Relaxed peripheral tolerance drives broad de novo autoreactivity in severe COVID-19

An emerging feature of COVID-19 is the identification of autoreactivity in patients with severe disease that may contribute to disease pathology, however the origin and resolution of these responses remain unclear. Previously, we identified strong extrafollicular B cell activation as a shared immune response feature between both severe COVID-19 and patients with advanced rheumatic disease. In autoimmune settings, this pathway is associated with relaxed peripheral tolerance in the antibody secreting cell compartment and the generation of de novo autoreactive responses. Investigating these responses in COVID-19, we performed single-cell repertoire analysis on 7 patients with severe disease. In these patients, we identify the expansion of a low-mutation IgG1 fraction of the antibody secreting cell compartment that are not memory derived, display low levels of selective pressure, and are enriched for autoreactivity-prone IGHV4-34 expression. Within this compartment, we identify B cell lineages that display specificity to both SARS-CoV-2 and autoantigens, including pathogenic autoantibodies against glomerular basement membrane, and describe progressive, broad, clinically relevant autoreactivity within these patients correlated with disease severity. Importantly, we identify anti-carbamylated protein responses as a common hallmark and candidate biomarker of broken peripheral tolerance in severe COVID-19. Finally, we identify the contraction of this pathway upon recovery, and re-establishment of tolerance standards coupled with a concomitant loss of acute-derived ASCs irrespective of antigen specificity. In total, this study reveals the origins, breadth, and resolution of acute-phase autoreactivity in severe COVID-19, with significant implications in both early interventions and potential treatment of patients with post-COVID sequelae.

One-Stop Serum Assay Identifies COVID-19 Disease Severity and Vaccination Responses

SARS-CoV-2 has caused over 100,000,000 cases and almost 2,500,000 deaths globally. Comprehensive assessment of the multifaceted antiviral Ab response is critical for diagnosis, differentiation of severity, and characterization of long-term immunity, especially as COVID-19 vaccines become available. Severe disease is associated with early, massive plasmablast responses. We developed a multiplex immunoassay from serum/plasma of acutely infected and convalescent COVID-19 patients and prepandemic and postpandemic healthy adults. We measured IgA, IgG, and/or IgM against SARS-CoV-2 nucleocapsid (N), spike domain 1 (S1), S1-receptor binding domain (RBD) and S1-N-terminal domain. For diagnosis, the combined [IgA + IgG + IgM] or IgG levels measured for N, S1, and S1-RBD yielded area under the curve values ≥0.90. Virus-specific Ig levels were higher in patients with severe/critical compared with mild/moderate infections. A strong prozone effect was observed in sera from severe/critical patients-a possible source of underestimated Ab concentrations in previous studies. Mild/moderate patients displayed a slower rise and lower peak in anti-N and anti-S1 IgG levels compared with severe/critical patients, but anti-RBD IgG and neutralization responses reached similar levels at 2-4 mo after symptom onset. Measurement of the Ab responses in sera from 18 COVID-19-vaccinated patients revealed specific responses for the S1-RBD Ag and none against the N protein. This highly sensitive, SARS-CoV-2-specific, multiplex immunoassay measures the magnitude, complexity, and kinetics of the Ab response and can distinguish serum Ab responses from natural SARS-CoV-2 infections (mild or severe) and mRNA COVID-19 vaccines.

Elevated SARS-CoV-2 Antibodies Distinguish Severe Disease in Early COVID-19 Infection

Background

SARS-CoV-2 has caused over 36,000,000 cases and 1,000,000 deaths globally. Comprehensive assessment of the multifaceted anti-viral antibody response is critical for diagnosis, differentiation of severe disease, and characterization of long-term immunity. Initial observations suggest that severe disease is associated with higher antibody levels and greater B cell/plasmablast responses. A multi-antigen immunoassay to define the complex serological landscape and clinical associations is essential.

Methods

We developed a multiplex immunoassay and evaluated serum/plasma from adults with RT-PCR-confirmed SARS-CoV-2 infections during acute illness (N=52) and convalescence (N=69); and pre-pandemic (N=106) and post-pandemic (N=137) healthy adults. We measured IgA, IgG, and/or IgM against SARS-CoV-2 Nucleocapsid (N), Spike domain 1 (S1), receptor binding domain (S1-RBD) and S1-N-terminal domain (S1-NTD).

Results

To diagnose infection, the combined [IgA+IgG+IgM] or IgG for N, S1, and S1-RBD yielded AUC values -0.90 by ROC curves. From days 6-30 post-symptom onset, the levels of antigen-specific IgG, IgA or [IgA+IgG+IgM] were higher in patients with severe/critical compared to mild/moderate infections. Consistent with excessive concentrations of antibodies, a strong prozone effect was observed in sera from severe/critical patients. Notably, mild/moderate patients displayed a slower rise and lower peak in anti-N and anti-S1 IgG levels compared to severe/critical patients, but anti-RBD IgG and neutralization responses reached similar levels at 2-4 months.

Conclusion

This SARS-CoV-2 multiplex immunoassay measures the magnitude, complexity and kinetics of the antibody response against multiple viral antigens. The IgG and combined-isotype SARS-CoV-2 multiplex assay is highly diagnostic of acute and convalescent disease and may prognosticate severity early in illness.

One Sentence Summary

In contrast to patients with moderate infections, those with severe COVID-19 develop prominent, early antibody responses to S1 and N proteins.

Extrafollicular B cell responses correlate with neutralizing antibodies and morbidity in COVID-19

A wide spectrum of clinical manifestations has become a hallmark of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) COVID-19 pandemic, although the immunological underpinnings of diverse disease outcomes remain to be defined. We performed detailed characterization of B cell responses through high-dimensional flow cytometry to reveal substantial heterogeneity in both effector and immature populations. More notably, critically ill patients displayed hallmarks of extrafollicular B cell activation and shared B cell repertoire features previously described in autoimmune settings. Extrafollicular activation correlated strongly with large antibody-secreting cell expansion and early production of high concentrations of SARS-CoV-2-specific neutralizing antibodies. Yet, these patients had severe disease with elevated inflammatory biomarkers, multiorgan failure and death. Overall, these findings strongly suggest a pathogenic role for immune activation in subsets of patients with COVID-19. Our study provides further evidence that targeted immunomodulatory therapy may be beneficial in specific patient subpopulations and can be informed by careful immune profiling.

Adenosine deaminase levels in cerebrospinal fluid in tuberculosis and bacterial meningitis

Adenosine deaminase activity was measured in cerebrospinal fluid of patients with confirmed tuberculous and bacterial meningitis. The values were compared with those of control subjects without meningitis. A statistically significant increase in the level of this enzyme was noted in the two types of meningitis, but no definite demarcation in the levels was observed between the two types. Therefore increases in adenosine deaminase activity may not be of such diagnostic significance as reported elsewhere.

Effects of feeding low protein diet with and without leucine supplementation on protein status of lactating females and their pups

Female rats were fed low protein diet (10% casein) either as such or supplemented with 3% leucine during pregnancy and lactation. Changes in litter size and the survival rate, growth and protein status of the pups were noted. The milk yield and hepatic and mammary gland protein status of the mothers were also studied. Feeding low protein diet reduced litter size, increased their mortality and resulted in poor growth of the pups. It also resulted in poor hepatic and mammary gland protein status of the mothers, as well as reduced their milk yield. On adding 3% leucine to 10% casein in the diet, the changes observed in the low protein group, did not alter in any manner.

Effect of vitamin D supplementation during pregnancy on the neonatal skeletal growth in the rat

In rats on normal intakes of calcium, phosphorus and vitamin D3, 3,000 and 7,500 IU of vitamin D3 were injected on the 10th day of pregnancy and the pups were investigated for the skeletal growth on 28th day of age. Compared to controls, the pups in the supplemented groups showed significantly greater dry weight and ash weight of the tibiae. However, the ash weight/dry bone weight ratios in the supplemented groups were not different from controls. Histological examination of the upper ends of decalcified tibiae and plasma calcium estimations revealed no abnormality in any group. The results suggest that vitamin D3 supplementation in pregnancy enhances the skeletal growth of the pups which involves both the organic and inorganic components.

Adrenocortical involvement in aluminium phosphide poisoning

The effect of aluminium phosphide (AlP) which is a systemic poison on the adrenal cortex was studied in 30 patients of AlP poisoning. A significant rise in the plasma cortisol level (greater than 1048 nmol/l) was observed in the twenty patients. Mortality was 50 per cent. Autopsy study could be undertaken only in 10 patients. Histopathology showed mild to moderate changes. In the rest (10 patients), the adrenal cortex was critically involved and the cortisol level failed to rise beyond normal levels (less than 690 nmol/l). The histopathology revealed severe changes (complete lipid depletion, haemorrhage, necrosis etc.) and all these patients died. In the critically ill patients, the cortisol levels remained low because of severe adreno-cortical involvement. The changes in the adrenal cortex could be due to shock or to cellular toxic effect of phosphine. The histopathological changes in various viscera showed congestion, edema and cellular infiltration. In the heart, there were patchy areas of necrosis, while the liver showed fatty changes and the lungs showed, in addition areas of gray/red hepatization. There was no adrenal apoplexy or extensive haemorrhage that could explain shock in these patients. Cardiogenic shock could not be confirmed due to lack of facilities for haemodynamic monitoring, but there was histopathological evidence in support of cardiovascular shock.

Effect of vitamin D administration during pregnancy on neonatal growth in the rat

Groups of rats on commercial diet were injected 3,000 IU (group 2) and 7,500 IU (group 3) of vitamin D3 on the 10th day of pregnancy. Compared to control pups (group 1), the pups in group 2 and 3 weighed significantly more on the 10th, 20th and 28th day of age. At 28th day of age, study of the gastrocnemius muscle revealed significantly greater organ weight, protein, DNA and RNA contents, protein/DNA and RNA/DNA ratios in group 2 and 3 pups than in controls. In the liver, whereas all these indices were significantly increased in group 3 pups, only protein/DNA and RNA/DNA ratios were significantly increased in group 2 pups. Brain weight, its RNA content and RNA/DNA ratio were significantly greater in group 2 and 3 pups than in controls. The results suggest that vitamin D administration in pregnancy promotes soft tissue growth in the pups by enhancing cellular proliferation and hypertrophy.

Adenosine-deaminase (ADA) activity in Psoriasis (A Preliminary Study)

Study of adenosine-deaminase activity 'in 23 patients hav-mg psoriasis compared with an equal number of healthy controls revealed significantly high ADA-activity in the psotiatic patients.

Serum immunoglobulin E levels in patients with head and neck cancer

Serum immunoglobulin E levels were estimated in 50 patients with head and neck cancer and in 25 controls. Mean serum IgE value was significantly higher in patients with various sites of cancer in the head and neck region other than carcinoma of the tonsil. The levels increased with advancement in the stage of cancer. There was, however, no difference in mean serum IgE value with respect to the character of the lesion, to the histopathological type of growth or to radiotherapy. In patients with carcinoma of the tonsil, the mean serum IgE concentration was significantly lowered.

Effect of acute environmental heat stress on urinary water and electrolyte excretion in the rat

Plasma cortisol and urinary excretion of water, sodium, potassium, calcium and magnesium have been studied in the rat after application of heat stress. There was a significant increase in plasma cortisol level after exposure to heat. During heat stress complete cessation of urine formation was observed. In the next 30 min there was statistically significant increase in the urinary excretion of water, sodium and calcium but not of potassium and magnesium. Urinary calcium/magnesium ratio was also significantly elevated. The increase in urinary water and electrolyte excretion seemed to be mediated through prostaglandins since it could be abolished by administration of indomethacin prior to the application of heat stress. On the basis of these results, the possible role of heat stress in the genesis of urolithiasis has been discussed.

Adenosine deaminase activity in leprosy (a preliminary study)

Adenosine deaminase (ADA) activity was studied in 25 patients having different types of leprosy and 25 healthy volunteer as control. There was definite rise of ADA activity in BL (72.9 +/- 6.85), LL (56.7 +/- 3.35) and BT (39.1 +/- 8.28) which was statistically significant when compared to ADA activity in healthy control (9.7 +/- 0.53).

Effect of dietary restriction with and without leucine supplementation on hepatic protein status in rats

In the present study effect of dietary restriction with and without leucine supplementation was observed on body and liver weights, and liver protein status, in adult rats. Animals were fed on two diets ad lib or were on 50 per cent and 25 per cent intakes. Dietary restriction resulted in loss of body and liver weights, hepatic protein, free-alpha-amino nitrogen and RNA contents and liver cell size (liver weight/DNA ratio). When compared with the control group, the decrease in these parameters was more in the dietary restricted leucine supplemented group. However, hepatic DNA content was not changed with the change in dietary regimen. The results suggest that leucine supplementation with dietary restriction may be more harmful for the animal than dietary restriction alone.

Serum enzymes in head and neck cancer III

Serum adenosine deaminase (ADA) levels were estimated in a group of 40 patients with head and neck cancer. The mean value was significantly higher in patients compared to controls. The increase was higher in cases of ulcerative growths than of proliferative growths, and activity was increased with advancement in the stage of the cancer. After radiotherapy, a gradual and significant decrease in serum ADA activity was observed.

Evaluation of enzymes in serum and cerebrospinal fluid in cases of cerebrovascular accidents

Gamma glutamyl transpeptidase (GGTP), glutamic oxaloacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) were measured serially in the serum and cerebrospinal fluid (CSF) of 22 patients with fresh stroke and an equal number of age- and sex-matched healthy control subjects. It was observed that levels of these enzymes in the CSF of control subjects were very low but were significantly elevated (p less than 0.001) in both serum and CSF in patients with stroke. The elevation was greater in the CSF than in the serum and was maximum during the first four days of stroke. Thereafter, the enzymatic activity declined. Of all these enzymes, GGTP in CSF correlated best with the clinical picture. It was possible to differentiate between the ischemic and hemorrhagic type of stroke on the basis of CSF levels of GGTP (greater than 60.0 units in hemorrhagic stroke). There was no correlation between GGTP levels in CSF and serum or among GOT, GPT, and GGTP in CSF. It can be concluded, therefore, that estimation of GGTP in CSF is helpful not only in predicting the degree of cerebral damage and functional outcome of the patient following stroke but also in differentiating the type of stroke.

Acute effects of neurogenic stress on urinary electrolyte excretion

Plasma Cortisol and urinary excretion of water, sodium, potassium, calcium and magnesium have been studied in the rat after application of 2 types of neurogenic stress:--(a) tight rubber band tourniquet and (b) electric shock. Plasma cortisol levels increased significantly after application of either type of stress. During both type of stress, there was statistically significant increase in the urinary excretion of water, sodium and calcium but not of potassium and magnesium. Urinary calcium/magnesium ratio was also significantly elevated. The results suggest that stress may be one of the factors involved in the genesis of urolithiasis.

Evaluation of E and EAC rosette-forming cells in patients with thermal injuries

Thermal injuries lead to changes in both the cell-mediated and humoral responses of the patient. This study was undertaken to assess these responses in the post-burn period and also to see if bacterial infection altered these responses. It has been concluded that alterations in the cell-mediated and humoral immune responses following thermal injuries are altered by infection and consequently are also important in the healing process.

Plasmodium berghei: oxidant defense system

Glutathione oxidant defense system protects the erythrocyte from oxidative damage. This defense system was studied in mouse erythrocytes infected with Plasmodium berghei and in isolated parasites. The efficiency of this system was found to be increased in parasitized erythrocytes compared to the normal erythrocytes. The increase in the components of the oxidant defense system in the parasitized cells could result from parasitic addition to these components. This defense system present in the parasite may protect the parasite from oxidative damage and help the parasite in its growth and development.

Biochemical aspects of malabsorption in marasmus: effect of dietary rehabilitation

1. Sixty marasmic children were investigated for the absorption of xylose, proteins and fats. Their duodenal juice samples were also analysed for bile salts and microflora. 2. The marasmic children were then studied in three groups of twenty by allocating them to three different dietary schedules: a high-protein diet (30% of the total energy from protein), a high-fat diet (40% of the total energy from fat) and a high-carbohydrate diet (70% of the total energy from carbohydrate) for 2 weeks and the previous measurements repeated. 3. Whereas the high-fat diet resulted in improved fat absorption, along with an increase in total and conjugated bile acids, and the high-carbohydrate diet led to improved xylose absorption, the diet rich in protein resulted in an improvement in the absorption of all three dietary ingredients. It appears that a high-protein diet improves the overall absorption process by improving the intestinal environment as a whole, while high-carbohydrate and high-fat diets bring about adaptive changes related to the respective absorptive processes.

Glutathione peroxidase activity and reduced glutathione content in erythrocytes of patients with chronic renal failure

Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients may predispose the cells to oxidative damage.

Effect of prolonged starvation and refeeding on fuel metabolism in rats

Body and liver weights, Liver lipids, glycogen, aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and blood glucose levels were determined in starved and starved-refed rats. Decrease in body and liver weights was rapid during the initial stage of starvation and slowed down thereafter. Water was the major liver constituent lost in early fast. Following 10 days of starvation, body weight was reduced by nearly 20%, liver weight 43%, liver glycogen 93% and blood glucose 34%. Liver lipids and the activities of the two transaminases however, were increased by about 30-50%. On refeeding body weight and its water content increased and became nearly double of the initial fasting value on day 2. Blood glucose, liver glycogen, liver lipids and transaminases were significantly altered and got normalised within 5-8 days.

Biochemical aspects of malabsorption in marasmus

Sixty marasmic children and fifteen normal age-matched controls were investigated for the absorption of fats and proteins. Their duodenal juice samples were also analysed for bile salts and microflora. A significant amount of malabsorption, with respect to both the dietary ingredients, was observed in the majority of the marasmic children. The levels of conjugated bile acids in the duodenal juice samples of marasmic children were significantly lower as compared with those of normal controls, while the reverse was true for free bile acids and bacterial counts. Significant correlations were observed between bile acid levels and fat absorption and also between microflora and free bile acids. The pathophysiology of malabsorption in marasmus is discussed in the light of these findings.

E-rosette forming cells (E-RFC) in squamous cell carcinoma of the larynx and laryngopharynx

The percentages of early and late E-RFC were measured in 25 proven cases of squamous cell carcinoma of the larynx and laryngopharynx. Both counts were depressed significantly in the patients compared to the controls (p less than 0.001). There was also a significant correlation of these counts with the severity of the disease, but there was no correlation between the counts and the duration of the disease.

Protein and electrolyte alterations in human senile cataract

Water content, wet and dry weights of the crystalline lens, and protein, free amino acid and electrolyte levels in serum, aqueous humour and lens were determined in patients with nuclear senile cataract and at the different stages of the maturation of cortical cataract. In immature senile cortical cataract wet weight and sodium contents of the lens were significantly higher while potassium levels were low when compared with the nuclear cataract. With the maturation of cortical cataract water content, wet weight and sodium concentrations of the crystalline lens significantly increased while protein, free amino acid and potassium levels decreased. The possible role of these changes in various types of cataracts is discussed.

Effect of dietary restriction with and without excess leucine on hepatic tryptophan oxygenase, 3-hydroxyanthranilate oxygenase and leucine aminotransferase in rats

Tryptophan oxygenase (EC 1.13.1.12), 3-hydroxyanthranilate oxygenase (EC 1.13.1.6) and leucine aminotransferase (EC 2.6.1.6) activities were determined in livers of rats subjected to different dietary restrictions, with and without excess leucine. The activities of all three enzymes were significantly increased with undernutrition in animals not receiving excess leucine. Excess leucine with moderate undernutrition (50% ad libitum intake) further induced this effect while excess leucine with severe restriction (25% ad libitum intake) acted in the opposite direction.

Effect of excess leucine on tryptophan oxygenase, 3-hydroxyanthranilate oxygenase and leucine aminotransferase in livers of young rats

Hepatic tryptophan oxygenase (EC 1.13.1.12) 3-hydroxyanthranilate oxygenase (EC 1.13.1.6) and leucine aminotransferase (EC 2.6.1.6) activities were determined in livers of rat pups of various ages whose mothers were fed on diets with or without excess leucine. Tryptophan oxygenase activity was detectable on the 20th day in both the groups and thereafter increased with age. Low activity of 3-hydroxyanthranilate oxygenase was observed at birth, the levels increased on the 10th day and thereafter remained unaltered on both diets. Leucine aminotransferase activity was highest at birth and thereafter decreased with age. Tryptophan oxygenase and leucine aminotransferase activities were significantly higher at all ages in livers of pups born to mothers given excess leucine in their diet.