Drugs acting on the renin-angiotensin-aldosterone system (RAAS) and deaths of COVID-19 patients: a systematic review and meta-analysis of observational studies.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARBs) are two of the most commonly used antihypertensive drugs acting on the renin-angiotensin-aldosterone system (RAAS). Previous research has shown that RAAS inhibitors increase the expression of angiotensin-converting enzyme, a cellular receptor for the severe acute respiratory syndrome coronavirus 2, raising concerns that the use of ACEi and ARBs in hypertensive patients may increase COVID-19 patient mortality. Therefore, the main aim of the current study was to find out the role of drugs acting on RAAS, particularly ACEi/ARBs in the deaths of COVID-19 patients. RESULTS: In total, 68 studies were found to be appropriate, reporting a total of 128,078 subjects. The odds ratio was found to be 1.14 [0.95, 1.36], which indicates the non-significant association of ACEi/ARBs with mortality of COVID-19 patients. Further, the association of individual ACEi/ARBs with mortality of COVID-19 patients was also found non-significant. The sensitivity analysis results have shown no significant effect of outliers on the outcome. CONCLUSIONS: Based on available evidence, ACEi/ARB were not significantly associated with deaths of COVID-19 patients.

Modulation of the immune response and infection pattern to Leishmania donovani in visceral leishmaniasis due to arsenic exposure: An in vitro study.

The arsenic contamination of ground water in visceral leishmaniasis (VL) endemic areas in Bihar, India leads to human exposure through drinking water. Possibly, the consumed arsenic (As) accumulates in the tissues of VL patients, who subsequently internalize intracellular amastigotes to confer resistance against chemotherapy to the parasite, leading to modulation in the host's immune response. This hypothesis appears to be consistent with the in vitro findings that in arsenic-exposed parasites, the mitochondrial membrane potential became depolarized, whereas the reduced thiol and lactate production was overexpressed with enhanced glucose consumption; therefore, the reduced thiol possibly supports an immunosuppressive state in the host cells. This observation was well supported by the down-regulated expression of pro-inflammatory cytokines (IL-2, IL-12, IFN-γ, and TNF-α) with a suppressed anti-leishmanial function of macrophage (NO, ROS). In contrast, the pathophysiological mechanism of VL has received ample support by the promotion of Th2 cytokines (IL-4 and IL-10) in the presence of arsenic-exposed Leishmania parasites (LdAS). Dysfunction of mitochondria and the overexpression of lactate production raise the possibility of the Warburg effect being operative through the up-regulation of glucose consumption by parasites to enhance the energy production, possibly augmenting virulence. Therefore, we surmise from our data that arsenic exposure to Leishmania donovani modulates the immune response and infection pattern by impairing parasite function, which may affect the anti-leishmanial effect in VL.

Exploring new immunological insight on SP15 (∼14 kDa) family protein in saliva of Indian sand-fly (Phlebotomus argentipes) in experimental visceral leishmaniasis.

Visceral leishmaniasis (VL) is a disease caused by protozoan species of the genus Leishmania and is transmitted through bites from the Phlebotomus sand fly; it is associated with considerable morbidity and mortality in many parts of world, including India. Reports on the protective role played by saliva proteins of Lutozomyia longipalpis, Phlebotomus papatasi and Phlebotomus duboscqi. are available. However, no studies have explored the salivary proteins of P. argentipes, which is the known proven vector for the transmission of VL in the Indian sub-continent. Herein we revealed the presence of two proteins of 14.2 and one protein of 13.6 kDa in Indian strain P. argentipes which is absolute identical to previously reported protein of SP15 family (PagSP01, PagSP02 and PagSP07) of P. argentipes of NIH colony, USA. In an experimental study on P. argentipes from Bihar, India, we demonstrated that a strong humoral and cellular immune response was triggered to reduce the concomitant Leishmania load in groups of immunized mice. The immunized group produced a considerable amount of IgG antibodies, and their splenocytes generated TH1 cytokines (IL-12, IFN-γ) with the support of delayed-type hypersensitivity (DTH) reactivity in such mice at the challenged site. We summarize from our data that some identical proteins to previous from SP15 family protein of 14.2 and 13.6 kDa molecular size, derived from Indian P. argentipes and reported its first time, can also be significant in resolution of VL infection after modulation of host protective T cell response in VL.

Direct evidence for role of anti-saliva antibodies against salivary gland homogenate of P. argentipes in modulation of protective Th1-immune response against Leishmania donovani.

Currently the main concerns regarding control of visceral leishmaniasis (VL) caused by L. donovani are immunosuppression, relating toxicity of anti-leishmanial drug and little development in appropriate vaccine and vector (P. argentipes) control. Reports available from ex-vivo studies reflect significance of vector salivary gland homogenate (SGH) in reverting immunosuppression of infected VL subjects and as such the immunogenic nature of SGH can be a strategy to modulate immune system and anti-leishmanial function to enable immune response to control the disease. Several related studies also identified a better utility of vector anti-saliva antibodies in achieving such effects by an adoptive transfer approach instead of direct stimulation with SGH protein. However, conclusive evidences on VL cases are far beyond satisfactory to suggest role of SGH into modulation of host immune response in VL subjects in India. This study was under taken to make comparison on change in cytokines (TH1 and TH2) response pattern and anti-leishmanial macrophage (Mϕ) function following stimulation of their PBMCS with SGH protein derived from P. argentipes sand fly vector for VL or anti SGH antibodies raised in rabbit. This study reports for the first time that L. donovani sensitized healthy subject demonstrates an up-regulated Interferon-γ (TH1) and down regulate Interleukin-10 (TH2) production following stimulation of their PBMCs by P. argentipes anti-saliva antibodies accompanied with an improvement in anti-leishmanial Mϕ function for nitric oxide (NO) production. Subsequent experiments suggest that P. argentipes based anti-SGH antibodies when used to stimulate LD infected PBMCs in healthy subjects resulted in better clearance of Leishmania amastigotes load compare to SGH protein. Possibly the immunogenic components of anti-saliva an antibody maintains the level of protective cytokine (INF-γ) and seems to restrict the infection by host protection by vector saliva.

Degree of anemia correlates with increased utilization of heme by Leishmania donovani parasites in visceral leishmaniasis.

Anemia in kala-azar patients is a serious problem. The present study has addressed this problem with the hypothesis that as the Leishmania parasite is completely devoid of heme biosynthetic pathway, therefore the excessive use of heme by the parasites in the human patients can be one of the possible reason of anemia. We investigated that whether, the inability of Leishmania donovani to synthesize heme, can enforce Leishmania parasite to utilize heme derived from host sources in Indian KA patients. Patients had higher tendency of their macrophages to bind with Hb which was pronounced after sensitization with drug resistant Leishmania strain compared to sensitive.

Mouse lymphoma thymidine kinase gene mutation assay: meeting of the International Workshop on Genotoxicity Testing, San Francisco, 2005, recommendations for 24-h treatment.

The Mouse Lymphoma Assay (MLA) Workgroup of the International Workshop on Genotoxicity Testing (IWGT), comprised of experts from Japan, Europe and the United States, met on September 9, 2005, in San Francisco, CA, USA. This meeting of the MLA Workgroup was devoted to reaching a consensus on issues involved with 24-h treatment. Recommendations were made concerning the acceptable values for the negative/solvent control (mutant frequency, cloning efficiency and suspension growth) and the criteria to define an acceptable positive control response. Consensus was also reached concerning the use of the global evaluation factor (GEF) and appropriate statistical trend analysis to define positive and negative responses for the 24-h treatment. The Workgroup agreed to continue their support of the International Committee on Harmonization (ICH) recommendation that the MLA assay should include a 24-h treatment (without S-9) in those situations where the short treatment (3-4 h) gives negative results.

Mouse lymphoma thymidine kinase gene mutation assay: follow-up meeting of the International Workshop on Genotoxicity Testing--Aberdeen, Scotland, 2003--Assay acceptance criteria, positive controls, and data evaluation.

The Mouse Lymphoma Assay (MLA) Workgroup of the International Workshop on Genotoxicity Testing (IWGT), comprised of experts from Japan, Europe, and the United States, met on August 29, 2003, in Aberdeen, Scotland, United Kingdom. This meeting of the MLA Workgroup was devoted to reaching a consensus on the appropriate approach to data evaluation and on acceptance criteria for both the positive and negative/vehicle controls. The Workgroup reached consensus on the acceptance criteria for both the agar and microwell versions of the MLA. Recommendations include acceptable ranges for mutant frequency, cloning efficiency, and suspension growth of the negative/vehicle controls and on criteria to define an acceptable positive control response. The recommendation for the determination of a positive/negative test chemical response includes both the requirement that the response exceeds a defined value [the global evaluation factor (GEF)] and that there also be a positive dose-response (evaluated by an appropriate statistical method).