Quinacrine as a potential treatment for COVID-19 virus infection

A novel coronavirus named severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a current outbreak of infection termed Coronavirus Disease 2019 (COVID-19) by the World Health Organization (WHO). COVID-19 is currently a global pandemic that may cause close to half a billion deaths around the world. Until now, there is no effective treatment for COVID-19. Quinacrine (Qx) has been used since the 1930s as preventive antimalarial compound. It is a recognized small molecule inhibitor of RNA virus replication, with known anti-prion activity, and identified as a potent Ebola virus inhibitor both in vitro and in vivo. Recently, Qx has showed anti-SARS-CoV-2 activity. Herein, we review the potential mechanisms associated with quinacrine as an antiviral compound.

Induction of β-defensins by l-isoleucine as novel immunotherapy in experimental murine tuberculosis

Tuberculosis is a worldwide health problem, and multidrug-resistant (MDR) and extensively multidrug-resistant (XMDR) strains are rapidly emerging and threatening the control of this disease. These problems motivate the search for new treatment strategies. One potential strategy is immunotherapy using cationic anti-microbial peptides. The capacity of l-isoleucine to induce beta-defensin expression and its potential therapeutic efficiency were studied in a mouse model of progressive pulmonary tuberculosis. BALB/c mice were infected with Mycobacterium tuberculosis strain H37Rv or with a MDR clinical isolate by the intratracheal route. After 60 days of infection, when disease was in its progressive phase, mice were treated with 250 µg of intratracheal l-isoleucine every 48 h. Bacillary loads were determined by colony-forming units, protein and cytokine gene expression were determined by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), respectively, and tissue damage was quantified by automated morphometry. Administration of l-isoleucine induced a significant increase of beta-defensins 3 and 4 which was associated with decreased bacillary loads and tissue damage. This was seen in animals infected with the antibiotic-sensitive strain H37Rv and with the MDR clinical isolate. Thus, induction of beta-defensins might be a potential therapy that can aid in the control of this significant infectious disease.

Mycobacterium bovis with different genotypes and from different hosts induce dissimilar immunopathological lesions in a mouse model of tuberculosis

With the hypothesis that genetic variability of Mycobacterium bovis could influence virulence and immunopathology, five M. bovis strains were selected from an epidemiological study in Argentina on the basis of their prevalence in cattle and occurrence in other species. We then determined the virulence and the immunopathology evoked by these strains in a well-characterized mouse model of progressive pulmonary tuberculosis. The reference strain AN5 was used as a control. BALB/c mice infected with this M. bovis reference strain showed 50% survival after 4 months of infection, with moderate bacillary counts in the lung. Two weeks after inoculation, it induced a strong inflammatory response with numerous granulomas and progressive pneumonia. In contrast, strain 04-303, isolated from a wild boar, was the most lethal and its most striking feature was sudden pneumonia with extensive necrosis. Strain 04-302, also isolated from wild boar but with a different spoligotype, induced similar pathology but to a lesser extent. In contrast, strains 534, V2 (both from cattle) and 02-2B (from human) were less virulent, permitting higher survival after 4 months of infection and limited tissue damage. Strain AN5 and the cattle and human isolates induced rapid, high and stable expression of interferon (IFN)-gamma and inducible nitric oxide synthase (iNOS). In contrast, the more virulent strains induced lower expression of IFN-gamma, tumour necrosis factor-alpha and iNOS. Interestingly, these more virulent strains induced very low expression of murine beta defensin 4 (mBD-4); whereas, the control strain AN5 induced progressive expression of this anti-microbial peptide, peaking at day 120. The less virulent strains induced high mBD-4 expression during early infection. Thus, as reported with clinical isolates of M. tuberculosis, M. bovis also showed variable virulence. This variability can be attributed to the induction of a different pattern of immune response.

Expression of cyclooxygenase type 2 in lepromatous and tuberculoid leprosy lesions

BACKGROUND

Leprosy is an infectious disease with two polar forms, tuberculoid leprosy (TL) and lepromatous leprosy (LL), which are dominated by T-helper (Th) 1 and Th2 cells, respectively. High concentrations of prostaglandin E2 produced by the inducible enzyme cyclooxygenase type 2 (COX-2) in LL could inhibit Th1 cytokine production, contributing to T-cell anergy.

OBJECTIVES

To compare the COX-2 expression in LL and TL.

METHODS

Skin biopsies from 40 leprosy patients (LL, n = 20; TL, n = 20) were used to determine by immunohistochemistry and automated morphometry the percentage of COX-2 immunostained cells.

RESULTS

Most COX-2-positive cells were macrophages; their percentages in the inflammatory infiltrate located in the papillary dermis, reticular dermis and periadnexally were significantly higher in LL than TL (P < 0.001 by Student's t-test).

CONCLUSIONS

The high expression of COX-2 in LL may be related to high prostaglandin production contributing to T-cell anergy.

Immunological and pathological comparative analysis between experimental latent tuberculous infection and progressive pulmonary tuberculosis

Mycobacterium tuberculosis produces latent infection or progressive disease. Indeed, latent infection is more common since it occurs in one-third of the world's population. We showed previously, using human material with latent tuberculosis, that mycobacterial DNA can be detected by in situ PCR in a variety of cell types in histologically-normal lung. We therefore sought to establish an experimental model in which this phenomenon could be studied in detail. We report here the establishment of such a model in C57Bl/6 x DBA/2 F1 hybrid mice by the intratracheal injection of low numbers of virulent mycobacteria (4000). Latent infection was characterized by low and stable bacillary counts without death of animals. Histological and immunological study showed granulomas and small patches of alveolitis, with high expression of tumour necrosis factor alpha (TNFalpha), inducible nitiric oxide synthase (iNOS), interleukin 2 (IL-2) and interferon gamma (IFNgamma). In contrast, the intratracheal instillation of high numbers of bacteria (1 x 106) produced progressive disease. These animals started to die after 2 months of infection, with very high bacillary loads, massive pneumonia, falling expression of TNF-alpha and iNOS, and a mixed Th1/Th2 cytokine pattern. In situ PCR to detect mycobacterial DNA revealed that the most common positive cells in latently-infected mice were alveolar and interstitial macrophages located in tuberculous lesions, but, as in latently-infected human lung, positive signals were also seen in bronchial epithelium, endothelial cells and fibroblasts from histologically-normal areas. Our results suggest that latent tuberculosis is induced and maintained by a type 1 cytokine pattern plus TNFalpha, and that mycobacteria persist intracellularly in lung tissue with and without histological evidence of a local immune response.

Increased expression of fas ligand in human tuberculosis and leprosy lesions: a potential novel mechanism of immune evasion in mycobacterial infection

To study the location and mechanism of apoptosis within the human tuberculosis (TB) and leprosy lesions, parallel sections were analyzed for mycobacterial antigens (M.Ag), Fas ligand (FasL), Fas, CD68 and Mac387 by immunohistochemistry, and apoptotic cells by the terminal deoxynucleotidyl-transferase-mediated dUTP-digoxigenin nick end labelling method. Cutaneous leishmaniasis and foreign body granulomas were analyzed for comparison. The heavily infected macrophages in multibacillary TB and leprosy granulomas very strongly expressed FasL, indicating that a mycobacterial infection can induce an increased expression of FasL in a population of infected macrophages, which may protect them from the attack of Fas-expressing lymphocytes. However, macrophages with high levels of leishmania amastigotes did not selectively express FasL, suggesting that this phenomenon is specific for the mycobacteria. Interestingly, in the well-formed TB granulomas, 84% of the multinucleated giant cells strongly expressed FasL. The expression of Fas was weak (34%) or absent. A higher number (33%) of epithelioid cells expressed FasL than Fas (23%). Lymphocytes were scanty among the epithelioid cells. The frequency of apoptotic cells was higher in the epithelioid cells (0.25%) than the mononuclear cells in the mantle zone (0.14%). Thus, the epithelioid cells and the multinucleated giant cells by virtue of the increased expression of FasL may make these granulomas an immune privileged site for mycobacteria.

[Chemokines, a new family of cytokines in inflammatory cell recruitment]

Cell recruitment is a crucial event in the establishment of both acute and chronic inflammatory responses, including acute and delayed type hypersensitivity reactions. Among other significant factors like adhesion molecules, chemokines and its receptors are crucial elements that lead leukocyte migration to the tissues. Chemokines are a large group of peptidic cytokines which have a conserved motif of 4 cisteins. These cistein residues form pairs which permit to classify them in two groups, the alpha and beta subfamilies. In general terms, alpha subfamily has preferential chemotactic activity on granulocytes, and beta subfamily attracts mainly lymphocytes and macrophages. Besides their chemotactic activity, chemokines also participate in some other important biological processes like hematopoiesis, angiogenesis, and anti-tumoral activity. Chemokines also play an important role in certain pathological conditions, for instance in some allergic processes they have an essential role in the pathogenesis. In autoimmune and infectious diseases, this cytokine family is also important as is suggested by the presence of chemokine receptors in rheumatoid arthritis inflammed synovia or the HIV receptor activity that chemokine receptors display which apparently play a significant role in the natural resistance against this infectious agent. Preferential leukocyte recruitment mediated by chemokines is a potential target for pharmacological modulation, which in turn may lead to a novel and efficient types of therapeutic control of inflammatory diseases with diverse etiology.

Dengue virus in the brain of a fatal case of hemorrhagic dengue fever

Neurologic complications associated with dengue fever are in general unusual. However, recent reports evidence more frequent neurologic alterations. In Mexico, neurologic involvement has not been reported in dengue cases. This report demonstrates the detection of dengue virus in the brain of a fatal case of dengue hemorrhagic fever. Serotype 4 was detected by immunohistochemistry and by RT-PCR in the inferior olivary nucleus of medulla and in the granular layer of cerebellum. Immunoreactivity was observed in neurons, astrocytes, microglia and endothelial cells. Our results emphasize the importance of neurologic manifestations in patients with dengue fever.

[Takayasu's arteritis. A seroimmunological test of its relationship to mycobacterial infection]

Takayasu's arteritis is an inflammatory arteritis of unknown origin. It affects the aorta, its main branches and at times the pulmonary artery. Takayasu's arteritis is a worldwide disease, however, there is predilection to affect young women of mongoloid ancestry, therefore most cases do occur in the Far East and Latin America. For more than 50 years a relationship with mycobacterial infection has been sought without definite proof. In this investigation we found a circulating IgG antibody in the sera of Takayasu's arteritis patients, which recognizes a 38 kD glycoprotein of M. tuberculosis. This glycoprotein is an specific antigen in the human immune response against mycobacterial infection.

[Nephropathy in a case of Fabry's disease]

The present communication describes a 22 year-old male with clinical, biochemical and histopathological signs of Fabry's disease (FD). This is the second case of FD reported in Mexico. The main clinical manifestations of this patient were during puberty: intermittent weakness, acroparesthesias and hypohidrosis. At age 21 he developed heavy proteinuria (7-12 g/day) systemic hypertension and moderate renal failure. The kidney biopsy showed the typical alterations described in FD. On light microscopy, the renal pathology showed numerous vacuolated epithelial cells in the glomerular wall, giving them a "foamy" appearance; vacuolization was due to the presence of lipid material within these cells and in the interstitium. In electron microscopy, dense, irregularly shaped osmiophilic, laminated bodies with myelinlike configuration, were seen within the glomerular epithelial cells and in the urinary spaces. The low alfa-galactosidase activity in serum (0.18 nmol/h/mL normal values: 12.8) confirmed the diagnosis. Our findings in this case indicate that patients with FD may start with renal symptoms alone, which were full blown nephrotic syndrome, hypertension and moderate renal failure.

[Multiple familial polyposis. Report of 4 cases and association with mucinous adenocarcinoma of the colon]

Four cases of familial polyposis coli (FPC), seen at Dr. Manuel Gea González General Hospital from 1985 to 1987, are presented. Three females and one male, with ages ranging between 23 and 52 years, are presented. The clinical picture included bloody feces, polyp prolapse, and a maxillary osteoma. In 3 cases the correct preoperative diagnosis was made by rectosigmoidoscopy, biopsy and barium enema. In one patient, urgently operated on, the diagnosis was postoperatively made by colonoscopy. The adenocarcinoma of the colon appeared associated with FPC in three cases (one of the mucinous variety). One total coloproctectomy and two abdominal colectomies with ileorectal anastomosis were performed. One patient operated on because of bowel obstruction was treated by right hemicolectomy. This case developed abdominal carcinomatosis afterwards. One woman died; another one was lost during follow-up, and the other one had no complications. The association of FPC and mucinous adenocarcinoma of the colon is reported for the first time.