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Microbes & Immunity RANTES/CCL5 and ezrin peptide RepG3 for long COVID

Experiments using inactive-mutant-constructs of EBP50 specific binding site on the ezrin-alpha domain. The
demonstrated that the PDZ-1, PDZ-2, and ezrin-binding FERM domain of ezrin also competes with TIRAP for the
EB domains of EBP50 are all necessary for IKK and NF-κB PIP2-rich submembrane anchorage adjacent to the TLR4
activation and proinflammatory cytokine expression: receptor. Termination of EBP50+PKC+TIRAP signaling
NF-κB activation is suppressed in null-EBP50 VSMC and to p38 MAPK completely shuts off proinflammatory
null-EBP50 macrophages. cytokine expression (Figure 8).
The dominant EBP50 regulation of NF-κB activity has 7. Conclusion
important consequences in different inflammatory states.
LPS-triggering of IL-1β and TNF-α expression in null- The similarity of the immune amplification activity of
EBP50 macrophages was significantly decreased relative to RANTES/CCL5 and ezrin peptides HEP1 and RepG3
wild-type macrophages with normal EBP50. In addition, suggests that ezrin peptides induce RANTES/CCL5
expression of classical M1-activation genes that are expression, which leads to effective T-cell help and
induced by proinflammatory cytokines IL-1β and TNF-α immunity against a wide range of viral, bacterial, fungal,
is also substantially decreased in null-EBP50 macrophages. and protozoan infections. Ezrin peptide RepG3, a
14-amino acid fully synthetic peptide (amino acid sequence
To stimulate NF-κB activity, EBP50 must be bound GEKKRRETVEREGG), has a unique combination of
to PKC on the membrane subsurface. In the cytoplasm, biological activities:
the newly produced EBP50 couples its PDZ-2 domain (i). Amplification of adaptive B-cell and T-cell responses
to the C-terminal PDZ-binding motif on PKC to form a to foreign antigens;
binary protein complex, which, then, migrates to the inner (ii). Amplification of NK activity to tumor-related
surface of the cell membrane. The PDZ-1 binding domain antigens;
of EBP50 then connects to the cytoplasmic tail of CFTR to (iii). Inhibition of expression of proinflammatory
form CFTR+EBP50+PKC. The PKC in the complex then cytokines (IL-1β, IL-6, IL-8, IL-13, and TNF-α) and
associates with TIRAP, which is bound to the cytoplasmic proinflammatory chemokines (MIP-1α and MIP-1β);
tail of TLR4. (iv). Activation of fibroblasts leads to the induction of
In null-EBP50 VSMC, LPS-triggered TLR4 fails tissue repair.
to activate NF-κB because PKC is not located on the Clinical trials in Russia from 2001 on ezrin peptide
membrane subsurface. Overexpression of wild-type PKC HEP1 (amino acid sequence TEKKRRETVEREKE)
cannot rescue proinflammatory signaling in these null- demonstrated that ezrin peptides induce immune
EBP50 VSMC cells because normal PKC does not migrate amplification, resulting in effective treatment for most
to the cell membrane in the absence of EBP50. However, of the infections that are controlled by RANTES/CCL5:
NF-κB-mediated proinflammatory cytokine expression SARS-CoV-2, HIV, HCV, HBV, RSV, Influenza A, HSV1,
can be rescued by adding myristoylated-PKC, which can HSV2, HPV, C. trachomatis, TV, and C. albicans. 83
translocate to the cell membrane independently. The observation of an increase in serum levels of
When cell surface TLR4 is triggered by LPS or spike, RANTES/CCL5 in volunteer patient G in response to
the CFTR+EBP50+TIRAP+PKC multi-protein complex ezrin peptide RepG3 therapy, together with the similar
phosphorylates and activates p38 MAPK, which, in turn, effects of ezrin peptides such as RepG3 and RANTES/
phosphorylates and activates IKK to phosphorylate the CCL5, suggests that ezrin peptides activate ezrin multi-
IκB-inhibitor in p65+IkB+p50 multi-protein complexes. protein complexes, resulting in upregulation of RANTES/
This results in the rapid ejection of phospho-IκB and CCL5 expression. Both RANTES/CCL5 and ezrin peptides
liberation of p65 and p50, which, then, migrate to the enhance programmed adaptive immunity against a
nucleus, bind to proinflammatory gene promoters, and broad spectrum of viral, bacterial, and fungal infections.
form transcription factor NF-κB, which, then, transcribes RANTES/CCL5 and ezrin peptides both reduce viral load
proinflammatory cytokine genes into mRNAs. in HCV infection. 84
Activated ezrin forces its FERM domain into the RANTES/CCL5 and ezrin peptides both amplify T-cell
CFTR+EBP50+TIRAP+PKC multi-protein complex activity and enhance CTL responses. RANTES/CCL5 and
and breaks up the protein connections, resulting in a ezrin peptides both amplify B-cell activity and increase
shutdown of proinflammatory signaling. The FERM protective antibody titers in mice. In addition, ezrin
domain of activated ezrin binds to the carboxy-terminal peptides significantly increased protective antibody titers
ezrin-binding (EB) site of EPB50, breaking the EBP50 against opportunistic infections in HIV-AIDS patients.
85
association with PKC. Ezrin also restrains PKC at a RANTES/CCL5 and ezrin peptides both amplify B-cell

Volume 1 Issue 1 (2024) 17 doi: 10.36922/mi.2474