Immune response by the human body to SARS-CoV 2 infection

A new virus SARS-CoV2 is responsible for Covid-19. Many existing drugs were tried but failed to treat Covid-19 patients. To begin with our immune system also couldn’t cope with Covid-19, therefore within no time it became pandemic. It is a well-known fact that our body fights against all infections and inflammations through well-organized immune system. The human immune system is made up of individual cells (T and B cells) and proteins as well as entire organs and organ systems. The organs of the immune system include skin and mucous membranes, and the organs of the lymphatic system. The skin and mucous membranes are the first line of defense against germs entering from outside the body and once the infection enter in the organs and tissues lymphatic organs take over. Additionally, here we also described gut bacteria and food to build up immunity. In this way human beings are fight against the new virus SARS-CoV2 infections.

Effect of β-mannanase enzyme supplementation on the morphofunctional state of broiler chickens’ immunocompetent organs

Identifying and eliminating factors that interfere with the nutrient absorption from feed is essential for successful poultry rearing. The nutritional value of feed mixtures used in the poultry industry can be increased by the use of enzyme supplements, in particular β-mannanase (Hemicell), which breaks down the anti-nutrients β-mannans that are present in significant quantities in soy products. For the study, two groups of 50 broiler chickens were formed. In the control group a standard feed mixture from cereals was used, particularly soybeans, and in the experimental group 0.05% β-mannanase enzyme supplement (Hemicell) in addition to the compound feed was used. Production indicators were established (average daily gain, survival rate, feed costs). On the 15th, 25th and 42nd days of rearing, lymphatic organs (cloacal bursa and spleen) were collected from seven chickens of each group, followed by macro, microscopic and morphometric evaluation. It was found that the addition of an enzyme supplement promotes an increase in the production indicators of poultry rearing, reduces feed use, does not affect the macroscopic characteristics of the lymphatic organs. β-mannanase (Hemicell) contributes to the maintenance of an active morphofunctional state of the cloacal bursa and spleen during the entire period of poultry rearing. This was manifested by high indices of the absolute and relative organ masses, a moderate development degree of tissue components and cloacal bursa histological structures (number, shape and average length of lymphatic nodules, density of lymphocytes in the cortex and medulla) and spleen (number and diameter of lymphatic nodules and periarterioal lymphatic sheaths). In the control group, at all stages of rearing, the morphofunctional state of the bursa was found to be lower and signs of immunosuppression were revealed by the end of the rearing period (a sharp decline in the bursa absolute mass, organ mass index, a decrease in the average length of nodules, change in their shape, thinned cortical layer and delymphotisation). The morphofunctional state of the spleen of chickens from the control group remained high throughout the entire study period. So use of the β-mannanase enzyme supplement (Hemicell) while rearing broiler chickens not only increased the efficiency of their rearing but also contributed to maintaining a high morphological and functional state of the cloacal bursa.

Morphogenesis of limph nodes in Muscovy ducks during early posnatal onthogenesis

The dynamics of mass and linear parameters of lymph nodes of ducks is a direct reflection of structural and functional transformations of their lymphatic parenchyma. The peculiarities of quantitative dynamics of tissue components of peripheral lymphatic organs at early stages of postnatal ontogenesis are to a great extent determined by advanced growth rates of their absolute mass against the background of sharp increase of their antigenic stimulation intensity. Parenchyma of lymph nodes of newborn ducklings is characterized by relatively low degree of differentiation and is represented by diffuse lymphatic tissue with no pronounced signs of its division into separate functional zones. Internally, the lymphatic channel is represented by only two lymphatic sinuses - the central one, which is located in the central part of the organ and occupies a large relative area and a discrete edge sinus, which borders on the node capsule and has a much smaller relative area and, accordingly, is located at its periphery. The organ parenchyma is a diffuse cluster of stromal and lymphatic cells in the enlarged lymphatic vessel between the central (inner) and edge (outer) lymphatic sinuses, without signs of its division into cortical and brain matter. Among the lymphatic tissue of the lymph node, reticular stroma cells and the population of small lymphocytes have the largest relative amount.

Pathological changes in the lungs and lymphatic organs of 12 COVID-19 autopsy cases

Systematic autopsy and comprehensive pathological analyses of COVID-19 decedents should provide insights into the disease characteristics and facilitate the development of novel therapeutics. In this study, we report the autopsy findings from the lungs and lymphatic organs of 12 COVID-19 decedents—findings that evaluated histopathological changes, immune cell signature and inflammatory factor expression in the lungs, spleen and lymph nodes. Here we show that the major pulmonary alterations included diffuse alveolar damage, interstitial fibrosis and exudative inflammation featured with extensive serous and fibrin exudates, macrophage infiltration and abundant production of inflammatory factors (IL-6, IP-10, TNFα and IL-1β). The spleen and hilar lymph nodes contained lesions with tissue structure disruption and immune cell dysregulation, including lymphopenia and macrophage accumulation. These findings provide pathological evidence that links injuries of the lungs and lymphatic organs with the fatal systematic respiratory and immune malfunction in critically ill COVID-19 patients.

IgM+ and IgT+ B Cell Traffic to the Heart during SAV Infection in Atlantic Salmon

B cells of teleost fish differentiate in the head kidney, and spleen, and either remain in the lymphatic organs or move to the blood and peripheral tissues. There is limited knowledge about piscine B cell traffic to sites of vaccination and infection and their functional roles at these sites. In this work, we examined the traffic of B cells in Atlantic salmon challenged with salmonid alphavirus (SAV). In situ hybridization (RNAScope) showed increased numbers of immunoglobin (Ig)M+ and IgT+ B cells in the heart in response to SAV challenge, with IgM+ B cells being most abundant. An increase in IgT+ B cells was also evident, indicating a role of IgT+ B cells in nonmucosal tissues and systemic viral infections. After infection, B cells were mainly found in the stratum spongiosum of the cardiac ventricle, colocalizing with virus-infected myocardial-like cells. From sequencing the variable region of IgM in the main target organ (heart) and comparing it with a major lymphatic organ (the spleen), co-occurrence in antibody repertoires indicated a transfer of B cells from the spleen to the heart, as well as earlier recruitment of B cells to the heart in vaccinated fish compared to those that were unvaccinated. Transcriptome analyses performed at 21 days post-challenge suggested higher expression of multiple mediators of inflammation and lymphocyte-specific genes in unvaccinated compared to vaccinated fish, in parallel with a massive suppression of genes involved in heart contraction, metabolism, and development of tissue. The adaptive responses to SAV in vaccinated salmon appeared to alleviate the disease. Altogether, these results suggest that migration of B cells from lymphatic organs to sites of infection is an important part of the adaptive immune response of Atlantic salmon to SAV.

IgM’s exit route

In this issue of JEM, Thierry et al. (https://doi.org/10.1084/jem.20180344) demonstrate that, once secreted by freshly activated plasmablasts, IgM leaves the lymph node via the microarchitecture of the fibroblastic reticular cell conduit. This work demonstrates how the very peculiar stromal compartment of lymphatic organs optimizes the systemic distribution of immune effectors.