Humanized mouse model for vaccine evaluation: an overview.

Animal models are essential in medical research for testing drugs and vaccines. These models differ from humans in various respects, so their results are not directly translatable in humans. To address this issue, humanized mice engrafted with functional human cells or tissue can be helpful. We propose using humanized mice that support the engraftment of human hematopoietic stem cells (HSCs) without irradiation to evaluate vaccines that influence patient immunity. For infectious diseases, several types of antigens and adjuvants have been developed and evaluated for vaccination. Peptide vaccines are generally used for their capability to fight cancer and infectious diseases. Evaluation of adjuvants is necessary as they induce inflammation, which is effective for an enhanced immune response but causes adverse effects in some individuals. A trial can be done on humanized mice to check the immunogenicity of a particular adjuvant and peptide combination. Messenger RNA has also emerged as a potential vaccine against viruses. These vaccines need to be tested with human immune cells because they work by producing a particular peptide of the pathogen. Humanized mice with human HSCs that can produce both myeloid and lymphoid cells show a similar immune response that these vaccines will produce in a patient.

Th17 overexpression in severe COVID-19: a prospective observational study.

INTRODUCTION: The objective of the study was to determine T-cell subtypes, Natural Killer cell activity and cytokines in COVID-19 patients with mild to moderate disease and compare them between patients who had recovered and those who had progressed to severe disease. METHODS: Peripheral blood samples of COVID-19 patients were collected at the time of hospital admission and after one week. These samples were analysed for interleukins (IL-6, IL-17a) using chemiluminescence ELISA. The T-cell subsets (T naïve, T regulatory, Th17, Th1, Th2, CD8+ T cells] were studied using flow cytometry. Mild, moderate and severe COVID-19 are defined as per CDC guidelines. RESULTS: Nineteen COVID-19-positive patients were enrolled between June 2020 to December 2021. Nine had mild COVID-19 and 10 had moderate COVID-19 at recruitment. All mild cases recovered without progression to severe disease, while five patients from the moderate group progressed to severe disease. Overall, there is a decrease in lymphocyte count in patients with moderate-severe disease, but the ratio of Th17 [5.91 (2.69-12.01)] was higher compared to Th1 [1.12 (0.27-3.13)] and Th2[2.34 (2-3.5)]. The high baseline level of IL-6 observed in patients with moderate disease leads to the proliferation of more Th17 type of CD4+ T-cells(p=0.002) and suppression of Treg cells. A higher Th17 subset leads to neutrophilic inflammation in patients with severe COVID-19. CONCLUSION: Interpretation conclusions: Higher baseline IL-6 leads to depletion of regulatory T-cells, Th1 Th2 CD4 cells. IL-6 leads to the proliferation of Th17 type of CD4+ subsets in moderate COVID-19. Higher Th17 cells in moderate COVID-19 patients lead to the production of IL-17a, which may result in intense neutrophilic inflammatory response and cytokine storm.

Outcomes of multisystem inflammatory syndrome in children temporally related to COVID-19: a longitudinal study.

To study the clinical, laboratory characteristics and outcomes of multisystem inflammatory syndrome in children (MIS-C) temporally related to coronavirus disease 2019 (COVID-19) in a resource-limited setting. All children meeting the World Health Organization case definition of MIS-C were prospectively enrolled. Baseline clinical and laboratory parameters were compared between survivors and non-survivors. Enrolled subjects were followed up for 4-6 weeks for evaluation of cardiac outcomes using echocardiography. The statistical data were analyzed using the stata-12 software. Thirty-one children with MIS-C were enrolled in an 11-month period. Twelve children had preexisting chronic systemic comorbidity. Fever was a universal finding; gastrointestinal and respiratory manifestations were noted in 70.9% and 64.3%, respectively, while 57.1% had a skin rash. Fifty-eight percent of children presented with shock, and 22.5% required mechanical ventilation. HSP like rash, gangrene and arthritis were uncommon clinical observations.The median duration of hospital stay was 9 (6.5-18.5) days: four children with preexisting comorbidities succumbed to the illness. The serum ferritin levels (ng/ml) [median (IQR)] were significantly higher in non-survivors as compared to survivors [1061 (581, 2750) vs 309.5 (140, 720.08), p value = 0.045]. Six patients had coronary artery involvement; five recovered during follow-up, while one was still admitted. Twenty-six children received immunomodulatory drugs, and five improved without immunomodulation. The choice of immunomodulation (steroids or intravenous immunoglobulin) did not affect the outcome. Most children with MIS-C present with acute hemodynamic and respiratory symptoms.The outcome is favorable in children without preexisting comorbidities.Raised ferritin level may be a poor prognostic marker. The coronary outcomes at follow-up were reassuring.

T372R Mutation Status in Yin Yang 1 Gene in Insulinoma Patients.

Insulinomas are rare pancreatic neuroendocrine tumors. The genetic causes underlying insulinoma are still being investigated. Recently, 3 independent studies reported a recurrent somatic mutation in YY1 gene (C>G; Thr372Arg) among insulinoma patients belonging to Chinese and Western Caucasian populations, which was found to increase insulin secretion by ß-cells. However, the status of this key gene variation remains unknown in patients of other ethnicities. We, therefore, screened Indian sporadic insulinoma patients for YY1 T372R mutation in the present study. Seventeen patients diagnosed with insulinoma were recruited retrospectively and their records of family history and clinical parameters were collected. Formalin-fixed paraffin-embedded tumor tissues were used to extract genomic DNA, which was subjected to PCR amplification of YY1 exon 5, followed by Sanger sequencing. Nucleotide sequences thus obtained were aligned against the documented sequence of YY1 exon 5. We found absence of C to G mutation at YY1 codon 372 in all 17 (100%) insulinoma tissues analyzed. On comparison with the mutation frequency observed in the Chinese patients, our results point to genetic heterogeneity in the pathogenesis of insulinoma. This is the first report on the status of YY1 T372R in insulinoma cases of Indian origin. This also warrants analysis of other documented as well as novel mutations in genes in insulinoma tumorigenesis.

Reticulate Pigmentation Associated with Scarring Alopecia in an Elderly Woman: An Unusual Manifestation of Lichen Planus Pigmentosus.

A 70-year-old woman presented with generalized reticulate pigmentation, scarring alopecia, and few discrete, violaceous plaques over the trunk and forearm. Dermoscopic evaluation of the reticulate plaque showed reticulate hyperpigmentation with multiple telangiectasias, and skin biopsy showed lichenoid interface dermatitis with marked pigment incontinence. Thus, a final diagnosis of poikiloderma due to lichen planus pigmentosus was considered.