamin B12 deficiency were identified and out of these 44 (57%) presented with antibodies to APCA and 11 (14%) to IFBA, 25 (32.5%) had anemia, and 25 (32.5%) had macrocytosis. The majority of APCA and/or IFBA positive patients were found in the age group >70 years. Both anemia and macrocytosis were more common among APCA positive patients but the association was not statistically significant, neither was the correlation between IFBA status and anemia and/or macrocytosis. Among the patients with anemia, 10 (39%) had macrocytosis, although the rate of macrocytosis among patients with or without anemia did not differ significantly. Conclusions The automated analysis strategy of measuring antibodies to APCA and IFBA in patients with severe vitamin B12 deficiency, efficiently detected positivity in more than 60% the patients. The result point to the presence of a high rate of otherwise undetected AAG and the potential clinical utility of APCA and IFBA as markers in primary care.

A Rare Cause of Pancytopenia in an Exclusively Breastfed Infant.

Vitamin B12 (B12) deficiency in infancy can present with nonspecific symptoms. We report a 5-month old exclusively breastfed full-term infant with emesis, lethargy, progressive pancytopenia, hemolysis, hypofibrinogenemia, elevated lactate dehydrogenase and a hypercellular bone marrow with dyserythropoiesis. The B12 level in the serum was undetectable. The infant's lethargy resolved within 48 hours of intramuscular B12 injection, followed by rapid improvement of pancytopenia. The asymptomatic mother had a normal hemoglobin and mean corpuscular volume, but undetectable B12 level and positive antibodies to intrinsic factor, consistent with pernicious anemia masked by folate supplementation in the mother but causing symptoms in her infant.

Challenging clinical presentations of pernicious anemia.

Pernicious anemia (PA) is an autoimmune disease of multifactorial etiologies characterized by autoimmune chronic atrophic gastritis, cobalamin deficiency (CD) due to defective absorption of dietary cobalamin from the terminal ileum, and by the presence of intrinsic factor and parietal cell antibodies. PA is a very common cause of CD-related anemia worldwide. Despite advances in the understanding molecular biology and pathophysiology of PA, the diagnosis of PA remains challenging in many circumstances for many clinicians because of its diverse clinical manifestations and the limitations of currently available diagnostic tools. Diagnostic dilemmas could occur when patients with PA present with spuriously normal or high cobalamin levels, normocytic or microcytic anemia, non-anemic macrocytosis, autoimmune hemolytic anemia, pseudo-thrombotic microangiopathy, hyperhomocysteinemia-associated thromboembolism, pseudoleu-kemia, bone marrow failure, bone marrow ring sideroblasts, and neurologic manifestations without anemia or macrocytosis. Herein, we provide an overview of the challenging clinical presentations of PA, diagnostic approach, and management.

Autoimmune gastritis.

Autoimmune gastritis is a chronic inflammatory disease with destruction of parietal cells of the corpus and fundus of the stomach. The known consequence is vitamin B12 deficiency and, consequently, pernicious anemia. However, loss of parietal cells reduces secretion of gastric acid which is also required for absorption of inorganic iron; thus, iron deficiency is commonly found in patients with autoimmune gastritis. This usually precedes vitamin B12 deficiency and is found mainly in young women. Patients with chronic iron deficiency, especially those refractory to oral iron therapy, should therefore be evaluated for the presence of autoimmune gastritis.

Inflammatory, immunological, and intestinal disease biomarkers in Chinese Shar-Pei dogs with marked hypocobalaminemia.

Chinese Shar-Pei dogs have a high prevalence of hypocobalaminemia and are commonly presented with clinical signs suggestive of severe and long-standing gastrointestinal disease such as diarrhea, vomiting, and/or weight loss. The aim of the current study was to evaluate serum concentrations of inflammatory markers, markers for intestinal disease, and immunological markers in Shar-Peis with hypocobalaminemia or normocobalaminemia (serum cobalamin concentrations within the reference interval). Serum samples from Shar-Peis were collected from various parts of the United States. Serum concentrations of inflammatory markers (i.e., C-reactive protein [CRP], calprotectin [CP], and S100A12), hyaluronic acid (HA, a marker for cutaneous mucinosis), and analytes commonly altered in chronic intestinal diseases (i.e., albumin, zinc, alpha1-proteinease inhibitor [α1PI], immunoglobulin [Ig]A, and IgM) were compared between Shar-Peis with hypocobalaminemia and Shar-Peis with normocobalaminemia. Serum concentrations of CRP, CP, S100A12, HA, zinc, and cα1-PI concentrations did not differ between hypocobalaminemic and normocobalaminemic Shar-Peis (P > 0.05). Serum concentrations of albumin were significantly lower in hypocobalaminemic Shar-Peis (median: 2.5 g/dl) than in normocobalaminemic Shar-Peis (median: 2.9 g/dl; P < 0.0001). Higher serum IgA concentrations and lower serum IgM concentrations were observed in hypocobalaminemic Shar-Peis (median: 1.7 g/l and 0.8 g/l, respectively) than in normocobalaminemic Shar-Peis (median: 0.7 g/l and 1.9 g/l, respectively; both P < 0.0001). In conclusion, no difference was found in serum concentrations of CRP, CP, S100A12, and HA between hypocobalaminemic and normocobalaminemic Shar-Peis whereas some differences were observed in analytes (e.g., albumin, IgA, and IgM) that may be altered in patients with chronic enteropathies.

Neurological manifestations of B(12) deficiency with emphasis on its aetiology.

BACKGROUND: It is believed that Pernicious anaemia (PA) is more common in the West. We postulate however that in India PA is probably an important aetiological factor as a cause of Vitamin B12 deficiency in patients having neurological disease. OBJECTIVE: To investigate the aetiological factors resulting in Vitamin B12 (Vit B12) deficiency in patients with subacute combined degeneration (SACD) and other neurological manifestations. METHODS: We undertook a prospective study of 50 patients, all clinically suspected to have Vit B12 deficiency; they were investigated clinically, haematologically, biochemically and radiologically. RESULTS: There was a dominance of males (41 of 50) with the majority in the age group of more than 40 years of age. There was no correlation between the socio-economic and dietary status on the one hand and the clinical manifestation on the other. Anti intrinsic factor antibodies (AIFAB) were positive in 19 of 50 patients (38%) and anti parietal cell antibodies (APCAB) were positive in 28 of 50 (56%) patients. CONCLUSION: We conclude that Pernicious anaemia is an important cause of various neurological manifestations including SACD in the Vitamin B12 deficient population in the age group of more than 40 years, irrespective of the socio-economic and dietary status in the Indian subcontinent. It is supported by the presence of AIFAB or APCAB in this group.

Micronutrient deficiency and treatment adherence in a randomized controlled trial of micronutrient supplementation in ART-naïve persons with HIV.

INTRODUCTION: The MAINTAIN study is an on-going RCT comparing high-dose micronutrient and anti-oxidant supplementation versus recommended daily allowance (RDA) vitamins in slowing HIV immune deficiency progression in ART-naïve people with HIV infection. OBJECTIVE: We planned analysis of the first 127 participants to determine the baseline prevalence of serum micronutrient deficiencies and correlates, as well as tolerance and adherence to study interventions. METHODS: Participants receive eight capsules twice daily of 1) high-dose or 2) RDA supplements for two years and are followed-up quarterly for measures of immune deficiency progression, safety and tolerability. Regression analysis was used to identify correlates of micronutrient levels at baseline. Adherence was measured by residual pill count, self-report using the General Treatment Scale (GTS) and short-term recall HIV Adherence Treatment Scale (HATS). RESULTS: Prior micronutrient supplementation (within 30 days) was 27% at screening and 10% of study population, and was not correlated with baseline micronutrient levels. Low levels were frequent for carotene (24%<1 nmol/L), vitamin D (24%<40 nmol/L) and serum folate (20%<15 nmol/L). The proportion with B12 deficiency (<133 pmol/L) was 2.4%. Lower baseline levels of B12 correlated lower baseline CD4 count (r = 0.21, p = 0.02) with a 21 pmol/L reduction in B12 per 100 cells/µL CD4. Vitamin D levels were higher in men (p<0.001). After a median follow-up of 1.63 years, there were 19 (15%) early withdrawals from the study treatment. Mean treatment adherence using pill count was 88%. Subjective adherence by the GTS was 81% and was moderately but significantly correlated with pill count (r = 0.29, p<0.001). Adherence based on short-term recall (HATS) was >80% in 75% of participants. CONCLUSION: Micronutrient levels in asymptomatic HIV+ persons are in keeping with population norms, but micronutrient deficiencies are frequent. Adherence levels are high, and will permit a valid evaluation of treatment effects. TRIAL REGISTRATION: ClinicalTrials.gov NCT00798772.

[Screening for autoimmune polyglandular syndrome in a cohort of patients with type 1 diabetes mellitus]. / Rastreio de síndrome poliglandular autoimune em uma população de pacientes com diabetes melito tipo 1.

OBJECTIVE: To characterize a cohort of patients with type 1 diabetes mellitus (T1DM) on the presence of other autoimmune disorders that could establish the diagnosis of autoimmune polyglandular syndrome (APS). SUBJECTS AND METHODS: We included 151 patients with T1DM. The following clinical parameters were analyzed: gender, current age, disease duration, previous history of autoimmune disorders, and familial history for diabetes mellitus. Each patient was analyzed to detect autoimmune markers of thyroiditis, adrenocortical insufficiency, gastritis, and celiac disease, as well as possible associated dysfunctions. RESULTS: A cohort with 51.7% males, average current age of 33.4 ± 13 years and disease duration of 14.4 ± 9.6 years was analyzed. Previous history of autoimmunity was found in 2%, and familial history for diabetes mellitus in 31.1% of the cohort. Frequency of autoimmune markers was 24% for thyroiditis, 9.4% for adrenocortical insufficiency, 17.2% for gastritis, and 2% for celiac disease. APS was diagnosed on 25.2% of the patients. APS and autoimmune thyroiditis risk was higher in females. Disease duration correlated directly with gastric autoantibodies, and inversely with positive islet cell, glutamic acid decarboxylase, and tyrosine phosphatase antibodies. We noticed a correlation between autoimmune markers for thyroiditis and gastritis, as well as between celiac disease and adrenocortical insufficiency. CONCLUSION: Considering APS prevalence and prognosis, the need for APS screening in patients with T1DM is emphasized. Early diagnosis of other autoimmune disorders will enable us to adjust each patient treatment and follow-up.

Parietal cell antibody identified by ELISA is superior to immunofluorescence, rises with age and is associated with intrinsic factor antibody.

Parietal cell antibody is a marker for autoimmune gastritis. With identification of gastric H/K ATPase as its molecular target, ELISAs have been introduced. We compared performance of ELISA with immunofluorescence in a retrospective and prospective sera set and correlated the results with intrinsic factor antibody. In 138 retrospective sera selected for positivity or negativity for intrinsic factor antibody, 87 reacted with gastric H/K ATPase by Euroimm ELISA but only 62 reacted by immunofluorescencence.. Similar results were obtained with Inova ELISA with 78 positives that were also positive by Euroimm ELISA. In 161 prospective sera, 29 sera tested positive by ELISA compared to 24 by immunofluorescence. ELISA positive but immunofluoresnce negative sera are bona fide positives because a representative set of 16 sera reacted with both 95kD α and 60-90kDß subunits of gastric H/K ATPase. ELISA values rose with age regardless of whether immunofluorescence tests were positive or negative. Of 53 sera containing antibody to intrinsic factor, 46/53 (87%) reacted to gastric H/K ATPase by ELISA. Taken together, the data indicates an enhanced detection rate by ELISA over immunofluorescence and validates it as a robust diagnostic assay for parietal cell antibody. As parietal cell antibody marks asymptomatic autoimmune gastritis that may progress to end stage gastric atrophy and haematological complications, and as autoimmune gastritis is associated with autoimmune thyroiditic and type 1 diabetes mellitus, early detection of parietal cell antibody by a sensitive ELISA will enable early follow-up of at risk subjects.

Corpus predominant gastritis: what does it mean?

PURPOSE OF REVIEW: To summarize this year's relevant literature on the causes and mechanisms of autoimmune gastritis. RECENT FINDINGS: It is increasingly recognized that parietal cell antibodies, previously assumed exclusive to autoimmune gastritis, are associated with Helicobacter pylori infection. Successful H. pylori eradication with antibiotic treatment decreases antiparietal cell antibodies. Interestingly, vitamin B(12) deficiency, previously associated with autoimmune gastritis, is increasingly described in the elderly, irrespective of H. pylori status. Autoimmune gastritis that mostly affects patients of Scandinavian descent, was reported this year from China, and corpus predominant gastritis (autoimmune associated) was reported from Japan. It is difficult to evaluate the role played by genetics, increased use of proton pump inhibitors, and H. pylori infection, as current patient work-up does not regularly include screening for parietal cell and intrinsic-factor antibodies. As these clinicopathologic changes are seen in both H. pylori-positive patients, and in H. pylori-naïve patients, the debate continues for mechanisms involved in H. pylori-naïve patients. SUMMARY: The clinical features commonly associated with autoimmune gastritis are increasingly seen in the elderly, irrespective of H. pylori status. Though some patients are genetically predisposed, long-term proton pump inhibitor use increases the prevalence of clinicopathologic features irrespective of genetic tendency.

Comparison of clinical and electrodiagnostic features in B12 deficiency neurological syndromes with and without antiparietal cell antibodies.

BACKGROUND AND AIMS: This study was undertaken to compare the clinical and electrodiagnostic (Edx) features in autoimmune and nutritional vitamin B12 deficiency neurological syndromes. METHODS: Consecutive patients with vitamin B12 deficiency neurological syndromes were evaluated and blood counts, red blood cell indices, serum chemistry, thyroid function, HIV serology, antiparietal cell antibody (APCA), serum B12, bone marrow and spinal MRI assessed. EDx studies included nerve conduction, tibial somatosensory (SEP) and motor evoked potential (MEP) to the tibialis anterior, and visual evoked potential (VEP). The results were compared between APCA positive and negative groups. RESULTS: 57 patients aged 17-80 years (mean 45.3) were studied; 48 were vegetarians. The presenting clinical syndromes were myeloneuropathy in 25, myelopathy in 14, myeloneuroencephalopathy in 13, myeloencephalopathy in four and behavioural abnormality only in one patient. Spinal MRI in 47 patients revealed posterior spinal cord hyperintensity in 21 and cord atrophy in six. Nerve conduction was abnormal in 15%, MEP in 56.6%, SEP in 87.3% and VEP in 63.6% of patients. At 3 months, 31 patients had complete, 11 partial and three poor recovery. APCA was positive in 49% of patients. There was no difference in clinical, MRI or Edx findings or outcome between the APCA positive and negative groups. CONCLUSION: APCA was positive in 49% of patients with B12 deficiency neurological syndrome but their clinical, MRI and Edx changes were not different from the APCA negative group. Neurological manifestations may be caused by B12 deficiency itself rather than the underlying cause.

[Oral treatment of vitamin B12 deficiency in subacute combined degeneration]. / Orale Vitamin-B12-Substitution bei funikulärer Myelose.

Vitamin B12 deficiency due to malnutrition or malabsorption may lead to pernicious anemia and neurological disorders. Although randomized prospective studies have shown that pernicious anemia can be safely treated with oral vitamin B12 even in the absence of intrinsic factor, it is still common practice to treat patients with neurological symptoms with intramuscular cyancobalamin injections. We report the successful oral treatment of subacute combined degeneration of the spinal cord in a 24-year-old woman closely monitored clinically with MRI and plasma levels of vitamin B12, homocysteine, and methylmalonic acid. We suggest monitored oral substitution therapy as first-line therapy for neurological disorders related to vitamin B12 deficiency.